| Cross flow micellar-enhanced ultrafiltration (MEUF) is a new membraneseparation technology for purification, separation and enrichment of trace organiccompounds and heavy metals from wastewater. Because of its low energyconsumption, high separation efficiency, good water quality, easy operation, low costsof operation and management, which has been widely used in the field of watertreatment. However, permeate flux decline caused by membrane fouling andconcentration polarization severely restricted the application of this technology inwater treatment industry. Due to cross flow MEUF is a new ultrafiltration technology,it is not suitable to describe its dynamic process by conventional ultrafiltration model.Therefore, the study of mathematical model for cross flow MEUF is extremelyimportant.Due to the flow type of liquid in cross flow micellar-enhanced ultrafiltration(MEUF) is laminar flow, the study is based on laminar Blake-kozeny theory. The totalfiltrate resistance is affected mainly by other resistances except membranehydrodynamic resistance. This part of resistances is collectively referred to as foulingresistance. As a breakthrough, the mathematical association between foulingresistance and time as well as concentration of fouling layer is established andverified under different operating conditions (Retentate recycled and Retentatenon-recycled). Combined with membrane hydrodynamic resistance, the relationshipbetween permeate flux and time as well as concentration of fouling layer isdetermined by using resistance in series theory. We made a comparative study infouling resistance and permeate flux under different feed concentration and differenttransmembrane pressure. We discussed the effect for feed concentration andtransmembrane pressure to fouling resistance and permeate flux.We selected high velocity polyethersulfone ultrafiltration membranes (MilliporeCorporation, USA) and Millipore LabscaleTMTFF system (Millipore Corporation,USA) to do ultrafiltration experiment and analyzed the experimental data. The resultsdemonstrate the relevance of the model. And the correlation coefficient is above0.9indifferent operating style, different feed concentration as well as differenttransmembrane pressure. This result fully proved the validity of the model. Inaddition, the model could be used as a bridge to regulating MEUF process. Theperformance of this regulation could be directly reflects on the fouling resistance andpermeate flux through controlling the relevant operating conditions (feed concentration, transmembrane pressure, concentration ratio). And the study provides atheoretical support for cross flow micellar-enhanced ultrafiltration extensive researchand application. |
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