Control of protein (BSA) fouling in RO system by antiscalants

The control of protein (bovine serum albumin, BSA) fouling by antiscalants was investigated in a bench-scale crossflow reverse osmosis (RO) system. Two antiscalants, polyaspartic acid (PASP) and an organophosphorus compound (LB-0100), were tested. The results indicated that BSA fouling could be greatly reduced by properly dosing antiscalants. The inhibition efficiency increased with PASP concentration but decreased when overdosing. LB-0100 was found to be less effective than PASP, and would greatly aggravate RO membrane fouling when overdosing. In the presence of PASP, Ca2+ had positive impact on fouling control within a certain concentration range and the foulant particle size decreased. This may be due to the possible formation of a water-soluble and highly stable complex BSA–Ca–PASP via Ca2+ bridging and not due to the electrostatic repulsion as measured by zeta potential. BSA fouling decreased at higher solution pH above the iso-electric point of BSA, lower initial permeate flux, and higher crossflow velocity in both the absence and presence of PASP. However, the fouling behaviors became less susceptible to these parameters in the presence of PASP. The effect of feed temperature in the presence of PASP was found to be opposite to that in the absence of PASP.

Research highlights▶ BSA fouling could be greatly reduced by properly dosing antiscalants. ▶ Ca2+ had positive impact on fouling control by antiscalant. ▶ A stable water-soluble complex BSA–Ca–PASP via Ca2+ bridging may be formed. ▶ Fouling behaviors became less susceptible to some parameters with PASP.