White Paper

White Paper: The Use Of Magnesium Hydroxide Slurry For Biological Treatment Of Municipal And Industrial Wastewater

By Aileen Gibson and Michael Maniocha
Martin Marietta Magnesia Specialties, LLC.

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In wastewater treatment, microorganisms transform the wastes into cell tissue and gaseous, liquid, or solid conversion products. Optimum growth conditions, such as pH, nutrient availability, and alkalinity, must exist in order for the microorganisms to continue to reproduce and function properly. Municipal wastewater typically contains adequate amounts of alkalinity to support the biological conversion of organic waste; however, in some cases, there is insufficient alkalinity to maintain optimum bacterial growth conditions. Typically, an alkali such as caustic soda or lime must be added to the wastewater stream in order to provide the alkalinity and maintain the pH within the optimum range. Currently, caustic soda and lime users are switching to magnesium hydroxide slurry because of the advantages it offers for biological treatment. Magnesium hydroxide slurry, which is recognized as "the milk of magnesia" for wastewater treatment, has been widely utilized for heavy metal precipitation and acid neutralization of industrial wastewater. Many industrial and municipal wastewater facilities are now converting over to magnesium hydroxide for utilization in aerobic and anaerobic biological treatment systems.

With magnesium hydroxide slurry, a nutrient in the form of magnesium is readily available to the microorganisms. Magnesium hydroxide provides more CaCO3 equivalent alkalinity on an equal weight basis when compared to hydrated lime and caustic soda which lowers chemical consumption. Additional benefits which make magnesium hydroxide slurry more attractive to end users are its buffering ability which provides the added benefit of excellent pH control, and its handling properties. Unlike caustic soda, magnesium hydroxide is non-hazardous and non-corrosive when used properly which makes handling safer and easier.

Magnesium hydroxide slurry, such as FloMag® H and MagneClear™ 58, have been used effectively in aerobic and anaerobic biological treatment systems at meat processing facilities, bakeries, chemical processing facilities, and municipalities, just to name a few. This paper will discuss the advantages of magnesium hydroxide over hydrated lime and caustic, and present case studies on the successful utilization of FloMag® and MagneClear™ Magnesium Hydroxide slurries for both aerobic and anaerobic treatment of municipal and industrial wastewater.

Click here to download the entire White Paper in pdf format.