Membrane fouling remediation in ultrafiltration of latex contaminated wastewater

The current study aimed to remediate membrane fouling by latex effluent by altering membrane surface charge or ionic strength of the effluent. Hydrophilic polysulfone and Ultrafilic flat membranes, with molecular weight cutoff (MWCO) of 60,000 and 100,000, respectively, and hydrophobic polyvinylidene difluoride membrane (PVDF; MWCO 100,000) were used under a constant flow rate and in cross-flow mode for ultrafiltration of latex effluent. The effect of linear alkyl benzene sulfonate (LAS) on the ionic strength of the effluent and the zeta potential of latex particles was investigated. LAS was also used to improve the anti-fouling properties of the membrane surface. The ionic strength of latex effluent was increased by raising its pH from 7 to 12, resulting in an increase of the zeta potential negativity of the latex particles from −26.61 to −42.66 mV. LAS was found to be an ineffective pretreatment for limiting the fouling propensity of latex effluent using hydrophilic membranes even at high concentration and long treatment times. It was concluded that LAS-treated membrane surface is much more favorable than pH changed feed pretreatment. The total mass of fouling decreased by 44.00 and 29.60%, when PVDF membrane surface was treated with LAS at a concentration of 1 × 10−4 g/L, and latex effluent at pH 11 was used, respectively.