The detectability and removal efficiency of SARS-CoV-2 in a large-scale septic tank of a COVID-19 quarantine facility in Japan

Ryo Iwamoto; Kiyoshi Yamaguchi; Chisato Arakawa; Hiroki Ando; Eiji Haramoto; Ken-Ichi Setsukinai; Kotoe Katayama; Takuya Yamagishi; Sumire Sorano; Michio Murakami; Shigeru Kyuwa; Hiroyuki Kobayashi; Satoshi Okabe; Seiya Imoto; Masaaki Kitajima

doi:10.1016/j.scitotenv.2022.157869

The detectability and removal efficiency of SARS-CoV-2 in a large-scale septic tank of a COVID-19 quarantine facility in Japan

Sci Total Environ. 2022 Nov 25:849:157869. doi: 10.1016/j.scitotenv.2022.157869. Epub 2022 Aug 6.

Authors

Affiliations

¹ Shionogi & Co., Ltd., 1-8 Doshomachi 3-Chome, Chuo-ku, Osaka, Osaka 541-0045, Japan; AdvanSentinel Inc., 1-8 Doshomachi 3-Chome, Chuo-ku, Osaka, Osaka 541-0045, Japan.
² Division of Clinical Genome Research, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
³ Division of Environmental Engineering, Faculty of Engineering, Hokkaido University, North 13 West 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan.
⁴ Interdisciplinary Center for River Basin Environment, Graduate Faculty of Interdisciplinary Research, University of Yamanashi, 4-3-11 Takeda, Kofu, Yamanashi 400-8511, Japan.
⁵ Shionogi & Co., Ltd., 1-8 Doshomachi 3-Chome, Chuo-ku, Osaka, Osaka 541-0045, Japan.
⁶ Human Genome Center, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
⁷ Antimicrobial Resistance Research Center, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.
⁸ Department of Disease Control, Faculty of Infectious and Tropical Disease, The London School of Hygiene & Tropical Medicine, Keppel St., London WC1E 7HT, UK; School of Tropical Medicine and Global Health, Nagasaki University, 1-14 Bunkyomachi, Nagasaki, Nagasaki 852-8521, Japan.
⁹ Center for Infectious Disease Education and Research, Osaka University, 2-8 Yamadaoka, Suita, Osaka 565-0871, Japan.
¹⁰ Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
¹¹ Division of Environmental Engineering, Faculty of Engineering, Hokkaido University, North 13 West 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan. Electronic address: mkitajima@eng.hokudai.ac.jp.

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is known to be present in sewage, and wastewater-based epidemiology has attracted much attention. However, the physical partitioning of SARS-CoV-2 in wastewater and the removal efficiency of treatment systems require further investigation. This study aimed to investigate the detectability and physical partitioning of SARS-CoV-2 in wastewater and assess its removal in a large-scale septic tank employing anaerobic, anoxic, and oxic processes in a sequential batch reactor, which was installed in a coronavirus disease 2019 (COVID-19) quarantine facility. The amount of SARS-CoV-2 RNA in wastewater was determined with polyethylene glycol (PEG) precipitation followed by quantitative polymerase chain reaction (qPCR), and the association of SARS-CoV-2 with wastewater solids was evaluated by the effect of filtration prior to PEG precipitation (pre-filtration). The amount of SARS-CoV-2 RNA detected from pre-filtered samples was substantially lower than that of samples without pre-filtration. These results suggest that most SARS-CoV-2 particles in wastewater are associated with the suspended solids excluded by pre-filtration. The removal efficiency of SARS-CoV-2 in the septic tank was evaluated based on the SARS-CoV-2 RNA concentrations in untreated and treated wastewater, which was determined by the detection method optimized in this study. Escherichia coli and pepper mild mottle virus (PMMoV) were also quantified to validate the wastewater treatment system's performance. The mean log₁₀ reduction values of SARS-CoV-2, E. coli, and PMMoV were 2.47 (range, 2.25-2.68), 2.81 (range, 2.45-3.18), and 0.66 (range, 0.61-0.70), respectively, demonstrating that SARS-CoV-2 removal by the wastewater treatment system was comparable to or better than the removal of fecal indicators. These results suggest that SARS-CoV-2 can be readily removed by the septic tank. This is the first study to determine the removal efficiency of SARS-CoV-2 in a facility-level sequencing batch activated sludge system.

Keywords: Activated sludge; Quantification method; SARS-CoV-2; Wastewater treatment; Wastewater-based epidemiology.

MeSH terms

COVID-19* / epidemiology
Escherichia coli
Humans
Japan
Polyethylene Glycols
Quarantine
RNA, Viral
SARS-CoV-2*
Sewage
Wastewater

Substances

RNA, Viral
Sewage
Waste Water
Polyethylene Glycols