ARS | Publication request: Technology for recovery of phosphorus from animal wastewater through calcium phosphate precipitation

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: January 13, 2009
Publication Date: May 10, 2009
Repository URL: http://hdl.handle.net/10113/46341
Citation: Vanotti, M.B., Szogi, A.A. 2009. Technology for recovery of phosphorus from animal wastewater through calcium phosphate precipitation. In: Ashley, K., Mavinic, D. and Koch, F. (editors). Nutrient Recovery from Wastewater Streams. London, United Kingdom:IWA Publishing. p. 459-468.

Technical Abstract: A wastewater treatment process was developed for removal of phosphorus from livestock wastewater. The phosphorus is recovered as calcium phosphate with addition of only small quantities of liquid lime. The process is based on the distinct chemical equilibrium between phosphorus and calcium ions when natural buffers are substantially eliminated. It was discovered that reduction of carbonate and ammonium buffers during nitrification substantially reduces the Ca(OH)2 demand needed for optimum P precipitation and removal at high pH. The technology produced consistent results in pilot tests on ten swine farms and successfully demonstrated full-scale on two swine farms in North Carolina, USA. It can be used to retrofit animal lagoons or in new systems without lagoons. The recovered calcium phosphate can be recycled into a marketable fertilizer without further processing due to its high content (> 90%) of plant available phosphorus. The concentration grade obtained during full-scale demonstration was 24.4 ± 4.5% P2O5. A second generation version of the technology is available for municipal and agricultural wastewater and includes the simultaneous separation of solids and phosphorus from wastewater and industrial effluents. The combined separation process is more efficient in terms of equipment needs and chemical use. Thus, it reduces installation and operational cost of manure treatment.