Feasibility of biological hydrogen production from organic fraction of municipal solid waste

Organic municipal solid waste (OFMSW) and two seed microorganisms, namely heat-pretreated digested sludge and hydrogen-producing bacteria enriched from soybean-meal silo, were varied according to a full factorial central composite experimental design with the aim of assessing the feasibility of hydrogen production from OFMSW. A simple model developed from the Gompertz equation was suitable for estimating the hydrogen production potential and rate. Through response surface methodology, empirical equations for specific hydrogen production potential and rate were fitted and plotted as contour diagrams in order to facilitate examination of experimental results. The contour plots showed that high hydrogen production potentials of 140 and 180 ml H2•g TVS−1 occurred when the pretreated digested sludge and the hydrogen-producing bacteria consumed OFMSW, respectively. A high hydrogenic activity for the pretreated digested sludge (45 ml•g VSS−1•h−1) was obtained at a high food-to-microorganism (F/M) ratio; however, that for the hydrogen-producing bacteria (36 ml•g VSS−1•h−1) was found at a low F/M ratio. The experimental results showed that the hydrogen composition of the biogas was greater than 60% except for initial incubation and no significant methane was found throughout this study. Further experiments confirmed that the results of this study were highly reliable and the OFMSW had a considerable potential on biological hydrogen production. Metabolic responses confirmed that characteristics of the heat-pretreated digested sludge converting the OFMSW into hydrogen were similar to that of anaerobic spore-forming bacteria of the genus Clostridium.