Microbial Attachment Inhibition through Low-Voltage Electrochemical Reactions on Electrically Conducting Membranes

Abstract

Bacterial biofilm formation on membrane surfaces remains a serious challenge in water treatment systems. The impact of low voltages on microbial attachment to electrically conducting ultrafiltration membranes was investigated using a direct observation cross-flow membrane system mounted on a fluorescence microscope. Escherichia coli and microparticle deposition and detachment rates were measured as a function of the applied electrical potential to the membrane surface. Selecting bacteria and particles with low surface charge minimized electrostatic interactions between the bacteria and charged membrane surface. Application of an electrical potential had a significant impact on the detachment of live bacteria in comparison to dead bacteria and particles. Image analysis indicated that when a potential of 1.5 V was applied to the membrane/counter electrode pair, the percent of dead bacteria was 32±2.1 and 67±3.6% when the membrane was used as a cathode or anode, respectively, while at a potential of 1 V, 92±2.4% were alive. The application of low electrical potentials resulted in the production of low (μM) concentrations of hydrogen peroxide (HP) through the electroreduction of oxygen. The electrochemically produced HP reduced microbial cell viability and increased cellular permeability. Exposure to low concentrations of electrochemically produced HP on the membrane surface prevents bacterial attachment, thus ensuring biofilm-free conditions during membrane filtration operations.

Carbon Nanotube Membranes: Synthesis, Properties, and Future Filtration Applications

“…The inhibition of microbial attachment was also demonstrated in experiments involving CNT/polyvinyl alcohol composite materials and E. coli [121]. The inhibition of bacterial cell attachment was achieved when the membrane was operated as either an anode or a cathode.…”

Single and binary protein electroultrafiltration using poly(vinyl-alcohol)-carbon nanotube (PVA-CNT) composite membranes

“…As can be seen, unlike electroultrafiltration processes with electrodes on each side of the membrane, the external electric field terminates with the poly(vinyl-alcohol)carbon nanotube layer, which is upstream of the semipermeable, polymeric membrane. Jassby et al [5][6][7][9][10][11] developed methods of coating commercial polymeric UF membranes with a thin layer of a poly(vinyl-alcohol) (PVA) polymer cross-linked with multiwalled carbon nanotubes to form highly electrically conductive PVA-CNT composite membranes. In a study of the effect of moderate applied electric potentials (-1.5 and -3.4 V vs Ag/AgCl references) on fouling of high concentrations (3-5 g/L) of synthetic wastewater containing negatively charged alginic acid during EUF using PVA-CNT composite membranes, Dudchenko and Jassby et al observed substantial fouling inhibition and reduction of operating pressure in a constant flux system [6].…”

Porous UHMWPE Membranes and Composites Filled with Carbon Nanotubes: Permeability, Mechanical, and Electrical Properties

“…Additionally, appropriate electric fields and surface charges alike were shown to affect bacteria and other microbes . If a membrane surface has a sufficiently strong electric charge or applied current, it can deactivate and repulse them . Polymer composite membranes prepared by several groups showed a good membrane performance and a very high electrical conductivity …”

“…[25,26] If a membrane surface has a sufficiently strong electric charge or applied current, it can deactivate and repulse them. [9,27] Polymer composite membranes prepared by several groups showed a good membrane performance and a very high electrical conductivity. [8,9,28,29] In a previous work, the preparation of electrically conductive, porous membranes from amorphous polyetherimide using powder particles decorated with multiwalled carbon nanotubes was shown to be an effective and simple approach to generate a MWCNT network.…”