Water Resources Research Act Program

Details for Project ID 2002TX49B

Reduced Phosphorus Pollution from Dairies by Removal of Phosphorus from Wastewater through Precipitation of Struvite

Institute: Texas
Year Established: 2002 Start Date: 2002-03-01 End Date: 2003-02-01
Total Federal Funds: $5,000 Total Non-Federal Funds: $28,476

Principal Investigators: Amanda Bragg, Kevin McInnes

Project Summary: Phosphorus enrichment of streams and lakes in Central Texas is a severe environmental problem, much of which originates, at specific key sites, from phosphorus loads in dairy wastewater. In simple terms, the problem is that wastewater from dairies is high in phosophorus levels. When applied to lands used for irrigation of crops and pastures, this nutrient-rich wastewater poses a significant non-point source pollution risk, especially during rainfall runoff events. The problem is especially severe since phosphorus is thought to be one of the main limiting factors that are responsible for algal growth and blooms in surface waters. In contrast, if the phosophorus content of dairy effluents were reduced significantly, the threats to water quality would likely diminish. Recently, municipal and industrial wastewater treatment plants have reduced phosphorus concentrations to minimal levels using precipitation by struvite, an ammonium and magnesium phosphate [Mg-NH4-PO4]. In these applications, the use of struvite also allows phosphorus in raw wastewater to be removed and then reused as a source of fertilizer. In this project, samples of dairy lagoon wastewater will be collected from privately-run dairies near Stephenville, TX in the Bosque River watershed of Central Texas. A series of tests will be conducted on subsamples taken from this wastewater. The ionic composition and pH buffer capacity will be determined. Then, after laboratory analysis has been conducted, tests will be run to determine the optimal way to use struvite to treat wastewaters with varying levels of phosphorus, magnesium, and nitrogen-related compounds. The anticipated result from this project is that a methodology could be developed that would remove significant levels of phosphorus from dairy wastewater, while increasing the nitrogen content that could be recovered by treating this effluent stream. The project would also determine how the recovered nitrogen could be reused for the iririgation of various grasses. In sum, these effects would lead to ways to improve water quality be removing potential sources of nutrients and non-point pollutants.