Thioguard®

Odor Control

Odors occur when waste water pH allows (H2S) hydrogen sulfide to evolve from liquid phase hydrosulfide (HS ^-).

Thioguard® prevents the formation and release of H2S gas in several important ways.

First, sulfate reducing bacteria operate best at pH levels 6.8 to 7.2. Above this ideal pH range, less sulfide is produced. Thioguard® raises wastewater pH above 8 ... so less sulfide is generated.

Second, H2S formation is extremely sensitive to pH. At pH levels < 7.0, the reaction favors hydrogen sulfide. At pH levels > 7.0, the reaction favors hydrosulfide.

Unlike other alkali choices, Thioguard® contains slowly dissolving magnesium hydroxide particles. These particles have high surface pH and high surface areas that make Thioguard® more effective.

Undissolved Thioguard® particles react directly with H2S, converting the small remaining percentage of H2S to magnesium polysulfide. Therefore, surface chemistry makes Thioguard® more effective than more highly soluble bases.

Thioguard® actually buffers water, gently raising pH without overshooting. Alkalinity is gradually released as needed. This automatically controls pH in the correct range to prevent the formation and release of H2S. Overdosing simply adds alkalinity.

Since wastewater ionization varies with location, a titration is necessary to determine the optimum rate of addition. It generally takes only 50 to 100 gallons of Thioguard® per million gallons of sewage to raise and hold the pH in a range of 8 to 8.5.

Once determined the feed rate is constant for all sulfide levels.

Overshooting or raising pH higher than 9.0 results in:

• Precipitation of unwanted sludge in the collection system
• Interference with treatment plant operations
• Evolution of ammonia from the flow

Adding Thioguard® automatically maintains pH in this critical range without overshooting. (see solubility graph, above)