ABSTRACT
F + coliphages are considered as potential enteric viral indicators in water systems as a tool for on-site validation of wastewater treatment processes. The present study evaluated the occurrence of F + coliphages in wastewaters collected from three wastewater treatment plants (WWTPs) in Mumbai city, to assess this potential. The detection and enumeration of F + coliphages was carried out from WWTPs Z1, Z3 and Z5 using the ISO 10705-1 and U.S EPA 1601 methods. F + coliphages were majorly detected in untreated wastewater samples followed by a few secondary treated samples in WWTP-Z1 and Z3 and one tertiary treated sample from Z1, these differences were found to be statistically significant. The difference in F + coliphage levels between the treatment stages highlight their potential as indicators for monitoring the efficiency of wastewater treatment. The overall positivity of F + coliphage was 35.09% for Salmonella. typhimurium WG49 host (as per ISO 10705-1), was higher by 10.52% for Escherichia coli Famp HS host (as per U.S EPA 1601) (45.61%), highlighting the efficiency of the latter host over the former in F + coliphage detection. Significant difference in F + coliphage counts using the two bacterial hosts were observed in WWTP-Z3 (p = 0.001) and WWTP-Z1 (p = 0.047) but not in WWTP-Z5 (p = 0.332). Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-023-01181-7.
ABSTRACT
Wastewater-based epidemiology has been recognized as a tool to monitor the progress of COVID-19 pandemic worldwide. The study presented herein aimed at quantitating the SARS-CoV-2 RNA in the wastewaters, predicting the number of infected individuals in the catchment areas, and correlating it with the clinically reported COVID-19 cases. Wastewater samples (n = 162) from different treatment stages were collected from three wastewater treatment plants (WWTPs) from Mumbai city during the 2nd surge of COVID-19 (April 2021 to June 2021). SARS-CoV-2 causing COVID-19, was detected in 76.2% and 4.8% of raw and secondary treated (n = 63 each) wastewater samples respectively while all tertiary treated samples (n = 36) were negative. The quantity of SARS-CoV-2 RNA determined as gene copies/100 mL varied among all the three WWTPs under study. The gene copy numbers thus obtained were further used to estimate the number of infected individuals within the population served by these WWTPs using two published methods. A positive correlation (p < 0.05) was observed between the estimated number of infected individuals and clinically confirmed COVID-19 cases reported during the sampling period in two WWTPs. Predicted infected individuals calculated in this study were 100 times higher than the reported COVID-19 cases in all the WWTPs assessed. The study findings demonstrated that the present wastewater treatment technologies at the three WWTPs studied were adequate to remove the virus. However, SARS-CoV-2 genome surveillance with emphasis on monitoring its variants should be implemented as a routine practice to prepare for any future surge in infections.
