You ask and we answer! MgWater Technical Director Matt Madolora offers solutions to common water treatment problems.

QUESTION: Does using magnesium hydroxide for odor control interfere with biological phosphorus removal?

ANSWER: Actually, among the more common odor control treating chemicals, including nitrates, iron salts, peroxide and more, magnesium hydroxide is the only chemical that does not interfere with biological phosphorus removal (BPR). High quality magnesium hydroxide such as the 60% slurry produced by Premier Magnesia is an effective alkalinity source that mitigates hydrogen sulfide (H2S) formation while maintaining biological and chemical conditions that support phosphorus-accumulating organisms (PAOs) responsible for BPR.

H2S forms under anaerobic conditions when sulfate-reducing bacteria (SRBs) break down organic matter. Mg(OH)2 helps by raising and stabilizing pH, providing gradual alkalinity release, and by chemically binding sulfides. BPR relies on phosphorus-accumulating organisms (PAOs), which need alternating anaerobic and aerobic conditions to take up and store phosphorus. Mg(OH)2 helps by keeping pH in an optimal biological range; maintaining chemical conditions that favor downstream processes such as BPR; facilitating nutrient recovery and preventing struvite scaling in reactors.

Following are best practices for a balanced approach to odor and BPR control:

• Monitor pH and Alkalinity: Regularly check pH levels to ensure they remain within an optimal range for both H2S suppression and BPR activity.
• Dose Strategically: Apply magnesium hydroxide upstream where H2S issues originate (such as in collection systems or in treatment processes) while ensuring PAOs still experience proper environmental conditions.
• Use Process Control Data: Adjust dosages based on real-time data from ORP (oxidation-reduction potential) and sulfide concentration measurements.
• Leverage Struvite Recovery: If excess phosphorus is present, controlled struvite capture can help remove phosphorus sustainably without interfering with BPR.

Would you like to connect with one of our technical experts at Premier Magnesia to talk about the benefits of a balanced approach to wastewater treatment? Contact us today.