Preliminary studies on H2 production from dark fermentation of the organic fraction of municipal wastes

The growing interest for hydrogen utilization in the energy sector can be explained when considering that H2; 1) is a carbon-free energy carrier, 2) could be used either as a natural gas or, in order to maximize the energy efficiency, in combination with fuel cells and 3) can be generated by fossil fuels and a variety of other sources, so that a reduction of the dependence on fossil fuels - as well as a decrease of CO2 emissions during the H2 generation phase - could be attained. Promising options for H2 generation thus include biophotolysis, indirect biophotolysis, photofermentation, electrolysis and dark fermentation, being fossil fuels not used as H2 sources. Among those options, dark fermentation of the organic fraction of municipal (or agro-industrial) wastes represents an attractive process as the H2 production can be integrated to CH4 generation and coupled with wastes stabilization in view of utilization or final disposal. Biological hydrogen production from organic residues is strongly dependent on a variety of operating parameters such as pH, temperature, hydraulic retention time, inoculum pre-treatment, substrate biodegradability and composition, hydrogen partial pressure and microbial actors as hydrogen producing bacteria, hydrogen consumers and metabolic competitors (like sulfate reducing bacteria, nitrate reducing bacteria, methane producing bacteria and homoacetogenic bacteria). The present paper shows the preliminary results on hydrogen production through dark fermentation of OFMSW achieved using lab-scale batch stirred tank reactors. Anaerobic and aerobic sludge from an anaerobic digester of municipal wastewater treatment plant was used as inoculum, with or without any pre-treatment. Under the investigated conditions the maximum H2 generation yield achieved was 149 NL H2/kg VS substrate.