Designning Of Novel Pendulum Model Oscillating Membrane Bioreactor And Its Fouling Control

The promotion and application of MBR are greatly influenced by the performance and economy of main unit membrane module. As previous reported, membrane fouling can be effectively alleviated by improving the shear rate of membrane surface. Considering the dynamic mode, a new pendulum membrane module was designed. This membrane module will greatly enhance the disturbances of water, gas and other fluid, and increase elastic collision between bubbles and membrane. Thus, adsorption and deposition of sludge particles on membrane surface will effectively restrained. Then the concentration polarization and membrane fouling will be relieved obviously. Compared with other dynamic membrane modules, the new pendulum membrane module has the unique advantages as follow:?1? swing cycle periodically is changeable, forming an alternating shear flow field conducive to reduce membrane fouling; ?2? realizing the promise transformation of rotation angle and frequency, easy to control; ?3? reducing energy consumption and saving costs.In this paper, we used the submerged membrane bioreactor with vertical pendulum motion ?Mode-1 ?V?? to treat oil wastewater. Compared with the traditional submerged membrane bioreactor ?Mode-2 ?T??, the influence of water shear force on wastewater treatment, membrane permeability, morphology and characteristics of microorganism in reactor was investigated. In our research, we analyzed effluent quality of two MBR systems, the results demonstrated that two systems all exhibited high COD, NH3-N and oil removal performance ?average above 80.0%?. However, the performance of the Mode-1 ?V? was better than Mode-2 ?T?, which indicated the enhanced water shear force by swinging of Mode-1 ?V? can effectively promote the contact between the oil molecules and microorganism. Secondly, compared with Mode-2 ?T? in membrane permeability, the Mode-1 ?V? presents superior filter performance and anti-pollution ability. The permeate flux was maintained at 22.0 L/m₂h·bar after a cycle of 30 days for Mode-1 ?V?, almost 7 times about Mode-2 ?T? whose permeate flux was 3.3 L/m₂h·bar. Scanning electron microscope images of tested membranes showed the cake layer formed on membrane surface of the Mode-1 ?V? is thin and loose contrast to Mode-2 ?T?. This loose structure not only can promoted the effluent ability, but also reduced membrane fouling, so it can improved water flux and extend membrane life. Meantime, we also analyzed the influence of enhanced water shear force on the morphology and characteristics of microorganism. The results demonstrated that the activated sludge particle sizes are 80.5 ?m?r=50 rpm?,104.5 ?m?r=20 rpm?,73.9 ?m?r=70 rpm? for Mode-1 ?V? and 91.1 ?m for Mode-2 ?T? which indicate that the properly swing of membrane module is helpful to increasing the sludge particle size. But when swing frequency is too large, the sludge particle size will be reduced. We also detected that the relative hydrophobicity of activated sludge increased obviously in Mode-1 ?V?, from 65.4% to 92.3%, however, the traditional submerged MBR was maintained at 65.0%. Through the analysis by electron microscopy, results indicated that the swing of membrane module can bring some impact on the morphology of microorganism. Compared with Mode-2 ?T?, the tightness of zoogloea will decline. Detecting degradation and anti-fouling performance, the Mode-1 ?V? shows great development potential in degrading refractory organic wastewater.