Phosphorus recovery from poultry litter

Authors: Szogi, Ariel; Vanotti, Matias; Hunt, Patrick

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/16/2008
Publication Date: 10/27/2008
Citation: Szogi, A.A., Vanotti, M.B., Hunt, P.G. 2008. Phosphorus recovery from poultry litter. Transactions of the American Society of Agricultural and Biological Engineers 51(5):1727-1734.

Interpretive Summary: 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, P bound to poultry litter is rapidly released as soluble-P using mineral or organic acids. The washed litter residue is subsequently separated from the liquid extract and dewatered. In step 2, P is precipitated by addition of lime to the liquid extract to form a containing P product. In step 3, a flocculant 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 with lower and more balanced nutrient content 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.

Technical 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 hydroloysis 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 earch 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.