2024年, 令和6年度北海道科学技術奨励賞　　　　　　　　　　　　　　　
白崎伸隆

2024年, 第61回環境工学研究フォーラム 環境技術・プロジェクト賞　　　　　　　　　　　　　　　
白崎伸隆;浅川高志;福井健暉;松下拓

2024年, 2024堀場雅夫賞　　　　　　　　　　　　　　　
白崎伸隆

2024年, 令和5年度日本水環境学会 論文賞　　　　　　　　　　　　　　　
白崎伸隆

2023年, 第60回環境工学研究フォーラム 優秀ポスター発表賞　　　　　　　　　　　　　　　
白崎伸隆, 胡秋晗, 白川大樹, 高木弘隆, 岡智一郎, 松下拓, 松井佳彦

2023年, 第7回バイオインダストリー奨励賞　　　　　　　　　　　　　　　
白崎伸隆

2023年, 令和5年度河川財団奨励賞　　　　　　　　　　　　　　　
白崎伸隆

2021年, 北海道大学大学院工学研究院 若手教員奨励賞　　　　　　　　　　　　　　　
白崎伸隆

2021年, 遠山椿吉記念 第7回食と環境の科学賞 山田和江賞　　　　　　　　　　　　　　　
白崎伸隆

2019年, 平成30年度建設工学研究振興会 建設工学研究奨励賞　　　　　　　　　　　　　　　
白崎伸隆

2017年, 平成29年度クリタ水・環境科学研究優秀賞　　　　　　　　　　　　　　　
白崎伸隆

2015年, 平成26年度日本水環境学会 論文奨励賞 (廣瀬賞)　　　　　　　　　　　　　　　
白崎伸隆

2013年, 土木学会平成25年度全国大会第68回年次学術講演会 優秀講演者表彰　　　　　　　　　　　　　　　
白崎伸隆

2013年, 第2回エヌエフ基金 研究開発奨励賞 (環境・エネルギー)　　　　　　　　　　　　　　　
白崎伸隆

2013年, 第49回環境工学研究フォーラム 論文賞　　　　　　　　　　　　　　　
白崎伸隆;松下拓;松井佳彦;大芝淳

2013年, 平成25年度前田記念工学振興財団 設立20周年記念特別論文賞 最優秀賞　　　　　　　　　　　　　　　
白崎伸隆

2012年, 平成24年度前田記念工学振興財団 山田一宇賞　　　　　　　　　　　　　　　
白崎伸隆, 日本国

2012年, 平成24年度文部科学大臣表彰 若手科学者賞　　　　　　　　　　　　　　　
白崎伸隆, 日本国

2011年, 平成22年度土木学会 論文奨励賞　　　　　　　　　　　　　　　
白崎伸隆, 日本国

2010年, 第46回環境工学研究フォーラム 論文奨励賞　　　　　　　　　　　　　　　
白崎伸隆, 日本国

2009年, 第12回日本水環境学会シンポジウム若手研究紹介（オルガノ）セッション 最優秀発表賞　　　　　　　　　　　　　　　
白崎伸隆, 日本国

2009年, 平成21年度日本水環境学会 博士研究奨励賞（オルガノ賞）　　　　　　　　　　　　　　　
白崎伸隆, 日本国

2008年, 第45回環境工学研究フォーラム 優秀ポスター発表賞　　　　　　　　　　　　　　　
白崎伸隆;浦崎稔史;小泓誠;松下拓;松井佳彦;大野浩一, 日本国

2005年, 平成16年度土木学会中部支部 優秀研究発表賞　　　　　　　　　　　　　　　
白崎伸隆

2005年, 岐阜大学工学部土木工学科 平成16年度優秀卒業研究賞　　　　　　　　　　　　　　　
白崎伸隆

2003年, 全国高等専門学校土木工学会 近藤賞　　　　　　　　　　　　　　　
白崎伸隆

Investigation of removal and inactivation efficiencies of human sapovirus in drinking water treatment processes by applying an in vitro cell-culture system
D. Shirakawa, N. Shirasaki, Q. Hu, T. Matsushita, Y. Matsui, H. Takagi, T. Oka
Water Research, 236, 2023年06月01日
研究論文（学術雑誌）, Here, we examined the efficiencies of drinking water treatment processes for the removal and inactivation of human sapovirus (HuSaV). We applied a recently developed in vitro cell-culture system to produce purified solutions of HuSaV containing virus concentrations high enough to conduct virus-spiking experiments, to develop an integrated cell culture-polymerase chain reaction (ICC-PCR) assay to quantify the infectivity of HuSaV, and to conduct virus-spiking experiments. In virus-spiking coagulation-sedimentation–rapid sand filtration (CS–RSF) and coagulation–microfiltration (C–MF) experiments, HuSaV removals of 1.6–3.7-log10 and 1.2–>4.3-log10, respectively, were observed. The removal ratios observed with CS–RSF were comparable and correlated with those of murine norovirus (MNV, a widely used surrogate for human noroviruses) and pepper mild mottle virus (PMMoV, a potential surrogate for human enteric viruses in physical and physicochemical drinking water treatment processes), and those observed with C–MF were higher than but still correlated with those of MNV and PMMoV, indicating that MNV and PMMoV are both potential surrogates for HuSaV in CS–RSF and C–MF. For astrovirus (AstV, a representative human enteric virus), removal ratios of 1.8–3.3-log10 and 1.1–>4.0-log10 were observed with CS–RSF and C–MF, respectively. The removal ratios of AstV observed with CS–RSF were comparable and correlated with those of PMMoV, and those observed with C–MF were higher than but still correlated with those of PMMoV, indicating that PMMoV is a potential surrogate for AstV in CS–RSF and C–MF. When the efficacy of chlorine treatment was examined by using the developed ICC-PCR assay, 3.8–4.0-log10 inactivation of HuSaV was observed at a CT value (free-chlorine concentration [C] multiplied by contact time [T]) of 0.02 mg-Cl2·min/L. The infectivity reduction ratios of HuSaV were comparable with those of MNV. For AstV, 1.3–1.7-log10 and >3.4-log10 inactivation, as evaluated by ICC-PCR, was observed at CT values of 0.02 and 0.09 mg-Cl2·min/L, respectively. These results indicate that HuSaV and AstV are both highly sensitive to chlorine treatment and more sensitive than a chlorine-resistant virus, coxsackievirus B5 (1.3-log10 inactivation at a CT value of 0.4 mg-Cl2·min/L, as evaluated by the ICC-PCR assay).

Overlooked effect of ordinary inorganic ions on polyaluminum-chloride coagulation treatment
Yize Chen, Yoshihiko Matsui, Tsutomu Sato, Nobutaka Shirasaki, Taku Matsushita
Water Research, 235, 2023年05月15日
研究論文（学術雑誌）, Application of poly-aluminum chloride (PACl) coagulant is a popular mode of water treatment worldwide because of the high capacity of PACl to neutralize charge. The manufacture and use of PACls with various basicities in different regions around the world suggest that the characteristics of the raw water are important determinants of the efficacy of PACl application. However, attention has not been fully paid to the effects of water quality other than the substances to be removed. In this study, two typical PACls with different basicities were used to investigate why the performance of PACls depends on the characteristics of the raw water. We focused on the concentrations of inorganic ions in the raw water. Use of high-basicity PACl (HB-PACl) with a high content of polymeric-colloidal species (Alb+Alc) resulted in very slow floc formation and little turbidity removal in raw water with low concentrations of sulfate ions. The performance of the HB-PACl was inferior to that of normal-basicity PACl (NB-PACl), although the charge-neutralization capacity of the HB-PACl was higher. Rates of floc formation were strongly correlated with the rate of aluminum precipitation by hydrolysis reaction, which was identified as an indicator for evaluating the compatibility of raw water with PACl treatment. Among the common ions in natural water, the sulfate ion had the greatest ability to hydrolyze and precipitate PACl because of its divalency and tetrahedral structure. This conclusion followed from experimental results showing similar effects for selenate and chromate ions as for sulfate ions and somewhat smaller effects for thiosulfate ions. Bicarbonate ions and natural organic matter affected PACl hydrolysis-precipitation, but chloride ions, nitrate ions, and cations had little effect on PACl hydrolysis-precipitation. Interestingly, the abilities of sulfate ions to hydrolyze HB-PACl and NB-PACl were very similar, but bicarbonate ions were less effective in hydrolyzing HB-PACl than NB-PACl, and bicarbonate ions contributed little to the hydrolysis-precipitation of HB-PACl in raw water with normal alkalinity. Therefore, sufficient coagulation with HB-PACl therefore usually requires a certain concentration of sulfate ions in water to be treated. The implication is that which anions are most influential to the hydrolysis-precipitation of PACl, and thus to PACl's coagulation ability depends on the constituents of the PACl.

Screening priority pesticides for drinking water quality regulation and monitoring by machine learning: Analysis of factors affecting detectability
Kentaro Narita, Yoshihiko Matsui, Taku Matsushita, Nobutaka Shirasaki
Journal of Environmental Management, 326, 2023年01月15日
研究論文（学術雑誌）, Proper selection of new contaminants to be regulated or monitored prior to implementation is an important issue for regulators and water supply utilities. Herein, we constructed and evaluated machine learning models for predicting the detectability (detection/non-detection) of pesticides in surface water as drinking water sources. Classification and regression models were constructed for Random Forest, XGBoost, and LightGBM, respectively; of these, the LightGBM classification model had the highest prediction accuracy. Furthermore, its prediction performance was superior in all aspects of Recall, Precision, and F-measure compared to the detectability index method, which is based on runoff models from previous studies. Regardless of the type of machine learning model, the number of annual measurements, sales quantity of pesticide for rice-paddy field, and water quality guideline values were the most important model features (explanatory variables). Analysis of the impact of the features suggested the presence of a threshold (or range), above which the detectability increased. In addition, if a feature (e.g., quantity of pesticide sales) acted to increase the likelihood of detection beyond a threshold value, other features also synergistically affected detectability. Proportion of false positives and negatives varied depending on the features used. The superiority of the machine learning models is their ability to represent nonlinear and complex relationships between features and pesticide detectability that cannot be represented by existing risk scoring methods.

Suppressing transmembrane-pressure rise by pulse dosing of submicron super-fine powdered activated carbon: Effects of filtration flux, coagulant types, and coagulant-dose timing during precoating
Yuanjun Zhao, Yoshihiko Matsui, Yusuke Kinouchi, Takumu Seko, Nobutaka Shirasaki, Taku Matsushita
Journal of Water Process Engineering, 49, 2022年10月, ［査読有り］
研究論文（学術雑誌）, Submicron-sized powdered activated carbon (SSPAC, diameter 200 nm) dosed in a pulse after coagulation pretreatment has recently been found to effectively mitigate membrane fouling and thus to suppress the rise of transmembrane pressure (TMP) in the microfiltration process because SSPAC has a higher capacity to adsorb membrane foulants, such as natural organic matter, than conventional PAC and a precoat layer formed by SSPAC on the membrane surface retards membrane fouling. This study investigated the effects of the filtration flux during precoating, the timing of coagulant dosing, and the types of coagulants on the suppression of TMP rise by pulse-dosed SSPAC. The TMP rise was insensitive to the filtration flux during precoating. However, the efficacy of the SSPAC was sensitive to the use of the coagulant polyaluminum-chloride (PACl). Unlike pulse dosing of SSPAC, pulse dosing of coagulant led to excessive aggregation and settling of SSPAC and insufficient formation of a precoating layer. The best filterability was achieved when the coagulant was dosed continuously in the entire operation period. It is also effective to use treated water for feeding during the preparation stage. For sulfated PACl, high basicity (70 %), with its high charge neutralization capacity, was preferred to medium basicity (50 %). Meanwhile, the TMP rise was more effectively suppressed by non-sulfated PACl with a low-to-medium basicity (20–40 %) than zero or high basicity (70 %). This behavior was explained by the fact that, as the basicity increases, hydrolysis of the coagulants is lessened, but the charge neutralization effect becomes stronger.

Factors affecting the catalytic oxidative removal of soluble manganese in natural water by superfine powdered activated carbon and free chlorine
Shun Saito, Yoshihiko Matsui, Nobutaka Shirasaki, Taku Matsushita
Journal of Water Process Engineering, 49, 2022年10月, ［査読有り］
研究論文（学術雑誌）, Catalytic oxidation of dissolved divalent Mn ion (Mn2+) by free chlorine and superfine powdered activated carbon (SPAC) before microfiltration has been emerged as a new technology to remove Mn from natural water for drinking water production. However, Mn was not sufficiently removed in pilot-plant experiments yet. The present study clarified underlaying removal mechanisms. In natural water, soluble Mn exists as colloidal Mn with a molecular weight ≥ 10,000 Da in the oxidized form in addition to Mn2+. Mn2+ was removed by SPAC‑chlorine, but Ca2+, Mg2+, and NOM decreased the Mn2+ removal rate as a result of competitive adsorption. The colloidal Mn was not removed by SPAC‑chlorine, but could be removed by coagulation and microfiltration or ultrafiltration alone. With the addition of coagulant (poly‑aluminum chloride), the soluble Mn concentration increased because of redissolution of precipitated-oxidized Mn due an increase in local acidity, in particular at low temperature, and coagulation reduced soluble Mn removal rate due to hindrance of mass transfer. These negative impacts may be partially attenuated by using high-intensity mixing or waiting to add the coagulant after the oxidation of Mn2+ has progressed sufficiently. Mn removal rate changed with temperature and mixing intensity in the same trend as predicted by the mass-transfer model, but it was smaller than the prediction. Together with the effects of Ca2+, Mg2+, and NOM, it appears that not only mass transfer but also the process of adsorption is a factor affecting the overall Mn removal rate.

Effectiveness of pulse dosing of submicron super-fine powdered activated carbon in preventing transmembrane pressure rise in outside-in-type tubular and inside-out-type monolithic ceramic membrane microfiltrations
Yuanjun Zhao, Yoshihiko Matsui, Shun Saito, Nobutaka Shirasaki, Taku Matsushita
Separation and Purification Technology, 296, 2022年09月01日, ［査読有り］
研究論文（学術雑誌）, Membrane fouling is still a major problem in water treatment that uses membrane separation. In this study, submicron-sized super-fine powdered activated carbon (SSPAC) was applied in a pulse/continuous dose to ceramic-membrane microfiltrations of two very different types: a submerged tubular membrane system that enabled vacuum-driven, outside-in filtration and a monolithic membrane system that enabled pressure-driven, inside-out filtration. Constant-flux filtration with repeated hydraulic backwashing was performed using diluted secondary-treated municipal wastewater and natural river water, and the effect and mechanism of membrane fouling mitigation were investigated. Pulse dosing with SSPAC alleviated a rise of transmembrane pressure (TMP) more than continuous dosing in the submerged tubular membrane system because of the effects, inter alia, associated with precoating the SSPAC layer as well as adsorption, by which soluble membrane foulants were effectively removed. Moreover, pulse-dosed SSPAC combined with a coagulant formed a precoat layer on the membrane that was easy to peel off with hydraulic backwashing. Continuous dosing of SSPAC was inferior to pulse dosing of SSPAC in terms of water quality, and some SSPAC was left on the membrane surface after hydraulic backwashing. In the monolithic membrane system, however, the superiority of pulse dosing of SSPAC was not observed: pulse and continuous dosing of SSPAC led to similar reductions of TMP rise. The SSPAC layer was unevenly distributed along the length of a channel and between channels in the monolithic membrane.

Removal of soluble divalent manganese by superfine powdered activated carbon and free chlorine: Development and application of a simple kinetic model of mass transfer–catalytic surface oxidation
Shun Saito, Yoshihiko Matsui, Nobutaka Shirasaki, Taku Matsushita
Water Research X, 16, 2022年08月01日, ［査読有り］
研究論文（学術雑誌）, Catalytic oxidative removal of Mn2+ on activated-carbon surfaces by free chlorine was recently discovered and found to be potentially practicable for water treatment when using micrometer-sized activated carbon. Herein, we newly derived a kinetic model for trace-substance removal by catalytic reaction and applied it to the Mn2+ removal. External-film mass transfer, adsorption, and oxidation/desorption contributed similarly to the Mn2+ removal rate under actual practical conditions. The low removal rate in natural water was attributed to decreases in available adsorption sites: e.g., a 50% decrease in available sites in water with 0.26 mmol-Ca2+/L caused a 15% reduction in removal rate. Low temperature greatly reduced the removal rate by both enhancing the decrease in available sites and hindering mass transfer through increased viscosity. While adsorption sites differed 8-fold between different carbon particles, causing a 2.2-fold difference in removal rates, carbon particle size was more influential, with a >10-fold difference between 2- and 30-μm sizes.

