title: Removal of human pathogenic viruses in a down-flow hanging sponge (DHS) reactor treating municipal wastewater and health risks associated with utilization of the effluent for agricultural irrigation.
abstract: A down-flow hanging sponge (DHS) reactor has been developed as a cost-effective wastewater treatment system that is adaptable to local conditions in low-income countries. A pilot-scale DHS reactor previously demonstrated stable reduction efficiencies for chemical oxygen demand (COD) and ammonium nitrogen over a year at ambient temperature, but the pathogen reduction efficiency of the DHS reactor has yet to be investigated. In the present study, the reduction efficiency of a pilot-scale DHS reactor fed with municipal wastewater was investigated for 10 types of human pathogenic viruses (norovirus GI, GII and GIV, aichivirus, astrovirus, enterovirus, hepatitis A and E viruses, rotavirus, and sapovirus). DHS influent and effluent were collected weekly or biweekly for 337 days, and concentrations of viral genomes were determined by microfluidic quantitative PCR. Aichivirus, norovirus GI and GII, enterovirus, and sapovirus were frequently detected in DHS influent, and the log10reduction (LR) of these viruses ranged from 1.5 to 3.7. The LR values for aichivirus and norovirus GII were also calculated using a Bayesian estimation model, and the average LR (±standard deviation) values for aichivirus and norovirus GII were estimated to be 1.4 (±1.5) and 1.8 (±2.5), respectively. Quantitative microbial risk assessment was conducted to calculate a threshold reduction level for norovirus GII that would be required for the use of DHS effluent for agricultural irrigation, and it was found that LRs of 2.6 and 3.7 for norovirus GII in the DHS effluent were required in order to not exceed the tolerable burden of disease at 10-4and 10-6disability-adjusted life years loss per person per year, respectively, for 95% of the exposed population during wastewater reuse for irrigation.
authors.affiliation: Department of Civil Engineering, National Institute of Technology, Nagaoka College, 888 Nishikatakaimachi, Nagaoka, Niigata, 940-0834, Japan.
authors.forename: Naohiro
authors.initials: N
authors.lastname: Kobayashi
authors.affiliation: Department of Civil Engineering, National Institute of Technology, Nagaoka College, 888 Nishikatakaimachi, Nagaoka, Niigata, 940-0834, Japan. Electronic address: oshiki@nagaoka-ct.ac.jp.
authors.forename: Mamoru
authors.initials: M
authors.lastname: Oshiki
authors.affiliation: Division of Environmental Engineering, Faculty of Engineering, Hokkaido University, North 13, West-8, Sapporo, Hokkaido, 060-8628, Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Ito
authors.affiliation: Transdisciplinary Research Integration Center, 4-3-13 Toranomon, Minato-ku, Tokyo, Japan; Transdisciplinary Research Integration Center, National Institute of Polar Research, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Segawa
authors.affiliation: Department of Environmental Systems Engineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata, 940-2188, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Hatamoto
authors.affiliation: Department of Computer Science, Gunma University, 3-39-22 Syowamachi, Maebashi, Gunma, 371-8511, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Kato
authors.affiliation: Department of Science of Technology Innovation, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata, 940-2188, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamaguchi
authors.affiliation: Department of Civil and Environmental Engineering, Tohoku University, 6-6-06 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, 980-8579, Japan.
authors.forename: Kengo
authors.initials: K
authors.lastname: Kubota
authors.affiliation: New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-06 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, 980-8579, Japan.
authors.forename: Masanobu
authors.initials: M
authors.lastname: Takahashi
authors.affiliation: Faculty of Applied Life Sciences, Niigata University of Pharmacy and Applied Life Sciences, 265-1 Higashiyama, Akiba-ku, Niigata, 956-0841, Japan.
authors.forename: Akinori
authors.initials: A
authors.lastname: Iguchi
authors.affiliation: Department of Civil Engineering, National Institute of Technology, Kagawa College, 355 Chokushicho, Takamatsu, Kagawa, 761-8058, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Tagawa
authors.affiliation: Department of Civil Engineering, National Institute of Technology, Kisarazu College, 2-11-1 Kiyomidaihigashi, Kisarazu, Chiba, 292-0041, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Okubo
authors.affiliation: Department of Civil Engineering, National Institute of Technology, Kisarazu College, 2-11-1 Kiyomidaihigashi, Kisarazu, Chiba, 292-0041, Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Uemura
authors.affiliation: New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-06 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, 980-8579, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Harada
authors.affiliation: Department of Civil Engineering, National Institute of Technology, Nagaoka College, 888 Nishikatakaimachi, Nagaoka, Niigata, 940-0834, Japan.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Motoyama
authors.affiliation: Department of Civil Engineering, National Institute of Technology, Nagaoka College, 888 Nishikatakaimachi, Nagaoka, Niigata, 940-0834, Japan.
authors.forename: Nobuo
authors.initials: N
authors.lastname: Araki
authors.affiliation: Division of Environmental Engineering, Faculty of Engineering, Hokkaido University, North 13, West-8, Sapporo, Hokkaido, 060-8628, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Sano
mesh_terms: D057914:Agricultural Irrigation; D000818:Animals; D001499:Bayes Theorem; D006801:Humans; D011161:Porifera; D014780:Viruses; D062065:Wastewater / Q000821:virology*
chemical_list: D062065:Wastewater
keywords: Down-flow hanging sponge reactor; Human pathogenic virus; Log(10) reduction; Microfluidic quantitative PCR; Quantitative microbial risk assessment; Wastewater reclamation and reuse