Demonstration and Transfer of Selected New Technologies for Animal Waste Pollution Control

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Texas Water Resources Institute

The Demonstration and Transfer of Selected New Technologies for Animal Waste Pollution Control project was conducted by the Texas AgriLife Extension Service and Texas Water Resources Institute and was designed as a means for evaluating animal waste treatment methods and their ability to remove phosphorus (P) from dairy waste. A variety of factors present in the North Bosque River watershed have led to the excessive loading of P and subsequent algal growth in the water body. As a result, the Texas Commission on Environmental Quality developed two Total Maximum Daily Loads (TMDLs) for the North Bosque River mandating that P loading to the water body be reduced by at least 50 percent. Upper portions of the North Bosque River watershed are home to numerous dairy operations that can be a source of manageable P and other nutrients to the watershed. Prior to the development of this project, dairy producers in the area were approached by different companies soliciting their respective products that ‘guaranteed’ P removal from their dairy waste and/or lagoons; however, the diary producers were not presented with scientific evidence to support these claims and were skeptical about actual results. This project was designed in response to the need for scientific evidence and evaluated the ability of four products/technologies to remove P from liquid dairy manure prior to its application on nearby fields. The program was set up so that an unbiased, third party laboratory analyzed samples collected from dairy waste prior, during, and after treatment by each respective product or technology to provide scientifically sound information to dairy producers so they can make an informed decision about implementing a specific treatment to reduce P from their dairies. Each technology provider utilized a different approach for applying or implementing their respective treatments; the providers were allowed to demonstrate their technology without any modifications recommended by Texas AgriLife Extension Service. Specific sampling procedures and locations were not consistent between each evaluation due to the nature of the technologies; two physiochemical methods treated the waste stream to separate solids and nutrients from liquid manure while two biological treatment methods utilized microbes to treat the entire lagoon. Though each technology resulted in improvements of lagoon characteristics, only the physiochemical treatments effectively removed more than 50 percent of P present in the dairy waste. As an addendum to the project, a demonstration was conducted to evaluate the feasibility of growing turfgrass on soils amended with byproduct from one of the physiochemical treatment evaluations. The large volume of solids remaining after treatment raised the question of how to effectively dispose of the solids in a beneficial way. The demonstration assessed the response of turfgrass growth and leachate/runoff water quality from small cylinders containing soils amended with the particular byproduct. Results showed that turf production increased as a result of the amendment and water quality was not drastically compromised. This report summarizes the results of each demonstrated product or technology and the turfgrass growth demonstration. It highlights both positive and negative aspects of each treatment methodology so producers who consider implementing one of the technologies may have science-based findings predicting respective performance.