Evaluation of reduction efficiencies of pepper mild mottle virus and human enteric viruses in full-scale drinking water treatment plants employing coagulation-sedimentation–rapid sand filtration or coagulation–microfiltration
D. Shirakawa, N. Shirasaki, T. Matsushita, Y. Matsui, R. Yamashita, T. Matsumura, S. Koriki
Water Research, 213, 2022年04月, ［査読有り］
研究論文（学術雑誌）, Here, we evaluated the reduction efficiencies of indigenous pepper mild mottle virus (PMMoV, a potential surrogate for human enteric viruses to assess virus removal by coagulation-sedimentation–rapid sand filtration [CS–RSF] and coagulation–microfiltration [C–MF]) and representative human enteric viruses in four full-scale drinking water treatment plants that use CS–RSF (Plants A and B) or C–MF (Plants C and D). First, we developed a virus concentration method by using an electropositive filter and a tangential-flow ultrafiltration membrane to effectively concentrate and recover PMMoV from large volumes of water: the recovery rates of PMMoV were 100% when 100-L samples of PMMoV-spiked dechlorinated tap water were concentrated to 20 mL; even when spiked water volume was 2000 L, recovery rates of >30% were maintained. The concentrations of indigenous PMMoV in raw and treated water samples determined by using this method were always above the quantification limit of the real-time polymerase chain reaction assay. We therefore were able to determine its reduction ratios: 0.9–2.7-log10 in full-scale CS–RSF and 0.7–2.9-log10 in full-scale C–MF. The PMMoV reduction ratios in C–MF at Plant C (1.0 ± 0.3-log10) were lower than those in CS–RSF at Plants A (1.7 ± 0.5-log10) and B (1.4 ± 0.7-log10), despite the higher ability of MF for particle separation in comparison with RSF owing to the small pore size in MF. Lab-scale virus-spiking C–MF experiments that mimicked full-scale C–MF revealed that a low dosage of coagulant (polyaluminum chloride [PACl]) applied in C–MF, which is determined mainly from the viewpoint of preventing membrane fouling, probably led to the low reduction ratios of PMMoV in C–MF. This implies that high virus reduction ratios (>4-log10) achieved in previous lab-scale virus-spiking C–MF studies are not necessarily achieved in full-scale C–MF. The PMMoV reduction ratios in C–MF at Plant D (2.2 ± 0.6-log10) were higher than those at Plant C, despite similar coagulant dosages. In lab-scale C–MF, the PMMoV reduction ratios increased from 1-log10 (with PACl [basicity 1.5], as at Plant C) to 2–4-log10 (with high-basicity PACl [basicity 2.1], as at Plant D), suggesting that the use of high-basicity PACl probably resulted in higher reduction ratios of PMMoV at Plant D than at Plant C. Finally, we compared the reduction ratios of indigenous PMMoV and representative human enteric viruses in full-scale CS–RSF and C–MF. At Plant D, the concentrations of human norovirus genogroup II (HuNoV GII) in raw water were sometimes above the quantification limit; however, whether its reduction ratios in C–MF were higher than those of PMMoV could not be judged since reduction ratios were >1.4-log10 for HuNoV GII and 2.3–2.9-log10 for PMMoV. At Plant B, the concentrations of enteroviruses (EVs) and HuNoV GII in raw water were above the quantification limit on one occasion, and the reduction ratios of EVs (>1.2-log10) and HuNoV GII (>1.5-log10) in CS–RSF were higher than that of PMMoV (0.9-log10). This finding supports the usefulness of PMMoV as a potential surrogate for human enteric viruses to assess virus removal by CS–RSF.

Desorption of micropollutant from superfine and normal powdered activated carbon in submerged-membrane system due to influent concentration change in the presence of natural organic matter: Experiments and two-component branched-pore kinetic model
Long Pan, Akiko Nakayama, Yoshihiko Matsui, Taku Matsushita, Nobutaka Shirasaki
Water Research, 208, 2022年01月01日, ［査読有り］
研究論文（学術雑誌）, Submerged-membrane hybrid systems (SMHSs) that combine membrane filtration with powdered activated carbon (PAC) take advantage of PAC's ability to adsorb and remove contaminants dissolved in water. However, the risk of contaminant desorption due to temporal changes in the influent concentration of the contaminant has not been thoroughly explored. In this study, we used a SMHS with conventionally-sized PAC or superfine PAC (SPAC) to remove 2-methylisoborneol (MIB), a representative micropollutant, from water containing natural organic matter (NOM), with the goal of elucidating adsorption–desorption phenomena in the SMHS. We found that 20–40% of the MIB that adsorbed on PAC and SPAC while the influent was contaminated with MIB (6 h, contamination period) desorbed to the liquid phase within 6 h from the time that the MIB-containing influent was replaced by MIB-free influent (no-contamination period). The percentage of desorption during the no-contamination period increased with increasing MIB breakthrough concentration during the contamination period. These findings indicate that the PAC/SPAC in the SMHS should be replaced while the breakthrough concentration is low, not only to keep a high removal rate but also to decrease the desorption risk. SPAC is fast in removal by adsorption, but it is also fast in release by desorption. SPAC (median diameter: 0.94 µm) showed almost the same adsorption-desorption kinetics as PAC (12.1 µm) of a double dose. A two-component branched-pore diffusion model combined with an IAST (ideal adsorbed solution theory)–Freundlich isotherm was used to describe and analyze the adsorption–desorption of MIB. The diffusivity of MIB molecules in the pores of the activated carbon particles decreased markedly in a short period of time. This decrease, which was attributed to fouling of the activated carbon in the SMHS by coagulant-treated water containing NOM, not only reduced the rate of MIB removal during the contamination period but also hindered the rate of MIB desorption during the no-contamination period and thus prevented the effluent MIB concentration from becoming high. On the other hand, coagulation did not change the concentration of NOM that competes with MIB for adsorption sites.

Metabolism-Coupled Cell-Independent Acetylcholinesterase Activity Assay for Evaluation of the Effects of Chlorination on Diazinon Toxicity
Taku Matsushita, Yuji Kikkawa, Kei Omori, Yoshihiko Matsui, Nobutaka Shirasaki
Chemical Research in Toxicology, 34, 9, 2070, 2078, 2021年09月20日, ［査読有り］
研究論文（学術雑誌）, Drinking water quality guideline values for toxic compounds are determined based on their acceptable daily intake. The toxicological end point for determining the acceptable daily intake of most organophosphorus insecticides is inhibition of acetylcholinesterase (AChE). Although insecticides ingested with drinking water are partly metabolized by the liver before transport to the rest of the body, no current cell-independent AChE activity assay takes the effects of metabolism into account. Here, we incorporated metabolism into a cell-independent AChE activity assay and then evaluated the change in anti-AChE activity during chlorination of a solution containing the organophosphorus insecticide diazinon. The anti-AChE activities of solutions of diazinon or diazinon-oxon, the major transformation product of diazinon during chlorination, were dramatically changed by metabolism: the activity of diazinon solution was markedly increased, whereas that of diazinon-oxon solution was slightly decreased, clearly indicating the importance of incorporating metabolism into assays examining toxicity after oral ingestion. Upon chlorination, diazinon was completely transformed, in part to diazinon-oxon. Although diazinon solution without metabolism did not show anti-AChE activity before chlorination, it did after chlorination. In contrast, with metabolism, diazinon solution did show anti-AChE activity before chlorination, but chlorination gradually decreased this activity over time. The observed anti-AChE activities were attributable solely to diazinon and diazinon-oxon having been contained in the samples before metabolism, clearly suggesting that the presence not only of diazinon but also of diazinon-oxon should be monitored in drinking water. Further examination using a combination of tandem mass spectrometry and in silico site-of-metabolism analyses revealed the structure of a single metabolite that was responsible for the observed anti-AChE activity after metabolism. However, because this compound is produced via metabolism in the human body after oral ingestion of diazinon, its presence in drinking water need not be monitored and regulated.

Differences in removal rates of virgin/decayed microplastics, viruses, activated carbon, and kaolin/montmorillonite clay particles by coagulation, flocculation, sedimentation, and rapid sand filtration during water treatment
Yoshifumi Nakazawa, Taketo Abe, Yoshihiko Matsui, Koki Shinno, Sakiko Kobayashi, Nobutaka Shirasaki, Taku Matsushita
Water Research, 203, 2021年09月15日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, One of the main purposes of drinking water treatment is to reduce turbidity originating from clay particles. Relatively little is known about the removal of other types of particles, including conventionally sized powdered activated carbon (PAC) and superfine PAC (SPAC), which are intentionally added during the treatment process; microplastic particles; and viruses. To address this knowledge gap, we conducted a preliminary investigation in full-scale water treatment plants and then studied the removal of these particles during coagulation-flocculation, sedimentation, and rapid sand filtration (CSF) in bench-scale experiments in which these particles were present together. Numbers of all target particles were greatly decreased by coagulation-flocculation and sedimentation (CS). Subsequent rapid sand filtration greatly reduced the concentrations of PAC and SPAC but not the concentrations of viruses, microplastic particles, and clay particles. Overall removal rates by CSF were 4.6 logs for PAC and SPAC, 3.5 logs for viruses, 2.9 logs for microplastics, and 2.8 logs for clay. The differences in removals were not explained by particle sizes or zeta potentials. However, for clays, PAC and SPAC, for which the particle size distributions were wide, smaller particles were less efficiently removed. The ratios of both clay to PAC and clay to SPAC particles increased greatly after rapid sand filtration because removal rates of PAC and SPAC particles were about 2 logs higher than removal rates of clay particles. The trend of greater reduction of PAC concentrations than turbidity was confirmed by measurements made in 14 full-scale water purification plants in which residual concentrations of PAC in treated water were very low, 40–200 particles/mL. Clay particles therefore accounted for most of the turbidity in sand filtrate, even though PAC was employed. The removal rate of microplastic particles was comparable to that of clays. Sufficient turbidity removal would therefore provide comparable removal of microplastics. We investigated the effect of mechanical/photochemical weathering on the removal of microplastics via CSF. Photochemical weathering caused a small increment in the removal rate of microplastics during CS but a small reduction in the removal rate of microplastics during rapid sand filtration; mechanical weathering decreased the removal rate via CS but increased the removal rate via rapid sand filtration. The changes of removal of microplastics might have been caused by changes of their zeta potential.

Corrigendum to ’Oxidative removal of soluble divalent manganese ion by chlorine in the presence of superfine powdered activated carbon’ [Water Research 187 (2020) 116412] (Water Research (2020) 187, (S0043135420309477), (10.1016/j.watres.2020.116412))
Shun Saito, Yoshihiko Matsui, Yasuhiko Yamamoto, Shuhei Matsushita, Satoru Mima, Nobutaka Shirasaki, Taku Matsushita
Water Research, 202, 2021年09月01日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, The authors regret that an error has occurred in this paper. On the pilot plant system described in section 2.2.1, “the hydraulic retention time for the coagulation in the pipe mixing of Line B was 3 min” should be changed to “the hydraulic retention time for the coagulation in the pipe mixing of Line B was 4.4 min”. Because of the error, several corrections noted below should be conducted. In abstract, section 3.1, and conclusion (1), SPAC and chlorine contact time of 4 min is replaced by 5.4 min. In Panel A of Fig. 8, the yellow plots of the pilot experiment (Run 1), to be exact their y-axis positions, are somewhat changed. The corrected figure is presented here. In section 3.4, “The kC values of the pilot experiment were higher than those of the batch experiments” is changed to “The kC values of the pilot experiment were similar to those of the batch experiments". The authors would like to apologise for any inconvenience caused. DOI of original article: < https://doi.org/10.1016/j.watres.2020.116412 >

Computational fluid dynamics–based modeling and optimization of flow rate and radiant exitance for 1,4-dioxane degradation in a vacuum ultraviolet photoreactor
Gang Shi, Shota Nishizawa, Taku Matsushita, Yuna Kato, Takahiro Kozumi, Yoshihiko Matsui, Nobutaka Shirasaki
Water Research, 197, 2021年06月01日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, 1,4-Dioxane is one of the most persistent organic micropollutants in conventional drinking-water-treatment processes. Vacuum ultraviolet (VUV) treatment is a promising means of removing micropollutants such as 1,4-dioxane from source water, but this approach has not yet been implemented in a full-scale water treatment plant, partly because the operating parameters for pilot and full-scale VUV photoreactors have not been optimized. Here, we developed a computational fluid dynamics–based method for optimizing VUV photoreactor performance through energy-based analyses that take into account the effects of two important operating parameters—flow rate and radiant exitance. First, we constructed a computational fluid dynamics model and determined the sole parameter required for the model, the pseudo-first-order rate constant for the reaction of 1,4-dioxane, by simple batch experiment. Then, we validated the model by using a pilot-scale flow-through annular photoreactor. Finally, we used the validated model to examine the effects of flow rate and radiant exitance on the efficiency of 1,4-dioxane degradation in a virtual annular photoreactor. Radiation efficiency, which was defined as the ratio of the logarithmic residual ratio of 1,4-dioxane to the theoretical minimum logarithmic residual ratio (best possible performance) under the given operating conditions, was calculated as an energy-based index of cost-effectiveness. Radiation efficiency was found to increase with increasing flow rate but decreasing radiant exitance. An electrical energy per order (EEO) analysis suggested that VUV treatment under laminar flow was most economical when low-power lamps and a high flow rate were used. In contrast, VUV treatment under turbulent flow was suggested to be most economical when high-power lamps were used at a high flow rate.

Stray particles as the source of residuals in sand filtrate: Behavior of superfine powdered activated carbon particles in water treatment processes
Yoshifumi Nakazawa, Taketo Abe, Yoshihiko Matsui, Nobutaka Shirasaki, Taku Matsushita
Water Research, 190, 2021年02月15日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2020 Although superfine powdered activated carbon has excellent adsorption properties, it is not used in conventional water treatment processes comprising coagulation–flocculation, sedimentation, and sand filtration (CSF) due to concerns about its residual in treated water. Here, we examined the production and fate of very fine carbon particles with lacking in charge neutralization as a source of the residual in sand filtrate after CSF treatment. Almost all of the carbon particles in the water were charge-neutralized by coagulation treatment with rapid mixing, but a very small amount (≤0.4% of the initial concentration) of very fine carbon particles with a lesser degree of charge neutralization were left behind in coagulation process. Such carbon particles, defined as stray carbon particles, were hardly removed by subsequent flocculation and sedimentation processes, and some of them remained in the sand filtrate. The concentration of residual carbon particles in the sand filtrate varied similarly with that of the stray carbon particles. The stray and residual carbon particles were similarly smaller than the particles before coagulation treatment, but the residual carbon particles had less charge neutralization than the stray carbon particles. The turbidity of water samples collected after sedimentation was not correlated with the residual carbon concentration in the sand filtrate, even though it is often used as an indicator of treatment performance with respect to the removal of suspended matter. Based on these findings, we suggest that reduction of the amount of stray particles should be a performance goal of the CSF treatment. Examining this concept further, we confirmed that the residence time distributions in the coagulation and flocculation reactors influenced the concentration of stray carbon particles and then the residual carbon particle concentration in sand filtrate, but found that the effect was dependent on coagulant type. A multi-chambered-reactor configuration lowered both the stray carbon particle concentration after coagulation treatment and the residual carbon particle concentration in sand filtrate compared with a single-chambered reactor configuration. When a normal basicity PACl that consisted mainly of monomeric Al species was used, the stray carbon particle concentration was decreased during coagulation process and then gradually decreased during subsequent flocculation process because the monomeric Al species were transformed to colloidal Al species via polymeric Al species. In contrast, when a high-basicity PACl that consisted mostly of colloidal Al species was used, coagulation treatment largely decreased the stray carbon particle concentration, which did not decrease further during subsequent flocculation process. These findings will be valuable for controlling residual carbon particles after the CSF treatment.

Selection of priority pesticides in Japanese drinking water quality regulation: Validity, limitations, and evolution of a risk prediction method
Kentaro Narita, Yoshihiko Matsui, Taku Matsushita, Nobutaka Shirasaki
Science of the Total Environment, 751, 2021年01月10日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2020 Elsevier B.V. Several risk scoring and ranking methods have been applied for the prioritization of micropollutants, including pesticides, and in the selection of pesticides to be regulated regionally and nationally. However, the effectiveness of these methods has not been evaluated in Japan. We developed a risk prediction method to select pesticides that have a high probability of being detected in drinking water sources where no monitoring data is available. The risk prediction method was used to select new pesticides for the 2013 Primary List in the Japanese Drinking Water Quality Guidelines. Here, we examined the effectiveness of the method on the basis of the results of water quality examinations conducted by water supply authorities across Japan, and studied ways to improve the risk prediction method. Of the 120 pesticides in the 2013 Primary List, 80 were detected in drinking water sources (raw water entering water treatment plants). The rates of detection of the newly selected pesticides and previously listed pesticides were not significantly different: 64% and 68%, respectively. When the risk predictor was revised to incorporate degradability of dry-field pesticides and current pesticide sales data, the rate of detection of pesticides selected as having a high risk of detection improved from 72% to 88%. We prepared regional versions of the Primary List using the revised risk predictors and verified their utility. The number of listed pesticides varied greatly by region, ranging from 32 to 73; all regional lists were much shorter than the national Primary List. In addition, 55% to 100% of the pesticides detected in each region were included in a Regional Primary List. This work verifies the ability of the risk prediction method to screen pesticides and select those with a high risk of detection.

Oxidative removal of soluble divalent manganese ion by chlorine in the presence of superfine powdered activated carbon
Shun Saito, Yoshihiko Matsui, Yasuhiko Yamamoto, Shuhei Matsushita, Satoru Mima, Nobutaka Shirasaki, Taku Matsushita
Water Research, 187, 2020年12月15日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2020 Elsevier Ltd Here, we examined the removal of soluble divalent manganese (Mn(II)) by combination treatment with superfine powdered activated carbon (SPAC) and free chlorine in a membrane filtration pilot plant and batch experiments. Removal rates >95% were obtained with 3 mg/L SPAC, 1 mg/L chlorine, and a contact time of 4 min, meeting practical performance standards. Mn(II) was found to be oxidized and precipitated on the surface of the activated carbon particles by chlorine. The Mn(II) removal rate was fitted to pseudo-first-order reaction kinetics, and the rate coefficient changed in inverse proportion to as-is particle size, but not to true particle size. The rate coefficient was independent of both Mn(II) concentration, except at high Mn(II) concentration, and the chlorine concentrations tested. The rate-determining step of Mn(II) removal was confirmed to be external-film mass transfer, not chemical oxidation. Activated carbon was found to have a catalytic effect on the oxidation of Mn(II), but the effect was minimal for conventionally sized activated carbon. However, Mn(II) removal at feasible rates for practical application can be expected when the activated carbon particle diameter is reduced to several micrometers. Activated carbon with a particle size of around 1–2 μm may be the most appropriate for Mn(II) removal because particles below this size were aggregated, resulting in reduced removal efficiency.

