Research On Vortex Flow Biofilm Membrane Bio-reactor Technique

Currently,the water environment pollution is seriously increasing and water resources are increasingly strained.Under this situation,the development of urban sewage reuse technology has got much significance.Traditional Membrane bioreactor?MBR?has combined the organically membrane separation technology and activated sludge process.This process is very efficient for the effluent water,covers less area,of which the membrane module and bioreactor are main components.Research and development for membrane bioreactor has been quite mature,however membrane fouling is a serious impact with higher energy consumption.It does not only bring inconvenience to the operating management but also is more restricted for the application of membrane bioreactor technology.This paper aimed at the problems existing in the traditional MBR technology,combined biofilm and membrane separation technology,microorganisms cultivation outside of the membrane tube wall which makes easier for the organisms to contact with air directly,consequently not only the oxygen mass transfer rate is increased but also the aerobic microbe environment is maintained and avoided from biochemical aeration.Additionally the energy consumption of the system's operation is also declined.Vortex wave current technique was applied to membrane bioreactor,traditional MBR was changed depending on turbulent fluid method to reduce membrane fouling.The fluid in the membrane module vortex formed through the membrane module structure design under low Reynolds number flow with flow pulse disturbance,which accordingly strengthened the pollutant mass transfer effect,and reduced membrane fouling with decreasing the energy consumption of the system simultaneously.After making a membrane bioreactor experimental device and particle image velocimetry?PIV?,determination of vortex flow test device along with numerical simulation analysis,the formation process of vortex flow in the membrane bioreactor and its influence factors have been studied.The vortex flow biofilm-membrane bioreactor is used to make continuous operation for sewage treatment?for thirty days?in order to examine the sewage treatment effect and system operational energy consumption.The research of vortex flow forming process results show that using membrane tube of dimensions;10 mm diameter and 300 mm length to test and adjust the water pressure equipment and maintaining the pulse frequency of 1 Hz.When the water pressure equipment increased the water velocity to 0.5 m/s,the Reynolds number?R_e?turned around 650.A stable vortex is formed in the 300 mm long membrane tube and a vortex wave flow field is formed in the fluid membrane tube.Continuing the increase in membrane tube fluid velocity further up to 0.9 m/s,the Reynolds number?R_e?approached at 1800,but the vortex structure began to destroy.Membrane tube with membrane pore size of 48?m is adopted in the vortex flow biofilm-membrane bioreactor,which was used to conduct sewage processing experiment for 30 days.The effluent including average COD_Cr of 38 mg/L,average NH₃-N of 3.8 mg/L,the COD_Crr and NH₃-N removal rate were 91%and 88%respectively.Effluent water quality satisfied the water quality standard of Discharge standard of pollutants in municipal wastewater treatment plant?GB/T 18918-2002?.Results of energy operational consumption show that the vortex flow biofilm-membrane bioreactor process per unit volume sewage consumed the average energy of about 0.8 to 1.2 kWh/m³,dealt with per unit weight COD_Cr consumed 2.0 to 2.7kW/h·kg-COD.Integrated with technical and economic analysis,it indicated that compared to a traditional membrane bioreactor,vortex wave current method of MBR system has reduced the energy consumption by 30%.