افزایش تولید الکتریسته در یاخته های زنده با تصفیه فاضلاب کارخانه ها با استفاده از سلول سوختی میکروبی Enhancement of Bioelectricity Generation from Treatment of Distillery Wastewater Using Microbial Fuel Cell

INTRODUCTION Sugar cane molasses is most important raw materials for production of alcohols and amino acids in fermentation industries. However, after use of raw materials, a large quantity (8–15 L of wastewater for every liter of alcohol production) of wastewater is discharged which creates serious environmental issues [1]. The molasses based distillery industries wastewater contains high organic matter in terms of Chemical Oxygen Demand (COD: 65,000–13,0000 mg/L), high concentration of minerals, dark brown color, and burnt sugar odor [2]. Several methods includes chemical, electrochemical, biological (aerobic and anaerobic) methods have been exploited for the treatment and disposal of molasses wastewater [3]. Conventionally, an anaerobic digestion method is used for treating such waste and generates methane gas followed by an aerobic treatment prior to disposal [4]. An intensive conventional wastewater treatment system are required to develop an alternative technology which should be reliable, cost effective and also energy recovery. Microbial fuel cell (MFC) is a novel bio-electrochemical system that generates bioelectricity and simultaneously removes pollutant such as COD, color, salinity etc. from wastewater which is one of the most advantageous [5–7]. The MFC consists of biotic anode and abiotic cathode chamber separated by a proton exchange membrane (PEM). The potential developed between metabolic respiration on electron donors and electron acceptors conditions in the anode and cathode generates electricity and water [8]. Earlier, the MFC was operated using pure organic matter such as glucose, acetate and lactose as a substrate to understand the fundamental of process [9,10]. Nowadays more complex substrates (dairy, domestic, starch processing, and paper recycling wastewater etc.) have been used to improve the performance and exploiting the waste into useful product [11–14]. Though, the molasses based distillery wastewater containing high organic matter that provides a great potential source for electricity generation. Additionally, the MFC used sulfide (that generated during the anaerobic process) as a fuel to generate electricity and oxidize sulfide into elemental sulfur [15]. In recent year, the MFC performance was enhanced by varying the operational and design parameters such as reactor configuration, electrode material, electrode distance, pH, microbial communities and substrate concentration etc. [16–19]. Nevertheless, the wastewater feed pH played a significant role on overall performance in dual chamber MFC, because it controls not only bacterial growth and also supports an efficient movement of protons through PEM. Generally, bacteria respond to change internal and external pH by adjusting their activity associated with many different processes, including proton translocation, amino acid degradation, adaptation to acidic or basic conditions [20]. Since, the wastewater pH in anode chamber should be identified to enhance power generation in the MFC. Mohanakrishna et al. [21] evaluated the MFC performance with distillery wastewater by keeping at acidic environment. Ha et al. [22] adjusted the distillery wastewater at pH 7 using buffer for evaluating the performance using bacteroidetes dominant thermophilic MFC.