Anaerobic Fermentation Of Biological Hydrogen Production Technology

Biological hydrogen was produced with anaerobic batch culture from simulated wastewater containing carbohydrate by natural anaerobic microorganism obtained from natural manure compost and anaerobic activated sludge.Hydrogen production potential and rate were selected to assess the hydrogen-producing clostridia fermentation, and could be systematically estimated using a simple model developed from the Gompertz equation. The orthogonal design was implemented to investigate the effect of environmental factors (incubation time, substrate concentration, pH value, etc.) on anaerobic hydrogen production process. Polynomial regression and response surface plots demonstrated that optimal sucrose concentration and pH for the composts generating hydrogen gas were 4.0+0.5 g/L and 5.4+0.2, respectively. High hydrogen potential of 146mL/g sucrose occurred under this condition. During the hydrogen fermentation process, the maximum hydrogen composition of biogas was 61% and no methanogenesis was observed. The optimal starch concentration and initial pH for hydrogen production were 4-5g/L and 7.0-8.0 (reaction pH value: 4.5-5.5). High hydrogen potential and the maximal hydrogen production rate were 166mL/g starch and 9.0mL/h, respectively. The optimal maltose concentration and pH for maltose fermentation were 10g/L and 4.5-5.5, respectively. High hydrogen potential of 180mL/g maltose and the maximal hydrogen production rate of 4.0mL/h occurred under the condition of pH 5.0. Experimental results of metabolites analysis led us to the belief that Clostridium sp. predominated in anaerobic composts, suggesting that inocula used to seed the batch experiment can be obtained from almost any natural source. Supplementary experiments confirmed that the optimum conditions evaluated in this study were highly reliable, and the COD reductions were approximately 40-60%, even as high as 71.4% could be achieved.Recently, continuous hydrogen production has been carried out from potato starch in a 30-litre UASB reactor and the hydrogen composition of 40-51% can be maintained throughout the process. High hydrogen composition of 97% can be achieved after carbon dioxide was absorbed by the solution of sodium hydroxide. The results also demonstrated that hydrogen fermentation can easily accomplish the dual goals of waste reduction and energy production and possesses a promising future in engineering practice.