Research On Biological Hydrogen Production By Anaerobic Fermentation From Carbohydrate-Containing Waste

Biological hydrogen production process by anaerobic fermentation is a new, low energy consuming and clean technology which includes the utilization of renewable energy resources which are inexhaustible with the production of high quality fuel gas. In this study, natural anaerobic microbes were used as inoculants by mixed culture. Continuous and batch experiment using simulating carbohydrate-containing waste water and simulating food waste were conducted to investigate the biological factors and the operation parameters, and to find the new avenue for the enhancement of the ability of reactor for biological hydrogen production.Continuous hydrogen production from simulating carbohydrate-containing waste water made by glucose was conducted. The effects of pH, HRT, the COD concentration of influent, loading rate, temperature and the alkalinity of influent on hydrogen production were investigated. The morphology of hydrogen producing bacteria was analyzed. At the optimal condition of pH5.5, HRT6h, 37℃, and the waste water containing 2.5g/L glucose, a yield of 1.83molH2/mol glucose and a production rate of 2.57L/L·d were obtained. The COD concentration of influent and the COD loading rate were directly related to the H2 production rate and inversely related to the H2 production yield. The yield of thermophilic reactor was little higher than that of mesophilic reactor, while the yield of psychrophilic reactor was only a half of that of mesophilic reactor. The bacteria were mostly short rod shaped, plus some long rod bacteria, filamentous bacteria and cocci in chain. The major microbial group may be Clostridium. butyricum because the major intermediate product was butyrate and the type of fermentation was butyrate fermentation type.In this study, NaHCO3 was used to adjust the alkalinity of influent and the pH value was controlled by the alkalinity of influent. The correlation of pH value, COD loading rate and the alkalinity of influent at various temperatures were obtained. It can be used for reference for practical operation.Batch experiments of mesophilic hydrogen production from simulating food waste made by rice were conducted. The effects of initial pH and substrate concentration on hydrogen production were investigated. At the optimal pH5.0 and the waste containing 10gCOD/L rice, the maximum hydrogen yield was 113mL/gCOD (or121mL/g carbohydrate).