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Extramural Research

Grantee Research Project Results

Grantee Research Project Results

Sustainably Overcoming Hindrance to Struvite Recovery from Anaerobically Digested Dairy Manure

EPA Grant Number: SU836013
Title: Sustainably Overcoming Hindrance to Struvite Recovery from Anaerobically Digested Dairy Manure
Investigators: Tao, Wendong , Moran, Sharon
Institution: SUNY College of Environmental Science and Forestry
EPA Project Officer: Lank, Gregory
Project Period: August 15, 2011 through August 14, 2012
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2011)
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Agriculture , P3 Challenge Area - Materials & Chemistry



This project will explore sustainable approaches to overcoming the hindrance of high Ca2+ concentration and ionic strength to struvite recovery from filtrate of anaerobically digested dairy manure.


Anaerobically digested dairy manure has high concentrations of phosphate, ammonium, and magnesium, which could be recovered at a higher pH (8.5-9.5) as struvite, MgNH4PO4∙6H2O. However, high ionic strength and calcium content interferes with struvite recovery from digested dairy manure. We propose to: 1) use furnace slag to raise pH for calcium precipitation and struvite recovery; 2) make proper use of dilution to minimize ionic strength and maximize phosphate activity for efficient struvite precipitation; 3) determine velocity gradient for efficient recovery of struvite in a batch crystallizer driven by an air-lift pump; and 4) assess the market share of struvite production with digested dairy manure.

Expected Results:

1) Struvite is a slow-release compound fertilizer. Struvite recovery from digested dairy manure could remove phosphate and ammonium while providing revenues for farmers. 2) Utilization of furnace slag and dilution will improve sustainability of struvite recovery. The optimum type and particle size of furnace slag will be identified based on efficient pH elevation and minimum PO43- adsorption. The optimum dilution ratio will be identified based on total mass of struvite recoverable. 3) Operational parameters will be optimized for the batch struvite crystallizer. 4) The market share of manure-based struvite among other manure products will be evaluated for New York State.

Supplemental Keywords:

Bio-based feedstock, phosphorus recovery, waste to value

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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