Oxidation reduction potential (ORP) as a real-time control parameter in swine manure treatment process
Creators: name: Ra, Chang-Six
Publisher: name: University of British Columbia
Year: 2009

description: This research evaluated the use of oxidation-reduction potential (ORP) as a control parameter in the treatment of high strength swine wastewaters. Newly developed real-time control technologies, which utilize ORP, were successfully applied to a new type of batch-scale process for the treatment of combined carbon, nitrogen and phosphorus removal. The new unit process, named the two-stage sequencing batch reactor system (TSSBR), was operated under four different control strategies (TSSBR#1 to #4). None of the operating strategies used a supplemental carbon source in order to achieve proper phosphorus release and denitrification. However, the feasibility of using an internally available carbon source for biological nitrogen and phosphorus removal was investigated . In the first and second operating strategies (TSSBR#1 and #2), the residual carbon manipulation point (designated RCMP by the author) on the ORP-time profile was used to achieve real-time process control. In the third operating strategy (TSSBR#3), the nitrogen break point (NBP) was designated as the real-time control point. In the fourth operating strategy (TSSBR #4), real-time control using ORP was not performed. This research established the ability of real-time control technologies to reflect the various stages of biological reaction. Indirect comparisons between the real-time and fixed-time strategies also revealed that the real-time operations had significant advantages over fixed-time operation as follows: 1) optimization of treatment capacity can be achieved by the application of real-time process control technologies; 2) a constant effluent quality can be obtained, despite variations in influent composition; 3) higher combined C, N and P removal can be achieved, 4) a treatment system for swine wastewater can be operated without a supplemental carbon source, optimizing simultaneous organic carbon, nitrogen and phosphorus; 5) in addition to the optimization of the length of aeration, a balance between aeration rate and systemic oxygen demand can be established. Based on the results of this research, both the pH pattern and ORP can be used as successful process control parameters in the optimization of organic carbon, nitrogen and phosphorus removal from wastewaters. The use of each parameter possesses advantages over the other. The data from this research also revealed that effective denitrification could be achieved without the addition of an external carbon source. In addition, the sludge transfer strategy performed in TSSBR#2 was shown to successfully enhance denitrification through utilization of an internal carbon source. The preliminary four-stage process operated with a batch-mode (FBM) was investigated in the treatment of swine manure using ORP for the control of organic and nitrogen loading. ORP tracking identified a significant correlation between the ammonia-N loading and the ORP values. In particular, the trend of ORP values in the aerobic reactor appeared to be directly related to the ammonia-N concentration after loading.