New Technologies Aim to Remove Excess Phosphorus

October 1st, 2004 | Posted in Uncategorized

By Jenna Smith, October 2004

Dairies within the Bosque and Leon River Watersheds will soon have the opportunity to participate in a program directed to assess a variety of technologies, which can decrease the level of phosphorus in dairy manure and process-generated wastewater.

Current dairy waste management systems utilize lagoons, which store and treat process water and other runoff waste. When lagoon effluent is irrigated onto waste application fields, it supplies essential plant nutrients including phosphorus (P) to receiving soils. If more P from effluent is applied than can be utilized by crops and pastures then over time, P levels can increase and runoff events from these fields may contribute excess nutrients to nearby waterways.

According to Saqib Mukhtar, associate professor and extension specialist with the Texas A&M University Department of Biological and Agricultural Engineering, utilizing technologies that remove or reduce the phosphorus content of dairy manure effluent will allow dairy operators to continue to apply the low P effluent to waste application fields without increasing soil P levels.

Since the historical use and performance of these technologies on dairy waste is limited, Mukhtar will lead a new project conducted by Texas Cooperative Extension and the Texas Water Resources Institute. The principal goal of this project is to provide a third party evaluation of selected technologies designed to reduce P levels in dairy manure effluent without negatively affecting onsite waste management systems or other waste constituents.

The project, funded by the Texas State Soil and Water Conservation Board through the Environmental Protection Agency Clean Water Act, will be implemented over the next three years on cooperating dairy operations within the Bosque and Leon River Watersheds. Two technologies will be selected each year and implemented in each of the two impacted watersheds.

“Electrocoagulation Technology” and “Phosphorus Removal by Chemical Precipitation and Geotube®” were selected for first year evaluation. The OSVE Dairy in the Bosque River Watershed and the Triple X Dairy in the Leon River Watershed will both cooperate with technology providers and project administrators to implement and evaluate performance efficacy. Both of these dairies use anaerobic lagoons to remove, store, treat, and land-apply effluent (manure and process-generated wastewater).

“Both Geotube® and Electrocoagulation will use two different technological methods to treat raw material and analyze the sludge or by-product for P stability,” said Mukhtar. “This testing is designed to reduce water quality impairment associated with animal production systems, specifically dairies.”

The Geotube® method will use chemical precipitation and Geotube dewatering of animal waste to remove P in raw, liquid manure. By utilizing Alum, a chemical proven to bind P from an animal waste stream, P will be rendered insoluble, unreactive and unavailable as a plant nutrient.

Electrocoagulation, on the other hand, will utilize aluminum and iron electrodes and electrical current for P removal. As animal wastewater flows through a series of electrodes, the electrical energy causes the contaminated wastewater to separate into an organic rich floating layer, a mineral rich sediment and clean water.

Besides reducing P levels in the dairy manure for continued, beneficial application on waste application fields, the technologies may potentially help reuse the treated water within the dairy operations for wash water, drinking water, misters and other on-site activities.