Impact of Pulsed Dielectrophoretic Supply on the Function of Microorganisms in Membrane Bioreactors

Abstract

This study aims to investigate the effect of dielectrophoretic (DEP) force on microorganisms' viability in a membrane bioreactor (MBR). The impact of different electrical potentials (5-150 V) and different exposure durations (20-120 min) on the viability of microorganisms were studied. An interdigitated cylindrical electrode (IDE) configuration was used in the membrane module. Each electrical potential application was operated intermittently with 10 s of the electric field on and 15 s of the electric field off. It was found that the bacteria were able to withstand voltage up to 50 V, and their activity even increased with time with the application of 5 V. At high electrical potentials (100 and 150 V), the microbial activity decreased as a result of the increased current flow and temperature build up due to the Joule heating effect. The decrease of the microbial activity caused the increase of the total organic carbon (TOC) and ammonium (NH4+) concentrations in the bulk solution. A comparison between the continuous and intermittent voltage supply for the 50 V further proved the Joule heating impact on the bacteria viability.