Towards Sustainable Struvite Production

Typography

Struvite may not be a household word, but it is all too familiar to the operators of wastewater treatment plants.

A crystalline mineral known chemically as magnesium ammonium phosphate hexahydrate, struvite occurs naturally in decomposing organic materials such as sludge from animal wastes and from treated wastewater.

Struvite may not be a household word, but it is all too familiar to the operators of wastewater treatment plants.

A crystalline mineral known chemically as magnesium ammonium phosphate hexahydrate, struvite occurs naturally in decomposing organic materials such as sludge from animal wastes and from treated wastewater.

When it crystallizes on equipment surfaces in treatment plants, says Jonas Baltrusaitis, struvite can clog pipes, requiring them to be chemically cleaned or replaced and, in some cases, forcing a plant to be shut down.

But there is a brighter side to the picture, says Baltrusaitis, an assistant professor of chemical and biomolecular engineering.

Struvite contains three nutrients vital to plant growth—nitrogen, phosphorus and magnesium. Treatment plant operators aim to recover these nutrients early in the wastewater treatment process and convert them to fertilizer. This must be done before the nutrients harm pipes and equipment and before they are discharged into the environment, where they pollute streams, rivers and lakes.

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Photo: The use of magnesium oxide and carbonate to convert wastewater nutrients to struvite, says Jonas Baltrusaitis, would give farmers a sustainable alternative to the application of manure, which is 70 to 80 percent water. (Photo by Alexsandar Dickov, iStock)