System-wide Benefits of THIOGUARD® Direct Addition

Today, biogenic sulfate reduction is the primary cause of odor and structural corrosion in municipal wastewater systems. As evidenced from small operations up to the largest systems in the country, wastewater treatment systems have less control of biologic and chemical conditions during the transport and treatment of muncipal wastewater.

THIOGUARD® provides slightly soluble non-carbonate alkalinity directly to municipal wastewater in the collection system. Hydroxyl ion reacts with free hydrogen raising the pH one to two points. This discourages biologic sulfate production and reduces hydrogen sulfide volatilization. THIOGUARD is a 60% magnesia slurry custom solution pioneered by the MgWater™ group of Premier Magnesia, LLC, in the 1990s and tailored for each wastewater facility. Magnesia-based solutions are often the best chemical choice because magnesia is non-hazardous, does not readily carbonate, and buffers in the ideal pH range for sulfide gas control. In addition to pH control, magnesium ion associates with sulfide, further preventing gas evolution and catalyzing more rapid oxidation.

In late June and early July of 2002, representative baseline data was collected at the West Lincoln discharge manhole (Control Point) and the WWTP headworks in Clarksville, Indiana. Average dissolved sulfide at the West Lincoln discharge manhole, was 15 – 17 mg/l with headspace hydrogen sulfide peaking over 100 ppmv. Average wastewater pH was 7.2. Data collected at the headworks was similar with H2S spikes in excess of 100 ppmv.

The addition of THIOGUARD virtually eliminated the odor problems compared with all other strategies and system changes tested prior. Results with THIOGUARD were both quantitatively and qualitatively by far the best. Hydrogen sulfide gas concentration at the West Lincoln discharge manhole and the plant headworks was reduced to an average of < 1 ppm with maximum peaks of 5 ppm.