Assessment of hydrogen sulfide emission in a wastewater pumping station.

Abstract

Wastewater collection systems can be a source of odors that lead to complaints from plant workers, the public, and nearby property owners. The primary source of odors released from such systems is the presence of hydrogen sulfide (H2S) gas at high concentrations. This study was conducted in the main pumping station in Kuwait with a capacity of 570,000 m3/day to assess H2S gas emission, determine factors affecting H2S generation, and evaluate the effectiveness of the odor control system comprising stripping using sodium hydroxide and carbon adsorption. Yearly data on wastewater flow rate, temperature, pH, BOD5, and H2S were obtained from plant records over the years 2013-2015, as well as monthly data measurements were conducted during May to December 2016, and weekly data were collected during a plant monitoring program in March and April 2017. Statistical analysis showed seasonal, daily, and hourly variations in H2S concentrations, with higher values reported in summer, cyclic hourly patterns obtained daily, and peak H2S level of 10ppm recorded at 7pm and 40°C. The ANOVA test indicated that the wastewater temperature, flow rate, and BOD5 were statistically significant factors affecting the formation of hydrogen sulfide gas because of the strong correlation and a p value less than the significance level of 0.05. It was evident that the wastewater temperature is the most influential factor. A model was developed to predict H2S emission. The odor control system used in the station proved to be highly effective and able to remove up to 99.9% of H2S released from wastewater.