Although there are many types of research with MFC for wastewater treatment, the optimum MFC configuration is still uncertain for actual field applications. However, no MFC research is reported with SBPW that focused on both treatment (e.g., pollutants removal rate, optimum loading rate, and types of microorganisms involved) and electricity generation. (2009) used an electrochemical process to treat simulated sugar beet wastewater and observed a significant reduction of COD. (2011) used sugar beet molasses and ferric oxide to select bacterial consortia capable of dissimilatory Fe(III) reduction. There is limited research where sugar beet derived wastewater was used as a substrate for MFC. Therefore, researchers and scientists are in search of alternative cost-effective and less energy intensive technologies for wastewater treatment. 2003 Rabaey & Verstraete 2005 Murray et al. Energy recovery from anaerobic processes, however, is not generally efficient, and the aerobic processes are highly energy intensive and produce a lot of solids which are costly to treat and dispose of ( Wei et al.
Biological treatments (e.g., combined anaerobic and aerobic treatments) are commonly used due to their high COD removal efficiency, lower sludge production, less space requirement, low odor emission, and energy recovery via anaerobic digestion ( Nahle 1998 Austermann-Haun et al. 2001) and algal production due to excess amount of nutrients contained in wastewater ( Nahle 1998). 1980), and may cause groundwater contaminations ( Nahle 1998 Wersin et al. However, they require a large surface area ( Nahle 1998), could be a source of odor emission to the neighbor if not managed properly ( Marden et al. Impoundments or lagoons are sometimes used for removing sediment-bound nutrients from wastewater as well as treating them before discharging ( Calero et al. Filtration, flow and load equalization, sedimentation, biological treatments (e.g., anaerobic followed by aerobic treatment and nutrient removal), chlorination, and composting are some of the common methods that are used ( IFC 2007). Often, under-treated wastewater is discharged into nearby streams, which may cause water pollution including odor and bad taste, and impacting city water supply and aquatic life ( Storry 1996).įor treating SBPW, a combination of different methods is used. The sugar beet processing wastewater (SBPW) is enriched with high organic loadings, and treatment of the wastewater requires a large amount of energy. A part of this wastewater is reused in the processes however, the remaining wastewater has to be treated in wastewater treatment facilities before discharging them into surface water. Combined with water contained in beets (about 75% of beet's weight), a large amount of wastewater is produced as a result of processing of beets. For each ton of sugar produced, processing of beets requires 20 m 3 of fresh water without considering reuse of it ( Gutteck 1989).
Over 18 million tons of sugar beet is produced annually in North Dakota and Minnesota, USA, to produce sugar from beets, and this is an important industry in the north central states ( USDA 2014). This study demonstrated that SBPW can be used as a substrate in the MFC to generate electricity as well as to treat for pollutant removal. Scanning electron microscopy of anode indicated that a diverse community of microbial consortia was active for electricity generation and wastewater treatment. In this study, >97% of the COD and up to 100% of the total suspended solids removals were observed from MFC-treated SBPW. Coulombic efficiency varied from 6.21% to 0.73%, indicating diffusion of oxygen through the cation exchange membrane and other methanogenesis and fermentation processes occurring in the anode chamber. A power density of 14.9 mW m −2 as power output was observed at a COD concentration of 2,565 mg L −1. Raw SBPW was diluted to several concentrations (chemical oxygen demand (COD) of 505 to 5,750 mg L −1) and fed as batch-mode into the MFC without further modification. A simple dual-chamber MFC was constructed with inexpensive materials without using catalysts. This study evaluated the synergy of electricity generation by the MFC while reducing pollutants from sugar beet processing wastewater (SBPW). Bioelectricity generation from biodegradable compounds using microbial fuel cells (MFCs) offers an opportunity for simultaneous wastewater treatment.
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