Risk management of viral infectious diseases in wastewater reclamation and reuse: Review

Abstract

Inappropriate usage of reclaimed wastewater has caused outbreaks of viral infectious diseases worldwide. International and domestic guidelines for wastewater reuse stipulate that virus infection risks are to be regulated by the multiple-barrier system, in which a wastewater treatment process composed of sequential treatment units is designed based on the pre-determined virus removal efficiency of each unit. The objectives of this review were to calculate representative values of virus removal efficiency in wastewater treatment units based on published datasets, and to identify research topics that should be further addressed for improving implementation of the multiple-barrier system. The removal efficiencies of human noroviruses, rotaviruses and enteroviruses in membrane bioreactor (MBR) and conventional activated sludge (CAS) processes were obtained by a systematic review protocol and a meta-analysis approach. The log10 reduction (LR) of norovirus GII and enterovirus in MBR were 3.35 (95% confidence interval: 2.39, 4.30) and 2.71 (1.52, 3.89), respectively. The LR values of rotavirus, norovirus GI and GII in CAS processes were 0.87 (0.20, 1.53), 1.48 (0.96, 2.00) and 1.35 (0.52, 2.18), respectively. The systematic review process eliminated a substantial number of articles about virus removal in wastewater treatment because of the lack of information required for the meta-analysis. It is recommended that future publications should explicitly describe their treatment of left-censored datasets. Indicators, surrogates and methodologies appropriate for validating virus removal performance during daily operation of wastewater reclamation systems also need to be identified.

Keywords: Meta-analysis; Multiple-barrier system; Viral infectious diseases; Virus log(10) reduction; Wastewater reclamation; Water reuse.

Graphical abstract

Fig. 1

Schematic representation of the multiple-barrier system for the pathogen risk management in wastewater reclamation. The multiple-barrier system consists of multiple steps where the pathogen log₁₀ reduction (LR) credit of each step has already been determined. The total pathogen LR in the system is compared with the performance target with respect to the usage purpose of reclaimed wastewater.

Fig. 2

Removal efficiency of norovirus genogroup II by membrane bioreactors. Black square is the mean value of virus log reduction (LR) obtained in each study, and a bar indicates 95% confidence interval (CI). The sample number in each study is indicated in a parenthesis next to 95% CI values. The total LR value is obtained by the calculation procedure indicated in Supplementary materials.

Fig. 3

Removal efficiency of enteroviruses by membrane bioreactors. Black square is the mean value of virus log reduction (LR) obtained in each study, and a bar indicates 95% confidence interval (CI). The sample number in each study is indicated in a parenthesis next to 95% CI values. The total LR value is obtained by the calculation procedure indicated in Supplementary materials.

Fig. 4

Removal efficiency of rotaviruses by activated sludge processes. Black square is the mean value of virus log reduction (LR) obtained in each study, and a bar indicates 95% confidence interval (CI). The sample number in each study is indicated in a parenthesis next to 95% CI values. The total LR value is obtained by the calculation procedure indicated in Supplementary materials.

Fig. 5

Removal efficiency of norovirus genogroup I by activated sludge processes. Black square is the mean value of virus log reduction (LR) obtained in each study, and a bar indicates 95% confidence interval (CI). The sample number in each study is indicated in a parenthesis next to 95% CI values. The total LR value is obtained by the calculation procedure indicated in Supplementary materials.

Fig. 6

Removal efficiency of norovirus genogroup II by activated sludge processes. Black square is the mean value of virus log reduction (LR) obtained in each study, and a bar indicates 95% confidence interval (CI). The sample number in each study is indicated in a parenthesis next to 95% CI values. The total LR value is obtained by the calculation procedure indicated in Supplementary materials.