Effect of chlorination on anti-acetylcholinesterase activity of organophosphorus insecticide solutions and contributions of the parent insecticides and their oxons to the activity
Taku Matsushita, Yuki Fujita, Kei Omori, Yuxiang Huang, Yoshihiko Matsui, Nobutaka Shirasaki
Chemosphere, 261, 2020年12月, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2020 Elsevier Ltd Organophosphorus insecticides are known to be partly transformed to their respective oxons during the chlorination step of drinking water treatment. For most organophosphorus insecticides, the toxicological endpoint for determining acceptable daily intake levels is inhibition of acetylcholinesterase (AChE). Like the parent insecticides, oxons also inhibit AChE, so the presence of oxons in drinking water is also evaluated. However, no attention is paid to the possible presence of transformation products (TPs) other than oxons. In the present study, we determined whether the anti-AChE activity observed for chlorinated solutions of the organophosphorus insecticides malathion and methidathion could be solely attributed to the parent compounds and their oxons. Upon chlorination, both malathion and methidathion were immediately transformed to their oxons; the maximum transformation ratios were 60% and 30%, respectively, indicating that at least 40% and 70% of these compounds were transformed into other TPs. Before chlorination, malathion- and methidathion-containing solutions exhibited little to no anti-AChE activity, but the solutions showed strong activity after chlorination. The contributions of the parent insecticides and their oxons to the activities of the chlorinated samples were calculated from the concentrations of the compounds in the samples and dose–response curves for chemical standards of the compounds. For both the malathion-containing solution and the methidathion-containing solution, the calculated anti-AChE activities were almost the same as the observed activities at every chlorination time. This suggests that the observed activities could be attributed solely to the parent insecticides and their oxons, indicating that other TPs need not be considered.

Suitability of pepper mild mottle virus as a human enteric virus surrogate for assessing the efficacy of thermal or free-chlorine disinfection processes by using infectivity assays and enhanced viability PCR
N. Shirasaki, T. Matsushita, Y. Matsui, S. Koriki
Water Research, 186, 2020年11月01日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2020 Elsevier Ltd Evaluating the efficacy of disinfection processes to inactivate human enteric viruses is important for the prevention and control of waterborne diseases caused by exposure to those viruses via drinking water. Here, we evaluated the inactivation of two representative human enteric viruses (adenovirus type 40 [AdV] and coxsackievirus B5 [CV]) by thermal or free-chlorine disinfection. In addition, we compared the infectivity reduction ratio of a plant virus (pepper mild mottle virus [PMMoV], a recently proposed novel surrogate for human enteric viruses for the assessment of virus removal by coagulation‒rapid sand filtration and membrane filtration) with that of the two human enteric viruses to assess the suitability of PMMoV as a human enteric virus surrogate for use in thermal and free-chlorine disinfection processes. Finally, we examined whether conventional or enhanced viability polymerase chain reaction (PCR) analysis using propidium monoazide (PMA) or improved PMA (PMAxx) with or without an enhancer could be used as alternatives to infectivity assays (i.e., plaque-forming unit method for AdV and CV; local lesion count assay for PMMoV) for evaluating virus inactivation by disinfection processes. We found that PMMoV was more resistant to heat treatment than AdV and CV, suggesting that PMMoV is a potential surrogate for these two enteric viruses with regard to thermal disinfection processes. However, PMMoV was much more resistant to chlorine treatment compared with AdV and CV (which is chlorine-resistant) (CT value for 4-log10 inactivation: PMMoV, 84.5 mg-Cl2·min/L; CV, 1.15–1.19 mg-Cl2·min/L), suggesting that PMMoV is not useful as a surrogate for these enteric viruses with regard to free-chlorine disinfection processes. For thermal disinfection, the magnitude of the signal reduction observed with PMAxx-Enhancer-PCR was comparable with the magnitude of reduction in infectivity, indicating that PMAxx-Enhancer-PCR is a potential alternative to infectivity assay. However, for free-chlorine disinfection, the magnitude of the signal reduction observed with PMAxx-Enhancer-PCR was smaller than the magnitude of the reduction in infectivity, indicating that PMAxx-Enhancer-PCR underestimated the efficacy of virus inactivation (i.e., overestimated the infectious virus concentration) by chlorine treatment. Nevertheless, among the PCR approaches examined in the present study (PCR alone, PMA-PCR or PMAxx-PCR either with or without enhancer), PMAxx-Enhancer-PCR provided the most accurate assessment of the efficacy of virus inactivation by thermal or free chlorine disinfection processes.

Formation of disinfection by-products from coexisting organic matter during vacuum ultraviolet (VUV) or ultraviolet (UV) treatment following pre-chlorination and their fates after post-chlorination
Shota Nishizawa, Taku Matsushita, Yoshihiko Matsui, Nobutaka Shirasaki
Science of the Total Environment, 737, 2020年10月01日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2020 Elsevier B.V. Vacuum ultraviolet (VUV) treatment is a promising advanced oxidation process for the removal of organic contaminants during water treatment. Here, we investigated the formation of disinfection by-products from coexisting organic matter during VUV or ultraviolet (UV) treatment following pre-chlorination, and their fates after post-chlorination, in a standard Suwannee River humic acid water and a natural lake water. VUV treatment after pre-chlorination decreased the total trihalomethane (THM) concentration but increased total aldehyde and chloral hydrate concentrations; total haloacetic acid (HAA) and haloacetonitrile (HAN) concentrations did not change. UV treatment after pre-chlorination produced similar changes in the by-products as those observed for VUV treatment, with the exception that the total THM concentration was not changed, and the total HAN concentration was increased. The final concentrations of by-products after post-chlorination were increased by VUV or UV treatment, except for the total HAA concentration, which remained unchanged after UV treatment. The increases were greater after VUV treatment than after UV treatment, probably because the larger amount of hydroxyl radicals generated during VUV treatment compared with during UV treatment transformed coexisting organic matter into precursors of by-products that were then converted to by-products during post-chlorination.

Sulfate ion in raw water affects performance of high-basicity PACl coagulants produced by Al(OH)3 dissolution and base-titration: Removal of SPAC particles by coagulation-flocculation, sedimentation, and sand filtration
Yize Chen, Yoshifumi Nakazawa, Yoshihiko Matsui, Nobutaka Shirasaki, Taku Matsushita
Water Research, 183, 2020年09月15日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2020 Elsevier Ltd Many PACl (poly-aluminum chloride) coagulants with different characteristics have been trial-produced in laboratories and commercially produced, but the selection of a proper PACl still requires empirical information and field testing. Even PACls with the same property sometimes show different coagulation performances. In this study, we compared PACls produced by AlCl3-titration and Al(OH)3-dissolution on their performance during coagulation-flocculation, sedimentation, and sand filtration (CSF) processes. The removal targets were particles of superfine powdered activated carbon (SPAC), which are used for efficient adsorptive removal of micropollutants, but strict removal of SPAC is required because of the high risk of their leakage after CSF. PACls of high-basicity produced by AlCl3-titration and Al(OH)3-dissolution were the same in terms of the ferron assay and colloid charge, but their performance in CSF were completely different. High-basicity Al(OH)3-dissolution PACls formed large floc particles and yielded very few remaining SPAC particles in the filtrate, whereas high-basicity AlCl3-titration PACls did not form large floc particles. High-basicity PACls produced by Al(OH)3-dissolution were superior to low-basicity PACl in lowering remaining SPAC particles by the same method because of their high charge neutralization capacity, although their floc formation ability was similar or slightly inferior. However, high-basicity Al(OH)3-dissolution PACl was inferior when the sulfate ion concentration in the raw water was low. Sulfate ions were required in the raw water for high-basicity PACls to be effective in floc formation. In particular, very high sulfate concentrations were required for high-basicity AlCl3-titration PACls. The rate of hydrolysis, which is related to the polymerization of aluminum species, is a key property, besides charge neutralization capacity, for proper coagulation, including formation of large floc particles. The aluminum species in the high-basicity PACls, in particular that produced by AlCl3-titration, was resistant to hydrolysis, but sulfate ions in raw water accelerated the rate of hydrolysis and thereby facilitated floc formation. Normal-basicity Al(OH)3-dissolution PACl was hydrolysis-prone, even without sulfate ions. Aluminum species in the high-basicity AlCl3-titration PACl were mostly those with a molecular weight (MW) of 1–10 kDa, whereas those of high-basicity Al(OH)3-dissolution PACls were mostly characterized by a MW > 10 kDa. Normal-basicity Al(OH)3-dissolution PACl was the least polymerized and contained monomeric species.

Effects of pre, post, and simultaneous loading of natural organic matter on 2-methylisoborneol adsorption on superfine powdered activated carbon: Reversibility and external pore-blocking
Akiko Nakayama, Asuka Sakamoto, Taku Matsushita, Yoshihiko Matsui, Nobutaka Shirasaki
Water Research, 182, 2020年09月01日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2020 Elsevier Ltd Three different natural organic matter (NOM)-loading methods were compared for the adsorptive removal of 2-methylisoborneol (MIB) by superfine powdered activated carbon (SPAC) and conventionally-sized powdered activated carbon (PAC). The three NOM-loading methods were: NOM adsorption followed by MIB (MIB adsorption on NOM-preloaded carbon), MIB adsorption followed by NOM (MIB adsorption on NOM post-loaded carbon), and simultaneous NOM and MIB loading (MIB adsorption on NOM-simultaneously loaded carbon). MIB removals were similar for the smaller-sized carbon (SPAC) at higher AC dosages and at lower initial NOM concentrations. The similar MIB removals indicate direct site competition between MIB and NOM with MIB adsorption reversibility (complete desorption of MIB by NOM). At lower AC doses, especially for PACs, and at higher initial NOM concentrations, the adsorption of MIBs depended on the sequence of MIB or NOM adsorption. MIB removal was lowest for the NOM-preloaded carbon, followed by NOM-simultaneously loaded carbon. The highest MIB removal was achieved by post-loading of NOM, indicating that the adsorption is irreversible. MIB adsorption on SPAC was more reversible than on PAC, although the pore size distributions of the two carbons were similar. The high degree of adsorption irreversibility for PAC compared with SPAC indicated that pore blocking occurs due to NOM loading at the PAC particle surface. Images of the external adsorption were obtained using isotope mapping and 15N-labeled effluent organic matter.

Precoating membranes with submicron super-fine powdered activated carbon after coagulation prevents transmembrane pressure rise: Straining and high adsorption capacity effects
Yuanjun Zhao, Ryosuke Kitajima, Nobutaka Shirasaki, Yoshihiko Matsui, Taku Matsushita
Water Research, 177, 2020年06月15日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2020 Elsevier Ltd Commercially available powdered activated carbon (PAC) with a median diameter of 12–42 μm was ground into 1 μm sized superfine PAC (SPAC) and 200 nm sized submicron SPAC (SSPAC) and investigated as a pretreatment material for the prevention of hydraulically irreversible membrane fouling during a submerged microfiltration (MF) process. Compared with PAC and SPAC, SSPAC has a high capacity for selective biopolymer adsorption, which is a characteristic found in natural organic matter and is commonly considered to be a major contributor to membrane fouling. Precoating the membrane surface with SSPAC during batch filtration further removes the biopolymers by straining them out. In lab-scale membrane filtration experiments, an increase in the transmembrane pressure (TMP) was almost completely prevented through a precoating with SSPAC based on its pulse dose after coagulation pretreatment. The precoated SSPAC formed a dense layer on the membrane preventing biopolymers from attaching to the membrane. Coagulation pretreatment enabled the precoated activated carbon to be rinsed off during hydraulic backwashing. The functionality of the membrane was thereby retained for a long-term operation. Precoating the membranes with SSPAC after coagulation is a promising way to control membrane fouling, and efficiently prevents an increase in the TMP because of the straining effect of the SSPAC and the high capacity of the SSPAC to adsorb any existing biopolymers.

Prediction of 1,4-dioxane decomposition during VUV treatment by model simulation taking into account effects of coexisting inorganic ions
Taku Matsushita, Wataru Sugita, Tomoya Ishikawa, Gang Shi, S. Nishizawa, Yoshihiko Matsui, Nobutaka Shirasaki
Water Research, 164, 2019年11月01日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2019 Elsevier Ltd 1,4-Dioxane is one of the most persistent organic micropollutants and is quite difficult to remove via conventional drinking water treatment consisting of coagulation, sedimentation, and sand filtration. Vacuum ultraviolet (VUV) treatment has recently been found to show promise as a treatment method for 1,4-dioxane removal, but the associated decomposition rate of 1,4-dioxane is known to be very sensitive to water quality characteristics. Some computational models have been proposed to predict the decomposition rate of micropollutants during VUV treatment, but the effects of only bicarbonate and natural organic matter have been considered in the models. In the present study, we attempted to develop a versatile computational model for predicting the behavior of 1,4-dioxane during VUV treatment that took into account the effects of other coexisting inorganic ions commonly found in natural waters. We first conducted 1,4-dioxane decomposition experiments with low-pressure mercury lamps and test waters that had been prepared by adding various inorganic ions to an aqueous phosphate buffer. The apparent decomposition rate of 1,4-dioxane was suppressed when bicarbonate, chloride, and nitrate were added to the test waters. Whereas bicarbonate and chloride directly suppressed the apparent decomposition rate by consuming HO•, nitrate became influential only after being transformed into nitrite by concomitant UV light (λ = 254 nm) irradiation. Cl-related radicals (Cl• and Cl2•−) did not react with 1,4-dioxane directly. A computational model consisting of 31 ordinary differential equations with respect to time that had been translated from 84 reactions (10 photochemical and 74 chemical reactions) among 31 chemical species was then developed for predicting the behavior of 1,4-dioxane during VUV treatment. Nine of the parameters in the ordinary differential equations were determined by least squares fitting to an experimental dataset that included different concentrations of bicarbonate, chloride, nitrate, and nitrite. Without further parameter adjustments, the model successfully predicted the behavior of 1,4-dioxane during VUV treatment of three groundwaters naturally contaminated with 1,4-dioxane as well as one dechlorinated tap water sample supplemented with 1,4-dioxane.

Assessment of indirect inhalation exposure to formaldehyde evaporated from water
Shunto Nishikawa, Yoshihiko Matsui, Taku Matsushita, Nobutaka Shirasaki
Regulatory Toxicology and Pharmacology, 106, 43, 49, 2019年08月, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2019 Elsevier Inc. Volatilization volumes and health risks associated with indirect inhalation exposure to formaldehyde evaporated from water have not been investigated quantitatively. We experimentally investigated formaldehyde volatility, compared with chloroform volatility, predicted formaldehyde inhalation exposure concentrations in Japanese bathrooms, and then re-evaluated drinking water quality standards. Although the Henry's law constant of formaldehyde is 1/10 4 that of chloroform, with a 30-min exposure period, the formaldehyde non-equilibrium partition coefficient (K' d )was 1/500th the chloroform value because of formaldehyde's faster volatilization rate. We used this ratio to estimate the cumulative probability distribution of formaldehyde concentrations in bathroom air. For a formaldehyde concentration in water of ≤2.6 mg/L-water (WHO tolerable concentration), the probability that the incremental formaldehyde concentration due to volatilization would exceed 100 μg/m 3 -air (WHO indoor air quality guideline)was low. However, major sources of formaldehyde in indoor air are building materials and furniture. We therefore calculated the allowable concentration in water by allocating a small percentage of the indoor air guideline value to indirect inhalation exposure via volatilization from tap water. With an allocation factor of 20% (10%), the allowable concentration was 0.52 (0.26)mg/L-water. These concentrations are similar to the Health Canada guideline concentration but they are 3–6 times the Japanese water quality standard.

Micro-milling super-fine powdered activated carbon decreases adsorption capacity by introducing oxygen/hydrogen-containing functional groups on carbon surface from water
Hideki Takaesu, Yoshihiko Matsui, Yuki Nishimura, Taku Matsushita, Nobutaka Shirasaki
Water Research, 155, 66, 75, 2019年05月15日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2019 Elsevier Ltd Superfine powdered activated carbon (SPAC) of micron to submicron particle size is produced by micro-milling of conventionally sized powdered activated carbon. SPAC has attracted attention because of its high adsorption capacity; however, milling to the submicron particle size range lowers its adsorption capacity. Here, we found that this decrease of adsorption capacity was due to the introduction of oxygen/hydrogen-containing functional groups into the graphene structure of the carbon from water during the milling, causing it to become less hydrophobic. This finding was supported by three analyses of SPAC particles before and after milling: 1) elemental analysis revealed increased oxygen and hydrogen content, 2) Boehm titration analysis revealed increased amounts of acidic functional groups, including carboxylic and phenolic hydroxyl groups, and 3) Fourier-transform infrared spectroscopy showed increased peaks at 1200, 1580, and 3400 cm−1, confirming the presence of those groups. Dissolved oxygen concentration did not strongly affect the increase of oxygen content in SPAC, and no evidence was found for hydroxyl radical production during micro-milling, suggesting that a mechanochemical reaction underlies the increase in oxygen/hydrogen-containing functional groups. An increase in 18O content in the SPAC particles after milling in water-18O indicated that the oxygen in the functional groups originated from the surrounding water.

Minimizing residual black particles in sand filtrate when applying super-fine powdered activated carbon: Coagulants and coagulation conditions
Yoshifumi Nakazawa, Yoshihiko Matsui, Yusuke Hanamura, Koki Shinno, Nobutaka Shirasaki, Taku Matsushita
Water Research, 147, 311, 320, 2018年12月15日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2018 Elsevier Ltd Because of the eminent adsorptive capacity and rate for dissolved organic molecules compared to conventionally-sized powdered activated carbon (PAC), super-fine powdered activated carbon (SPAC) is gathering momentum for use in not only the pretreatment for membrane filtration for drinking water purification but also the conventional water purification process consisting of coagulation-flocculation, sedimentation, and rapid sand-filtration (CSF). However, the probability of SPAC particles to leak through a sand bed is higher than that of PAC, and their strict leakage control is an issue to be challenged when applying SPAC to CSF. However, study focusing on very high particle removal, which yield residual concentrations down to around 100 particles/mL, has been very limited. A previous study mentioned that the tendency of SPAC leakage is related to its low destabilization. In response to this, the present study focused on the two key components of coagulation (mixing intensity and coagulants) and investigated how to effectively reduce the residual SPAC after CSF. Astonishingly, the flash mixing (the first process of CSF), especially its G (velocity gradient) value, played the most important role in determining the residual SPAC in the filtrate of sand filter (the fourth process). Even if the slow mixing time was short, a sufficiently large G value but short T (mixing time) value in flash mixing effectively reduced the residual SPAC. When the total GT value of flash and slow mixing was fixed at a constant, priority should be given to flash mixing to reduce the residual SPAC. Among 23 PACl (poly-aluminum chloride) coagulants, PACl with a high-basicity (basicity 70%) and with sulfate ion (0.14 of sulfate/aluminum in molar ratio), produced by Al(OH)3-dissolution, were the most effective to reduce the residual SPAC after CSF. PACls produced by base-titration, which have been intensively investigated in previous researches, were not effective due to lack of floc-formation ability. However, their Al species composition determined by the ferron method were almost the same as those of PACl by Al(OH)3-dissolution, and their charge-neutralization capacities were higher. PACls produced by Al(OH)3-dissolution possessed both charge-neutralization and floc-formation abilities, but the former ability was more important to minimize the residual of SPAC.

