Study On Water Purification Efficiency And Antifouling Of Ultrafiltration Membrane Based On Electric Field

Membrane separation technology is a highly efficient separation technology developed rapidly in recent decades,and is expected to be the prevalent water treatment technology for the 21 century.It has been widely used in watersoftening,desalination,water and wastewater treatment and resuse.However,membrane fouling is the main problem of membrane technology encountered in practical engineering applications.In this paper,ultrafiltration membrane was selected as the research object,which investigate the anti-pollution under the electric field.We choose the hydrophilic and hydrophobic of natural organic matter（NOM）、humic acids（humic acid,HA）、the current density、pH and the electric field intensity on membrane flux.The main conclusions as follows:The natural organic matter（NOM）extracted from water and sediment are divided into different polar components by XAD-8 resin.We can found that the homologous substances in water and sediment in 10 kinds of NOM are not the same,sediment and water contained C=C unsaturated structure,oxygen containing functional group structure and-C=O structure,and nitrogen functional groups;humic acid and fulvic acid contain more aromatic chromophore than other substances.The degree of molecular NOM in the sediment amount basically is higher than that of water NOM.The sediment humic acid,fulvic acid,hydrophilic substance under the electric field of the membrane fouling were studied.In the absence of the electric field,hydrophilic substances causes membrane flux decreasing seriously.When adding the electric field,hydrophilic substances with high polarity was influenced by electric field,and the flux promote 15%higher than the previous.We select the humic acid as organic material,which simulate the water samples.We study the membrane fouling with different molecular weights of humic acid under the action of electric field.The results shows that adding the electric field,the membrane flux increases first and then decreases,which reaches the maximum at E=0.5V/cm.The humic acid of 10kDa-30kDa was selected as the research object.It was found that the membrane flux gradually increased with the increasing of pH,and the removal rate decreased gradually.The NaCl with different ionic strength were added to 10kDa-30kDa humic acid solution.It was found that the greater the ionic strength is,the greater the electric field intensity required when the membrane flux reached maximum.The humic acid solution with Na⁺and Ca²⁺to membrane flux influence were compared.It is found that the covalent bond between HA and Na⁺is more easy break than that of HA and Ca²⁺.HA solution of NaCl further more easily contaminated by HA.The electrocoagulation membrane reactor（ECMR）was investigated,which embraces EC,UF,and electric field,all in one individual reactor by arranging the membrane module between the anode-cathode electrodes.The results showed that increasing the current density the ECMR process could maintain a higher flux;and the electric field also shown an important effect on cake layer that was formed of the polarized charged flocs,which make the cake layer was more porous,hydrophilic and stabilized with the increasing of electric field intensity.When the electric field intensity increased from 2 V/cm up to 10V/cm,The membrane flux showed a significant upward trend.The ECMR not only alleviate membrane fouling but also can improve the quality of permeate during operation.