Application of mixed and aerated pond for nitrification and denitrification of flushed swine manure

A nitrification/denitrification system for flushed swine manure was evaluated for treating manure from 3000 finishing pigs. The system consisted of a pond with a mixing zone for denitrification (anoxic) and an aeration zone for nitrification, with recirculation from aeration zone to mixing zone and also recycling from aeration zone to the barns for flushing. The system was designed by an engineering consulting firm and constructed, operated, and evaluated in cooperation with a swine production company and North Carolina State University as part of an effort by the North Carolina Governor's Office to help fund demonstration and evaluation of innovative treatment technologies for swine manure. The process startup was not successful during winter with high loading (manure from 6750 finishing pigs), but was successful during summer with lower loading (manure from 3000 finishing pigs). Due to delays and funding limits for operation, the system was fully operational and monitored for only 16 weeks (28 July-17 November 1998). After initial problems with foaming and the liner floating were addressed, the treatment system had good stability with relatively few operational problems. The estimated nitrogen reduction was between 65 and 90%, depending on estimation method. Reduction of nitrogen would be expected to decrease with lower temperature it? winter More than 90% of the effluent total nitrogen (N) was organic N. Odor perception ratings for intensity, irritation, and unpleasantness for liquid samples were significantly reduced by the treatment system. Approximately 78-kW (105-hp) energy use was required continuously, resulting in a high energy cost for operation.