Effect Of Ultrafiltration-activated Carbon Process For Removal Sudden Cadmium Pollution And Study On Membrane Fouling Mechanism

With the rapid economic development and industrialization of China,emergent environmental pollution frequently occurred,especially emergent cadmium(Cd)pollution in water.Due to serious damage,extensive area and complex mechanism of water Cd pollution,Cd pollution has been a hotspot.Ultrafiltration(UF)technology has good effluent quality and its operation cost and used field area is less than that of conventional treatment process,so that UF technology may gradually take the place of conventional treatment process.The aim of this work is to investigate the influence of the relation between cadmium and natural organic matter(NOM)in water on the removal of Cd and NOM(such as humic acid,polysaccharides and proteins)by UF treatment.In addition,activated carbon adsorption and UF are combined to treat Cd and humic acid to explore the variation of membrane flux and the removal of Cd and humic acid under various solution conditions.By flat UF tests,the membrane flux and the removal rate of Cd and humic acid under various solution conditions were investigated.The results indicated that UF membrane could well retain humic acid.Additional Ca2+ or ionic strength led to lower removal of Cd.By contrast,the removal of Cd would be increased as solution pH was elevated.However,in all instances,the complexation between humic acid and Cd could not result in low Cd concentration which meets standards for drinking.The change of solution condition also affected membrane flux.With increasing Cd concentration,membrane flux decline could be mitigated.The addition of Ca2+ or Na+ could effectively mitigate membrane flux decline for water containing humic acid and Cd.Compared to Na+,Ca2+ could better retard membrane flux decline.With higher pH values,membrane flux decline was accelerated,leading to more serious membrane fouling.By UF,the removal of Cd with SA or BSA existence in water was higher than that with HA existence in water.If SA,BSA and HA were existed in water,the removal of Cd was maximum.For PAC-UF technology,the removal of HA were higher than 90 % and the removal of Cd had not significant change.In all instances,PAC-UF would lead to lower membrane flux decline compared to UF.That is,PAC-UF could effectively postpone membrane fouling.It was studied the heavy metal cadmium in water after interaction with NOM,and was investigated effluent cadmium and humic acid concentration after direct ultrafiltration treatment.It was studied the infiltration of Cd ions into natural water bodies and the action of HA represented by NOM in sudden Cd pollution events and then removed them by UF-PAC process.It was focused on the effect of Cd ions penetrating into natural water bodies and simulated NOM in sudden Cd pollution events.The removal of ultrafiltration flux and fouling resistance of UF membrane in simulated Cd-NOM were investigated by ultrafiltration process.In this work,the effect of NOM on the removal of Cd after UF and corresponding membrane flux change have been fully investigated.This can give some meaningful indications for the treatment of emergent Cd pollution by UF.