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ARS Home » Southeast Area » Florence, South Carolina » Coastal Plain Soil, Water and Plant Conservation Research » Research » Publications at this Location » Publication #365292

Research Project: Improvement of Soil Management Practices and Manure Treatment/Handling Systems of the Southern Coastal Plain

Location: Coastal Plain Soil, Water and Plant Conservation Research

Title: Innovative process for the recovery of magnesium phosphate (Newberyite) and ammonia from digester effluents

item Vanotti, Matias
item DUBE, PATRICK - Water Environment Federation

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/22/2019
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Conservation and recovery of nitrogen and phosphorus from wastes is important because of economic and environmental reasons. Phosphorus recovery of anaerobically digested municipal wastewater (centrate) via magnesium chloride (MgCl2) precipitation was enhanced by combining it with the recovery of ammonia (NH3) through gas-permeable membranes. The wastewater tested was a centrate collected from James River municipal plant, Hampton Roads Sanitation District, Virginia. The ammonia capture process substantially reduced both carbonate alkalinity, from 2990 mg/L (milligrams per liter) to 130 mg/L, and ammonia concentration, from 730 mg N/L to 50 mg/L. These conditions benefited subsequent P recovery. The combined process provided quantitative (ca 100%) P recovery efficiency. With active NH3 capture, the magnesium phosphates that were produced contained high P2O5 grade (> 42%) and high plant availability as fertilizer (> 98%). The phosphorus product was similar to the composition of newberyite (MgHPO4.3H2O), a biomineral found in guano deposits, which has approximately 40.8% P2O5 and 13.9% Mg composition and 1:1 P:Mg molar ratio. However, in other tests conducted with the same municipal wastewater, without N recovery or when carbonate alkalinity was being added, the phosphate minerals obtained had lower grade (27-29% P2O5). Therefore, simultaneous removal of ammonia and carbonates are important considerations for production of very-high grade phosphate products. Similar results were also obtained using digester livestock wastewater.