Title: Water quality improvements of wastewater from confined animal feeding operations after advanced treatment Authors
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 4, 2007
Publication Date: August 28, 2008
Citation: Vanotti, M.B., Szogi, A.A. 2008. Water quality improvements of wastewater from confined animal feeding operations after advanced treatment. Journal of Environmental Quality 37(5):S86-S96. Interpretive Summary: We conducted a study to determine the water quality improvements by an alternative on-farm technology operating at full-scale during a 2-yr evaluation period. In addition, we evaluated water quality changes in the converted lagoon that were compared with an adjacent traditional lagoon with similar production management. The on-farm system greatly increased the efficiency of liquid-solid separation by polymer injection to increase solids flocculation. Nitrogen management to reduce NH3 emissions was accomplished using nitrification/denitrification. Subsequent alkaline treatment of the wastewater in a P removal unit precipitated P and produced a disinfected liquid effluent. The on-farm system removed 98% of the suspended solids, 100% of the BOD, 98% of the ammonia, 95% of the phosphorus, 99% of the copper and 51% of the salinity. These high treatment efficiencies were obtained consistently cold and warm weather conditions with varying strength of the manure from typical livestock growth cycles. As the treatment system cleansed the liquid manure and replaced the anaerobic lagoon liquid with clean water, it transformed the anaerobic lagoon into a treated water aerobic pond. By the second year, the following reductions in water constituents were realized: 73% of suspended solids, 77% of the BOD, 92% of the ammonia, 38% of the phosphorus, 37% of the zinc Zn, 39% of the copper, and 55% of the salinity. These reductions showed an additional environmental benefit obtained when advanced treatment technology is retrofitted to a swine operation with an existing anaerobic lagoon; that is, the clean up of the lagoon liquid without additional cost to the farmer. These findings overall showed that cleaner alternative technologies can have significant positive impacts on the environment and the livestock industry.
Technical Abstract: Current trends of animal production concentration and new regulations promote the need of environmentally safe alternatives to land application for handling of liquid manure. These technologies must be able to capture nutrients and heavy metals, reduce emissions of ammonia and odors, and disinfect the effluent.To meet these needs, one of two 4,360-pig production units on a finishing farm in Duplin Co., NC, was retrofitted with a full-scale wastewater treatment system, while the second unit continued under the traditional lagoon management. The new treatment system was tested for two years as part of an agreement between government and swine industry to demonstrate environmentally superior technology (EST) that could replace the anaerobic lagoon treatment. The new treatment system used liquid-solids separation, nitrification/denitrification, and phosphorus removal processes. Once the treatment plant was operational, flow of raw manure into the unit’s corresponding lagoon was discontinued and the lagoon was used to store treated wastewater. Water quality was monitored in three sites: the treatment plant as the raw manure liquid was depurated in the various processes, the converted lagoon as it was being cleaned up, and in the second unit’s traditional lagoon. The on-farm treatment system removed 98% of TSS, 76% of TS, 100% of BOD5, 98% of TKN and NH4-N, 95% of TP, 99% of Zn, 99% of Cu, and 51% of EC. The quality of the liquid in the converted lagoon improved rapidly as cleaner effluent from the plant-replaced anaerobic lagoon liquid. The converted lagoon became aerobic (DO = 6.95 mg L-1, Eh = 342 mv) with the following mean reductions in the second year of the conversion: 73% of TSS, 40% of TS, 77% of BOD5, 85% of TKN, 92% of NH4-N, 38% of TP, 37% of Zn, 39% of Cu, and 55% of EC. Based on performance obtained, the treatment system was determined an EST. These findings overall showed that cleaner alternative technologies are technically and operationally feasible and that they can have significant positive impacts on the environment and on the livestock industries.