Phosphorus Recovery from Poultry Litter

Abstract

Land application of large amounts of poultry litter is an environmental concern often associated to excess phosphorus (P) in soils and potential pollution of water resources. Recovery of P from poultry litter waste is an attractive approach when on-farm application of poultry litter is not an option. A treatment process, called quick wash, was developed for extraction and recovery of P from poultry litter and animal manure solids. The quick wash process consists of three consecutive steps: (1) P extraction, (2) P recovery, and (3) P recovery enhancement. In step 1, organically bound P is converted to soluble P by rapid hydrolysis reactions using selected mineral or organic acids. This step also releases P from insoluble inorganic phosphate complexes. The washed litter residue is subsequently separated from the liquid extract and dewatered; unnecessary carbon (C) and nitrogen (N) transformations are prevented by dewatering the residue. In step 2, P is precipitated by addition of lime to the liquid extract to form an alkaline earth metal-containing P product. In step 3, an organic poly-electrolyte is added to enhance the P grade of the product. This approach of extracting and recovering P from poultry litter using the quick wash process produces a final P product that can be reused as fertilizer. In addition, the remaining washed solid residue has a more balanced N to P (N:P) ratio that is more environmentally safe for land application and use by crops. As an alternative, washed poultry litter residue can be used for energy production or reutilized as bedding, especially in areas where bedding material is in short supply.