Removals of pesticides and pesticide transformation products during drinking water treatment processes and their impact on mutagen formation potential after chlorination
Taku Matsushita, Ayako Morimoto, Taisuke Kuriyama, Eisuke Matsumoto, Yoshihiko Matsui, Nobutaka Shirasaki, Takashi Kondo, Hirokazu Takanashi, Takashi Kameya
Water Research, 138, 67, 76, 2018年07月01日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2018 Elsevier Ltd Removal efficiencies of 28 pesticide transformation products (TPs) and 15 parent pesticides during steps in drinking water treatment (coagulation–sedimentation, activated carbon adsorption, and ozonation) were estimated via laboratory-scale batch experiments, and the mechanisms underlying the removal at each step were elucidated via regression analyses. The removal via powdered activated carbon (PAC) treatment was correlated positively with the log Kow at pH 7. The adjusted coefficient of determination (r2) increased when the energy level of the highest occupied molecular orbital (HOMO) was added as an explanatory variable, the suggestion being that adsorption onto PAC particles was largely governed by hydrophobic interactions. The residual error could be partly explained by π-π electron donor–acceptor interactions between the graphene surface of the PAC particles and the adsorbates. The removal via ozonation correlated positively with the energy level of the HOMO, probably because compounds with relatively high energy level HOMOs could more easily transfer an electron to the lowest unoccupied molecular orbital of ozone. Overall, the TPs tended to be more difficult to remove via PAC adsorption and ozonation than their parent pesticides. However, the TPs that were difficult to remove via PAC adsorption did not induce strong mutagenicity after chlorination, and the TPs that were associated with strong mutagenicity after chlorination could be removed via PAC adsorption. Therefore, PAC adsorption is hypothesized to be an effective method of treating drinking water to reduce the possibility of post-chlorination mutagenicity associated with both TPs and their parent pesticides.

Identifying, counting, and characterizing superfine activated-carbon particles remaining after coagulation, sedimentation, and sand filtration
Yoshifumi Nakazawa, Yoshihiko Matsui, Yusuke Hanamura, Koki Shinno, Nobutaka Shirasaki, Taku Matsushita
Water Research, 138, 160, 168, 2018年07月01日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2018 Elsevier Ltd Superfine powdered activated carbon (SPAC; particle diameter ∼1 μm) has greater adsorptivity for organic molecules than conventionally sized powdered activated carbon (PAC). Although SPAC is currently used in the pretreatment to membrane filtration at drinking water purification plants, it is not used in conventional water treatment consisting of coagulation–flocculation, sedimentation, and rapid sand filtration (CSF), because it is unclear whether CSF can adequately remove SPAC from the water. In this study, we therefore investigated the residual SPAC particles in water after CSF treatment. First, we developed a method to detect and quantify trace concentration of carbon particles in the sand filtrate. This method consisted of 1) sampling particles with a membrane filter and then 2) using image analysis software to manipulate a photomicrograph of the filter so that black spots with a diameter >0.2 μm (considered to be carbon particles) could be visualized. Use of this method revealed that CSF removed a very high percentage of SPAC: approximately 5-log in terms of particle number concentrations and approximately 6-log in terms of particle volume concentrations. When waters containing 7.5-mg/L SPAC and 30-mg/L PAC, concentrations that achieved the same adsorption performance, were treated, the removal rate of SPAC was somewhat superior to that of PAC, and the residual particle number concentrations for SPAC and PAC were at the same low level (100–200 particles/mL). Together, these results suggest that SPAC can be used in place of PAC in CSF treatment without compromising the quality of the filtered water in terms of particulate matter contamination. However, it should be noted that the activated carbon particles after sand filtration were smaller in terms of particle size and were charge-neutralized to a lesser extent than the activated carbon particles before sand filtration. Therefore, the tendency of small particles to escape in the filtrate would appear to be related to the fact that their small size leads to a low destabilization rate during the coagulation process and a low collision rate during the flocculation and filtration processes.

Monte-Carlo and multi-exposure assessment for the derivation of criteria for disinfection byproducts and volatile organic compounds in drinking water: Allocation factors and liter-equivalents per day
Megumi Akiyama, Yoshihiko Matsui, Junki Kido, Taku Matsushita, Nobutaka Shirasaki
Regulatory Toxicology and Pharmacology, 95, 161, 174, 2018年06月, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2018 Elsevier Inc. The probability distributions of total potential doses of disinfection byproducts and volatile organic compounds via ingestion, inhalation, and dermal exposure were estimated with Monte Carlo simulations, after conducting physiologically based pharmacokinetic model simulations to takes into account the differences in availability between the three exposures. If the criterion that the 95th percentile estimate equals the TDI (tolerable daily intake) is regarded as protecting the majority of a population, the drinking water criteria would be 140 (trichloromethane), 66 (bromodichloromethane), 157 (dibromochloromethane), 203 (tribromomethane), 140 (dichloroacetic acid), 78 (trichloroacetic acid), 6.55 (trichloroethylene, TCE), and 22 μg/L (perchloroethylene). The TCE criterion was lower than the Japanese Drinking Water Quality Standard (10 μg/L). The latter would allow the intake of 20% of the population to exceed the TDI. Indirect inhalation via evaporation from water, especially in bathrooms, was the major route of exposure to compounds other than haloacetic acids (HAAs) and accounted for 1.2–9 liter-equivalents/day for the median-exposure subpopulation. The ingestion of food was a major indirect route of exposure to HAAs. Contributions of direct water intake were not very different for trihalomethanes (30–45% of TDIs) and HAAs (45–52% of TDIs).

Identification of mutagenic transformation products generated during oxidation of 3-methyl-4-nitrophenol solutions by orbitrap tandem mass spectrometry and quantitative structure–activity relationship analyses
Taku Matsushita, Shiho Honda, Taisuke Kuriyama, Yuki Fujita, Takashi Kondo, Yoshihiko Matsui, Nobutaka Shirasaki, Hirokazu Takanashi, Takashi Kameya
Water Research, 129, 347, 356, 2018年02月01日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2017 Elsevier Ltd We used Ames assays to investigate the effects of ozonation (designated O3), ozonation followed by chlorination (O3/Cl), an advanced oxidation process (AOP, UV/H2O2), and AOP followed by chlorination (AOP/Cl) on the mutagenicity of solutions of 3-methyl-4-nitrophenol (3M4NP), a major environmental degradation product of the organophosphorus insecticide fenitrothion. Whereas O3 did not induce mutagenicity, O3/Cl, AOP, and AOP/Cl converted 3M4NP into mutagenic transformation products (TPs). Using liquid chromatography–mass spectrometry, we detected a total of 138 peaks in the solutions subjected to O3/Cl, AOP, and AOP/Cl. To elucidate the TPs responsible for the observed mutagenicity, we performed simple regression analyses of the relationship between the area of each peak and the observed mutagenicity of samples withdrawn periodically during each oxidation process. The area of each of 10 peaks was found to be positively correlated (r2 ≥ 0.8) with the observed mutagenicity, suggesting that the TPs corresponding to these peaks contributed to the mutagenicity. After taking into account the consistency of mutagenicity induction by the oxidation processes and analyzing the peaks by tandem mass spectrometry, we identified 3 TPs, corresponding to 6 peaks, as candidate mutagens. These TPs were assessed by means of 4 quantitative structure–activity relationship (QSAR) models, and all 3 were predicted to be mutagenic by at least one model. This result was consistent with our assumption that these TPs were mutagens. Ames assays of an authentic sample of one of the 3 TPs revealed that it did not contribute to the mutagenicity. This left 3-methoxy-4-nitrophenol and 2-[ (E)-[ (2,5-dihydroxyphenyl) methylidene]amino]-5-dihydroxybenzaldehyde on the list of mutagens suspected of contributing to the mutagenicity induced by AOP. No TPs were identified as candidate mutagens responsible for the mutagenicity induced by O3/Cl and AOP/Cl.

Evaluation of the suitability of a plant virus, pepper mild mottle virus, as a surrogate of human enteric viruses for assessment of the efficacy of coagulation–rapid sand filtration to remove those viruses
N. Shirasaki, T. Matsushita, Y. Matsui, R. Yamashita
Water Research, 129, 460, 469, 2018年02月01日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2017 Elsevier Ltd Here, we evaluated the removal of three representative human enteric viruses — adenovirus (AdV) type 40, coxsackievirus (CV) B5, and hepatitis A virus (HAV) IB — and one surrogate of human caliciviruses — murine norovirus (MNV) type 1 — by coagulation–rapid sand filtration, using water samples from eight water sources for drinking water treatment plants in Japan. The removal ratios of a plant virus (pepper mild mottle virus; PMMoV) and two bacteriophages (MS2 and φX174) were compared with the removal ratios of human enteric viruses to assess the suitability of PMMoV, MS2, and φX174 as surrogates for human enteric viruses. The removal ratios of AdV, CV, HAV, and MNV, evaluated via the real-time polymerase chain reaction (PCR) method, were 0.8–2.5-log10 when commercially available polyaluminum chloride (PACl, basicity 1.5) and virgin silica sand were used as the coagulant and filter medium, respectively. The type of coagulant affected the virus removal efficiency, but the age of silica sand used in the rapid sand filtration did not. Coagulation–rapid sand filtration with non-sulfated, high-basicity PACls (basicity 2.1 or 2.5) removed viruses more efficiently than the other aluminum-based coagulants. The removal ratios of MS2 were sometimes higher than those of the three human enteric viruses and MNV, whereas the removal ratios of φX174 tended to be smaller than those of the three human enteric viruses and MNV. In contrast, the removal ratios of PMMoV were similar to and strongly correlated with those of the three human enteric viruses and MNV. Thus, PMMoV appears to be a suitable surrogate for human enteric viruses for the assessment of the efficacy of coagulation–rapid sand filtration to remove viruses.

Trichloramine Removal with Activated Carbon is Governed by Two Reductive Reactions: A Theoretical Approach with Diffusion-Reaction Models
Taku Matsushita, Yoshihiko Matsui, Shohei Ikekame, Miki Sakuma, Nobutaka Shirasaki
Environmental Science and Technology, 51, 8, 4541, 4548, 2017年04月, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2017 American Chemical Society. Mechanisms underlying trichloramine removal with activated carbon treatment were proven by batch experiments and theoretical analysis with diffusion-reaction models. The observed values of trichloramine and free chlorine were explained only by the model in which (1) both trichloramine and free chlorine were involved as reactants, (2) the removals of reactants were affected both by the intraparticle diffusion and by the reaction with activated carbon, and (3) trichloramine decomposition was governed by two distinct reductive reactions. One reductive reaction was expressed as a first-order reaction: the reductive reaction of trichloramine with the basal plane of PAC, which consists of graphene sheets. The other reaction was expressed as a second-order reaction: the reductive reaction of trichloramine with active functional groups located on the edge of the basal plane. Free chlorine competitively reacted with both the basal plane and the active functional groups. The fact that the model prediction succeeded even in experiments with different activated carbon doses, with different initial trichloramine concentrations, and with different sizes of activated carbon particles clearly proved that the mechanisms described in the model were reasonable for explaining trichloramine removal with activated carbon treatment.

Elimination of representative contaminant candidate list viruses, coxsackievirus, echovirus, hepatitis A virus, and norovirus, from water by coagulation processes
N. Shirasaki, T. Matsushita, Y. Matsui, K. Murai, A. Aochi
Journal of Hazardous Materials, 326, 110, 119, 2017年03月15日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2016 Elsevier B.V. We examined the removal of representative contaminant candidate list (CCL) viruses (coxsackievirus [CV] B5, echovirus type [EV] 11, and hepatitis A virus [HAV] IB), recombinant norovirus virus-like particles (rNV-VLPs), and murine norovirus (MNV) type 1 by coagulation. Water samples were subjected to coagulation with polyaluminum chloride (PACl, basicity 1.5) followed by either settling or settling and filtration. Together with our previously published results, the removal ratio order, as evaluated by a plaque-forming-unit method or an enzyme-linked immunosorbent assay after settling, was HAV > EV = rNV-VLPs ≥ CV = poliovirus type 1 = MNV > adenovirus type 40 (range, 0.1–2.7-log10). Infectious HAV was likely inactivated by the PACl and therefore was removed to a greater extent than the other viruses. A nonsulfated high-basicity PACl (basicity 2.1), removed the CCL viruses more efficiently than did two other sulfated PACls (basicity 1.5 or 2.1), alum, or ferric chloride. We also examined the removal ratio of two bacteriophages. The removal ratios for MS2 tended to be larger than those of the CCL viruses, whereas those for φX174 were comparable with or smaller than those of the CCL viruses. Therefore, φX174 may be a useful conservative surrogate for CCL viruses during coagulation.

Erratum: Corrigendum to “Investigation of enteric adenovirus and poliovirus removal by coagulation processes and suitability of bacteriophages MS2 and φX174 as surrogates for those viruses” (Science of the Total Environment (2016) 563–564 (29–39)(S0048969716307707)(10.1016/j.scitotenv.2016.04.090))
N. Shirasaki, T. Matsushita, Y. Matsui, T. Marubayashi, K. Murai
Science of the Total Environment, 576, 472, 2017年01月15日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2016 Elsevier B.V. The authors regret that there was an error done in Table 1 of the article. They would like to change it from “mM-Al” to “μM-Al”. Coagulant dosage at sampling day (mM-Al) → “mM” (millimole) is an error and “μM” (micromole) is the correct one. The authors would like to apologise for any inconvenience caused.

Characteristics and components of poly-aluminum chloride coagulants that enhance arsenate removal by coagulation: Detailed analysis of aluminum species
Yoshihiko Matsui, Nobutaka Shirasaki, Takuro Yamaguchi, Kenta Kondo, Kaori Machida, Taiga Fukuura, Taku Matsushita
Water Research, 118, 177, 186, 2017年, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2017 Elsevier Ltd We evaluated 51 poly-aluminum chloride (PACl) coagulants to determine the coagulant characteristics that were responsible for effective arsenate removal from contaminated river water by means of experiments involving coagulation, settling, and microfiltration. Some of the high-basicity PACls exhibited high arsenate removal percentages, particularly under alkaline conditions, and we investigated various relevant properties and characteristics of these high-basicity PACls. Effective arsenate removal was correlated with the content of polymeric and colloidal aluminum species (Alb and Alc) in the PACls but was not well correlated with colloid charge or zeta potential. Multiple regression analysis revealed that a portion of Alb and Alc, which reacted with the ferron reagent during the period from 30 min to 3 h, that is, the (Al30min−3h) fraction, had the highest arsenate sorption capacity, followed by a colloidal aluminum fraction (Al>3h, which reacted with ferron at a time of >3 h). The Al30min−3h fraction was stable, and its arsenate sorption capacity did not decrease markedly with increasing pH. The Al30min−3h fraction did not correspond to the Keggin-type e-Al13 polycation or the δ-Al30 polycation; it is likely to be an aluminum polymer that is unobservable by 27Al NMR spectroscopy. Our results suggest that PACls with a high proportion of the Al30min−3h fraction should be used for enhanced arsenate removal by coagulation. A high content of the e-Al13 polycation or the δ-Al30 polycation was not indispensable for effective arsenate removal.

Effects of decreasing activated carbon particle diameter from 30 Μm to 140 nm on equilibrium adsorption capacity
Long Pan, Yuki Nishimura, Hideki Takaesu, Yoshihiko Matsui, Taku Matsushita, Nobutaka Shirasaki
Water Research, 124, 425, 434, 2017年, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2017 Elsevier Ltd The capacity of activated carbon particles with median diameters (D50s) of >∼1 μm for adsorption of hydrophobic micropollutants such as 2-methylisolborneol (MIB) increases with decreasing particle size because the pollutants are adsorbed mostly on the exterior (shell) of the particles owing to the limited diffusion penetration depth. However, particles with D50s of <1 μm have not been thoroughly investigated. Here, we prepared particles with D50s of ∼30 μm–∼140 nm and evaluated their adsorption capacities for MIB and several other environmentally relevant adsorbates. The adsorption capacities for low-molecular-weight adsorbates, including MIB, deceased with decreasing particle size for D50s of less than a few micrometers, whereas adsorption capacities increased with decreasing particle size for larger particles. The oxygen content of the particles increased substantially with decreasing particle size for D50s of less than a few micrometers, and oxygen content was negatively correlated with adsorption capacity. The decrease in adsorption capacity with decreasing particle size for the smaller particles was due to particle oxidation during the micromilling procedure used to decrease D50 to ∼140 nm. When oxidation was partially inhibited, the MIB adsorption capacity decrease was attenuated. For high-molecular-weight adsorbates, adsorption capacity increased with decreasing particle size over the entire range of tested particle sizes, even though particle oxygen content increased with decreasing particle size.

Use of gas chromatography–mass spectrometry–olfactometry and a conventional flask test to identify off-flavor compounds generated from phenylalanine during chlorination of drinking water
Taku Matsushita, Miki Sakuma, Shiori Tazawa, Taiki Hatase, Nobutaka Shirasaki, Yoshihiko Matsui
Water Research, 125, 332, 340, 2017年, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2017 Elsevier Ltd Off-flavor in drinking water can be caused by transformation products (TPs) generated from organic compounds, such as amino acids, present during chlorination. However, the contributions of many of these TPs to overall off-flavor have not been quantified, mainly because the lack of appropriate chemical standards prevents sensory evaluation by means of a conventional flask test. In the present study, we used gas chromatography–mass spectrometry–olfactometry (GC-MS-O) to identify compounds responsible for the off-flavor generated by chlorination of an aqueous solution of the amino acid phenylalanine, and we propose a sensory evaluation procedure for quantification of the contributions of the identified TPs to the overall off-flavor, regardless of the availability of chemical standards of the TPs. GC-MS-O revealed that two TPs, N-chlorophenylacetaldimine and 2-chloro-2-phenylacetaldehyde, for which chemical standards are not commercially available, were the main components responsible for the off-flavor of the chlorinated solution. By using a sensory evaluation procedure involving a combination of GC-MS-O and a conventional flask test, we quantified the contributions of TPs to the overall off-flavor of the chlorinated solution. Approximately 60% of the off-flavor was attributable to free chlorine (13%), 2-chloro-2-phenylacetaldehyde (13%), trichloramine (12%) phenylacetaldehyde (11%) phenylacetonitrile (8%), and N-chlorophenylacetaldimine (2%). Treatment with powdered activated carbon (PAC) removed the off-flavor. Experiments with chlorination of 15N-labeled phenylalanine suggested that PAC reductively decomposed trichloramine into N2 gas and adsorbed all of the other identified TPs. Superfine PAC (median diameter, 0.7 μm) removed the off-flavor more rapidly than normal-size PAC (median diameter, 8.0 μm).

