Dark Hydrogen Fermentation From Paper Mill Effluent (PME): The influence of Substrate Concentration and Hydrolysis

Abstract

Paper mill effluent (PME) was used as an organic feedstock for production of biohydrogen via dark fermentation using heat-shock pretreated anaerobic sludge under mesophilic conditions. The influence of substrate concentration (5, 10 and 15 g-COD/L) and the initial pH (5 and 7) on the efficiency of dark hydrogen fermentation from PME were investigated. The highest hydrogen yield of 55.4 mL/g-COD was obtained at substrate concentration and pH of 5 g-COD/L and 5, respectively. By increasing the concentration of substrate from 5 to 10 and 15 g-COD/L, at fixed initial pH, the hydrogen production efficiency was reduced from 55.4 mL/g-COD to 38.5 and 32.7 mL/g-COD. Furthermore, by increasing pH from 5 to 7, biohydrogen efficiency was reduced up to 40.8%. Different hydrolysis of PME including acidic, acidic-thermal and alkaline hydrolysis prior to fermentation were studied which the alkaline hydrolysis led to the highest hydrogen yield of 62.2 mL/g-COD. Moreover, methane production efficiency of 569 mL/g-COD was obtained at substrate concentration and pH of 5 g-COD/L and 7, respectively. Paper mill effluent (PME) was used as an organic feedstock for production of biohydrogen via dark fermentation using heat-shock pretreated anaerobic sludge under mesophilic conditions. The influence of substrate concentration (5, 10 and 15 g-COD/L) and the initial pH (5 and 7) on the efficiency of dark hydrogen fermentation from PME were investigated. The highest hydrogen yield of 55.4 mL/g-COD was obtained at substrate concentration and pH of 5 g-COD/L and 5, respectively. By increasing the concentration of substrate from 5 to 10 and 15 g-COD/L, at fixed initial pH, the hydrogen production efficiency was reduced from 55.4 mL/g-COD to 38.5 and 32.7 mL/g-COD. Furthermore, by increasing pH from 5 to 7, biohydrogen efficiency was reduced up to 40.8%. Different hydrolysis of PME including acidic, acidic-thermal and alkaline hydrolysis prior to fermentation were studied which the alkaline hydrolysis led to the highest hydrogen yield of 62.2 mL/g-COD. Moreover, methane production efficiency of 569 mL/g-COD was obtained at substrate concentration and pH of 5 g-COD/L and 7, respectively.