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Membrane systems are used increasingly for water treatment, recycling water from wastewater, during food processing, and energy production. They thus are a key technology to ensure water, energy, and food sustainability. However, biofouling, the build-up of microbes and their polymeric matrix, clogs these systems and reduces their efficiency. Realizing that a microbial film is inevitable, we engineered a beneficial biofilm that prevents membrane biofouling, limiting its own thickness by sensing the number of its cells that are present via a quorum-sensing circuit. The beneficial biofilm also prevents biofilm formation by deleterious bacteria by secreting nitric oxide, a general biofilm dispersal agent, as demonstrated by both short-term dead-end filtration and long-term cross-flow filtration tests. In addition, the beneficial biofilm was engineered to produce an epoxide hydrolase so that it efficiently removes the environmental pollutant epichlorohydrin. Thus, we have created a living biofouling-resistant membrane system that simultaneously reduces biofouling and provides a platform for biodegradation of persistent organic pollutants. [ABSTRACT FROM AUTHOR]

Reverse osmosis and nanofiltration membranes are used for desalination, wastewater reuse, and industrial water recovery but suffer from high-energy usage during operation. High-energy usage results from membrane fouling and concentration polarization (CP). Fouling is the time dependent deposition of organic macromolecules and particles, as well as the growth of bacterial biofilms on membranes. CP is the accumulation of rejected solutes on the membrane, which reduces the driving force for filtration. We demonstrate a simple, nanoparticle-based, in situ approach of inducing chemical reaction-based micromixing on the membrane surface that can simultaneously eliminate fouling and CP. Commercial desalination membrane surfaces were modified with the bioinspired adhesive polymer, polydopamine, and catalytic metal oxide nanoparticles (CuO or MnO 2 ) were grown and anchored to its surface. This modified membrane catalyzed the degradation of hydrogen peroxide pulse-injected into the feed solution at low concentrations (2–7 mM). The oxygen molecules and hydroxyl radicals generated degraded organic matter and efficiently prevented particle and cell deposition through bubble-generated mixing while causing no observable membrane damage. The reaction generated convection also enhanced solute back diffusion mass transfer coefficients by more than an order of magnitude, resulting in near-complete elimination of CP. Our preliminary results also indicate control of E. coli biofilm using the immobilized CuO nanoparticles. [ABSTRACT FROM AUTHOR]