Adjusting for dilution in wastewater using biomarkers: A practical approach

Area of Science:

• Environmental Science
• Environmental Engineering
• Public Health

Background:

• Wastewater treatment works (WWTW) management relies on accurate flow data.
• In-sewer dilution, influenced by rainfall-derived inflow and infiltration (RDII), complicates accurate load estimations.
• Wastewater-based epidemiology (WBE) requires reliable data on population health and environmental interactions.

Purpose of the Study:

• To develop and validate a biomarker-based approach for quantifying in-sewer dilution.
• To enhance the operational efficiency and environmental management of WWTW.
• To provide a cost-effective tool for WBE.

Main Methods:

• Measured key wastewater quality parameters: ammoniacal-N, orthophosphate, and crAssphage.
• Established site-specific baselines for each biomarker, excluding RDII influence.
• Utilized ammoniacal-N as a proxy for dilution and compared biomarker-derived dilution with measured flow data.

Main Results:

• The biomarker-based dilution quantification correlated well with measured flow data.
• Biomarkers indicated higher dilution than measured flows in certain instances.
• Discrepancies were attributed to flow volume loss at WWTW due to combined sewer overflows (CSOs) and storm tanks.

Conclusions:

• Biomarker-based dilution measurement offers a robust alternative to direct flow measurement.
• This method enhances WWTW operational optimization and provides valuable data for WBE.
• Direct flow measurement at WWTW may underestimate target analyte loads due to CSO and storm tank activations.