Comparative Performance between Heat-shocked Anaerobic Sludge and Clostridium butyricum TISTR1032 Inocula in Biohydrogen Production from Food waste

Dark H-2 fermentation of a synthetic non-sterile food waste with varying food waste content in the range of 2.5 - 10 % (w v(-1)) was carried out in 0.5 L batch reactors under the condition of initial pH 6 and 37 degrees C. Comparative performance of heat-shocked anaerobic sludge and C. butyricum TISTR1032 inocula in the H-2 fermentation was evaluated. No CH4 was detected in all cases. Food waste content influenced the hydrogen production potential, specific rate and yield. The H-2 yield was achieved maximum at 2.5% food waste and declined at the increased food waste content. The highest H-2 yields of 84.0 and 133.9 mL g(-1) VS were obtained in the anaerobic sludge and C. butyricum reactors at 2.5% food waste. Better performance of H-2 fermentation was observed regarding the H-2 yield and specific rate by C. butyricum over the anaerobic sludge for most food waste content. Acetate and butyrate are the main end-products at 2.5-5.0% food waste while propionate and ethanol are predominant at higher food waste content for both inocula. This work demonstrated C. butyricum inoculum achieved a better performance in the H-2 fermentation than the heat-shocked anaerobic sludge which presumably contained spore-forming H-2 producers. Maximum energy recovery was observed in C. butyricum fermentation at 2.5% food waste that is higher than that in anaerobic sludge at 5% food waste by 9% while the energy recovery in anaerobic sludge fermentation tended to be increased at the high organic loading (5 -7.5% food waste).