Studies on ultrafiltration membrane process of simulated wastewater containing humic acid organic substances

The purified process of simulated wastewater containing humic acid(HA) substances by using hollow fiber ultrafiltration membrane module was studied.The effects of Ca~(2+) concentration,ionic strengh and pH value on the membrane process were investigated.The experiment results indicate that the membrane flux decrease is accelerated with increasing Ca~(2+) concentration due to its complex formation with the functional groups of HA.The change of the ionic strengh can influence the configuration of the HA macromolecule,and also affect the interaction between the solutes as well as between the solutes and the membrane surface.The decreasing extent of membrane flux increases with the increasing ionic strengh.Furthermore,decreasing pH value reduces the dissociation degree of H~+ in the functional group of HA macromolecule chain,therefore the membrane fouling increases with decreasing solution pH.The results also show that the rejection of HA decreases with increasing Ca~(2+) concentration and ionic strengh,and with decreasing pH value.