Evaluation of selected new technologies for animal waste pollution control

Abstract

In 1998, two upper North Bosque River segments were designated as impaired due to the nonpoint source (NPS) pollution of phosphorus (P) to these segments in the watershed. As a result, two Total Maximum Daily Loads (TMDLs) were applied which called for the reduction of annual loading and annual average soluble reactive P (Sol P) concentrations by 50 %. This study was conducted to evaluate the efficacy of two prospective new technologies, an Electrocoagulation (EC) system, and a Geotube® dewatering system to potentially aid the dairy farmers in meeting the goals set by the TMDLs. The EC system analyzed in this study used chemical pretreatment to coagulate and separate solids in effluent pumped from the dairy lagoon; the liquid then flowed over charged iron electrodes giving off ions that cause coagulation and precipitation of P and other metals. Overall, the performance of the system was consistently highly effective in reducing total phosphorus (TP) and Sol P, on average, reducing these constituents by 96% and 99.6% respectively from the dairy lagoon effluent. However this consistency did not hold for the rest of the analytes. In the Geotube® dewatering system geotextile tubes were utilized to dewater dairy lagoon effluent. Results showed this system performed very well in filtering solids from the dairy lagoon effluent, removing an average of 93.5 % of the total solids between the two pumping and dewatering events of March and April. It was effective in removing nutrients and metals as well. The average percent reduction of TP and Sol P for the two events were very high at 97% and 85 % respectively.