Table 1.

A summary of the commonly used methods for viral detection in wastewater.

Method	Sensitivity	Time required	LOD (SARS-COV2)	Specificity	Advantages	Disadvantages	References
RT-PCR	89-95%	2 h	10 copies/μL	93%	→Highly sensitive towards specific organisms	→Requires expensive instruments →Requires the knowledge of the detected organisms →Requires concentration of samples →Highly susceptible to contamination by inhibitors →Have low limit of detection →Cannot differentiate between dead and alive organisms →Interference of humic acids →Relatively slow detection time	(Asif et al., 2021; Nassir et al., 2020; Pilevar et al., 2020; Rabiee et al., 2020; Russo et al., 2020)
NASBA	Up to 95%	60-90 mins	1 copy/reaction	98.9%	→Highly sensitive and specificity →Simple procedure →Relatively fast →Sample contamination resistance	→Expensive kits →Few available essays for environmental sampling →False positive has higher chances over false negative	(Fakruddin et al., 2012; Lahrich et al., 2021; Matovu et al., 2010; Chantratita et al., 2004)
Biosensors	Up to 96.7%	15 mins	0.22 pM	Up to 100%	→Affordable cost →High sensitivity →Rapid real time detection →Simple procedure →Portability →Requires small samples	→Antibody binding is influenced by environmental parameters such as pH, temperature, etc. →Binding of antibody-antigen can be influenced by reagents, solvents, or radiation →Transcription regulation is a complex process	(Choi, 2020; Ejeian et al., 2018; Lahrich et al., 2021; Qiu et al., 2020)
Flow cytometry (FCM)	NA	15-45 mins	NA	NA	→Rapid detection →High throughput →High accuracy →Ease of use	→Requires fresh samples →Only detect alive cells	(Brown et al., 2015; Brussaard, 2004; Ma et al., 2013)
ELISA	20-80%	2 h	1 ng/mL	>98%	→Affordable costs →Relatively simple procedure	→Low specificity →Concentration of sample is required →Time consuming →Low limit of detection	(Feng et al., 2020; Pilevar et al., 2020; Sakamoto et al., 2018; Saville et al., 2001; Streeck et al., 2020)
PFGE	NA	24-26 h	NA	NA	→Very sensitive to genetic differences →High throughput	→Too sensitive to differentiate between sources →A prior database is required →Time consuming	(Meays et al., 2004)