Keywords: aeration, anaerobic treatment, COD, chemical oxygen demand, wastewater treatment, effluent treatment, regression modelling, oxygen transfer, diffusers, UASB reactors, upflow anaerobic sludge blanket, sewage treatment
Evaluation of polishing of the effluent from UASB reactor by diffusers
Effluents from bench scale 56 L upflow anaerobic sludge blanket (UASB) reactor and four UASB based sewage treatment plants (STPs) of capacities ranging from 27 ML/d to 70 ML/d were aerated in batch as well as in continuous mode of operation. The process was monitored by measuring temporal trend in Oxidation Reduction Potential (ORP), dissolved oxygen (DO), chemical oxygen demand (COD) and biochemical oxygen demand (BOD). With the increase in ORP from ?150 mV to +200 mV, COD of the effluent decreased by ~50% with a decay rate of 0.36 per hour. A multiple regression equation has been established to correlate ORP, COD and DO.