Effects of a dynamic membrane formed with polyethylene glycol on the ultrafiltration of natural organic matter

The formation of a dynamic membrane(DM)was investigated using polyethylene glycol(PEG)(molecular weight of 35000 g/mol,concentration of 1 g/L).Two natural organic matters(NOM),Dongbok Lake NOM(DLNOM)and Suwannee River NOM(SRNOM)were used in the ultrafiltration experiments along with PEG.To evaluate the effects of the DM with PEG on ultrafiltration,various transport experiments were conducted,and the analyses of the NOM in the membrane feed and permeate were performed using high performance size exclusion chromatography,and the effective pore size distribution(effective PSD)and effective molecular weight cut off(effective MWCO)were determined.The advantages of DM formed with PEG can be summarized as follows:(1)PEG interferes with NOM transmission through the ultrafiltration membrane pores by increasing the retention coefficient of NOM in UF membranes,and(2)low removal of NOM by the DM is affected by external factors,such as pressure increases during UF membrane filtration,which decreases the effective PSD and effective MWCO of UF membranes.However,a disadvantage of the DM with PEG was severe flux decline;thus,one must be mindful of both the positive and negative influences of the DM when optimizing the UF performance of the membrane.

Controlling various contaminants in wastewater effluent through membranes and engineered wetland

For effective wastewater reclamation and water recovery,the treatment of natural and effluent organic matters(NOM and EfOM),toxic anions,and micropollutants was considered in this work.Two different NOM(humic acid of the Suwannee River,and NOM of US and Youngsan River,Korea),and one EfOM from the Damyang wastewater treatment plant,Korea,were selected for investigating the removal efficiencies of tight nanofiltration(NF)and ultrafiltration(UF)membranes with different properties.Nitrate,bromate,and perchlorate were selected as target toxic anions due to their well known high toxicities.Tri-(2-chloroethyl)-phosphate(TCEP),oxybenzone,and caffeine,due to their different K_(ow) and pK_(a) values,were selected as target micropollutants.As expected,the NF membranes provided high removal efficiencies in terms of all the tested contaminants,and the UF membrane provided fairly high removal efficiencies for anions(except for nitrate)and the relatively hydrophobic micropollutant,oxybenzon.Through the wetlands,nitrate was successfully removed.Therefore,a fair process of combining membranes with an engineered wetland could be proposed for sustainable wastewater reclamation and optimum control of contaminats.