Table 2.

Methods of concentration of viruses in wastewater samples.

Method	Sample Volume (L)	Advantages	Disadvantages	References
VIRADEL	0.50–400	Reduces amount of PCR inhibitors	Higher sample volume needed Requires pre-conditioning of samples (when using electronegative membranes) Multiple steps lead to viral loss	Falman et al., 2019; Kuo et al., 2010; Masclaux et al., 2013; O’Brien et al., 2017; Osuolale and Okoh, 2017; Prado et al., 2011; Soto-Beltran et al., 2013
Ultrafiltration	1–10	May be used for simultaneous concentration of viruses and other microbes	Clogging of filters when sample is of high turbidity (except for tangential ultrafiltration) Slow filtration rate	Cashdollar and Wymer, 2013; Jahne et al., 2020; Morales-Morales et al., 2003; Sidhu et al., 2018
Centrifugal ultrafiltration	0.01–0.10	Lower sample volume needed Reduces amount of PCR inhibitors Rapid and simpler method Easier processing of multiple samples	Small pore size may result to clogging of filters High turbidity samples may need pre-filtration	Nordgren et al., 2009; Sidhu et al., 2013
Precipitation with PEG	0.40–1	Higher efficiency in concentrating RNA viruses	Concentrates enzymatic inhibitors (PCR inhibitors)	Amdiouni et al., 2012; Ibrahim et al., 2017; Masclaux et al., 2013; Strubbia et al., 2019