Surveillance and measurement of SARS-CoV-2 RNA in wastewater: a case study of Bangkok, Thailand

Wastewater-based epidemiology (WBE) has emerged as a powerful tool for monitoring the presence of SARS-CoV-2 infected population. Herein, the study aims to apply the WBE for surveillance and monitoring SARS-CoV-2 in Bangkok, where the highest official covid-19 cases reported in Thailand, during the fully opening for international tourists in early 2023. A total of 200 wastewater samples (100 influent and 100 effluent samples) were collected from 10 wastewater treatment plants (WWTPs) during January-May 2023. SARS-CoV-2 RNA was detected by real time qRT-PCR with accounting for 51% (102/200). Of these, 88% (88/100) and 14% (14/100) were detected in influent and effluent samples, respectively. The SARS-CoV-2 RNA concentration was detected in ranged of 4.76x102 -1.48x105 copies/L. The amount of SARS-CoV-2 RNA has increased approximately 4 times from the lag phase (January-March) to the log phase (April-May). Spearman’s correlation coefficient revealed that correlation between estimated infected population and weekly reported cases was statistically significant (p-value = 0.017). SARS-CoV-2 RNA in influent had a statistically significant relationship with weekly reported (r = 0.481, p-value < 0.001). Lag time analysis revealed early warning 1-3 weeks before rising covid-19 cases were observed. Further analysis indicated significant correlations we found the correlation between the official reported covid-19 cases and wastewater characteristics, Which is Biochemical oxygen demand loading (BOD loading), Total phosphorus (TP), Total nitrogen (TN), Total Kjeldahl Nitrogen (TKN), Suspended solid (SS) and flow rate can be used to estimate the infected covid-19 cases. Those parameter can be summarized into linear equation for prediction estimated infected population, that will help the public health organization to proactive surveillance, prepare preventive care and measure effectively. geographic information system (GIS) was applied for spatial-temporal analysis at the province level, suggesting real time dashboard should be further developed.