Micro-milling of spent granular activated carbon for its possible reuse as an adsorbent: Remaining capacity and characteristics
Long Pan, Yuichi Takagi, Yoshihiko Matsui, Taku Matsushita, Nobutaka Shirasaki
Water Research, 114, 50, 58, 2017年, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2017 Elsevier Ltd We milled granular activated carbons (GACs) that had been used for 0–9 years in water treatment plants and produced carbon particles with different sizes and ages: powdered activated carbons (PAC, median diameter 12–42 μm), superfine PAC (SPAC, 0.9–3.5 μm), and submicron-sized SPAC (SSPAC, 220–290 nm). The fact that SPAC produced from 1-year-old GAC and SSPAC from 2-year-old GAC removed 2-methylisoborneol (MIB) from water with an efficiency similar to that of virgin PAC after a carbon contact time of 30 min suggests that spent GAC could be reused for water treatment after being milled. This potential for reuse was created by increasing the equilibrium adsorption capacity via reduction of the carbon particle size and improving the adsorption kinetics. During long-term (>1 year) use in GAC beds, the volume of pores in the carbon, particularly pores with widths of 0.6–0.9 nm, was greatly reduced. The equilibrium adsorption capacities of the carbon for compounds with molecular sizes in this range could therefore decrease with increasing carbon age. Among these compounds, the decreases of capacities were prominent for hydrophobic compounds, including MIB. For hydrophobic compounds, however, the equilibrium adsorption capacities could be increased with decreasing carbon particle size. The iodine number, among other indices, was best correlated with the equilibrium adsorption capacity of the MIB and would be a good index to assess the remaining MIB adsorption capacity of spent carbon. Spent GAC can possibly be reused as SPAC or SSPAC if its iodine number is ≥ 600 mg/g.

Assessment of the efficacy of membrane filtration processes to remove human enteric viruses and the suitability of bacteriophages and a plant virus as surrogates for those viruses
N. Shirasaki, T. Matsushita, Y. Matsui, K. Murai
Water Research, 115, 29, 39, 2017年, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2017 Elsevier Ltd Here, we evaluated the efficacy of direct microfiltration (MF) and ultrafiltration (UF) to remove three representative human enteric viruses (i.e., adenovirus [AdV] type 40, coxsackievirus [CV] B5, and hepatitis A virus [HAV] IB), and one surrogate of human caliciviruses (i.e., murine norovirus [MNV] type 1). Eight different MF membranes and three different UF membranes were used. We also examined the ability of coagulation pretreatment with high-basicity polyaluminum chloride (PACl) to enhance virus removal by MF. The removal ratios of two bacteriophages (MS2 and φX174) and a plant virus (pepper mild mottle virus; PMMoV) were compared with the removal ratios of the human enteric viruses to assess the suitability of these viruses to be used as surrogates for human enteric viruses. The virus removal ratios obtained with direct MF with membranes with nominal pore sizes of 0.1–0.22 μm differed, depending on the membrane used; adsorptive interactions, particularly hydrophobic interactions between virus particles and the membrane surface, were dominant factors for virus removal. In contrast, direct UF with membranes with nominal molecular weight cutoffs of 1–100 kDa effectively removed viruses through size exclusion, and >4-log10removal was achieved when a membrane with a nominal molecular weight cutoff of 1 kDa was used. At pH 7 and 8, in-line coagulation–MF with nonsulfated high-basicity PACls containing Al30species had generally a better virus removal (i.e., >4-log10virus removal) than the other aluminum-based coagulants, except for φX174. For all of the filtration processes, the removal ratios of AdV, CV, HAV, and MNV were comparable and strongly correlated with each other. The removal ratios of MS2 and PMMoV were comparable or smaller than those of the three human enteric viruses and MNV, and were strongly correlated with those of the three human enteric viruses and MNV. The removal ratios obtained with coagulation–MF for φX174 were markedly smaller than those obtained for the three human enteric viruses and MNV. However, because MS2 was inactivated after contact with PACl during coagulation pretreatment, unlike AdV, CV, MNV, and PMMoV, the removal ratios of infectious MS2 were probably an overestimation of the ability of coagulation–MF to remove infectious AdV, CV, and caliciviruses. Thus, PMMoV appears to be a suitable surrogate for human enteric viruses, whereas MS2 and φX174 do not, for the assessment of the efficacy of membrane filtration processes to remove viruses.

Superiority of wet-milled over dry-milled superfine powdered activated carbon for adsorptive 2-methylisoborneol removal
Long Pan, Yoshihiko Matsui, Taku Matsushita, Nobutaka Shirasaki
Water Research, 102, 516, 523, 2016年10月01日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2016 Elsevier Ltd Superfine powdered activated carbon (SPAC), which is produced from conventionally sized powdered activated carbon (PAC) by wet milling in a bead mill, has attracted attention for its high adsorptive removal ability in both research and practice. In this study, the performance of dry-milled SPAC was investigated. 2-Methylisoborneol (MIB), an earthy-musty compound commonly targeted by water treatment systems, was used as the target adsorbate. Dry-milled SPAC exhibited lower adsorptive removal of MIB than wet-milled SPAC, even when both SPACs were produced from the same PAC and were composed of particles of the same size. One reason for the lower removal of MIB by the dry-milled SPAC was a higher degree of aggregation in the dry-milled SPAC after production; as a result the apparent particle size of dry-milled SPAC was larger than that of wet-milled SPAC. The dry-milled SPAC was also more negatively charged than the wet-milled SPAC, and, owing to its higher repulsion, it was more amenable to dispersion by ultrasonication. However, even after the dry-milled SPAC was ultrasonicated so that its apparent particle size was similar to or less than that of the wet-milled SPAC, the dry-milled SPAC was still inferior in adsorptive removal to the wet-milled SPAC. Therefore, another reason for the lower adsorptive removal of dry-milled SPAC was its lower equilibrium adsorption capacity due to the oxidation during the milling. The adsorption kinetics by SPACs with different degrees of particle aggregation were successfully simulated by a pore diffusion model and a fractal aggregation model.

Investigation of enteric adenovirus and poliovirus removal by coagulation processes and suitability of bacteriophages MS2 and φX174 as surrogates for those viruses
N. Shirasaki, T. Matsushita, Y. Matsui, T. Marubayashi, K. Murai
Science of the Total Environment, 563-564, 29, 39, 2016年09月01日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2016 Elsevier B.V. We evaluated the removal of enteric adenovirus (AdV) type 40 and poliovirus (PV) type 1 by coagulation, using water samples from 13 water sources for drinking water treatment plants in Japan. The behaviors of two widely accepted enteric virus surrogates, bacteriophages MS2 and φX174, were compared with the behaviors of AdV and PV. Coagulation with polyaluminum chloride (PACl, basicity 1.5) removed AdV and PV from virus-spiked source waters: the infectious AdV and PV removal ratios evaluated by means of a plaque-forming-unit method were 0.1-1.4-log10 and 0.5-2.4-log10, respectively. A nonsulfated high-basicity PACl (basicity 2.1) removed infectious AdV and PV more efficiently than did other commercially available PACls (basicity 1.5-2.1), alum, and ferric chloride. The MS2 removal ratios tended to be larger than those of AdV and PV, partly because of differences in the hydrophobicities of the virus particles and the sensitivity of the virus to the virucidal activity of PACl; the differences in removal ratios were not due to differences in the surface charges of the virus particles. MS2, which was more hydrophobic than the other viruses, was inactivated during coagulation with PACl. Therefore, MS2 does not appear to be an appropriate surrogate for AdV and PV during coagulation. In contrast, because φX174, like AdV and PV, was not inactivated during coagulation, and because the hydrophobicity of φX174 was similar to or somewhat lower than the hydrophobicities of AdV and PV, the φX174 removal ratios tended to be similar to or somewhat smaller than those of the enteric viruses. Therefore, φX174 is a potential conservative surrogate for AdV and PV during coagulation. In summary, the surface hydrophobicity of virus particles and the sensitivity of the virus to the virucidal activity of the coagulant are probably important determinants of the efficiency of virus removal during coagulation.

Effect of coagulant basicity on virus removal from water by polyferric chloride
Nobutaka Shirasaki, Taku Matsushita, Yoshihiko Matsui, Takuya Marubayashi
Journal of Water Supply: Research and Technology - AQUA, 65, 4, 322, 329, 2016年06月, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © IWA Publishing 2016. We investigated the effect of coagulant basicity on bacteriophage removal from river water by polyferric chloride (PFC). PFC at three basicities (basicity 0.9-2.1) was prepared by means of base titration (NaOH was added to ferric chloride (FeCl3) solution) and the virus removal efficiencies of those PFCs were compared with that of FeCl3 (basicity 0). The virus removal efficiencies of the PFCs were equal to or less than that of FeCl3 at both pH 6 and pH 8. This suggests that, unlike aluminum-based coagulants, increasing the basicity of iron-based coagulants does not improve virus removal efficiency. Furthermore, the relative abundance of monomeric iron(III) species in the PFCs decreased, whereas that of precipitated iron(III) species increased with increasing basicity, as assessed with a ferron method. Colloid charge density also decreased with increasing basicity. Therefore, it is likely that the reduction in the abundance of monomeric iron(III) species led to the reduction in colloid charge density, which then reduced virus removal efficiency. Thus, the development of novel iron-based coagulants with increased virus removal efficiency may not be possible by simply increasing the basicity of the coagulant.

Characterization of recombinant norovirus virus-like particles and evaluation of their applicability to the investigation of norovirus removal performance in membrane filtration processes
N. Shirasaki, T. Matsushita, Y. Matsui, K. Ohno
Water Science and Technology: Water Supply, 16, 3, 737, 745, 2016年06月, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © IWA Publishing 2016. Noroviruses (NVs) are one of the leading causes of epidemic gastroenteritis around the world. Water treatment technologies using membrane filtration for virus removal are becoming increasingly important. However, experiments to test removal of NVs fromwater have been hampered because NVs do not grow in cell culture or in small-animal models and therefore cannot be easily artificially propagated. Expression of the NV genome in a baculovirus-silkworm expression system has produced recombinantNV virus-like particles (rNV-VLPs) that aremorphologically and antigenically similar to native NV. Here, we characterized these rNV-VLPs and evaluated their potential use in assessing NV removal. Electron microscopic analysis and peptide mass fingerprinting showed that the rNV-VLPs were morphologically identical to nativeNV. In addition, surface charge and particle size distribution, which are important factors for explaining virus particle behavior during membrane filtration, were successfully evaluated by using rNV-VLPs. The rNV-VLPswere easy to quantify with a commercially available enzymelinked immunosorbent assay kit, they remained stable for several days at 4 °C after dilution in riverwater, and theywere easy to concentrate with the ultrafiltration entrapment method used. Thus, rNV-VLPs can be used to facilitate our understanding of the behavior of NVs during membrane filtration processes.

Use of orbitrap-MS/MS and QSAR analyses to estimate mutagenic transformation products of iopamidol generated during ozonation and chlorination
Taku Matsushita, Masahiro Hashizuka, Taisuke Kuriyama, Yoshihiko Matsui, Nobutaka Shirasaki
Chemosphere, 148, 233, 240, 2016年04月, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2016 Elsevier Ltd. The effects of two water purification processes (ozonation, and chlorination after ozonation) on the mutagenicity of a solution containing iopamidol (X-ray contrast medium) were investigated by using the Ames assay. No mutagenicity was observed during ozonation. In contrast, mutagenicity was induced by the ozone-treated iopamidol-containing solution after subsequent chlorination, indicating that mutagenic transformation-products (TPs) were generated. Ten of 70 peaks detected on the LC/MS total ion chromatogram (TIC) of the ozone-treated iopamidol-containing solution after chlorination had a positive correlation (r2 > 0.6) between their peak areas and the observed mutagenicity, suggesting that TPs detected as these peaks may induce mutagenicity. To narrow down the possible contributors to the observed mutagenicity, we compared the areas of the peaks on the TIC-charts with and without chlorination. Of the ten peaks, six were also detected in the ozone-treated iopamidol-containing solution without chlorination, which did not induce mutagenicity, indicating that these peaks were not related to the observed mutagenicity. Accurate m/z values and MS/MS analysis with an orbitrap MS of the remaining four peaks revealed that two of them represented the same TP in the negative and positive ion modes. The three remaining TPs were assessed in four quantitative structure-activity relationship models for predicting Ames mutagenicity. At least one model predicted that two of the three TPs were mutagenic, whereas none of the models predicted that the other TP was a mutagen, suggesting that the former TPs, estimated as N1-acetyl-5-amino-6-chloro-2-iodobenzene-1,3-dicarboxamide and 3-hydroxy-{2-3-[ (2-hydroxyethoxy)carbonyl]-2,4,6-triiodo-5-nitrobenzoyl}amino)propanoic acid, could be the candidate compounds that contributed to the observed mutagenicity.

Effect of aluminum hydrolyte species on human enterovirus removal from water during the coagulation process
N. Shirasaki, T. Matsushita, Y. Matsui, T. Marubayashi
Chemical Engineering Journal, 284, 786, 793, 2016年, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2015 Elsevier B.V. We prepared different types of aluminum-based coagulants, consisting of mainly monomeric aluminum species, polymeric aluminum species, or colloidal aluminum species, to investigate the effect of aluminum hydrolyte species on the removal of two types of human enteroviruses, poliovirus (PV) type 1 and the free-chlorine-resistant virus coxsackievirus (CV) B5, from lake and river water samples during the coagulation process. We found that differences in the distribution of the aluminum hydrolyte species in the coagulant affected the removal of these enteroviruses during coagulation: the removal ratios of PV and CV observed with polyaluminum chloride (PACl) with a high colloidal aluminum content and a basicity of 2.1 (i.e., PACl-2.1c) were larger than those observed with high monomeric aluminum content coagulant (i.e., AlCl3 solution) and with high polymeric aluminum content coagulant PACl (PACl-2.1b). Unlike AlCl3 or PACl-2.1b, PACl-2.1c contains Al30 species, indicating that Al30 species probably play a major role in the removal of enteroviruses. The PV and CV removal ratios were almost identical, regardless of the coagulant type or viral quantification method used (plaque-forming unit method or real-time polymerase chain reaction method), suggesting that PV and CV behaved similarly during the coagulation process. We also experimentally confirmed that the main mechanism for virus removal was coprecipitation into growing aluminum hydroxide during charge neutralization; virus adsorption onto formed aluminum hydroxide flocs also contributed to virus removal, but played a limited role.

Adsorption capacities of activated carbons for geosmin and 2-methylisoborneol vary with activated carbon particle size: Effects of adsorbent and adsorbate characteristics
Yoshihiko Matsui, Soichi Nakao, Asuka Sakamoto, Takuma Taniguchi, Long Pan, Taku Matsushita, Nobutaka Shirasaki
Water Research, 85, 95, 102, 2015年11月05日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2015 Elsevier Ltd. The adsorption capacities of nine activated carbons for geosmin and 2-methylisoborneol (MIB) were evaluated. For some carbons, adsorption capacity substantially increased when carbon particle diameter was decreased from a few tens of micrometers to a few micrometers, whereas for other carbons, the increase of adsorption capacity was small for MIB and moderate for geosmin. An increase of adsorption capacity was observed for other hydrophobic adsorbates besides geosmin and MIB, but not for hydrophilic adsorbates. The parameter values of a shell adsorption model describing the increase of adsorption capacity were negatively correlated with the oxygen content of the carbon among other characteristics. Low oxygen content indicated low hydrophilicity. The increase of adsorption capacity was related to the hydrophobic properties of both adsorbates and activated carbons. For adsorptive removal of hydrophobic micropollutants such as geosmin, it is therefore recommended that less-hydrophilic activated carbons, such as coconut-shell-based carbons, be microground to a particle diameter of a few micrometers to enhance their equilibrium adsorption capacity. In contrast, adsorption by hydrophilic carbons or adsorption of hydrophilic adsorbates occur in the inner pores, and therefore adsorption capacity is unchanged by particle size reduction.

Changes in mutagenicity and acute toxicity of solutions of iodinated X-ray contrast media during chlorination
Taku Matsushita, Nozomi Kobayashi, Masahiro Hashizuka, Haruki Sakuma, Takashi Kondo, Yoshihiko Matsui, Nobutaka Shirasaki
Chemosphere, 135, 101, 107, 2015年09月01日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2015 Elsevier Ltd. In the present study, the effects of chlorination on the mutagenicity (assessed via the Ames assay) and acute toxicity (assessed via a bioluminescence inhibition assay) of solutions containing one of five commonly used iodinated X-ray contrast media (ICM) (iopamidol, iohexol, iopromide, iomeprol, and diatrizoate) were investigated. Of the five ICM tested, only iopamidol was degraded by chlorine. Chlorination of the iopamidol-containing solution induced both mutagenicity and acute toxicity, which increased with chlorination time (up to 96h). The areas of five out of 54 peaks detected on the LC/MS total ion chromatogram had good correlation (r2>0.90) between peak area and observed mutagenicity. To identify possible contributors to the observed mutagenicity, the Ames assay and LC/MS analysis were conducted on samples collected at 48-h chlorination time and extracted under different pH conditions. Of the five peaks, one peak was detected in the sample extracted at pH 7, but this sample was not mutagenic, indicating that the peak was not related to the observed mutagenicity. MS/MS analysis with an orbitrap mass spectrometer of the remaining four peaks revealed that two of the peaks represented the same TP (detected in negative and positive ion modes). Finally, three TPs were identified as suspected contributors to the mutagenicity induced by the iopamidol-containing solution after chlorination: 5-[ (1,3-dihydroxypropan-2-yl)carbamoyl]-3-[ (3-hydroxypropanoyl)oxy]-2,4-diiodobenzoic acid; N-(1,3-dihydroxypropan-2-yl)-3-(2,3-dioxopropyl)-2,4,6-triiodobenzamide; and 3-[ (1,3-dihydroxypropan-2-yl)carbamoyl]-5-[ (3-hydroxybutanoyl)oxy]-2,4,6-triiodobenzoic acid. Prediction of the mutagenicity potential of these three TPs with a battery of four quantitative structure-activity relationship models did not contradict our conclusion that these TPs contributed to the observed mutagenicity.

