DYNAMIC SIMULATION IS NECESSARY TO UNDERSTAND DIFFERNCES INDESIGN OF BIOLOGICAL NUTRIENT REMOVAL MBR PROCESSES

摘要

The increasingly stringent quality of effluent and the need to reclaim and reuse water arernpromoting application of biological nutrient removal (BNR) membrane reactor (MBR) systems.rnAt a given site, selection of a BNR process depends on influent characteristics and effluentrnquality expected from the treatment plant. Ideally, dynamic influent data should be used forrnprocess design. However, in most cases, average wastewater quality and flow is available at therndesign stage, without a detailed understanding of the dynamic nature of the specific source. Thisrnis a limitation in practice that can be addressed, to an extent, by incorporating sufficient safety inrnthe design.rnThis paper examined the design of BNR-MBR processes using BIOWIN? process simulationrnsoftware under average and dynamic wastewater conditions. The intent is to demonstrate thernnecessity of using dynamic quality to arrive at a proper design, since the actual influentrnconcentrations can vary by orders of magnitude with respect to average values. Regardless, thernplant is supposed to produce uniform effluent quality at all times. The MBR processes evaluated,rnmodified UCT (conventional), modified UCT (membrane) and modified Johannesburg, producedrndifferent design and operating conditions at steady state simulation compared to dynamicrnsimulation for the same target effluent quality. The dynamic simulation, using actual flows andrnwastewater quality data, showed significant differences in the process design and processresponses,rnconfirming the limitation of using the average wastewater quality for design.rnFurthermore, the evaluation indicated that modified Johannesburg (MJ) process, where a deoxygenationrnand denitrification reactor was introduced, to utilize the excess dissolved oxygenrn(DO) in mixed liquor from the membrane tank, resulted in an economical design for the specificrnwastewater and effluent criteria considered in this study.