Nan Zhang, Hye-Jin Lee, Yichen Wu, Mohamed A. Ganzoury, Charles-François de Lannoy (2022). Integrating biofouling sensing with fouling mitigation in a two-electrode electrically conductive membrane filtration system. Proceedings of the GWF Annual Open Science Meeting, May 16-18, 2022.

Detection of biofouling evolution in filtration processes enables the adoption of effective cleaning strategies for biofouling prevention. This work investigates the use of electrical impedance spectroscopy (EIS) to monitor the biofilm development and the use of electric fields to mitigate biofouling on the surface of gold-coated membranes. The multi-bacterial suspension was injected into a two-electrode crossflow filtration system where the permeate flux and impedance spectra were recorded to monitor the biofilm growth. Permeate flux declined over time as a result of bacterial community attachment and secretion of extracellular polymeric substances (EPS). Correspondingly, impedance spectra indicated that the impedance at low frequency regions (< 10 Hz) rapidly decreased with fouling at the early stages of fouling, and then gradually decreased as biofilm matured. Impedance data were fitted using an equivalent circuit, from which the normalized diffusion-related impedance (Rd), an EIS-derived parameter, was extracted to determine the sensitivity of EIS detection. We observed that the impedance-based detection was more sensitive to changes as compared to the decline of permeate flux during the early stage of biofouling. Further, under the same conditions as fouling detection, either applying an intermittent cathodic potential (-1.5 V) or cross-flow flushing delayed the biofilm growth on the electrically conductive membranes (ECMs). While intermittent applied potential delayed biofilm growth, it was insufficient to recover EIS signal strength, however EIS sensitivity was repeatably recovered across four cycles of mechanical fouling removal. Hence ECMs were demonstrated to play a dual function: EIS-enabled detection of biofouling evolution and surface biofouling mitigation.

AOSM2022 GWF sensors First Author: Nan Zhang, McMaster University Additional Authors: Hye-Jin Lee, Yichen Wu, Mohamed A. Ganzoury, Charles-François de Lannoy, McMaster University