TREATMENT OF LIQUID SWINE MANURE IN THE SEQUENCING BATCH REACTOR UNDER AEROBIC AND ANOXIC CONDITIONS

Laboratory studies were conducted on a sequencing batch reactor (SBR) for the treatment of screened liquid swine manure. The SBR was operated on the basis of a 24 hours cycle at 6 and 9 days hydraulic retention time and 20 days solids biological retention time. Nitrification and denitrification processes were carried out in the same reactor by alternating aerobic/anoxic conditions, and the tested time ratios were 19/3, 16/6, 14/8 and 10/12 (hours). The results from the overall performance indicated that above 99% NH3-N, 93% TKN, 97% COD and 97% TSS removal were achieved in the SBR treatment. Anoxic operation did not adversely affect the activity of the nitrifiers, and NO2-NO3-N concentration increased up to 230 mg/L following air supply. However, sludge settling was poor in those reactors functioning with an anoxic period greater than 8 hours. As a result of nitrification and denitrification the removal of ammonia and nitrite plus nitrates nitrogen was 80 to 93%.