Abstract:
Water scarcity has become the worldwide issue. In many applications such as crop irrigation, groundwater recharge and industrial processes, there is an increase in demand for domestic wastewater reclamation and recycling due to water shortages and expanding population. In order to accomplish high level of wastewater treatment, a large input of energy is required. The heavy demands of energy for traditional wastewater processes make it important to explore other treatment processes to minimize operational costs using more energy efficient processes such as anaerobic treatment processes. One of the process is microbial fuel cell (MFC). In a standard MFC process, anaerobic microbes are used in an anodic chamber to degrade organic compounds and thus treat wastewater. Bacteria-generated electrons are transmitted to the negatively charged electrode (anode) and from where they flow towards the positively charged electrode (cathode) connected by some conductive wire consisting of a resistor or operated under a load. In the current research two dual chamber MFCs were used with two different categories of electrodes installed in each of reactor chamber. One of the electrodes was carbon fiber brush (CFB) and the other was graphite rod (GR). Domestic wastewater was utilized as a substrate and the reactors were run in a semi continuous flow at HRTs of 48, 36, 24, 12, 8, 4 and 2 h. Both reactors were run at 1000 Ω internal resistance. Maximum COD removals of 80.3% and 73.9% were achieved for CFBMFC and GRMFC at an HRT of 48 h respectively, which indicates higher COD removals are obtained at longer HRTs. Voltage generation and power production in both reactors were continuous. At an HRT of 8 h maximum voltage of 319 mV and 308 mV was generated for CFBMFC and GRMFC respectively. Similarly, at the same 8 h HRT, maximum power production was 58 mW/m2 and 77 mW/m2 for GRMFC and CFBMFC respectively. Power generation showed decreasing trend with increasing HRT. The CE was in the range of 4.2 to 5.44% for both MFC reactors with CFBMFC showed relatively higher CE than GRMFC. Thus, the current research shows that domestic wastewater can be treated in an MFC along with the subsequent power generation. The power generation and treatment performance of an MFC can be enhanced by using suitable electrodes such as carbon fiber brushes and by optimizing HRT.
