Environmental and microbial factors shaping SARS-CoV-2 RNA decay in wastewater: insights from batch tests and a lab-scale sewer pipeline simulator

초록

Wastewater-based surveillance (WBS) can provide early warning of outbreaks, but wastewater RNA signals may be underestimated due to analytical limitations and in-sewer attenuation driven by matrix conditions and conveyance. Using human coronavirus NL63 (HCoV-NL63) as a BSL-2 surrogate to characterize coronavirus RNA decay (distinct from SARS-CoV-2), we quantified loss kinetics as a function of pH (2, 5, 7, 8), temperature (20, 30 degrees C), microbial abundance, suspended solids (SS; 74-216 mg L- 1), and transport distance. Batch tests showed that higher microbial concentrations markedly increased decay rates: in raw wastewater at 30 degrees C, the first-order decay constant k reached 2.21 d(- 1), whereas filtration and/or microbial suppression reduced k to 1.12-0.47 d(- 1). A lab-scale sewer pipeline simulator further showed faster decay with increasing transport distance, and faster decay in wastewater than in dechlorinated tap water at 25 degrees C (k = 0.52 vs. 0.28 d(- 1)). Across the conditions evaluated, microbially mediated processes were the dominant drivers of viral RNA loss. These decay kinetics provide a basis to interpret-and, where appropriate, adjust-SARS-CoV-2 wastewater RNA measurements across diverse environmental and conveyance conditions.

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