Concentration techniques tailored for the detection of SARS-CoV-2 genetic material in domestic wastewater and treatment plant sludge: A review

Upon the outbreak of COVID-19 pandemic, detection and quantification of SARS-CoV-2 genetic material in domestic wastewater have led to an increase in the efforts to define and implement the wastewater-based epidemiology (WBE). This application provides valuable information to define local contamination monitoring, emergence of COVID-19 and its variants and many other aspects to cope with and control the pandemic. WBE surveillance, however, requires several consecutive steps such as sampling, pretreatment and concentration of samples, and detection and quantification of SARS-CoV-2 genetic material in wastewater. In this review paper, the literature regarding to all these applications reviewed considering their advantages, disadvantages as well as their applicability. A specific emphasis was placed on the last step, detection and quantification since it covers the most critical procedure for concentrating the virus before measurement. Evaluation of the existing data indicating ultrafiltration, polyethylene glycol (PEG) precipitation and electronegative membrane filtration (ENMF) were the most promising techniques for concentration. The ongoing studies are proposed to be continued within the context of standard methods. Future research needs are delineated and suggestions are made for details.