Study On Membrane Bioreactor Reclaimed-water Reuse Project Operation

This paper studied the membrane bioreactor (MBR) of Tianjin University Natatorium Reclaimed-water Reuse Project and monitored and recorded nearly its operation datas from May 1st 2004 to April 30th 2005 since the start-up date of the MBR. The start-up process of MBR was summarized on the basis of that, and the pollutant removal performance and mechanism of wastewater was analyzed. The removal rate of CODcr, BOD5, LAS, NH3-N and turbitidy are 34.1%~89.4%, 95.5%~99.3%, 94%~97.9%, 84.9%~99.8% and 93.7%~99.9% respectively. The contamination removal is mainly depended on biochemical action and the membrane's physico-chemical action has a role as well.The problems which are different from conventional treatment process occurred in the operation of membrane bioreactor, and why the value of SV and SVI are high is discussed. Those problems are caused by two factors. First, the filamentous bacterium is dominant in MBR or amylose beside zoogloea is used by microbia because of the low value of F/M, which caused the microbial floc loosed, consequently, the value of SVI is high. Second, the MBR's aeration quantity is more than conventional biochemical process, and the strong aeration break up zoogloea floc, which make the value of SVI high. Simultaneously, the influencing factors of membrane fouling and the methods of alleviating membrane fouling are discussed in this paper according to the membrane fouling in this project.A mathematical model of soluble microbial products (SMPs) formation-degradation was established based on the activated sludge model No 1 and the conception of SMP. This model is applied to the membrane bioreactor process with high concentration of activated sludge under aerobic condition. According to the present monitoring status of water quality, this paper set up the conversion method between the model components and general measured data and the measured data are applied into the model. Then the model is simulated with the software of MATLAB7.1. Sensitivity analysis of parameters was investigated in order to determine which parameter influence the system most,then estimate parameter value for getting accurate results.The model can be applied to analyze the change of effluent quality and determine reasonable operational parameters through changing one operational parameter and maintaining other parameters unchanged.Based on the model simulation, it can be deduced that the good treatment performance and energy saving can be achieved by controllingHRT=6~8hr and SRT=30d be controlled.The paper introduced optimal membrane washing interval and its application to the engineering optimization should be studied in the future.