Study on Fermentative Conversion of Raw and Pretreated Starch to Hydrogen Using Anaerobic Mixed Micro Flora

The present paper reports the use of starch effluent for biohydrogen production with anaerobic mixed microbial cultures and demonstrates that an acclimated mixed bacterial consortium was able to produce H₂ from sugar substrates. To reduce cost of the medium for more commercially viable H₂ production, starch waste water was used as the feedstock via dark fermentation. Yields of hydrogen under varying conditions of pH (ranges 5.5–7.5), temperatures (45°C-65°C) and initial substrate concentrations (5g/l20g/l) were monitored. Different pretreatment strategies for the effluent were also tried for optimization of pretreatment process. Optimization studies were initially carried out in a 80ml reactor and were subsequently scaled up to an 6 liter bioreactor. Anaerobic sewage sludge was used as inoculum after heat and alkaline treatment. After 24 hrs of incubation at 65°C and at an initial pH of 5.5, a yield of 5.1 mmol/g starch was observed in the initial optimization studies. Study with the 6 liter batch reactor has yielded 5.9 mmol/g starch H₂ and COD reduction of 71%.