Investigation of different levels of reducing oxidation potential (ORP) on quality indices of warm-water aquaculture wastewater

Water Oxidation Reduction Potential (ORP)is a physicochemical index of water affected by a combination of oxidation and reduction agents in water and wastewater. In addition to affecting many water quality parameters, this index indicates a general quality of water and wastewater. The purpose of this study was to investigate the effect of different levels of water ORP on quality indices of warm-water aquaculture wastewater parameters, including COD, BOD, TOC, nitrate and phosphate. To conduct this research, triplicate wastewater treatment in four ORP treatments with levels of 250-200 (control treatment), 250-200 (first treatment), 350-300 (second treatment), 400-350 (third treatment) mv in 70 L tanks conducted in for four weeks. Different levels of ORP in treatments were performed by ozonizing device on a daily basis and the ORP was measured with an ORP digital meter. According to the results, by increasing the ORP level in treatments, BOD, COD and nitrate factors decreased significantly but increasing of ORP level did not show significant effect on phosphate and TOC factors. In addition, the results of the study showed using of oxidizing agents such as ozone and regulating of ORP range could be used as an appropriate tool for improving the quality indices of warm-water aquaculture wastewater.