Microalgae filtration by UF membranes: influence of three membrane materials

To evaluate the impact of membrane material on the ultrafiltration performance of microalgae medium, three types of UF membranes: polysulfone membrane GR40PP (PS, MWCO=100,000 Da), fluoro polymer membrane FS40PP (PVDF, MWCO=100,000 Da), regenerated cellulose acetate membrane RC70PP (RCA, MWCO=10,000 Da) were used in this work. Influence of transmembrane pressure (1.3, 1.8, 2.3 bar) and cross-flow velocity (3.86, 4.83, 5.79, 7.72 m/s) on the permeate flux was studied. It was observed that the permeate flux increased with increasing transmembrane pressure for all membranes. Moreover, permeate flux increased as the cross-flow velocity increased. The fluoro polymer membrane showed the most significant improvement of flux (from 83.27 to 136.32L/m(2)h) with increase in cross-flow velocity, which may suggest that the fouling materials attached more weakly on the membrane surface as the cross-flow velocity increased. Hydrophilic RCA membrane had a much lower fouling tendency than hydrophobic PS and PVDF membranes. To maximize flux recovery for the algae-fouled membranes, NaOH, NaOCl, and Ultrasil 10 were applied as cleaning agents. Ultrasil 10 with concentration of 0.5 wt.% was more effective than other agents for membrane cleaning.