Magnesium Hydroxide Slurry as a Cost Effective Solution for Effective H2S Odor and Corrosion Control in Sanitary Sewer Systems

Corrosion in sanitary sewer systems occurs when hydrogen sulfide (H2S) is biologically converted to sulfuric acid. Although reducing metals was necessary to protect public health, pretreatment has contributed significantly to increased sulfides, leading to heightened H2S odor and ultimately to accelerated corrosion. As the main contributor to odor and corrosion in collection systems, H2S is typically treated with odor control agents that can be costly and ineffective in providing long lasting H2S removal throughout the collection system. Magnesium hydroxide is effective in eliminating H2S by reducing both dissolved sulfide production and headspace H2S gas, but it also offers additional benefits as well. The introduction of magnesium hydroxide does not lead to the formation of additional unwanted sludge, as often happens with lime and iron salts. Additionally, it provides long-lasting alkalinity, slowly dissolving to increase the pH of wastewater to an optimum pH range that significantly reduces the formation of H2S and prevents further corrosion of sewer lines. Magnesium hydroxide’s pH buffering ability provides effective treatment for miles downstream from the addition point thus reducing the number of chemical injection points needed. In addition to H2S odor and corrosion control and saponification of fats, oils, and greases, adding magnesium hydroxide to the sanitary sewer system provides additional benefit downstream in the wastewater treatment plant. Competing odor control agents do not provide total system treatment as does magnesium hydroxide, making it a more effective solution for municipalities. Source: WEFTEC 2008 Proceedings