Modeling and Optimization of Biohydrogen Production from De-oiled Jatropha Using the Response Surface Method

In this study, optimization of hydrogen fermentation process from de-oiled Jatropha waste using a central composite design was modeled. A series of batch assays was performed at various substrate concentrations (32-368 g/L), temperatures (38-72A degrees C) and pHs (4.8-8.2) according to the experimental design. The optimal conditions for cumulative hydrogen production (CHP) were determined by response surface methodology. The optimal substrate concentration, pH and temperature values were 211g/L, 6.5 and 55.4A degrees C, respectively. Under these circumstances, the highest achievable CHP of 296 mL H-2 was predicted. To validate the model, verification experiments were conducted. The results were satisfactorily matched with the statistically estimated values with peak CHP value of 307.4 +/- 4.5mL H-2. Microbial community profiling (PCR-DGGE) has revealed that the dominant bacterial community present belonged to Clostridium thermopalmarium, Clostridium buytricum, Bacillus ginsengihumi and Bacillus coagulans.