This Paper shows different biological routes to valorise the metabolic products of acidogenesis fermentation after H2 production and to increase the overall balance of bioenergy production as well. The routes go from a conventional anaerobic digestion till to a novel microbial electrolysis cells. We have demonstrated that methane production from volatile fatty acids can easily be established not only from anaerobic digestion technology, but also from a membraneless Microbial Electrolysis Cells (MEC) at ambient temperatures. The two­stages (H2+CH4) by AD is nowadays the most feasible and can increase energy efficiency from 11% (hydrogen only production) to 55%, leading to a positive net energy balance which is 11% more than traditional AD for only biogas production. Furthermore, test in a standard MEC was successfully conducted to produce H2 from sodium acetate, demonstrating that also this novel biotechnology can be used to extract further energy by end­products of H2­dark fermentation. Finally, a test was conduced to utilize in loco the produced H2 by MEC for the production of PHB. Results of this test reveals the feasibility of such process, even if further investigation are essential to increase the efficiency of PHB production.

Proceedings of the 18th European Biomass Conference and Exhibition, 3-7 May 2010, Lyon, France, pp. 1395-1404