Application Of D-tyrosine And Glycoside Hydrolase For Membrane Fouling Inhibition In Membrane System

Biofouling is a critical issue in membrane separations,which restrict the further development of membrane technology.Hence,develop a novel approaches for biofouling mitigation is of crucial importance for membrane-based technologies.In this research,we chosed bacteria self-produced D-tyrosine and glycosyl hydrolase(PslG)to control membrane fouling and explore their mechanism.D-tyrosine was immobilized on a polyethersulfone(PES)ultrafiltration membrane via a two-step method to mitigate biofouling with the synergistic effects of surface hydrophilicity and anti-microbial properties.Results showed that the grafting of D-tyrosine increased the surface hydrophilicity and imparted a smoother surface to the membrane without altering its transport properties.During bovine serum albumen(BSA)filtration tests,the unified membrane fouling index(UMFI)of D-tyrosine-polydopamine(PDA)/PES membrane was only 0.00162,probably half of the PDA/PES membrane's UMFI without D-tyrosine.The flux recovery ratio(FRR)of the D-tyrosine-PDA/PES membrane was up to 79%,higher than the virgin PES membrane.Moreover,bacterial adhesion efficiency dropped from 29.2%to 19%after D-tyrosine modification.The D-tyrosine-PDA/PES membrane showed better anti-biofouling performance when inoculated with E.coli culture.The proposed membrane surface modification technique paves the way toward realization of biological control for mitigating biofouling by simultaneously enhancing the anti-adhesive and antimicrobial properties of the membrane.The research explored the exogenous supply of PslG could mitigate membrane biofouling.Cell attachment was significantly reduced at a wide range of PslG concentrations after a relatively short time contact,and the inhibition effect showed non-monotonic change with the increase of PslG concentration.Bacterial zeta potential and surface hydrophobicity were not affected in the presence of PslG.High concentrations of PslG(500 and 1000 nM)could inhibit bacterial attachment after 24 h incubation.The permeate flux decline after 4 h filtration was lower when added PslG to the wastewater,which means that PslG could mitigate membrane biofouling.In addition,the presence of PslG decrease exopolysaccharides production,which was the main reason for the decrease of bacterial attachment and biofouling mitigation.