Membrane fouling mechanisms on organic matter in the secondary effluent by GAC-NF combined process
This study utilized two types of filtration units(GAC and BAC)in combination with NF to evaluate the effects of three different treatment processes(direct NF,GAC-NF,BAC-NF)on organic compounds in the secondary effluent from wastewater treatment plant,as well as analyze the mechanisms of membrane contamination.Based on the findings,BAC-NF exhibited the highest removal efficiencies for DOC,microbial metabolism by-products,and humic acids,with the removal rates of 85.2%,76.2%and 82.0%,respectively.BAC-NF offered the greatest membrane specific fluxes of 0.69,0.65 and 0.63 at the end of each cycle,whereas the total membrane contamination resistance was the lowest(5.97×1010m-1).In addition,the characteristic curve of membrane contamination suggests that the direct NF was filter cake layer pollution,which is attributed to the middle blockage caused by GAC-NF and BAC-NF.It is noteworthy that the membrane middle pore blocking was dominant for BAC-NF,whereas the degree of membrane pollution was the mildest.According to xDLVO theory,the membrane surface polluted by BAC-NF offered the lowest hydrophobicity,corresponding to the highest Zeta potential.The organic matters in water were less reachable to membrane surface at the initial filtration stage using BAC-NF technology,resulting in less membrane pollution.During the middle and late stages of filtration,the adhesion of organic matters in water and on membrane surface rarely occurred,leading to the formation of loosest cake layer.Overall,BAC-NF is able to effectively mitigate membrane contamination,holding the potential for advanced treatment and reuse of reclaimed water.
secondary effluentnanofiltrationgranular activated carbonmembrane contaminationxDLVO theory
NETL
NSTL
万方数据
