SWINE WASTE-WATER TREATMENT BY A BATCH-MODE 4-STAGE PROCESS - LOADINGRATE CONTROL USING ORP

A bench-scale, four-stage process operated in a batch-mode (FBM) was s tudied for the treatment of swine manure. The objectives of the study were two-fold: first, to evaluate the effectiveness of the FBM process in the treatment of swine manure; and second, to study the potential of using ORF for the control of organic and nitrogen loading. Two SRT periods were assessed with all other operational conditions kept const ant. Phase I of the study (FBMa) had a system SRT of about 17 days, in cluding a 3.5 day SRT in the aerobic reactor. Phase II (FBMb) had a 47 day system SRT, with a 22.7 day SRT in the aerobic reactor. The avera ge concentrations of COD, NH4-N and TKN of the swine waste influent us ed for this research were 5,085, 1,254 and 2,018 mg L-1 in the FBMa op eration, and 3,878, 1,142 and 1,896 mg L-1 in the FBMb operation, resp ectively. Under FBMa operating conditions, removal efficiencies for BO D5, COD, ammonia-N and TKN were 92 %, 83.1%, 85.3% and 82.1%, respecti vely, while 85%, 58.3%, 86.0% and 76.5%, respectively, were also obtai ned under FBMb conditions. A high rate of denitrification was achieved in Phase II, with the nitrate concentrations dropping from 508 mg L-1 in the aerobic reactor to less than 2 mg L-1 in the final effluent. O RP tracking identified a significant correlation between the ammonia-N loading and the ORP value. In particular, the trend of ORP values in the aerobic reactor appeared to be directly related to the ammonia-N c oncentration after loading. This suggests that ORF may be successfully utilized to control this swine manure treatment system.