Odour control and management in Hong Kong sewage treatment infrastructures

Abstract

Many complaints were received from the residential area around the Shatin Sewage Treatment Works (STSTW) about the presence of odour. The dominant odour marker H2S was selected to be studied. A review of the odour measurement and sampling methods, together with the specification of the standard limits and health effects were made. The formation process of H2S was investigated and the abatement and control measures in terms of physical, chemical and biological techniques were compared. The monthly rate of H2S emission in the atmosphere was calculated from the soluble sulfide and the measured wastewater flow at the inlet works, primary sedimentation tanks, aeration tanks, and sludge digestive and storage tanks, and the H2S mapping was carried out at the same places. Meteorological data including wind speed, wind direction, temperature and pressure were collected. The effect of temperature and pH on H2S generation is shown, and the effectiveness of odour control and deodourization processes was studied. A Gaussian dispersion model of Industrial Source Complex version 3 (ISC3) was applied in predicting the ground H2S level at various air sensitive receivers in the vicinity of STSTW. None of the places exceeded the recommended H2S concentration of World Health Organization (WHO) and the odour is a localized problem in STSTW of 35% area having H2S ranging in 0.01--‐0.023ppm. Recommendations are suggested in both short-term improvement in operation and maintenance practice and long-term design and construction of sewage treatment facilities.