Swine Wastewater Treatment by a Batch-Mode 4-Stage Process: Loading Rate Control Using Orp

Author: Ra C. S.  

Publisher: Taylor & Francis Ltd

ISSN: 0959-3330

Source: Environmental Technology, Vol.18, Iss.6, 1997-06, pp. : 615-621

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Abstract

A bench-scale, four-stage process operated in a batch-mode (FBM) was studied 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 ORP for the control of organic and nitrogen loading. Two SRT periods were assessed with all other operational conditions kept constant. Phase I of the study (FBMa) had a system SRT of about 17 days, including 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 average concentrations of COD, NH4-N and TKN of the swine waste influent used for this research were 5,085, 1,254 and 2,018 mg L−1 in the FBMa operation, and 3,878, 1,142 and 1,896 mg L−1 in the FBMb operation, respectively. Under FBMa operating conditions, removal efficiencies for BOD5, COD, ammonia-N and TKN were 92 %, 83.1%, 85.3% and 82.1%, respectively, while 85 %, 58.3%, 86.0% and 76.5%, respectively, were also obtained 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. ORP 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 concentration after loading. This suggests that ORP may be successfully utilized to control this swine manure treatment system.