Hydrogen sulfide generation and emission in urban sanitary sewer in China: what factor plays the critical role?

Abstract

Identifying hydrogen sulfide (H₂S) hotspots is critical for preventing/controlling odor and corrosion problems in sewer systems. However, relatively little is known regarding H₂S hotspots and variation characteristics in China's urban sewer networks. A comprehensive field investigation was carried out on the impacts of sewer structures, season, water flow and wastewater quality on H₂S emission. The results indicated that H₂S diurnal variation mainly followed the dry weather flow fluctuation in gravity sewer networks. The manhole downstream of septic tanks was identified as a H₂S emission hotspot due to potential significant sulfide generation in the septic tanks. The effect of temperature on H₂S emission was related to variations in the sulfide production rate and flow turbulence at different locations in the sewer system. Significant reduction in sulfide concentration was observed with rainfall-derived high water flow rate. The local water quality was identified as a key factor for sulfide generation from different sites along the sewer system. These findings are useful in understanding and predicting H₂S emission in China's sewer systems.