The potential of microbial fuel cell technology will be investigated for the treatment and reuse of industrial (textile) wastewater.
With the increase in population and advances in industrial, agricultural and household demands, the need for clean water is essential. There is need for robust, efficient, cost effective, and impactful technology for water conservation e.g. through reuse. We propose, through collaborative research between Egyptian Atomic Energy Authority (AEA) and University of Westminster (UOW), to develop a novel microbial fuel cell (MFC) system for industrial wastewater treatment. MFC technology uses naturally occurring bacteria in biofilm-based reactors to treat wastewater and generate a small amount of electricity.
The treated water can be used by communities where water is scarce for non-potable purposes e.g. irrigation or reused by industries e.g. for cleaning or cooling. This project addresses the challenge of water scarcity and water quality in Egypt, creates opportunities for innovative collaborative research, and has the potential to positively impact the economy and social welfare of both countries by mitigating pollution of water bodies from contaminated wastewater while providing water for reuse.
Microorganisms depend on continuous electron flow for the formation of electrochemical gradients that enable the synthesis of adenosine triphosphate (ATP) to sustain key cellular processes. To gain energy, bacteria obtain electrons by oxidizing organic/inorganic compounds (electron donors) and discard the respiratory electrons to a terminal electron acceptor, for instance, oxygen. Some anaerobic bacteria are even able to transfer electrons extracellularly to insoluble, solid-state electron acceptors such as oxide minerals and synthetic surfaces such as electrodes. The ability to transfer electrons extracellularly could potentially be employed for practical applications such as energy generation, wastewater treatment, bioremediation and materials synthesis in devices called microbial fuel cells (MFCs).
Common MFC systems consist of an anode chamber and a cathode chamber separated by a membrane. The bacteria grow on the anode and convert the organic molecules to carbon dioxide, protons and electrons. The electrons are transferred via an external circuit to the cathode. The protons pass through the membrane to the cathode chamber. In the cathode chamber oxygen is reduced and reacts with the protons and the electrons at the electrode to water.
Schematic of a microbial fuel cell. Electrons generated from substrate oxidation in the anode recombine with protons and a terminal electron acceptor in the cathode.
Textile wastewater is challenging to treat as it contains recalcitrant dyes (e.g. Azo dyes) and the wastewater is usually complex containing particulates, high salt concentrations, with low/high pH all of which pose problems to conventional wastewater treatment methods. The task is to develop a microbial fuel cell reactor system which can treat textile wastewater such that the treated water can be reused for purposes such as irrigation, cleaning or cooling in industries.
Scale-up remains one of the challenges for the practical application of MFCs and one of the objectives of the proposal is to design, construct and operate scaled-up MFCs (10 – 20 L volumes) that are able to maintain the same level of performance as lab-scale systems. This will be achieved by investigation of design/operational factors e.g. loading rate, integration with conventional wastewater treatment systems etc. for their influence on colour removal, COD reduction and power production. The other hurdle is understanding/maximising electron transfer from bacteria to the anode. The Egyptian Atomic Authority team will research this by isolation and identification by denaturing gradient gel electrophoresis of new electrogens and investigating the performance of Egyptian mixed microflora in MFCs.