Water quality improvements of wastewater from confined animal feeding operations after advance treatment

Current trends of animal production concentration and new regulations promote the need for environmentally safe alternatives to land application of liquid manure. Th ese technologies must be able to substantially remove nutrients, heavy metals, and emissions of ammonia and odors and disinfect the effl uent. A new treatment system was tested full-scale in a 4360-swine farm in North Carolina to demonstrate environmentally superior technology (EST) that could replace traditional anaerobic lagoon treatment. Th e system combined liquid–solids separation with nitrogen and phosphorus removal processes. Water quality was monitored at three sites: (i) the treatment plant as the raw manure liquid was depurated in the various processes, (ii) the converted lagoon as it was being cleaned up with the treated effl uent, and (iii) an adjacent traditional anaerobic lagoon. Th e treatment plant removed 98 % of total suspended solids (TSS), 76 % of total solids (TS), 100 % of 5-d biochemical oxygen demand (BOD5), 98 % of total Kjeldahl nitrogen (TKN) and NH4–N, 95 % of total phosphorus (TP), 99 % of Zn, and 99 % of Cu. Th e quality of the liquid in the converted lagoon improved rapidly as cleaner effl uent from the plant replaced anaerobic lagoon liquid. Th e converted lagoon liquid became aerobic (dissolved oxygen, 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