ORP and pH Based Control of SBR Cycles for Nutrient Removal from Wastewater

Continuous monitoring of multiple process functions were conducted involving removals of BOD, TSS and nutrients, in each cycle of the SBR reactor at the wastewater treatment plant of the City of Carrabelle, FL. On line, real time, monitoring of pH, oxidation reduction potential (ORP), dissolved oxygen (DO), ammonia-N, nitrite-N, nitrate-N and orthophosphate-P demonstrated excellent correspondence between these parameters and the individual biochemical reactions in each step. Subsequently, the SBR cycle control logic was changed on a trial basis from time and DO based, to ORP based. This led to a superior performance of the SBR reactors and has the potential of resulting in a better energy efficiency while maintaining the effluent quality complying with the State of Florida regulation for BOD, TSS, TN, TP of 5, 5, 3 and 1 mg/L, respectively.