Production of Gaseous Biofuels and Electricity from Cheese Whey

Abstract

In this paper, the potential of energy recovery from cheese whey in the form of gas biofuels (hydrogen, methane) as well as electricity generation through application of the microbial fuel cell technology are studied.Hydrogen and methane production from cheese whey in a two-stage process has already been studied at a lab scale in a continuous stirred tank reactor (CSTR) of 3 L and a periodic anaerobic baffled reactor of 15 L, respectively. In this work, to scale up the hydrogen production step, the cheese whey fermentation process was studied at a larger scale using a 13.8 L bioreactor of CSTR type. The chemical oxygen demand concentration of the cheese whey fed to the CSTR was 53.3 ( 3.8 g/L. The pH in the bioreactor was maintained at 5.14 ( 0.15 with NaOH addition. The hydrogen produced reached up to 4.8 ( 0.5 L/L/d at an hydraulic retention time of 24 h (corresponding to a yield of 1.3 mol H 2 /mol consumed carbohydrates), approximately twice as much obtained in previous lab-scale experiments in a 3 L bioreactor. In addition, diluted cheese whey at different initial concentrations, was used as feedstock for electricity generation, using a two-chamber microbial fuel cell (MFC). The experiments showed that the MFC performance was not limited by the wastewater strength since the substrate removal efficiency and maximum power output were not affected by the increase of the initial concentration. The time needed for complete substrate degradation increased linearly with the wastewater strength.

Cheese whey management: A review

“…This drawback is of special concern in sensitive areas, where the N and P can cause the eutrophication of surface waters. Only few study cases presented the effluent with COD values below the limit discharge and in these instances the initial substrate used was diluted to apply: -aerobic digestion by activated sludge, with initial COD ¼ 0.547 kg m À3 (Cordi et al, 2007); -anaerobic digestion, with initial COD ¼ 0.5e4.0 kg m À3 (Mockaitis et al, 2006); -MFC technology, with initial COD ¼ 0.35e2.7 kg m À3 (Stamatelatou et al, 2011).…”

“…This electron flow produces an electrical current that can be measured (Rachinski et al, 2010). MFC technology has been used to produce direct electricity from non-sterilized and diluted cheese whey (Antonopoulou et al, 2010), filter-sterilized and diluted cheese whey (Stamatelatou et al, 2011), raw cheese whey, raw cheese whey inoculated with Enterobacter cloacae subspecies dissolvens and heat treated cheese whey inoculated with E. cloacae (Kassongo and Togo, 2010).…”

“…Thus, Stamatelatou et al (2011) used cheese whey after centrifugation, filtration and sterilization to eliminate solids and microorganisms. In this work cheese pre-treated whey with 5 different initial concentrations (0.35e6.7 kg m À3 ) was used.…”

“…The maximum power density increased approximately 99.7% when sterilized raw cheese whey inoculated with E. cloacae (initial COD of 96.5 kg m À3 ) was used (Kassongo and Togo, 2010), comparatively to sterilized and diluted cheese whey (initial COD of 6.7 kg m À3 ) (Stamatelatou et al, 2011).…”

Biotechnological Utilization with a Focus on Anaerobic Treatment of Cheese Whey: Current Status and Prospects

“…The coulombic efficiency was only 1.9%, which could be attributed to biochemical oxidation of the organic substratum by the indigenous non-electrogenic microbial consortium contained in the raw wastewater. Optimization and further development by the improvement of MFC design and with pretreatment of the CW (sterilization or pasteurization) might increase both density and couloumbic efficiency making the procedure economically viable [60]. Finally, the economic and environmental importance of CW utilization for the production of bio-hydrogen has recently been identified and there is a growing research interest focusing on this subject [29,[60][61][62][63][64][65][66].…”