Strategies for phosphorus recovery in livestock operations: Assessing decentralized and distributed recovery systems

Phosphorus recovery and recycling are crucial to ensure the sustainable supply of this resource while preserving soils and water bodies. Livestock operations are a major source of phosphorus releases through manure generation. Manure storage and over-application may result in the transportation of phosphorus to water bodies by runoff, leading to nutrient pollution. However, their lack of economies of scale and spatial scattering hinders phosphorus recovery at livestock operations. To address these issues, this work explores the implementation of decentralized and distributed strategies for phosphorus recovery at livestock operations through manure processing centers and mobile processing units, respectively. A multi-objective optimization model is developed to design optimal networks for each strategy studied considering environmental and economic aspects. The optimal location of processing centers is determined according to the processing capacity of each phosphorus recovery technology, the location of the livestock operations, and the manure generated by each operation. The decentralized and distributed strategies for phosphorus recovery are assessed using the State of Minnesota in the USA as a case study. Phosphorus recovery can be performed using a decentralized recovery system with minimum greenhouse gas emissions, resulting in an investment cost of 45 million USD. Nevertheless, integrating a distributed phosphorus recovery approach based on mobile units in the decentralized system results in a more cost-effective recovery strategy. This strategy is also estimated to reduce the cost of phosphorus recovery at livestock operations to 23 million USD.