Enhanced bioenergy production through dual-chamber microbial fuel cells: Utilizing citric acid factory wastewater and grape waste as substrates.

ABSTRACT

INTRODUCTION: Microbial fuel cell (MFC) is a variant of the bio-electro-chemical system that uses microorganisms as biocatalysts to generate bioenergy by oxidizing organic matter. Due to its two-prong feature of simultaneously treating wastewater and generating electricity, it has drawn extensive interest by scientific communities around the world. However, the pollution purifying capacity and power production of MFC at the laboratory scale have tended to remain steady, and there have been no reports of a performance breakthrough. PROBLEM STATEMENT This research was conducted to produce electricity and evaluate the efficiency of chemical oxygen demand (COD) removal from wastewater containing Citric Acid using a two-chamber microbial fuel cell without an intermediary. METHODOLOGY: In this research, citric acid factory wastewater was used as the substrate, graphite as the electrode, Nafion membrane for proton transfer from anode to cathode, and grape waste as a carbon source. These Experiments were performed at room temperature and neutral pH. Also, the effect of three independent variables mixed liquor suspended solid (MLSS), Carbon Nitrogen Phosphorus stoichiometric ratio (CODTKNP), and grape waste on electricity production and wastewater treatment was investigated. Then, the optimal values of each variable were determined under favorable conditions for electricity generation and COD reduction. RESULTS: The MFC was conducted at the optimal values of MLSS 1400 mg/L, the stoichiometric ratio of CODTKNP 140101, and the grape waste dose of 1.4 g/L. At these conditions, the obtained maximum power density and current density were 18228.10 mW/m2 and 244.44 mA/m2, respectively. The maximum COD removal was 72% achieved in the values of MLSS 1400 mg/L, the stoichiometric ratio of CODTKNP equal to 260101, and 1.4 g/L of grape waste. The maximum open circuit voltage was also recorded as 678 mV, obtained at MLSS 3000 mg/L, the stoichiometric ratio of CODTKNP equal to 200101, and for a grape waste dose of 2 g/L. CONCLUSION: The results of this research showed that the use of grape waste to supply glucose to microorganisms in the MFC system has a significant effect on increasing energy production and COD removal, and it is recommended to conduct additional research in the future to improve the efficiency. However, scalability and practical application potential of these integrated technologies are the challenges towards their real-world applications in small scale trials.