The significance of interactions between organic compounds on low pressure membrane fouling

摘要

Fouling of hollow fibre microfiltration and ultrafiltration membranes by solutions of pure organicncompounds and mixtures of these compounds was studied with a backwashable membranenfiltration apparatus. Small molecular weight compounds resulted in little fouling, while theirnpolymeric analogues resulted in more severe fouling. Neutrally charged dextran resulted in minor,nirreversible fouling, that was considered to be associated with blocking of small pores. Cationicallyncharged chitosan produced gross fouling for which the extent of reversibility increased with saltnaddition. Anionically charged alginic acid resulted in gross irreversible fouling, except when beingnfiltered by a hydrophilic membrane in the absence of calcium where a high degree of flux recoverynwas observed. Calcium addition to the alginic acid solutions resulted in gross fouling of allnmembranes and calcium bridging was considered to be responsible for this behaviour. Greaternfouling occurred on the hydrophilic membrane compared to the hydrophobic membranes for bovinenserum albumin (BSA) solutions, and this was considered to be due to physical blocking of pores,nbecause addition of calcium resulted in lower flux declines. Addition of BSA and calcium to alginicnacid solutions resulted in lower flux recoveries for the alginic acid system, consistent with thenproposition that interactions between polysaccharide and other compounds are required fornirreversible fouling on hydrophilic membranes.