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Fouling Of MF and UF membranes in the filtration of the secondary effiuent of the waste water iS mainlycaused bV the high concentration organic matters in the feed water.In order to solve this problem，the new innovativepoly(vinylidene fluoride)(PVDF)hollow fiber UF membranes were developed.These series of membranes were developed by applying the thermally induced phase separation technology，which showed high chemical resistance and physical strength，and they enabled various physical and chemical cleaning for the stable operation for the wide ranges of feed water composition.At first，we have tested the the permeabilities and fouling properties of three PVDF hollow fiber membranes in order to correlate with their structures and pore sizes.and selected one type of membranes named HFU withl50.000 dartons as the nominal molecular weight cut off size，because it showed the best anti-fouling property.Then，in order to achieve higher flux operation of the filtration process with HFU.it was tried to apply the combination of the coagulation and improved Chemical Enhanced Backwashing(CEB)technique，which was much more effective than the conventional method. Firstly，the coagulation condition was focused，and then it was found out that the membrane cleaning efficiencies were related to the zeta potentials of coagulated flOC and the membrane surfaces，and the coagulation condition was optimized based on the monitoring of the zeta potentials.Secondly，the investigation was conducted for the improved Chemical Enhanced Backwashing(CEB)in order to remove more effectively the organic matters from membrane surface and inside Of the micro-pores.As a result of the investigations above.the HFU filtration process achieved the extremely higher flux 167 LMH (4.O m/d)than before(52～83 LMH[1.25～2.0 m/d])，Which could reduce the operational cost as well as the initial equipment cost.The major difficulty in the RO operation for WWR is the membrane fouling due to the chemical and biological reasons.It was confirmed that the low fouling RO membrane had the excellent performance and could be operated without chemical fouling or bio-fouling by the intermittent biocide dosing.