Membrane Science, Engineering & Technology (MAST) Center, University of Arkansas, Ralph E Martin Department of Chemical Engineering, Fayetteville, AR 72701, USA
Prof. Dr. Sumith Ranil Wickramasinghe
Membrane Science, Engineering & Technology (MAST) Center, University of Arkansas, Ralph E Martin Department of Chemical Engineering, Fayetteville, AR 72701, USA
Water is a very valuable natural resource. As the demand for water increases the presence of emerging contaminants in wastewater has become a growing concern. This is particularly true when one considers direct reuse of wastewater. Obtaining sufficient removal of emerging contaminants will require determining the level of removal for the various unit operations in the wastewater treatment process. Membrane bioreactors are attractive as they combine an activated sludge process with a membrane separation step. They are frequently used in a wastewater treatment process and can operate at higher solid loadings than conventional activated sludge processes. Determining the level of removal of emerging contaminants in the membrane bioreactor step is, therefore, of great interest. Removal of emerging contaminants could be by adsorption onto the biomass or membrane surface, biotransformation, size exclusion by the membrane, or volatilization. Given the fact that most emerging contaminants are low molecule weight non-volatile compounds, the latter two methods of removal are usually unimportant. However, biotransformation and adsorption onto the biomass are important mechanisms of removal. It will be important to determine if the microorganisms present at given treatment facility are able to remove ECs present in the wastewater.
Superhydrophilic zwitterions on the membrane surface have been widely exploited to improve antifouling properties. However, the problematic formation of a <20 nm zwitterionic layer on the hydrophilic surface remains a challenge in wastewater treatment. In this work, we focused on the energy consumption and time control of polymerization and improved the strong hydrophilicity of the modified polyvinylidene difluoride (PVDF) membrane. The sulfobetaine methacrylate (SBMA) monomer was treated with UV-light through polymerization on the PVDF membrane at a variable time interval of 30 to 300 s to grow a poly-SBMA (PSBMA) chain and improve the membrane hydrophilicity. We examined the physiochemical properties of as-prepared PVDF and PVDF–PSBMAx using numeric analytical tools. Then, the zwitterionic polymer with controlled performance was grafted onto the SBMA through UV-light treatment to improve its antifouling properties. The PVDF–PSBMA120s modified membrane exhibited a greater flux rate and indicated bovine serum albumin (BSA) rejection performance. PVDF–PSBMA120s and unmodified PVDF membranes were examined for their antifouling performance using up to three cycles dynamic test using BSA as foulant. The PVDF-modified PSBMA polymer improved the antifouling properties in this experiment. Overall, the resulting membrane demonstrated an enhancement in the hydrophilicity and permeability of the membrane and simultaneously augmented its antifouling properties.