Opportunities for nutrient recovery in handling of animal residuals

Treatment methods are presented that can be used for nutrient recovery from animal manure and these processes are compared to the current practice. Using swine feeding operations as an example, the current practice for waste handling is that 97% of all produced waste is applied to owned or rented land after storing the waste in below-floor slurry pits or anaerobic lagoons without cover. This current practice has resulted in a significant environmental pollution. Slurry storage results in emission of odor, VOCs (mainly CH4) and ammonia under normal operating conditions. In many cases there is not sufficient farmland for a sustainable land application without exceeding maximum nitrogen and phosphorus levels. New government regulations will encourage the treatment of animal residuals. Both aerobic and anaerobic process can be used to produce a valuable product from animal manure that can be reused. Phosphorus can be recovered by precipitation in combination with a biological phosphorus removing activated sludge system or by membrane separation in combination with anaerobic digestion.