δ34S Variability in Wastewater: A Study on Water Use Behaviors and Drainage Area Characteristics

This research explored the variation patterns of δ34S in wastewater under different water use behaviors and at the end of the drainage area. The monitoring results demonstrated Restaurant 2's flow advantage during specific daytime and nighttime periods. A strong correlation was found between the δ34S in wastewater generated from its kitchen activities and the δ34S at the drainage area's end, explaining the δ34S trends in the wastewater. Overall, the δ34S values in the wastewater were consistently higher than the tap water baseline throughout the monitoring period, except for a decrease in certain nighttime periods.

An uncertainty assessment was performed using a formula specific to wastewater quality indicators at the drainage area's end. The study found the uncertainty range of δ34S in the wastewater at the drainage area's end to be 0.36‰ to 0.59‰ over three consecutive monitoring cycles, indicating a moderate level of uncertainty stability.

The study concluded that:

1. δ34S exhibited good stability under various water use behaviors. Kitchen activities resulted in a 64.69% increase, while other behaviors, like washing, showering, toilet flushing, and dishwashing, showed an average relative change range of -14.37% to 5.62% compared to tap water.

2. The fluctuation of δ34S in the wastewater at the drainage area's end relative to the tap water baseline was minimal, with an average relative change of 25.99%. The overall variation trend of δ34S with time was small and stable, with daily fluctuations exhibiting some reproducibility.

3. The stability of δ34S across different water use behaviors in drainage households and in the wastewater at the drainage area's end makes it a suitable water quality characteristic factor for pipe network diagnosis.