Volatile solids outperform pepper mild mottle virus as a normalizing parameter in wastewater-based epidemiology: a...

Area of Science:

• Environmental Science
• Public Health
• Analytical Chemistry

Background:

• Wastewater-based epidemiology (WBE) relies on normalization to adjust for population and dilution variations.
• Pepper Mild Mottle Virus (PMMoV) is a common viral marker for normalization, but its stability is inconsistent across different locations.
• The effectiveness of PMMoV as a normalization marker can be influenced by factors like wastewater pH.

Purpose of the Study:

• To evaluate volatile solids (VS) as an alternative normalization marker in WBE.
• To compare the stability and population correlation of VS against PMMoV over multiple years and sites.
• To assess the practicality of using routine physicochemical parameters for WBE normalization.

Main Methods:

• Analysis of 1,611 wastewater samples from five diverse locations over three years.
• Measurement of Pepper Mild Mottle Virus (PMMoV) and volatile solids (VS) concentrations.
• Statistical comparison of temporal stability, variability, and correlation with population size for both markers.

Main Results:

• Volatile solids (VS) demonstrated significantly lower variability (CV 0.11-0.18) compared to PMMoV (CV 0.30-0.52).
• VS concentrations were stable (<6-fold variation) and strongly correlated with population size (R² = 0.721, p = 0.044).
• PMMoV showed high fluctuations (up to 100-fold), year-wise decline, no significant population correlation (R² = 0.054, p = 0.706), and negative correlation with wastewater pH.

Conclusions:

• Volatile solids (VS) are a more consistent and reliable normalization parameter than PMMoV for WBE in similar sewersheds.
• VS can be practically implemented due to simple, cost-effective measurement and independence from dietary factors.
• Routine physicochemical parameters like VS offer a robust alternative for wastewater-based epidemiology normalization.