Eliminate Hydrogen Sulfide in Wastewater Sludge and Biosolids
Biosolids moving through a wastewater treatment plant carry a hidden hazard. Sludge pumped from an anaerobic digester routinely contains dissolved sulfides at levels exceeding 10 mg/L, and as long as it remains contained within a pipe, those sulfides stay put. The problem starts the moment that sludge is distributed, such as when it hits a belt filter press. As the sludge spreads over the belt, hydrogen sulfide gas rapidly escapes into the surrounding building, and airborne concentrations can climb well past safety thresholds within minutes. Facilities are often left with a difficult tradeoff: run ventilation to protect workers and push the odor problem outside to the surrounding community, or turn ventilation off and let hydrogen sulfide build up inside the building, corroding concrete, metal, and electrical components with every hour of exposure.
Ultra-S3® is designed to remove that tradeoff entirely. Injected directly into the sludge line before it reaches the belt filter press, or any other point where biosolids are handled or distributed, Ultra-S3 combines with an oxidant such as hydrogen peroxide to generate hydroxyl radicals that destroy dissolved sulfides before they ever have the chance to off-gas. Because the reaction happens in the line itself, with only a few minutes of contact time required, the hydrogen sulfide is gone before the sludge ever reaches open air.
The result is a level of control that ventilation alone can’t achieve. Properly dosed, Ultra-S3 can bring airborne hydrogen sulfide inside a sludge handling building down to non-detectable levels, even with ventilation switched off, eliminating the exposure hazard for workers, the odor problem for neighboring communities, and the slow corrosion damage that untreated hydrogen sulfide inflicts on plant infrastructure.
Proven Results at the Springville, Utah Wastewater Treatment Plant
At the Springville, Utah Wastewater Treatment Plant, biosolids pumped from the anaerobic digester to a belt filter press building were releasing hydrogen sulfide at concentrations approaching 30 ppm with the ventilation system off and 5 to 10 ppm even with the ventilation system running. Beyond the odor complaints this generated in the surrounding area, the sustained exposure to hydrogen sulfide raised real safety and equipment corrosion concerns for the plant.
Ultra-S3 and dilute hydrogen peroxide were injected inline as biosolids moved from the Sludge Pump Station to the belt filter press building, at a combined oxidant feed rate of approximately 2.5 ppm per 1.0 ppm of anticipated sulfide, with contact times ranging from 4.3 to 5.4 minutes depending on flow rate. The trial ran for a full day, with the ventilation system deliberately left off to measure the treatment’s effect directly. The results:
- Hydrogen sulfide levels, which spiked to 26 ppm as pumping began, dropped steadily once Ultra-S3 was engaged and reached 0 ppm within roughly an hour of treatment
- Airborne hydrogen sulfide was held at 0 ppm for over four hours of continuous processing, even as sludge pump rates increased from 60 to 70 to 75 gpm
- No grease buildup was observed on equipment during the treatment period
- When treatment was stopped at the end of the trial, hydrogen sulfide levels climbed quickly, and plant personnel had to turn the ventilation system back on within minutes as levels exceeded the 10 ppm safety standard, confirming that Ultra-S3, not ventilation, was responsible for the results
The study’s conclusions were direct: properly dosed Ultra-S3 was capable of eliminating hydrogen sulfide from the air inside the belt filter press building entirely, even with ventilation off, and sustained 0 ppm sulfide levels of this kind would be expected to significantly reduce corrosion to concrete, metal, and electrical components throughout the facility.