Study On Front-face Fluorescence Excitation-emission Matrix For Membrane Foulants Characterization In Ultrafiltration Technology

As a technology with excellent removal of turbidity and microorganism,ultrafiltration can meet the needs of national standard in drinking water,which has been widely used in the field of water treatment.Despite the rapid development of ultrafiltration technology,the membrane fouling issue during ultrafiltration was still thorny.Since the membrane fouling issue seriously restricts the application and popularization of ultrafiltration technology in drinking water treatment,it has always been a hot topic in the field of membrane water treatment technology.The characterization of membrane pollutants is fundamental to the analysis of membrane fouling mechanism and the premise of membrane fouling control.However,the existing methods for characterization of membrane pollution were still limited.So far,we estimated the foulants on membrane through removing the foulants or measuring the foulants in the solutions coupled with mass balance calculation,but both of them would make more measuring error and complicated operation.A variety of novel techniques using ultrasonic,electrical,or optical approach have been developed for directly characterizing fouling layer evolution during membrane filtration.However,they were also limited by the low sensitivity and complicated analysis method.Therefore,a effective and accurate method should be developed to characterize the membrane fouling,which was the basic premise for understanding membrane fouling process and developing membrane fouling control technology at this stage.This research tried to characterize the fluorescent organic membrane fouling directly through the Front-face Fluorescence Excitation-emission Matrix(FF-EEM)and the Parallel factor analysis(PARAFAC).In the first place,the in-situ characterization method of membrane fouling was established,and the membrane fouling of Effluent organic matter(Ef OM)was analyzed by this method.In addition,the feasibility of the technology applied in the coagulation ultrafiltration process for in-situ monitoring of coagulation and prediction of membrane fouling potential were also studied.First of all,bovine serum albumin(BSA)and Humic acid(HA),were used as the standard pollutants to deposit on the Polyvinylidene fluoride(PVDF)membrane.And then their standard curves on the PVDF membrane were set up through the FF-EEM and the PARAFAC.Beside,the pollutants on PVDF membrane were quantified using FF-EEM coupled with PARAFAC in this ultrafiltration experiment,of which result was compared with the liquid EEM.The research had confirmed the validity and more accuracy of the application of FF-EEM on membrane fouling characterization,due to the error propaganda in the mass balance calculation and the ineffectiveness of inner filter correction for overcoming humic quenching effect in the liquid EEM based method.The ultrafiltration experiment result also showed that the fouling resistance did not correlated well with the foulants mass,and the major fouling mechanism would be more determinative in the fouling resistance increase.Finally,the research also make an exploration to characterize the Ef OM with flocs after coagulation treatment through the FF-EEM based method.The consequence showed that the fluorescence of the Ef OM with flocs is irrelevant to the sizes of floc particle but the concentration of fluorescent organic matter in water sample,and also the Modify Fouling Index(MFI)in the follow-up ultrafiltration treatment.Accordingly,it seems that the FF-EEM based method could be used to characterize turbid water after coagulation treatment in situ,which could provide technical support of the online-detection system,the forecast of the membrane fouling behavior and the adjustment in coagulation.In summary,FF-EEM had more accuracy and convenience in the characterization of the membrane fouling.It had good research value and application prospect in the characterization of ultrafiltration membrane pollution and the monitoring of coagulation ultrafiltration combined process.It can also provide theoretical basis and technical support for the further analysis of membrane pollution and organic membrane pollution on-line monitoring.