AWWA WQTC58934

Control of hydrogen sulfide in drinking water is widely practiced in groundwater systems to prevent odor complaints and to help control sulfur induced corrosion and associated black water problems in distribution systems. While chemical oxidation of hydrogen sulfide is well understood, the pH, oxidant chemical, and effective dose influence the reaction products (e.g. sulfate or elemental sulfur) and reaction rates. The purpose of this study was to investigate the feasibility of using hydrogen peroxide oxidation coupled with filtration for removal of hydrogen sulfide. Bench-scale and pilot-scale testing were conducted on groundwater from South/Central Hillsborough County. Chemical addition followed by filtration of oxidized elemental sulfur was tested using a two-stage continuously backwashed upflow filter operated at a hydraulic loading rate of about 5gpm/ft². The use of hydrogen peroxide to oxidize hydrogen sulfide at ambient pH (7.2-8.0) required excessive reaction times (>20 minutes). However, when iron coagulants were used in tandem with hydrogen peroxide, dissolved hydrogen sulfide was converted to particulate sulfur (most likely iron sulfide or colloidal sulfur) in less than 3 minutes at molar ratios ranging from 0.5 to 2. The combination of oxidation and two-stage upflow filtration was capable of producing water with turbidities below 0.08 NTU. Includes 15 references, tables, figures.