Bio-electrochemical assisted anaerobic digestion of the liquid fraction of dairy manure in a UASB reactor
Wednesday, April 30, 2014: 9:45 AM
Grand Ballroom F-G, lobby level (Hilton Clearwater Beach)
Carlos Zamalloa1, Hongjian Lin2 and Bo Hu2, (1)Department of Bioproducts and Biosystems Engineering, University of Minnesota, Saint Paul, MN, (2)Department of Bioproducts and Biosystems Engineering, University of Minnesota, Minneapolis, MN
Electrochemical assisted anaerobic digestion has been recently introduced as a new alternative to improve the anaerobic digestion process. The implementation of a bio-electrochemical system such as a microbial electrolysis cell (MEC) coupled with a digester can allow in situ (i) the increase biogas energy content and quality and (ii) the precipitation of struvite (MgNH4PO4) by applying an electric field. Subsequently, the concentration of hydrogen sulfide (H2S) in the biogas can be decreased at the cathode following SO4−2 +6e + 8H+ -> S0 + 4H2O (Ecat -0.19 V vs NHE) and at the anode following H2S -> S° + 2 H+ + 2e (Ean +0.27 V vs NHE) and due to the production of micro-aerobic conditions sulphate reducing bacteria (SRB) will reduce sulphide following 2H2S + O->S° + H2O. The objectives of this work were the development and assessment of an improved UASB reactor through the implementation of a bio-electrochemical system. Our results showed that at an applied voltage of 0.5 V, an increase of about 10% of methane content and a removal of 40% of H2S in the biogas of UASB-MEC reactor was observed. This system has shown the potential implementation for the H2S removal of digesters.