Iron salts are a proven technology for long-duration hydrogen sulfide control in collection system gravity and forcemains; solids processing units, solids transfer lines and anaerobic digesters. They have been used for over 30 years in hydrogen sulfide control applications and are a well understood technology. Depending on the wastewater plant unit process configuration, iron salts may also provide improvements in clarification, phosphate removal, struvite control, solids dewatering and anaerobic digester performance. Theoretical dose ratios of ferrous iron to H2S are 1.75 lbs Fe2+:lb H2S with practical dose rates anywhere from 2 to 6 depending on the application. Theoretical dose ratios of ferric iron to H2S are 1.2 lbs Fe3+:lb H2S with practical dose rates anywhere from 1.5 to 4 depending on the application. Access USP Technologies’ iron management experts for help improving sulfide and phosphate control in your system.