Hydraulically irreversible membrane fouling during coagulation-microfiltration and its control by using high-basicity polyaluminum chloride
Masaoki Kimura, Yoshihiko Matsui, Shun Saito, Tomoya Takahashi, Midori Nakagawa, Nobutaka Shirasaki, Taku Matsushita
Journal of Membrane Science, 477, 115, 122, 2015年03月01日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2014 Elsevier B.V. The extent of hydraulically irreversible membrane fouling in a coagulation-filtration system depends on several factors, including properties of the coagulant. Effects of polyaluminum chloride (PACl) coagulant properties, specifically basicity and sulfation, were investigated by conducting long-term direct filtration experiments. Elemental analysis determined Al and Si to be the major foulants, though the Si/Al ratios of the foulants differed from those of coagulated floc particles. While floc particle size depended on the concentrations of sulfate ions and polymeric species in the PACls, floc-size changes did not affect transmembrane pressure (TMP) buildup and thus did not affect irreversible fouling. Differences in PACl basicity, which affected the distribution of aluminum species, resulted in changes to the degree of irreversible fouling.Pretreatment with high-basicity (71%) PACl was superior to pretreatment with normal-basicity (51%) PACl in reducing irreversible fouling and attenuating TMP buildup during filtration. Higher basicities resulted in less Al breakthrough and a decrease in the Si/Al ratio of the foulants. However, TMP buildup was the same for PACls with basicities of 71% and 90%; therefore, TMP buildup is not simply related to Al breakthrough and deposition. Increasing the basicity of PACls would be an effective way to reduce the amount of foulant deposited on the membrane by decreasing the amount of aluminum that passes through the membrane.

Mechanisms of trichloramine removal with activated carbon: Stoichiometric analysis with isotopically labeled trichloramine and theoretical analysis with a diffusion-reaction model
Miki Sakuma, Taku Matsushita, Yoshihiko Matsui, Tomoko Aki, Masahito Isaka, Nobutaka Shirasaki
Water Research, 68, 839, 848, 2015年01月01日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2014 Elsevier Ltd. This study investigated the mechanism by which activated carbon removes trichloramine, a byproduct of water treatment that has a strongly offensive chlorinous odor. A stoichiometrical mass balance for 15N before and after activated carbon treatment of laboratory-prepared 15N-labeled trichloramine solutions clearly revealed that the mechanism of trichloramine removal with activated carbon was not adsorption but rather reductive decomposition to nitrogen gas. There was a weak positive correlation between the surface decomposition rate constant of trichloramine and the concentration of basic functional groups on the surface of the carbon particles, the suggestion being that the trichloramine may have been reduced by sulfhydryl groups (-SH) on the activated carbon surface. Efficient decomposition of trichloramine was achieved with super powdered activated carbon (SPAC), which was prepared by pulverization of commercially available PAC into very fine particles less than 1μm in diameter. SPAC could decompose trichloramine selectively, even when trichloramine and free chlorine were present simultaneously in water, the indication being that the strong disinfection capability of residual free chlorine could be retained even after trichloramine was effectively decomposed. The residual ratio of trichloramine after carbon contact increased somewhat at low water temperatures of 1-5°C. At these low temperatures, biological treatment, the traditional method for control of a major trichloramine precursor (ammonium nitrogen), is inefficient. Even at these low temperatures, SPAC could reduce the trichloramine concentration to an acceptable level. A theoretical analysis with a diffusion-reaction model developed in the present study revealed that the increase in the trichloramine residual with decreasing water temperature was attributable to the temperature dependence of the rate of the reductive reaction rather than to the temperature dependence of the diffusive mass transfer rate.

Removal of iodide from water by chlorination and subsequent adsorption on powdered activated carbon
Mariya Ikari, Yoshihiko Matsui, Yuta Suzuki, Taku Matsushita, Nobutaka Shirasaki
Water Research, 68, 227, 237, 2015年01月01日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2014 Elsevier Ltd. Chlorine oxidation followed by treatment with activated carbon was studied as a possible method for removing radioactive iodine from water. Chlorination time, chlorine dose, the presence of natural organic matter (NOM), the presence of bromide ion (Br-), and carbon particle size strongly affected iodine removal. Treatment with superfine powdered activated carbon (SPAC) after 10-min oxidation with chlorine (1mg-Cl2/L) removed 90% of the iodine in NOM-containing water (dissolved organic carbon concentration, 1.5mg-C/L). Iodine removal in NOM-containing water increased with increasing chlorine dose up to 0.1mg-Cl2/L but decreased at chlorine doses of >1.0mg-Cl2/L. At a low chlorine dose, nonadsorbable iodide ion (I-) was oxidized to adsorbable hypoiodous acid (HOI). When the chlorine dose was increased, some of the HOI reacted with NOM to form adsorbable organic iodine (organic-I). Increasing the chlorine dose further did not enhance iodine removal, owing to the formation of nonadsorbable iodate ion (IO3-). Co-existing Br- depressed iodine removal, particularly in NOM-free water, because hypobromous acid (HOBr) formed and catalyzed the oxidation of HOI to IO3- However, the effect of Br- was small in the NOM-containing water because organic-I formed instead of IO3- SPAC (median particle diameter, 0.62μm) had a higher equilibrium adsorption capacity for organic-I than did conventional PAC (median diameter, 18.9μm), but the capacities of PAC and SPAC for HOI were similar. The reason for the higher equilibrium adsorption capacity for organic-I was that organic-I was adsorbed principally on the exterior of the PAC particles and not inside the PAC particles, as indicated by direct visualization of the solid-phase iodine concentration profiles in PAC particles by field emission electron probe microanalysis. In contrast, HOI was adsorbed evenly throughout the entire PAC particle.

Decomposition of 1,4-dioxane by vacuum ultraviolet irradiation: Study of economic feasibility and by-product formation
T. Matsushita, S. Hirai, T. Ishikawa, Y. Matsui, N. Shirasaki
Process Safety and Environmental Protection, 94, C, 528, 541, 2015年, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2014 The Institution of Chemical Engineers. We report the first use of vacuum ultraviolet (VUV) treatment to decompose 1,4-dioxane, a persistent organic contaminant that is difficult to remove by conventional drinking water treatment processes. The efficiency of VUV treatment was compared to that of VUV- and UV-based advanced oxidation processes (AOPs) (VUV/TiO2, VUV/H2O2, UV/TiO2, and UV/H2O2), and by-product formation was investigated. VUV treatment decomposed 1,4-dioxane more rapidly than did UV and UV/TiO2 treatments. The decomposition rate was enhanced when VUV irradiation was combined with TiO2 or H2O2. VUV/H2O2 decomposed 1,4-dioxane more rapidly than UV/H2O2 at a low H2O2 dose (1 mg/L), but the rate difference became small at a high H2O2 dose (5 mg/L). Electrical energy per order analysis revealed that VUV treatment, and the VUV- and UV-based AOPs, were economically feasible for 1,4-dioxane decomposition. Using raw water samples, we investigated by-product formation during VUV treatment and the effect of VUV irradiation on chlorinated disinfection by-product formation potential. Although the samples contained high concentrations of bromide, no bromate was produced by VUV treatment. VUV treatment slightly decreased trihalomethane formation potential (THMFP), whereas haloacetic acid formation potential (HAAFP) was unchanged, and total aldehyde concentration increased. The trend in HAAFP agreed with that had been reported for the VUV irradiation with much higher dose (Buchanan et al., 2006), whereas the trend in THMFP was different from that with much higher dose. THMFP, HAAFP, and aldehyde concentration were reduced by subsequent treatment with granular activated carbon (GAC) or biological activated carbon (BAC). Nitrite was produced by VUV treatment but disappeared after subsequent BAC treatment. These results suggest that VUV treatment should be combined with GAC or BAC treatment to suppress by-product formation.

Effect of growth phase of cyanobacterium on release of intracellular geosmin from cells during microfiltration process
Taku Matsushita, Keisuke Nakamura, Yoshihiko Matsui, Nobutaka Shirasaki
Membrane Water Treatment, 6, 3, 225, 235, 2015年, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2015 Techno-Press, Ltd. During low-pressure membrane treatments of cyanobacterial cells, including microfiltration (MF) and ultrafiltration (UF), there have reportedly been releases of intracellular compounds including cyanotoxins and compounds with an earthy-musty odor into the water, probably owing to cyanobacterial cell breakage retained on the membrane. However, to our knowledge, no information was reported regarding the effect of growth phase of cyanobacterial cells on the release of the intracellular compounds. In the present study, we used a geosmin-producing cyanobacterium, Anabaena smithii, to investigate the effect of the growth phase of the cyanobacterium on the release of intracellular geosmin during laboratory-scale MF experiments with the cells in either the logarithmic growth or stationary phase. Separate detection of damaged and intact cells revealed that the extent of cell breakage on the MF membrane was almost the same for logarithmic growth and stationary phase cells. However, whereas the geosmin concentration in the MF permeate increased after 3 h of filtration with cells in the logarithmic growth phase, it did not increase during filtration with cells in the stationary phase: the trend in the geosmin concentration in the MF permeate with time was much different between the logarithmic growth and stationary phases. Adsorption of geosmin to algogenic organic matter (AOM) retained on the MF membrane and/or pore blocking with the AOM were greater when the cells were in the stationary phase versus the logarithmic growth phase, the result being a decrease in the apparent release of intracellular geosmin from the stationary phase cells. In actual drinking water treatment plants employing membrane processes, more attention should be paid to the cyanobacterial cells in logarithmic growth phase than in stationary phase from a viewpoint of preventing the leakage of intracellular earthy-musty odor compounds to finished water.

Isotope microscopy visualization of the adsorption profile of 2-methylisoborneol and geosmin in powdered activated carbon
Yoshihiko Matsui, Asuka Sakamoto, Soichi Nakao, Takuma Taniguchi, Taku Matsushita, Nobutaka Shirasaki, Naoya Sakamoto, Hisayoshi Yurimoto
Environmental Science and Technology, 48, 18, 10897, 10903, 2014年09月16日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, © 2014 American Chemical Society. Decreasing the particle size of powdered activated carbon may enhance its equilibrium adsorption capacity for small molecules and micropollutants, such as 2-methylisoborneol (MIB) and geosmin, as well as for macromolecules and natural organic matter. Shell adsorption, in which adsorbates do not completely penetrate the adsorbent but instead preferentially adsorb near the outer surface of the adsorbent, may explain this enhancement in equilibrium adsorption capacity. Here, we used isotope microscopy and deuterium-doped MIB and geosmin to directly visualize the solid-phase adsorbate concentration profiles of MIB and geosmin in carbon particles. The deuterium/hydrogen ratio, which we used as an index of the solid-phase concentration of MIB and geosmin, was higher in the shell region than in the inner region of carbon particles. Solid-phase concentrations of MIB and geosmin obtained from the deuterium/hydrogen ratio roughly agreed with those predicted by shell adsorption model analyses of isotherm data. The direct visualization of the localization of micropollutant adsorbates in activated carbon particles provided direct evidence of shell adsorption.

Selecting pesticides for inclusion in drinking water quality guidelines on the basis of detection probability and ranking
Kentaro Narita, Yoshihiko Matsui, Kensuke Iwao, Motoyuki Kamata, Taku Matsushita, Nobutaka Shirasaki
Environment International, 63, 114, 120, 2014年02月, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, Pesticides released into the environment may pose both ecological and human health risks. Governments set the regulations and guidelines for the allowable levels of active components of pesticides in various exposure sources, including drinking water. Several pesticide risk indicators have been developed using various methodologies, but such indicators are seldom used for the selection of pesticides to be included in national regulations and guidelines. The aim of the current study was to use risk indicators for the selection of pesticides to be included in regulations and guidelines. Twenty-four risk indicators were created, and a detection rate was defined to judge which indicators were the best for selection. The combination of two indicators (local sales of a pesticide for the purposes of either rice farming or other farming, divided by the guideline value and annual precipitation, and amended with the scores from the physical and chemical properties of the pesticide) gave the highest detection rates. In this case study, this procedure was used to evaluate 134 pesticides that are currently unregulated in the Japanese Drinking Water Quality Guidelines, from which 44 were selected as pesticides to be added to the primary group in the guidelines. The detection probability of the 44 pesticides was more than 72%. Among the 102 pesticides currently in the primary group, 17 were selected for withdrawal from the group. © 2013 The Authors.

Improved virus removal by high-basicity polyaluminum coagulants compared to commercially available aluminum-based coagulants
N. Shirasaki, T. Matsushita, Y. Matsui, A. Oshiba, T. Marubayashi, S. Sato
Water Research, 48, 1, 375, 386, 2014年01月01日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, We investigated the effects of basicity, sulfate content, and aluminum hydrolyte species on the ability of polyaluminum chloride (PACl) coagulants to remove F-specific RNA bacteriophages from river water at a pH range of 6-8. An increase in PACl basicity from 1.5 to 2.1 and the absence of sulfate led to a reduction of the amount of monomeric aluminum species (i.e., an increase of the total amount of polymeric aluminum and colloidal aluminum species) in the PACl, to an increase in the colloid charge density of the PACl, or to both and, as a result, to high virus removal efficiency. The efficiency of virus removal at around pH 8 observed with PACl-2.1c, a nonsulfated high-basicity PACl (basicity 2.1-2.2) with a high colloidal aluminum content, was larger than that observed with PACl-2.1b, a nonsulfated high-basicity PACl (basicity 2.1-2.2) with a high polymeric aluminum content. In contrast, although extremely high basicity PACls (e.g., PACl-2.7ns, basicity 2.7) effectively removed turbidity and UV260-absorbing natural organic matter and resulted in a very low residual aluminum concentration, the virus removal ratio with PACl-2.7ns was smaller than the ratio with PACl-2.1c at around pH 8, possibly as a result of a reduction of the colloid charge density of the PACl as the basicity was increased from 2.1 to 2.7. Liquid 27Al NMR analysis revealed that PACl-2.1c contained Al30 species, which was not the case for PACl-2.1b or PACl-2.7ns. This result suggests that Al30 species probably played a major role in virus removal during the coagulation process. In summary, PACl-2.1c, which has high colloidal aluminum content, contains Al30 species, and has a high colloid charge density, removed viruses more efficiently (>4 log10 for infectious viruses) than the other aluminum-based coagulants-including commercially available PACls (basicity 1.5-1.8), alum, and PACl-2.7ns-over the entire tested pH (6-8) and coagulant dosage (0.54-5.4mg-Al/L) ranges. © 2013 Elsevier Ltd.

Virus removal by an in-line coagulation-ceramic microfiltration process with high-basicity polyaluminum coagulation pretreatment
N. Shirasaki, T. Matsushita, Y. Matsui, T. Urasaki, M. Kimura, K. Ohno
Water Science and Technology: Water Supply, 14, 3, 429, 437, 2014年, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, The ability of in-line coagulation pretreatment with high-basicity polyaluminum chloride (PACl) coagulants to enhance virus removal by ceramic microfiltration (MF) was examined by comparing virus removal efficiencies from water pretreated with PACl-2.2 (basicity 2.2) and PACl-2.5 (basicity 2.5) versus alum, a synthetic aluminum chloride (AlCl3) solution, and two commercially available PACls, PACl-1.5 and PACl-1.8. The virus removal ratios for AlCl3, alum, PACl-1.5, and PACl-1.8 decreased markedly when the pH of the treated water shifted from 6.8 to 7.8, but was high at both pHs for PACl-2.2 and PACl-2.5. PACl-2.5 contains Al13 species and possibly Al30 species, and has a high colloid charge density. It removed viruses more efficiently than the other aluminum-based coagulants, not only at neutral pH, but also under weakly alkaline conditions. Moreover, the in-line coagulation-ceramic MF process with PACl-2.5 pretreatment removed not only viruses but also dissolved organic carbon and UV260-absorbing natural organic matter more efficiently and resulted in a lower residual aluminum concentration than did commercially available PACls, especially under weakly alkaline conditions. A combination of coagulation pretreatment with a high-basicity PACl and ceramic MF can provide effective treatment of drinking water over a broader pH range than is possible with commercially available aluminum-based coagulants. © IWA Publishing 2014.

Relative source allocation of TDI to drinking water for derivation of a criterion for chloroform: A Monte-Carlo and multi-exposure assessment
Shun Niizuma, Yoshihiko Matsui, Koichi Ohno, Sadahiko Itoh, Taku Matsushita, Nobutaka Shirasaki
Regulatory Toxicology and Pharmacology, 67, 1, 98, 107, 2013年10月, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, Drinking water quality standard (DWQS) criteria for chemicals for which there is a threshold for toxicity are derived by allocating a fraction of tolerable daily intake (TDI) to exposure from drinking water. We conducted physiologically based pharmacokinetic model simulations for chloroform and have proposed an equation for total oral-equivalent potential intake via three routes (oral ingestion, inhalation, and dermal exposures), the biologically effective doses of which were converted to oral-equivalent potential intakes. The probability distributions of total oral-equivalent potential intake in Japanese people were estimated by Monte Carlo simulations. Even when the chloroform concentration in drinking water equaled the current DWQS criterion, there was sufficient margin between the intake and the TDI: the probability that the intake exceeded TDI was below 0.1%. If a criterion that the 95th percentile estimate equals the TDI is regarded as both providing protection to highly exposed persons and leaving a reasonable margin of exposure relative to the TDI, then the chloroform drinking water criterion could be a concentration of 0.11. mg/L. This implies a daily intake equal to 34% of the TDI allocated to the oral intake (2. L/d) of drinking water for typical adults. For the highly exposed persons, inhalation exposure via evaporation from water contributed 53% of the total intake, whereas dermal absorption contributed only 3%. © 2013 Elsevier Inc.

