Decay of SARS-CoV-2 RNA along the wastewater treatment outfitted with Upflow Anaerobic Sludge Blanket (UASB) system evaluated through two sample concentration techniques

Abstract

For the first time, we present, i) an account of decay in the genetic material loading of SARS-CoV-2 during Upflow Anaerobic Sludge Blanket (UASB) treatment of wastewater, and ii) comparative evaluation of polyethylene glycol (PEG), and filtration as virus concentration methods from wastewater for the quantification of SARS-CoV-2 genes. The objectives were achieved through tracking of SARS-CoV-2 genetic loadings i.e. ORF1ab, N and S protein genes on 8th and 27th May 2020 along the wastewater treatment plant (106 million liters per day) equipped with UASB system in Ahmedabad, India. PEG method performed better in removing materials inhibiting RT-qPCR for SARS-CoV-2 gene detection from the samples, as evident from constant and lower C T values of control (MS2). Using the PEG method, we found a reduction >1.3 log 10 in SARS-CoV-2 RNA abundance during UASB treatment, and the RNA was not detected at all in the final effluent. The study implies that i) conventional wastewater treatment systems is effective in SARS-CoV-2 RNA removal, and ii) UASB system significantly reduces SARS-CoV-2 genetic loadings. Finally, PEG method is recommended for better sensitivity and inhibition removal during SARS-CoV-2 RNA quantification in wastewater.

Estimating the minimum number of SARS-CoV-2 infected cases needed to detect viral RNA in wastewater: To what extent of the outbreak can surveillance of wastewater tell us?

“…The average abundance of N1 and N3 genes decreased by 0.3-log (i.e., 50%) and 0.5-log (i.e., 70%), respectively, from the underground septic tanks to the biological activated sludge tank. The use of upflow anaerobic sludge blanket reactor for municipal wastewater treatment resulted in a higher reduction of N genes (1.53-log), with a similar log reduction of >1.5-log also observed for other genes associated with SARS-CoV-2 ( Kumar et al, 2021 ) ( Table 2 b).…”

“…Besides the lower log reduction of N1 and N3 genes compared to that reported by Kumar et al (2021) , there was also an increase by 44% in the average abundance of N2 genes sampled from the activated sludge tank compared to that in the underground septic tank. This suggests a potential accumulation of N2 genes in the activated sludge tank, possibly due to better persistence or sorption of N2 compared to N1 and N3 genes in the sludge tank.…”

Potential discharge, attenuation and exposure risk of SARS-CoV-2 in natural water bodies receiving treated wastewater

“…The use of QMRA could be helpful for the management of the potential risk of SARS-CoV-2 in water bodies rather than without any quantitative idea on possible risk. Although this study focused on the impacts of SARS-CoV-2 in treated wastewater on water bodies, many natural water bodies are often affected by untreated wastewater, as the decay of SARS-CoV-2 is still a debated issue 93 . Discharge of untreated wastewater from combined sewer overflows (CSOs) is highly significant and very common in many countries, including Central Europe (around 70% systems are combined sewer systems) and in the United States (serving more than 40 million individuals) 94,95 .…”

Uncertainties in estimating SARS-CoV-2 prevalence by wastewater-based epidemiology

“…human excretion), and catchment population, the catchment-level prevalence can be estimated. To date, the existence of SARS-CoV-2 virus RNA in wastewater have been confirmed in many countries, including, Australia [8] , [9] , Brazil [10] , China [11] , [12] , Czech Republic [13] , Ecuador [14] , France [15] , [16] , India [17] , [18] , Italy [19] , [20] , [21] , [22] , Japan [23] , Spain [24] , [25] , the Netherlands [7] , United Kingdom (UK) [26] , Slovenia [27] , Sweden [28] , United Arab Emirates (UAE) [29] , [30] and United States (USA) [31] , [32] , [33] , [34] , [35] . The successful detection of SARS-CoV-2 virus RNA through reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and sequencing approaches in wastewater demonstrated the high potential of applying WBE as a tool to estimate the COVID-19 prevalence in their communities.…”