Microbial electrosynthesis (MES) portrays a new method for transforming organic and inorganic compounds to value added products. Volatile fatty acids (VFAs) from anaerobic digestion (AD) effluent needs to be further treated using activated sludge systems. The present study exhibits the feasibility of transforming acetic and butyric acid from AD effluent using an electrode as an electron donor in MES systems. The bioelectrochemical reduction of VFAs using biocathodes was pursued at different external power inputs with an oxidation of water in an anode chamber. Variation in cell voltage (1.0, 1.5 and 2.0 V) resulted in cathode potentials of -0.45±0.02, -0.68±0.018, and -0.84±0.032V (vs Ag/AgCl) with a maximum current generations of -0.48±0.03, -0.64±0.02, and 0.78±0.01 mA, respectively. At relatively low cell voltage of 1 V, the composition of initial AD effluent was converted to lactic and formic acid without alcohol formation at the end of operation. As higher cell voltage (1.5 and 2.0 V) was applied, the formation of organic solvents such as ethanol, acetone, methanol, proponal, butanol and glycerol was observed with elevated current generation. These results suggest that external energy input greater than 1 volt would be requisite for producing valuable alcohols and other chemicals from AD effluent. The presence of neutral red (NR) mediator accelerated the formation of ethanol and butanol, and enhanced current generations with higher cathode potentials. Besides, gaseous products such as H<sub>2 </sub>andCH<sub>4 </sub>were found in the headspace, which is possibly used as possible energy carriers. This study suggests that MES system with optimum operational conditions can be used to produce high-value chemicals from anaerobic digestion effluent along with biogas production in anaerobic digestion

Microbial electrosynthesis of high-value products from volatile fatty acids present in anaerobic digestion effluent

249th National Meeting (2015)

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