Occurrence, fates and potential treatment approaches for removal of viruses from wastewater: A review with emphasis on SARS-CoV-2

Abstract

The world is combating the emergence of Coronavirus disease 2019 (COVID-19) caused by novel coronavirus; severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Further, due to the presence of SARS-CoV-2 in sewage and stool samples, its transmission through water routes cannot be neglected. Thus, the efficient treatment of wastewater is a matter of utmost importance. The conventional wastewater treatment processes demonstrate a wide variability in absolute removal of viruses from wastewater, thereby posing a severe threat to human health and environment. The fate of SARS-CoV-2 in the wastewater treatment plants and its removal during various treatment stages remains unexplored and demands immediate attention; particularly, where treated effluent is utilised as reclaimed water. Consequently, understanding the prevalence of pathogenic viruses in untreated/treated waters and their removal techniques has become the topical issue of the scientific community. The key objective of the present study is to provide an insight into the distribution of viruses in wastewater, as well as the prevalence of SARS-CoV-2, and its possible transmission by the faecal-oral route. The review also gives a detailed account of the major waterborne and non-waterborne viruses, and environmental factors governing the survival of viruses. Furthermore, a comprehensive description of the potential methods (physical, chemical, and biological) for removal of viruses from wastewater has been presented. The present study also intends to analyse the research trends in microalgae-mediated virus removal and, inactivation. The review also addresses the UN SDG 'Clean Water and Sanitation' as it is aimed at providing pathogenically safe water for recycling purposes.

Keywords: ASP, Activated Sludge Process; COVID-19; COVID-19, Coronavirus Disease 2019; DUV-LED, Deep Ultraviolet Light-Emitting Diode; E.coli, Escherichia coli; EPS, Exopolysaccharide; LRV, Log Reduction Value; MBR, Membrane Bioreactor; MERS-CoV, Middle East Respiratory Syndrome Coronavirus; MLSS, Mixed Liquor Suspended Solids; Microalgaee; PMR, Photocatalytic Membrane Reactor; Phycoremediationn; RH, Relative Humidity; SARS-CoV, Severe Acute Respiratory Syndrome Coronavirus; SARS-CoV-2, Severe Acute Respiratory Syndrome Coronavirus 2; SBBGR, Sequencing Batch Biofilter Granular Reactor; SEM, Scanning Electron Microscopy; SSF, Slow Sand Filtration; UASB, Upflow Anaerobic Sludge Blanket; UN SDG, United Nations Sustainable Development Goal; UV, Ultraviolet; WHO, World Health Organisation; WWTP, Wastewater Treatment Plant; Waterbornee; dsDNA, Double stranded Deoxyribonucleic Acid; dsRNA, Double stranded Ribonucleic acid; ssRNA, Single stranded Ribonucleic Acid.

Graphical abstract

Fig. 1

Possible transmission routes of viruses through contaminated water.

Fig. 2

Graphical illustration of possible modes of microalgae-mediated virus inactivation, (a): EPS entrapment; (b): Sunlight-mediated inactivation (exogenous mode of indirect mechanism); (c) Toxic algal exudates; (d): Electrostatic attraction; (Abbreviations: EPS, exopolysaccharide; ROS, reactive oxygen species).