Anaerobic Digester Hydrogen Sulfide Removal at the Manatee County, FL Southwest Water Reclamation Facility

ABSTRACT

The results of a full-scale trial initiated in May 2006 by the Manatee County Southwest Water Reclamation Facility are presented, and the impacts of peroxide regeneration of spent iron salts on the removal of hydrogen sulfide (H₂S) from anaerobic digesters at the SWWRF are examined. Treatment with hydrogen peroxide was initiated in a thickened primary sludge line containing an average 300 Lbs/day Fe (primarily as FeS) and 80 mg/L dissolved sulfide. Prior to treatment, dissolved sulfide levels in the primary digester averaged 20 mg/L and were found to drop to < 0.1 mg/L throughout the course of the trial. The vents of the primary digesters exhausted biogas containing an average 200 ppm H₂S. After treatment, biogas H₂S concentration reduced to 20 ppm on average. Within two sludge ages, similar effects were noted in the secondary digester. Additional positive changes were noted in the volume and quality of biogas produced, and in finished biosolids quality.

KEYWORDS Anaerobic digestion, odor control, corrosion control, hydrogen sulfide, hydrogen peroxide, iron salts, mercaptan, peroxide regenerated iron…

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