Investigating norovirus removal by microfiltration, ultrafiltration, and precoagulation-microfiltration processes using recombinant norovirus virus-like particles and real-time immuno-PCR
Taku Matsushita, Nobutaka Shirasaki, Yuichi Tatsuki, Yoshihiko Matsui
Water Research, 47, 15, 5819, 5827, 2013年10月01日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, The removal of microorganisms by drinking water treatment processes has been widely investigated in laboratory-scale experiments using artificially propagated microorganisms. However, this approach cannot be applied to norovirus removal, because this virus does not grow in cell or organ culture, and this fact has hampered our ability to investigate its behavior during drinking water treatment. To overcome this difficulty, our research group previously used recombinant norovirus virus-like particles (rNV-VLPs), which consist of an artificially expressed norovirus capsid protein, in laboratory-scale drinking water treatment experiments. However, the enzyme-linked immunosorbent assay (ELISA) method generally used to detect rNV-VLPs is not sensitive enough to evaluate high removal ratios such as those obtained by ultrafiltration (UF). We therefore developed and applied a real-time immuno-polymerase chain reaction (iPCR) assay for rNV-VLP quantification to investigate norovirus removal by microfiltration (MF), UF, and hybrid precoagulation-MF processes. The rNV-VLP detection limit with the developed iPCR assay was improved at least 1000-fold compared with ELISA. Whereas MF with a nominal pore size of 0.1μm could not eliminate NV-VLPs, a 4-log reduction was achieved by UF with a molecular weight cutoff of 1kDa. When MF was combined with precoagulation (≥10μmol-Fe/L for ferric chloride; ≥20μmol-Al/L for polyaluminum chloride; ≥40μmol-Al/L for alum), the performance of the hybrid process in eliminating rNV-VLPs was greater than that achieved by the 1kDa UF. For all processes, the removal ratios of the bacteriophages MS2 and Qβ were greater than the rNV-VLP removal ratios by 1-2 logs, so neither bacteriophage can be recommended as a possible conservative surrogate for predicting the behavior of native NV during these processes. © 2013 Elsevier Ltd.

Minimizing residual aluminum concentration in treated water by tailoring properties of polyaluminum coagulants
Masaoki Kimura, Yoshihiko Matsui, Kenta Kondo, Tairyo B. Ishikawa, Taku Matsushita, Nobutaka Shirasaki
Water Research, 47, 6, 2075, 2084, 2013年04月, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, Aluminum coagulants are widely used in water treatment plants to remove turbidity and dissolved substances. However, because high aluminum concentrations in treated water are associated with increased turbidity and because aluminum exerts undeniable human health effects, its concentration should be controlled in water treatment plants, especially in plants that use aluminum coagulants. In this study, the effect of polyaluminum chloride (PACl) coagulant characteristics on dissolved residual aluminum concentrations after coagulation and filtration was investigated. The dissolved residual aluminum concentrations at a given coagulation pH differed among the PACls tested. Very-high-basicity PACl yielded low dissolved residual aluminum concentrations and higher natural organic matter (NOM) removal. The low residual aluminum concentrations were related to the low content of monomeric aluminum (Ala) in the PACl. Polymeric (Alb)/colloidal (Alc) ratio in PACl did not greatly influence residual aluminum concentration. The presence of sulfate in PACl contributed to lower residual aluminum concentration only when coagulation was performed at around pH 6.5 or lower. At a wide pH range (6.5-8.5), residual aluminum concentrations <0.02 mg/L were attained by tailoring PACl properties (Ala percentage ≤0.5%, basicity ≥85%). The dissolved residual aluminum concentrations did not increase with increasing the dosage of high-basicity PACl, but did increase with increasing the dosage of normal-basicity PACl. We inferred that increasing the basicity of PACl afforded lower dissolved residual aluminum concentrations partly because the high-basicity PACls could have a small percentage of Ala, which tends to form soluble aluminum-NOM complexes with molecular weights of 100 kDa-0.45 μm. © 2013 Elsevier Ltd.

Adsorptive virus removal with super-powdered activated carbon
Taku Matsushita, Hideaki Suzuki, Nobutaka Shirasaki, Yoshihiko Matsui, Koichi Ohno
Separation and Purification Technology, 107, 79, 84, 2013年, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, We investigated the removal of bacteriophages by adsorption on commercially available powdered activated carbon (N-PAC, median diameter >10 μm) and super-powdered activated carbon (S-PAC, median diameter 0.7-2.8 μm). N-PACs failed to remove the virus in Milli-Q water buffered with 100 μM Ca 2+, but some S-PACs successfully removed it under the same condition. Three factors contributed substantially to virus removal: a smaller electrophoretic repulsive force between the virus and the PAC particles, a large proportion of pores 20-50 nm in diameter, and a greater hydrophobicity of the virus surface. © 2013 Published by Elsevier B.V.

Aluminum concentrations of sand filter and polymeric membrane filtrates: A comparative study
Yoshihiko Matsui, Tairyo B. Ishikawa, Masaoki Kimura, Kaori Machida, Nobutaka Shirasaki, Taku Matsushita
Separation and Purification Technology, 119, 58, 65, 2013年, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, The residual aluminum concentration in treated water after aluminum coagulation and solid-liquid separation is one of the key factors in evaluating the effectiveness of water treatments. Polymeric membrane filters have been widely used to operationally define dissolved substances from particulate matter, and have sometimes been employed in laboratories and pilot studies to approximately simulate media filtration. A comparison between media and membrane filters, however, has not yet been fully investigated. This study compared aluminum concentrations in the filtrate after sand bed and membrane filtrations. The aluminum concentration after sand bed filtration was lower than that after filtration using a membrane with a pore size of 0.1 μm, irrespective of the membrane material, with one exception. A PVDF membrane with a pore size of 0.1 μm produced a similar residual aluminum concentration to that obtained using a sand bed. When the natural organic matter concentration was very low, the aluminum concentration in the PVDF membrane (pore size 0.1 μm) and sand bed filtrates was lower than that obtained using other membranes with the same pore size. It is believed that adsorption of dissolved aluminum may enhance aluminum removal by the sand bed and the PVDF membrane when the aluminum exists in an uncomplexed form with natural organic matter. © 2013 Elsevier B.V. All rights reserved.

A new approach to estimate norovirus removal performance in a membrane filtration process by using virus-like particles and immuno-PCR method　　　　　　　　　　　　　　　
Nobutaka Shirasaki, Taku Matsushita, Yuichi Tatsuki, Yoshihiko Matsui
AWWA/AMTA Membrane Technology Conference and Exposition 2012, 1024, 1028, 2012年
英語, 研究論文（国際会議プロシーディングス）

Coagulation by novel high-basicity poly-aluminum chloride effectively reduces ceramic membrane fouling and residual aluminum　　　　　　　　　　　　　　　
Masaoki Kimura, Yoshihiko Matsui, Taku Matsushita, Nobutaka Shirasaki, Tairyou B. Ishikawa
AWWA/AMTA Membrane Technology Conference and Exposition 2012, 774, 777, 2012年
英語, 研究論文（国際会議プロシーディングス）

Difference in behaviors of F-specific DNA and RNA bacteriophages during coagulation-rapid sand filtration and coagulation-microfiltration processes
N. Shirasaki, T. Matsushita, Y. Matsui, T. Urasaki, K. Ohno
Water Science and Technology: Water Supply, 12, 5, 666, 673, 2012年, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, Difference in behaviors of F-specific DNA and RNA bacteriophages during coagulation-rapid sand filtration and coagulation-microfiltration (MF) processes were investigated by using river water spiked with F-specific DNA bacteriophage f1 and RNA bacteriophage f2. Because the particle characteristics of f1 (filamentous) and f2 (spherical) are quite different and the surface charge of f1 in the river water was slightly more negative than that of f2, the removal ratios of f1 were approximately 1-log lower than the removal ratio of f2 after any treatment process used in the present study. This result indicates that the behaviors of the two bacteriophages during the treatment processes were different, and that the removal of f1 by the combination of coagulation and filtration processes was more difficult than that of f2. The removal ratios for f1 and f2 were approximately 3-log and 4-log, respectively, in the coagulation-rapid sand filtration process, and 6-log and 7-log, respectively, in the coagulation-MF filtration process. Therefore, as expected, the coagulation-MF process appears to be more effective than the coagulation-rapid sand filtration process for the removal of not only spherical viruses but also filamentous viruses. © IWA Publishing 2012.

Virus inactivation during coagulation with aluminum coagulants
Taku Matsushita, Nobutaka Shirasaki, Yoshihiko Matsui, Koichi Ohno
Chemosphere, 85, 4, 571, 576, 2011年10月, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, We used the bacteriophages Qβ and MS2 to determine whether viruses are inactivated by aluminum coagulants during the coagulation process. We performed batch coagulation and filtration experiments with virus-containing solutions. After filtering the supernatant of the coagulated solution through a membrane with a pore size of 50 nm, we measured the virus concentration by both the plaque forming unit (PFU) and polymerase chain reaction (PCR) methods. The virus concentration determined by the PFU method, which determines the infectious virus concentration, was always lower than that determined by the PCR-based method, which determines total virus concentration, regardless of infectivity. This discrepancy can be explained by the formation of aggregates consisting of several virus particles or by the inactivation of viruses in the coagulation process. The former possibility can be discounted because (i) aggregates of several virus particles would not pass through the 50-nm pores of the filtration membrane, and (ii) our particle size measurements revealed that the virus particles in the membrane filtrate were monodispersed. These observations clearly showed that non-infectious Qβ particles were present in the membrane filtrate after the coagulation process with aluminum coagulants. We subsequently revealed that the viruses lost their infectivity after being mixed with hydrolyzing aluminum species during the coagulation process. © 2011 Elsevier Ltd.

Estimation of norovirus removal performance in a coagulation-rapid sand filtration process by using recombinant norovirus VLPs
N. Shirasaki, T. Matsushita, Y. Matsui, A. Oshiba, K. Ohno
Water Research, 44, 5, 1307, 1316, 2010年03月, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, Norovirus (NV) is an important human pathogen that causes epidemic acute nonbacterial gastroenteritis worldwide. Because of the lack of a cell culture system or an animal model for this virus, studies of drinking water treatment such as separation and disinfection processes are still hampered. We successfully estimated NV removal performance during a coagulation-rapid sand filtration process by using recombinant NV virus-like particles (rNV-VLPs) morphologically and antigenically similar to native NV. The behaviors of two widely accepted surrogates for pathogenic waterborne viruses, bacteriophages Qβ and MS2, were also investigated for comparison with that of rNV-VLPs. Approximately 3-log10 removals were observed for rNV-VLPs with a dose of 40 μM-Al or -Fe, as polyaluminum chloride at pH 6.8 or ferric chloride at pH 5.8, respectively. Smaller removal ratios were obtained with alum and ferric chloride at pH 6.8. The removal performance for MS2 was somewhat larger than that for rNV-VLPs, meaning that MS2 is not recommended as an appropriate surrogate for native NV. By comparison, the removal performance for Qβ was similar to, or smaller than, that for rNV-VLPs. However, the removal performances for rNV-VLPs and Qβ differed between the coagulation process and the following rapid sand filtration process. Therefore, Qβ also is not recommended as an appropriate surrogate for native NV. © 2009 Elsevier Ltd. All rights reserved.

Evaluation of norovirus removal performance in a coagulation-ceramic microfiltration process by using recombinant norovirus virus-like particles
N. Shirasaki, T. Matsushita, Y. Matsui, T. Urasaki, A. Oshiba, K. Ohno
Water Science and Technology, 61, 8, 2027, 2034, 2010年, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, Norovirus (NV) is a prototype strain of a group of human caliciviruses responsible for epidemic outbreaks of acute gastroenteritis worldwide. Because of the lack of a cell culture system or an animal model for this virus, studies on drinking water treatment such as separation and disinfection processes are still hampered. In the present study, we investigated NV removal performance as particles during a coagulation-ceramic microfiltration (MF) process by using recombinant NV virus-like particles (rNV-VLPs), which are morphologically and antigenically similar to native NV. We also experimentally investigated the behaviors of two widely accepted surrogates for pathogenic waterborne viruses, bacteriophages Qβ and MS2, for comparison with the behavior of rNV-VLPs. More than 4-log removal was observed for rNV-VLPs with a 1.08 mg-Al/L dose of polyaluminium chloride in the coagulation-ceramic MF process. This high removal ratio of rNV-VLPs satisfies the U.S. Environmental Protection Agency requirement of 4-log removal or inactivation. In addition, the removal ratios of Qβ and MS2 were approximately 2-log and 1-log, smaller than the ratio of rNV-VLPs. Accordingly, both bacteriophages have the potential to become appropriate surrogates for native NV in the coagulation-ceramic MF process, and, of the two, Qβ is the more conservative surrogate. © IWA Publishing 2010.

Feasibility of in-line coagulation as a pretreatment for ceramic microfiltration to remove viruses
Nobutaka Shirasaki, Taku Matsushita, Yoshihiko Matsui, Makoto Kobuke, Koichi Ohno
Journal of Water Supply: Research and Technology - AQUA, 59, 8, 501, 511, 2010年, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, The feasibility of in-line coagulation as a pretreatment for ceramic microfiltration (MF) was verified by comparing its efficiency in the removal of viruses with that of the traditional mechanical mixing approach for coagulation, and by examining the effect of coagulant dose and coagulation time on virus removal. The in-line coagulation-ceramic MF system efficiently removed bacteriophage Qβ and MS2: removal ratios were.>8.2 log for infectious viruses and >5.4 log for total (infectious+ inactivated) virus particles. These values were similar to those of the mechanical coagulation-ceramic MF system. The in-line coagulation system has potential as a useful pretreatment for the removal of viruses as an alternative to the mechanical mixing system, because the former efficiently removes viruses and has a smaller footprint in treatment plants. For the in-line coagulation-ceramic MF system, a coagulant dose of 1.08 mg-Al/L and a coagulation time of 1 min were required to achieve a high level of virus removal. Infectious Qβ and MS2 were removed to similar levels by the two precoagulation methods tested, but the removal of total MS2 particles was higher than that of Qβ particles, possibly because of the selective interaction with the cake layer. © IWA Publishing 2010.

Comparison of behaviors of two surrogates for pathogenic waterborne viruses, bacteriophages Qβ and MS2, during the aluminum coagulation process
N. Shirasaki, T. Matsushita, Y. Matsui, T. Urasaki, K. Ohno
Water Research, 43, 3, 605, 612, 2009年02月, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, Differences in the behaviors of two surrogates for pathogenic waterborne viruses, F-specific RNA bacteriophages Qβ and MS2, were investigated during the coagulation process by using river water spiked with these bacteriophages. The particle size and electrophoretic mobility of Qβ and MS2 were similar, but the removal performances of infectious Qβ and MS2, as measured by a plaque forming unit (PFU) method, differed markedly during the coagulation process. The removal ratio of the infectious Qβ concentration was approximately 2 log higher than that of the infectious MS2 concentration at all coagulant doses tested. The total Qβ and MS2 bacteriophage concentrations, which were measured by a real-time reverse transcription-polymerase chain reaction (RT-PCR) method and represented the total number of bacteriophages regardless of their infectivity, were similar after the coagulation process, suggesting that the behaviors of Qβ and MS2 as particles were similar during the coagulation process. The difference between total concentration and infectious concentration indicated that some of the bacteriophages were probably inactivated during the coagulation process. This difference was larger for Qβ than MS2, meaning that Qβ was more sensitive to the virucidal activity of the aluminum coagulant. Analysis of the PFU and real-time RT-PCR findings together suggested that the difference in removal performances of Qβ and MS2 during the coagulation process was probably caused by differences not in the extent of bacteriophage entrapment in the aluminum floc particles but in the sensitivity to virucidal activity of the aluminum coagulant. © 2008 Elsevier Ltd. All rights reserved.

Comparison of removal performance of two surrogates for pathogenic waterborne viruses, bacteriophage Qβ and MS2, in a coagulation-ceramic microfiltration system
N. Shirasaki, T. Matsushita, Y. Matsui, M. Kobuke, K. Ohno
Journal of Membrane Science, 326, 2, 564, 571, 2009年01月20日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, The removal performance of two surrogates for pathogenic waterborne viruses, F-specific RNA bacteriophages Qβ and MS2, was evaluated during the coagulation-ceramic microfiltration process. River water spiked with these bacteriophages was used to investigate differences in their behaviors. Infectious and total (infectious + inactivated) bacteriophage concentrations were measured by plaque forming unit and real-time reverse transcription-polymerase chain reaction methods, respectively. Removal of infectious Qβ and MS2 was similar under each coagulation condition. Approximately 6-log reduction was achieved for both bacteriophages at 1.08 mg-Al/L of coagulant dose and 5-min coagulation time. At least 4-log reduction occurred even when coagulant dose and coagulation time were reduced to 0.54 mg-Al/L and 1.8 s, respectively. In contrast, removal of total Qβ and MS2 differed markedly. Removal of total MS2 was approximately 2-log larger than that of total Qβ, possibly owing to selective interaction with the cake layer, although the particle diameters and electrophoretic mobilities of Qβ and MS2 were similar. The total number of bacteriophages retained in the microfiltration compartment after 4-h filtration was similar for Qβ and MS2, but there were approximately 3 log fewer infectious Qβ than infectious MS2, probably owing to the difference in sensitivity to the virucidal activity of aluminum coagulant. © 2008 Elsevier B.V. All rights reserved.

