Specialists in the Control of Odors and Corrosion in Sewer Systems and Wastewater Treatment Plants.
CHEMICAL ADDITION TO CONTROL ODORS AND CORROSION

Chemicals are often injected into or applied to odor sources to reduce the generation and/or release of odor and to control corrosion. Injection of chemicals into wastewater or sludge for the purpose of controlling hydrogen sulfide (H2S) is common practice. The following table summarizes the chemicals commonly used to control hydrogen sulfide in wastewater.

SUMMARY OF HYDROGEN SULFIDE CONTROL TECHNIQUES
Technique Frequency  Of Use Advantages Disadvantages
I. OXIDATION
Air injection Low Low cost, adds DO to wastewater to prevent sulfide generation Applicable only to force mains; potential for air binding. Limited rate of O2 transfer
Oxygen injection Low 5 times solubility of air; high DO possible; economical for force mains Applicable only to force mains; requires on-site generation or purchase as liquid O2
Hydrogen peroxide Medium Effective for sulfide control in gravity sewers or force mains; simple installation Costs can be high to achieve low (<0.5 mg/L) sulfide; safety
Sodium hypochlorite High Applicable to gravity sewers or force mains; effective for broad range of odorants Safety considerations; high chemical costs
Potassium permanganate Medium Effective, powerful oxidant; good for sludge handling applications High cost, difficult to handle
II. PRECIPITATION
Iron salts High Economical for sulfide control in gravity sewers or force mains Does not control non-H2S odors; sulfide control to low levels may be difficult; increased sludge production
III. pH ELEVATION
Sodium hydroxide  (shock dosing) Medium Intermittent application; simple, little equipment required Does not provide consistent control; safety considerations
Magnesium hydroxide Low Maintains pH at 8-8.5; adds alkalinity; economical for high (>5 mg/L) sulfide levels; safe Requires mixer to maintain slurry in suspension; cost is independent of sulfide concentration
IV. PREVENTION
Nitrate formulations High Can be used to prevent sulfide generation or oxidize sulfide in gravity sewers and force mains; safe to handle Dosages vary depending on use: prevention vs. removal
Anthraquinones Low Prevents sulfide generation biochemically by disrupting sulfur cycle Not well developed; results inconsistent and difficult to predict