Characteristics of hydrogen production from bean curd manufacturing waste by anaerobic microflora

The hydrogen production from bean curd manufacturing waste by anaerobic mic roflora was investigated using batch experiments at 35 degreesC. The anaero bic microflora was obtained from fermented soybean-meals and maintained usi ng a sucrose-limited medium in continuous culture. A solution of an organic substrate without solid component such as rough fiber in bean curd manufac turing waste was used for the experiments. After the inoculation, hydrogen production immediately occurred and almost ceased at 12 h. The final concen tration of hydrogen in gas produced was 63% H-2. During hydrogen production , carbohydrate was rapidly degraded while protein degradation was hardly ob served, suggesting that carbohydrate was the main source of the hydrogen pr oduction. The hydrogen yield was 2.54 mol of H-2 mol(-1) of hexose utilized if hydrogen gas was produced from only carbohydrate degradation. At a carb ohydrate concentration greater than 3,720 mg l(-1), the rate of hydrogen pr oduction rate significantly decreased. The rate of alcohol production was r emarkably increased with increasing carbohydrate while the rate of volatile fatty acid production was hardly changed. The results indicated that the m etabolic pathway and the amount of hydrogen production would be significant ly influenced by the carbohydrate concentration.