Application of a Ferric Chloride System to Simultaneously Control Biogas Sulfide and Enhance Activated Sludge Settling

摘要

The Thorn Creek Basin Sanitary District (TCBSD) provides wastewater treatment services insouth suburban Chicago. The TCBSD operates a wastewater treatment facility comprised ofpreliminary treatment, primary settling, activated sludge treatment, sand filtration, chlorination,and dechlorination. Primary and waste activated sludges are anaerobically digested and landapplied. The biogas produced in the digesters is currently used for heating of the anaerobicdigesters. Rhodia Incorporated (Rhodia) is the largest discharger of industrial wastewater to theDistrict.Rhodia would like to increase silica production at its facility, which would result in an increasein discharge of sodium sulfate, the waste product of silica production. Rhodia has requested thatTCBSD increase its permitted discharge of sulfate by approximately 40 percent to 142,862pounds per day corresponding to a total dissolved solids (TDS) discharge of 211,100 pounds perday. This paper provides a summary of the evaluation of potential impacts of increased TDS andsulfate discharge on the performance and operation of the District’s plant, and describes thedevelopment of a ferric chloride delivery system to mitigate the impacts of sodium sulfateloading on the treatment plant.