Factors Affecting Hydrogen Production from Food Wastes by Clostridium-Rich Composts

This study used the technique of response surface approach to analyze the combined effects of heat-shocking temperature and time on anaerobic grass composts. Results indicate that the grass composts under heat-shocking temperature and time of 80°C and 3  h, respectively, could yield high populations of hydrogen-producing microorganisms. Metabolic results demonstrate that the composts are reliable, having considerable hydrogen-producing Clostridia. The multivariate analysis with response surface by considering specific hydrogen-producing potential and rate simultaneously indicate that the cultural media with Fe2+=132  mg/L; NH+4=537  mg/L; and PO(3-)4 =1,331  mg/L were optimal for the hydrogen-producing Clostridia-rich composts using high-solids food wastes. The specific hydrogen production potential and rate were 77±3  mL  H2/gTVS and 520±20  mL  H2/g  TVS/day, respectively. The former was 38% of theoretical hydrogen-producing potential of Clostridium sp. using glucose. Of these factors, ammonium and phosphate are nutrients for the hydrogenproducing Clostridia growth while iron exerts a synergistic influence on them in the conversion of the food wastes into hydrogen.