Primary Clarifier Odor Control – Replacing Nitrates with Dissolved Oxygen

Primary clarifiers are often the source of sulfide formation and hydrogen sulfide (H2S) odors. While the wastewater sits in the settling tank, BOD degrading bacteria use sulfates as an oxygen source and produce dissolved sulfides. When the water flows over the effluent weirs, the resulting turbulence strips H2S from the wastewater, resulting in odor and corrosion.The Anson-Madison Sanitary District in Madison, Maine treats 4 MGD of wastewater from Madison Paper Industries as well as the communities of Anson and Madison, Maine. The treatment facility is located in close proximity to neighbors and had experienced odor issues for years. H2S levels had been recorded at 150 ppm on average with spikes of up to 800 ppm. An ECO2 SuperOxygenation system was installed in early 2012. The odors have been successfully eliminated and the SuperOxygenation system is saving the District approximately $300,000 per year over previously used calcium nitrate chemicals.