Study On Characters Of MBR In Electric Field And Membrane Fouling Control

As one of potential technology of wastewater reuse, membrane bioreactor (MBR)had been widely using in sewage treatment plants and on-site sewage treatment facilitiesin some developed country. Membrane module in it can separate solid and liquidperfectly instead of the secondary settler which requires land occupation and cost highly.Membrane fouling is one of the most important factors in fluencing the development ofMBR. For control membrane fouling, electric field technology is introduced in MBR.Then, electronegativity microbe can be protected from accumulating in the hole ofmembrane and electric field in biological dephosphorization can come application.Because of huge MLSS and excessive populations in MBR, Interference on microbe canbe fight back.The results showed the best current density of experiment is determined:0.09mA/cm2. membrane fouling is alleviated and the activity of microbe also didn'tdecrease in the condition. Comparisons of curve fitting of models, logarithmic model ismore suitable than linear model for the decline of MBR flux in short period of time.It can be detected that the decline of flux in 1# MBR that the electric field isintroduced in is different from the one in 2# MBR with operation in longer time. Theelectric field is becoming to membrane fouling control, because cubic spline functionscan be in 1# MBR and linear model can be in 2# MBR by mathematical expression inevidence. Membrane flux in the front of 5 days when MBR takes best operation timekeep better level of membrane flux in 1# MBR.Electric field is not suitable to the removal of COD and NH₄⁺-N, even negativeinfluence can be detected. COD has some contact with NH₄⁺-N in removal rate, theremoval of TP takes max rate of 99% which make another substitute of chemicalphosphorus removal.Preliminary identification of depositional gradation and substance contributionthrough which trend of average flux decline with accumulation of operation time.Concentration polarization which means soluble matters that is mixed liquid sludge hereinduce the accumulation of solute dense the one side of membrane is the most importantreason in the first moment of MBR. Deposition on the surface and fouling pore haverelation to the run of later moment. So, electric field can keep from concentration polarization in some extent.Average concentration of MLSS in 1# MBR is 3556 mg/L and 2# MBR is 3689mg/L in the whole operation period. It's difficult to keep a high level of MLSS, butother parameters are normal. In the last 3 days, the water quality deterioration is takeplace.Experiments have proved electric field which can accelerate growth rate ofmicrobe and then decease quickly is dual nature. The Influence of electric field onmicrobe takes reflection by the change of physical chemistry and electric chemistrycharacters in the cell. It's relation to propagation, accretion aging and aberrance.Macroscopically, it has difficulty with holding operating condition in a last runningtime.