CONTROLLING ODORS FROM THE SOUTHEAST WATER POLLUTION CONTROL PLANT IN SAN FRANCISCO, CA

The City and County of San Francisco completed an Odor Control Master Plan (OCMP) for the Southeast Water Pollution Control Plant (SEWPCP) in August 1998 in response to numerous complaints from local residents. The SEWPCP is located in a mixed light industrial, commercial, and residential zone. The predominant sources of odor are the plant's solids handling facilities, which are located in close proximity to the nearby residential area. The main objectives of the OCMP were to: 1) characterize existing odor sources during normal peak and extreme operating conditions, 2) prioritize immediate and long-term improvements, and 3) provide capital and operating cost estimates for each alternative. The major odor sources identified in the report include the dissolved air flotation thickeners (DAFTs), anaerobic digesters, sludge cake storage and loadout facility, and primary sedimentation tanks. A suite of odor control improvements were recommended and are divided into four main categories: 1) chemical addition, 2) process modifications, 3) operational improvements, and 4) foul air collection and treatment. The estimated capital cost for implementation of the OCMP is approximately 27.3 million. The OCMP provides a framework for planning and implementing various odor control improvements over the next five years to effectively minimize odors from the SEWPCP. The City has already implemented or is currently designing a number of important odor control projects, including: 1) installation of submerged effluent launders at the primary sedimentation facility, 2) design of a new gravity belt thickener facility to replace the existing DAFTs, 3) addition of ferric chloride to the anaerobic digesters, 4) replacement of corroded digester gas piping, 5) covering the mixed liquor channels, and 6) design of cover, vent, and treat systems at the primary effluent pump station, sludge dewatering facility, and sludge storage/loadout facility.