Modeling of fouling considering behavior of EPS accumulated on membrane in MBRs

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In this research, EPS were extracted from sludge accumulated on membrane surface and relationship between change of permeate flux and change of molecular weight profile was investigated.EPS more than 500,000 Da increased on membrane surface and filtration resistance decreased with the decrease of highe-molecular-weight EPS on membrane surface suggesting strong influence of decomposition of high-molecular-weight EPS to smaller molecular weight substances on the performance of MBRs.A mathematical model was developed to simulate detachment of EPS from membrane surface. Relationship between shear stress on membrane and detachment rate of EPS was modeled for both of flat-sheet and hollow-fiber membrane modules. Relationship between shear stress and velocity of bubble flow was modeled for flat-sheet membrane module while velocity profile inside hollow fiber module and bubble flow velocity was modeled for hollow fiber membrane modules.Relationship between decomposition rate of EPS and trans-membrane pressure was modeled. EFS on membrane surface was categorized into high-molecular weight(more than 1000kDa), medium molecular weight(100k-1000k Da), and low molecular-weight(less than 100kDa) and change of each component was modeled using differential equations, whose parameter values were determined using experimental data. The experimental results were in good agreement with the simulation results using the developed model. Also permeate flux and the behavior of EPS was related using the model and experimental results suggested the validity of the model.