Effect Of Membrane Fouling Progress By Hybrid Process Of Pre-Ozonation And Carbon Nanotube Modification On Polyvinylidene Fluoride Membrane

During past decades,ultrafiltration had become a significant technology in the field of water reuse and wastewater treatment.However,membrane fouling is an obstacle that always hinders the widespread application and development of UF process.However,seldom study was focued on the hybrid process of pre-ozonation and carbon nanotube（CNT）modification on polyvinylidene fluoride（PVDF）membrane fouling control.Our investigation took the sewage secondary effluent as the research object,investigated the hybrid process fouling progress under critical flux,threshold flux and low flux.At the same time,effluent quality was analyzed in the fouling progress.Further more,the effect of organic fouling and biological fouling on membrane fouling was investigated in this paper.The critical flux and membrane fouling was investigated in hybrid process of pre-ozonation and CNT modification.This study indicated that the anti-fouling property enhanced with CNT loading mass increased.The growth of trans-membrane pressure（TMP）was similarity when CNT loading mass at 3 g?m^-2 and 5 g?m^-2,indicated that both tow of modification membrane anti-fouling property were similarity.In the aspect of bettering effluent quality,ozonation was better than loading CNT.But much ozone dosage will result in the membrane fouling serious.Overall consideration the optimal combination in this hybrid process was CNT loading mass of 3g?m^-2 and ozone dosage of 0.22mgO₃?mgDOC^-1.The critical flux of zero pollution in the traditional did not exist in the dead end ultrafiltration system.The threshold flux and carbon balance was investigated in hybrid process of pre-ozonation and CNT modification.The results showed that hybrid process provided higher threshold flux and reduced the rate of membrane fouling.Ensure the membrane operating for a long time.The carbon balance experimentation showed that the hybrid process not only improved the anti-fouling property of the membrane,but also enhanced the rato of filtration volume recovery.Fouling of protein was more easily removal than humic acid type matters by hydraulic back wash.We concluded that humic acid caused more irreversible membrane fouling and leaded to low recovery rato of TMP.The mechanisms of biological fouling mitigation under hybrid process were researched.With flux of 18L?（m²?h）^-1 and operating for 15 days,the filtration volume was promoted to 2950L/m²,which was 20 times of the unmodified membrane.The fouling membrane surface was observed with confocal laser scanning electron microscopy（CLSM）.The results demonstrated that more living bacteria were presented on membrane surface of the unmodified membrane,which had a rapid Trans-membrane pressure（TMP）growth.Both pre-ozonation and CNT modification could decrease the total amount of microorganism and the amount of the living bacteria as well,which mitigated the growth of TMP.After pre-ozonation,the presence of CNT layer on membrane surface could further decrease the number of living bacteria.Although the existence of CNT layer captured some dead bacteria,it had no obvious relationship with the growth of TMP.