A Whole Cell Bioelectrochemical Sensor for the Monitoring of Benzene in Water

Abstract

Bioelectrochemical Systems (BES) are a novel technology in which microorganisms degrade the organic matter in anaerobic conditions by using an electrode (anode) as final electron acceptor. Therefore, BES can be used as an effective strategy in environments where the absence of suitable electron acceptors limits classic bioremediation. Researches in progress demonstrated the possibility of apply innovative microbial electrochemical technologies for the monitoring and recovering of low concentration of organics, metals and micronutrients from polluted water environments, out of the electric grid. Recently BES have been also studied to stimulate the anaerobic degradation of hydrocarbons [1,2]. Although bioremediation is often inexpensive compared to physical-chemical methods, it typically requires more time and it is currently applied to a limited variety of pollutants. Benzene is a very toxic hydrocarbon and the pollution of this compound in fresh and groundwater causes many health and environmental problems. By monitoring the current produced by a BES, the rate of specific metabolic processes and the substrate concentration can be quantified in real time. The aim of this work is to study the correlation between the current produced in a BES and the concentration of benzene, in the rage of 10–60 mg/L. Tests were performed in single cell membraneless bioelectrochemical systems. The first run consisted in the inoculation of a BES with a refinery waste water in order to colonize the anode with an electroactive benzene-degrading bacterial community. Benzene was periodically supplemented to select a community able to degrade benzene. Current and benzene concentration were monitored, in order to correlate these parameters with the development of an electroactive biofilm. The application of this technology as biosensor for the monitoring of toxic compounds in water presents several advantages: low operational cost, versatility and the possibility to monitor in real time the concentration of pollutants from the environment. [1] M. Daghio, A. Espinoza Tofalos, B. Leoni, P. Cristiani, M. Papacchini, E. Jalilnejad, G. Bestetti, A. Franzetti. Bioelectrochemical BTEX removal at different voltages: assessment of the degradation and characterization of the microbial communities. Journal of Hazardous Materials, Volume 341, 5 November 2018, Pages 120-127 [2] S. Zhanga, J.Youa, C. Kennes, Z. Cheng, J. Ye, D. Chen, J. Chen, L. Wang. Current advances of VOCs degradation by bioelectrochemical systems: A review. Chemical Engineering Journal, Volume 334, 15 February 2018, Pages 2625-2637