The problem of membrane biofouling is a major challenge for efficient low-pressure membrane filtration of drinking water. The work in this thesis evaluated the efficacy of a photoreactive membrane coating for the control of biofouling. The major objectives of this work were: (1) synthesizing reactive membrane filters by applying highly active TiO2 nanoparticle photocatalyst coatings to filter membranes, (2) characterizing the physical and chemical properties of these reactive membranes and relating these to microbial attachment, (3) characterizing the long-term impact of photoreactive coatings on biofilm growth and structure, (4) designing a rotating annular filtration system that couples the for photoexcitation of active membrane surfaces and Taylor-Couette flow for enhanced fouling control, and (5) characterizing the biofouling control of this rotating reactive system with model and real surface waters.;Ceramic ultrafiltration and microfiltration membranes were coated with several types of photoreactive titanium dioxide coatings, and tested for bacterial attachment, biofilm formation, and fouling control with real or model surface waters containing Pseudomonas putida, a model organism which colonizes biofilms. Metrics of membrane effectiveness include visualization of biofilms by confocal laser scanning microscopy, and measurement of membrane flux and membrane resistance.;Reactive photocatalytic ultratfiltration membranes synthesized through the dip-coating of ceramic ultrafiltration membranes with high surface area mixed phase titania photocatalysts were found to be effective at preventing bacterial attachment, achieving cell inactivation, and reducing biofilm formation. These were achieved through three mechanisms: photolysis, superhydrophilicity, and photocatalysis. Experiments in the rotating reactor geometry suggest that this reactive coating may control biofouling in ultrafiltration as well. These filtration systems have potential applications in a variety of water treatment and reuse scenarios, and may offer special advantage to small-scale water purification in developing countries or remote locations.
展开▼