Effects of reversible and irreversible membrane fouling on virus removal by a coagulation-microfiltration system
Nobutaka Shirasaki, Taku Matsushita, Yoshihiko Matsui, Koichi Ohno
Journal of Water Supply: Research and Technology - AQUA, 57, 7, 501, 506, 2008年11月, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, We evaluated the removal of virus (bacteriophage Qβ) after hydraulic backwashing and the effects of reversible and irreversible membrane fouling on virus removal by a coagulation-microfiltration (MF) system. The rate of virus removal in the coagulation-MF system was low at the beginning of filtration but increased with filtration time, owing to the accumulation of foulant on the membrane. The rate of virus removal thereafter remained high, even after hydraulic backwashing of the membrane to remove reversible membrane foulant. The presence of irreversible, rather than reversible, membrane foulant contributed to the increase in virus removal rate observed at the beginning of filtration. The irreversible membrane fouling maintained a high virus removal rate even after hydraulic backwashing. Moreover, irreversible fouling of the membrane during long-term filtration (1 month) improved virus removal in the coagulation-MF system, and the membrane excluded virus particles even in the absence of coagulation pretreatment. Therefore, the accumulation of irreversible membrane foulant with filtration time played an important role in virus removal by the coagulation-MF system. © IWA Publishing 2008.

Virus removal in a hybrid coagulation-microfiltration system - Investigating mechanisms of virus removal by a combination of PCR and PFU methods
N. Shirasaki, T. Matsushita, Y. Matsui, K. Ohno, M. Kobuke
Water Science and Technology: Water Supply, 7, 5-6, 1, 8, 2007年, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, Virus removal performance and mechanisms were investigated in a hybrid coagulation - microfiltration (MF) system by using river water spiked with bacteriophage Qβ. Virus removal increased with filtration time: the rate of virus removal was 4 log at the beginning of filtration and gradually increased to 6 log over 5 h, probably because of the growth of a cake layer that accumulated on the membrane surface. Quantification of the virus particles in the MF compartment by a combination of a polymerase chain reaction (PCR) method and a plaque forming unit (PFU) method revealed that most of the virus (> 99.999%) in the MF compartment was entrapped in the aluminium floc and then located in the solid phase; most of the virus (> 99.9%) in the solid phase was inactivated. The rate of recovery of virus particles from the MF compartment decreased with filtration time: after 3 h of filtration approximately half of the virus particles in the MF compartment were not recovered by hydraulic backwashing, indicating that the virus might have been retained on the MF membrane as part of an irreversible foulant. © IWA Publishing 2007.

Analysing mass balance of viruses in a coagulation - Ceramic microfiltration hybrid system by a combination of the polymerase chain reaction (PCR) method and the plaque forming units (PFU) method
Taku Matsushita, Y. Matsui, N. Shirasaki
Water Science and Technology, 53, 7, 199, 207, 2006年, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, Virus removal experiments using river water spiked with bacteriophages were conducted by an inline coagulation-ceramic microfiltration hybrid system to investigate the effects of filtration flux (62.5 and 125 L/ (m2 × h)) and type of virus (Qβ and MS2) on virus removal. In addition, the mass balance of viruses through the hybrid system was analysed by quantifying the infectious and inactive viruses by a combination of the polymerase chain reaction (PCR) method and the plaque forming units (PFU) method. Even when the system was operated at high filtration flux (125 L/(m2 × h)), high virus removal (>6 log) with short coagulation time (2.4 s) was successfully achieved by dosing polyaluminium chloride (PACl) at more than 1.08 mg-Al /L. Removal performances were different between Qβ and MS2, although their diameters are almost the same: greater virus removal was achieved for MS2 at PACl dosing of 0.54 mg-Al/L, and for Qβ at PACl dosing of more than 1.08 mg-Al/L. The combination of the PCR and PFU methods revealed that two phenomena, adsorption to/entrapment in aluminium floc and virucidal activity of PACl, partially account for the high virus removal in the coagulation-MF hybrid system. © IWA Publishing 2006.

Effect of membrane pore size, coagulation time, and coagulant dose on virus removal by a coagulation-ceramic microfiltration hybrid system
Taku Matsushita, Y. Matsui, N. Shirasaki, Y. Kato
Desalination, 178, 1-3 SPEC. ISS., 21, 26, 2005年07月10日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, We studied virus removal from spiked river water by an in-line coagulation-ceramic microfiltration hybrid system to investigate the effects of (1) coagulant dose (0.54, 1.08, and 1.62 mg Al/L), (2) pore size of the MF membrane (0.1, 0.5, and 1.0 μm), and (3) coagulation time (1.1, 2.4, and 60 s). We found that (1) coagulant dose strongly affected virus removal. Whereas 7.4 log removal was achieved with 1.62 mg Al/L PACl dosing, only 2.8 log removal was observed with 0.54 mg Al/L; thus, the larger the coagulant dose, the greater the virus removal. (2) Pore size of the MF membrane also affected virus removal: pore sizes of 0.5 and 1.0 μ showed about 1 log less removal than the 0.1-μm pore-size MF membrane. (3) Coagulation time slightly affected virus removal: the longer the coagulation time, the greater the reduction in virus level, but the effect was not large. Overall, the combination of in-line coagulation prior to microfiltration enables much shorter coagulation times than in conventional treatment plants: dosing with at least 1.08 mg Al/L PACl in the hybrid system allowed the coagulation time to be only 2.4 s. © 2005 Elsevier B.V. All rights reserved.

流体工学Ⅱ　　　　　　　　　　　　　　　
北海道大学

反応工学　　　　　　　　　　　　　　　
北海道大学

環境創生工学特別研究　　　　　　　　　　　　　　　
北海道大学

環境創生工学特別演習　　　　　　　　　　　　　　　
北海道大学

卒業論文　　　　　　　　　　　　　　　
北海道大学

環境工学ゼミナールⅡ　　　　　　　　　　　　　　　
北海道大学

環境工学ゼミナールⅠ　　　　　　　　　　　　　　　
北海道大学

環境工学概論　　　　　　　　　　　　　　　
北海道大学

環境工学　　　　　　　　　　　　　　　
北海道大学

環境工学序論　　　　　　　　　　　　　　　
北海道大学

一般教育演習　　　　　　　　　　　　　　　
北海道大学

環境工学実験Ⅱ　　　　　　　　　　　　　　　
北海道大学

工学基礎演習　　　　　　　　　　　　　　　
北海道大学

反応工学演習　　　　　　　　　　　　　　　
北海道大学

環境リスク解析学　　　　　　　　　　　　　　　
北海道大学

革新的VLPsの創成が拓くウイルス浄水処理の新展開　　　　　　　　　　　　　　　
科学技術推進機構 創発的研究支援事業
2022年 - 2028年
白崎伸隆
研究代表者

水道原水河川に存在する病原ウイルスの感染力評価：活性炭と限外ろ過膜を組み合わせた新規ウイルス濃縮法の構築と適用　　　　　　　　　　　　　　　
河川財団 令和6年度河川基金助成 一般研究者
2024年 - 2025年
白崎伸隆
研究代表者

遺伝子組換と非ウイルスベクター技術を用いた培養に頼らないウイルスの浄水処理性評価　　　　　　　　　　　　　　　
日本学術振興会科学研究費補助金 基盤研究（A）
2022年 - 2024年
松下拓, 白崎伸隆
研究分担者

単離技術と遺伝子操作系を駆使した遺伝的に多様な病原ウイルスの浄水消毒処理性評価　　　　　　　　　　　　　　　
日本学術振興会科学研究費補助金 基盤研究（B）
2022年 - 2024年
白崎伸隆, 松下拓
研究代表者

サポウイルスに対する浄水消毒処理の有効性評価：In vitro細胞培養増殖系の活用　　　　　　　　　　　　　　　
前田記念工学振興財団 令和6年度研究助成
2024年
白崎伸隆
研究代表者

汎用細胞増殖系を活用した浄水処理工程におけるサポウイルスの未知動態の解明　　　　　　　　　　　　　　　
日本学術振興会科学研究費補助金 挑戦的研究（萌芽）
2022年 - 2023年
白崎伸隆
研究代表者

超微粉炭プレコートと超高塩基度PACl凝集によるファウリングフリー膜ろ過　　　　　　　　　　　　　　　
日本学術振興会科学研究費補助金 基盤研究（A）
2021年 - 2023年
松井佳彦, 松下拓, 白崎伸隆, 安藤直哉
研究分担者

ICC-PCR法とPMAxx-PCR法を併用した水道原水における感染力を有する病原ウイルスの存在実態の把握　　　　　　　　　　　　　　　
前田記念工学振興財団 令和5年度研究助成
2023年
白崎伸隆
研究代表者

感染力評価と外殻タンパク質損傷評価を併用した水道原水河川における病原ウイルスの存在実態の把握　　　　　　　　　　　　　　　
大林財団 2022年度研究助成
2023年
白崎伸隆
研究代表者

急速砂ろ過方式から膜ろ過方式への浄水施設更新前後におけるウイルス除去性能の比較　　　　　　　　　　　　　　　
クボタ若手研究者研究奨励制度（水道分野） 第2回
2021年 - 2022年
白崎伸隆
研究代表者

浄水処理におけるヒト感染コロナウイルスの除去・不活化特性の評価　　　　　　　　　　　　　　　
フソウ技術開発振興基金 令和2年度研究助成
2020年 - 2021年
白崎伸隆
研究代表者

リバースジェネティクス法を用いたウイルス野生株・流行株の塩素消毒不活化特性の把握　　　　　　　　　　　　　　　
日本学術振興会科学研究費補助金 挑戦的研究（萌芽）
2020年 - 2021年
白崎伸隆
研究代表者

遺伝的多様性を考慮した水道原水中に存在する病原ウイルスの浄水処理性評価　　　　　　　　　　　　　　　
日本学術振興会科学研究費補助金 基盤研究（B）
2019年 - 2021年
白崎伸隆, 松井佳彦, 松下拓
研究代表者

培養に頼らないウイルスの浄水処理性評価手法と高効率浄水ウイルス処理システムの構築　　　　　　　　　　　　　　　
日本学術振興会科学研究費補助金 基盤研究（A）
2018年 - 2021年
松下拓, 松井佳彦, 白崎伸隆
研究分担者

ヒト感染コロナウイルスの浄水処理性の評価：凝集ろ過分離性及び消毒不活化性の把握　　　　　　　　　　　　　　　
前田記念工学振興財団 令和3年度研究助成
2021年
白崎伸隆
研究代表者

遺伝子封入VLPsを用いた培養困難なノロウイルスの浄水処理性評価　　　　　　　　　　　　　　　
フソウ技術開発振興基金 令和元年度研究助成
2019年 - 2020年
白崎伸隆
研究代表者

安全良質な水の持続的供給のための革新的前処理－膜分離浄水システム　　　　　　　　　　　　　　　
日本学術振興会科学研究費補助金 基盤研究（S）
2016年 - 2020年
松井佳彦, 松下拓, 白崎伸隆
研究分担者

標識ラベルした凝集剤と同位体顕微鏡観察による膜ろ過ファウリングの解明　　　　　　　　　　　　　　　
日本学術振興会科学研究費補助金 挑戦的研究（萌芽）
2018年 - 2019年
松井佳彦, 白崎伸隆
研究分担者

水道原水中に高濃度で存在するトウガラシ微斑ウイルスを指標とした実浄水処理場におけるウイルスの処理性評価　　　　　　　　　　　　　　　
フソウ技術開発振興基金 平成30年度研究助成
2018年 - 2019年
白崎伸隆
研究代表者

DNAを封入したウイルス外套蛋白粒子を用いた培養困難なウイルスの浄水処理性評価　　　　　　　　　　　　　　　
日本学術振興会科学研究費補助金 挑戦的研究（萌芽）
2017年 - 2018年
松下拓, 白崎伸隆
研究分担者

水道原水中に高濃度で存在するトウガラシ微斑ウイルスを用いた実浄水処理場における水系感染症ウイルスの処理性の推定　　　　　　　　　　　　　　　
平成29年度クリタ水･環境科学振興財団 国内研究助成 自然科学・技術（1）
2017年 - 2018年
白崎伸隆
研究代表者

遺伝子型の差異を考慮した培養不可能なウイルス及び消毒耐性ウイルスの浄水処理性評価　　　　　　　　　　　　　　　
日本学術振興会科学研究費補助金 若手研究（A）
2016年 - 2018年
白崎伸隆
研究代表者

カプシドタンパクの精密質量分析によるウイルス消毒不活化・消毒耐性メカニズムの解明　　　　　　　　　　　　　　　
日本学術振興会科学研究費補助金 挑戦的萌芽研究
2016年 - 2017年
白崎伸隆
研究代表者

遺伝子封入VLPsを用いた培養困難なウイルスの浄水処理性評価　　　　　　　　　　　　　　　
ノースティック財団・若手研究人材育成事業 若手研究人材・ネットワーク育成補助金（ノースタレント補助金）
2017年
白崎伸隆
研究代表者

PMA-PCR法による水道原水河川における感染性を有する病原ウイルスの存在実態の把握　　　　　　　　　　　　　　　
河川財団 平成29年度河川基金助成 若手研究者 一般的助成
2017年
白崎伸隆
研究代表者

水系感染症ウイルスを高度・高効率に処理可能な先端的ウイルス除去システムの開発　　　　　　　　　　　　　　　
向科学技術振興財団 平成28年度研究助成
2017年
白崎伸隆
研究代表者

ヒト嗅覚を検出器としたGC/MS法の確立とそれを用いた浄水異臭味の全体像の把握　　　　　　　　　　　　　　　
日本学術振興会科学研究費補助金 挑戦的萌芽研究
2015年 - 2016年
松下拓, 白崎伸隆
研究分担者

分離膜のどこでファウリングが生じているのか：安定同位体顕微鏡による解明　　　　　　　　　　　　　　　
日本学術振興会科学研究費補助金 挑戦的萌芽研究
2015年 - 2016年
松井佳彦, 白崎伸隆
研究分担者

先端的要素技術と膜分離の統合による水処理システムの革新　　　　　　　　　　　　　　　
日本学術振興会科学研究費補助金 基盤研究（S）
2012年 - 2016年
松井佳彦, 松下拓, 白崎伸隆
研究分担者

Contaminant Candidate Listに掲載された水系感染症ウイルスの浄水処理性評価及びウイルス処理性指標の探索　　　　　　　　　　　　　　　
平成26年度クリタ水･環境科学振興財団 国内研究助成 自然科学・技術（1）
2014年 - 2015年
白崎伸隆
研究代表者

精密質量分析を応用した新手法による水系感染症ウイルスの消毒不活化メカニズムの解明　　　　　　　　　　　　　　　
日本学術振興会科学研究費補助金 挑戦的萌芽研究
2014年 - 2015年
白崎伸隆
研究代表者

培養不可能な水系感染症ウイルスの浄水処理性評価とウイルス処理技術の高度・高効率化　　　　　　　　　　　　　　　
日本学術振興会科学研究費補助金 若手研究（A）
2013年 - 2015年
白崎伸隆
研究代表者

培養不可能な水系感染症ウイルスの新規浄水処理性評価手法の開発と応用　　　　　　　　　　　　　　　
住友財団 2012年度環境研究助成
2012年 - 2013年
白崎伸隆
研究代表者

ウイルス様粒子と新規免疫PCR法を併用したノロウイルスの膜ろ過処理性評価　　　　　　　　　　　　　　　
服部報公会 平成24年度工学研究奨励援助金
2012年 - 2013年
白崎伸隆
研究代表者

蛍光偏光を用いた感染性を有する水系感染症ウイルスの迅速且つ簡便な新規定量法の開発　　　　　　　　　　　　　　　
日本学術振興会科学研究費補助金 挑戦的萌芽研究
2012年 - 2013年
白崎伸隆
研究代表者

機能性凝集剤による前凝集とセラミック膜ろ過を融合した先端的ウイルス処理システムの開発　　　　　　　　　　　　　　　
前田記念工学振興財団 平成25年度研究助成
2013年
白崎伸隆
研究代表者

ウイルス様粒子（VLPs）を用いた培養不可能な水系感染症ウイルスの浄水処理性評価　　　　　　　　　　　　　　　
平成23年度クリタ水･環境科学振興財団 国内研究助成 自然科学分野 萌芽的研究
2011年 - 2012年
白崎伸隆
研究代表者

ウイルスを含む広範な原水水質に対応し得る新規凝集剤の開発　　　　　　　　　　　　　　　
国際科学技術財団 2012年研究助成
2012年
白崎伸隆
研究代表者

吸着・凝集・膜分離を融合した次世代型ウイルス除去システムの開発　　　　　　　　　　　　　　　
JFE21世紀財団 2011年度技術研究助成 地球環境・地球温暖化防止技術研究
2012年
白崎伸隆
研究代表者

ウイルス処理に有効な新規凝集剤の開発　　　　　　　　　　　　　　　
日本学術振興会科学研究費補助金 研究活動スタート支援
2011年
白崎伸隆
研究代表者

ウイルス様粒子（VLPs）を用いたノロウイルスの浄水処理性の評価
日本学術振興会科学研究費補助金 特別研究員奨励費
2009年 - 2010年
白崎伸隆
水系感染症を引き起こす病原性ウイルスの中でも,感染事例が世界中で増加しているヒトノロウイルスは,未だ効率的な培養法が確立されていないことから,添加実験による浄水処理性の評価を行うために必要なウイルス量を確保することが極めて困難であり,培養可能な病原性ウイルスと比べて研究が格段に遅れている.そこで,本研究では,ヒトノロウイルスの物理的な浄水処理性を,遺伝子組換えバキュロウイルスとカイコを用いたタンパク質発現法により発現させたヒトノロウイルス外套タンパク粒子(VLPs)を用いて評価することを目的とした.
本年度は,凝集沈澱-MF膜ろ過処理におけるVLPsの処理性を調べた.凝集沈澱-MF膜ろ過処理においては,凝集剤としてPACIを用いた場合,4log以上のVLPsの除去率が得られた.従って,凝集沈澱-MF膜ろ過処理を用いることにより,米国環境保護局の要求する4logの腸管系ウイルスの除去率を達成し得ることが示唆された.一方,凝集剤としてalumを用いた場合,VLPsの除去率は約3logとなり,PACIを用いた場合の除去率よりも低くなった.従って,凝集沈澱-MF膜ろ過処理においては,PACIを用いることにより,alumを用いる場合に比べて効果的にVLPsを除去できることが分かった.加えて,VLPsと大腸菌ファージQβおよびMS2の処理性を比較したところ,いずれの凝集剤を用いた場合でも,QβおよびMS2の除去率は,VLPsの除去率よりも低くなった.従って,凝集沈澱-MF膜ろ過処理においては,Qβ,MS2共にヒトノロウイルスの安全側の指標と成り得る可能性が示された.
研究代表者