In the last half century, intensive phosphate mining has increased the global phosphorus influx into the biogeochemical cycle of the earth by 400%. Such a rapid intensification is concerning as phosphorus reserves are limited and geospatially concentrated; additionally, large amounts of valuable phosphorus are lost to water bodies through over-application of phosphorus-laden fertilizers and animal manure on agricultural land. The concentrated poultry operations on the Delmarva Peninsula are an interesting case study. This region generates, and land applies, 7 million tons of phosphorus rich poultry litter each year. Over time, these practices have introduced excessive phosphorus in the soil, which has subsequently led to a high influx of phosphorus into the Chesapeake Bay. Implementation of an appropriate nutrient recovery process can recover 140,000 tons of phosphorus that can be exported to phosphorus deficient watersheds. The goal of this work was to recover phosphorus from poultry litter using an innovative technology that generates three valuable products (<i>i.e.</i>, struvite-based minerals, low nutrient manure, and liquid fertilizer) with low chemical/water costs. In general, greater than 80% of the phosphorus was recovered from poultry litter as struvite or potassium struvite, which are slow release fertilizers, although some calcium phosphate products were also observed. To further improve product quality, the impacts of pH, Mg/P ratio, and dissolved organic matter content were investigated. The recovery process was scaled up to an automated two stage process; furthermore, the water demand was reduced by operating at high solid loading and introducing a recycle stream. Acid demand was reduced by bubbling (synthetic) CO<sub>2</sub> rich flue gas. Overall, implementation of this phosphorus extraction and recovery system is expected to contribute to ongoing efforts at mitigating the impacts of limited phosphorus reserves on food security and preventing detrimental impacts on ecologically sensitive water bodies.

Recovering phosphorus from poultry litter: A step towards improving food security and protecting ecologically sensitive water bodies

251st National Meeting (2016)

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