Magnesium Hydroxide Slurry vs. Potassium Hydroxide (Caustic Potash) for Wastewater Treatment

Magnesium Hydroxide Slurry vs. Potassium Hydroxide (Caustic Potash) for Wastewater Treatment

Martin Marietta Magnesia Specialties has received numerous inquiries from customers looking to replace potassium hydroxide (caustic potash) as a source of alkalinity in their wastewater treatment system. Many of these customers initially sought out caustic potash as an alternative to sodium hydroxide (caustic soda) due to discharge limits on sodium. Martin Marietta Magnesia Specialties' FloMag^® H magnesium hydroxide slurry is a safer and potentially more cost-effective alkali than either caustic potash or caustic soda.

Considerable freight savings can be realized with a conversion from caustic potash to FloMag^® H magnesium hydroxide slurry. On a dry solids basis, only 52 pounds of magnesium hydroxide is required for every 100 pounds of potassium hydroxide. This is because each magnesium hydroxide molecule contains two OH- ions, while each potassium hydroxide ion contains only one OH- ion. This difference is compounded even further on a wet basis because FloMag^® H magnesium hydroxide slurry is available as a 60% solids slurry, where caustic potash is typically sold as a 45% solids solution. Therefore, 100 gallons of caustic potash can be replaced with only 37 gallons of FloMag^®H magnesium hydroxide slurry.

FloMag^® H is also a safer option to caustic potash. Caustic potash is a corrosive material and will cause burns from all exposure routes. The NFPA health risk for potassium hydroxide is a THREE, where magnesium hydroxide is rated ZERO and will not burn a person upon bodily exposure.

In biological wastewater treatment systems, FloMag^® H can be a much more reliable alkali than caustic potash. Because magnesium hydroxide has low solubility in water and is a weaker base, a buffering effect is achieved in wastewater treatment systems, which prevents pH excursions when the alkali is overdosed. A wastewater treatment plant operator will generally see a much steadier pH over time when using FloMag^® H versus other alkalis such as caustic potash.

Martin Marietta Magnesia Specialties has a full-time technical support and engineering group, which can help a customer make the conversion from caustic potash to magnesium hydroxide slurry. Please contact us for more information, for a sample request, or to speak with our technical support group to schedule a trial.