CFD Simuiations And PIV Measurements On Hydrodynamic Behaviour Of Submerged Flat Membrane Bioreactor Equipped With Micro-channel Turbulence Promoter

Global water shortage, coupled with people’s inadequate protection of water resources,the phenomenon of water resources wasting and pollution is very serious, so wastewatertreatment and reuse is imminent. Compared with the traditional method of sewage disposal,Membrane bioreactor (MBR) is a new and efficient water treatment technology with manyadvantages (such as the complete removal of solids from effluent, lower sludge production,small footprint), these advantages attract more and more researchers attention. However,membrane fouling is still the technical problem which has not been well-solved yet.Turbulence promoter, which can enhance fluid flowing state on the membrane surface, hasa big effect on fluid turbulence state and can improve the state of the fluid flow and controlmembrane fouling and concentration polarization. However, the turbulence promoter wasconfigured directly in a tubular membrane bioreactor in present researches which reducesthe effective membrane area and increasing the footprint of membrane bioreactor. In orderto overcome these shortcomings, the micro-channel turbulence promoter was configuredon the flat membrane surface and porous between thorns was added to increase theeffective membrane area in this study.Effect of micro-channel turbulence promoter placements, turbulence promoter shapesand thorn angles, radius between thorns, the distance between membranes, onhydrodynamic conditions were investigated by CFD simulation. The simulation resultsshowed that cyclical changes along the membrane channel and the maximum in thevicinity of the micro-channel turbulence promoter by analyzing the fluid velocity,turbulence intensity, turbulent kinetic energy, wall shear stress, turbulence dissipation rateand the static pressure drop in membrane channel have increased when the micro-channelturbulence promoter is configured in MBR. And this indicates the micro-channelturbulence promoter plays a significant role in enhancing fluid flow. Though CFDsimulation, confirmed rectangle micro-channel turbulence promoter sided parallel placedon membrane, the thorn angle60°, radius between thorns0.3mm, the distance betweenmembranes8mm is the best way to improve hydrodynamic conditions along themembrane channel. Make a comparison of dynamic parameters between the optimum results with the membrane channel without micro-channel turbulence promoters, the fluidvelocity, turbulence intensity and wall shear stress in membrane channel which was placedwith micro-channel turbulence promoters have average increased22.7%，66.1%，88.1%respectively, turbulent kinetic energy has average increased11.7times, this phenomena cansuppress the formation of the filter cake, increase flux, slow down membrane fouling,extend the service life of the membrane. At the same time, the static pressure drop hasaverage increased10.9%, and turbulence dissipation rate has average increased23.2times,this phenomena shows that the energy consumptions have increased. However, in view ofits effective role on membrane fouling, the use of micro-channel turbulence promoter wasmore advantages than disadvantages.The simulation results and experimental results are in good agreement by comparingthe Particle Image Velocimetry (PIV) with CFD simulation results, therefore,reasonableness of model selection and boundary conditions setting are verified.