114 / 2021-06-30 23:28:04

Optimization of agricultural waste for photo-fermentative biohydrogen performance under mixing using box-behnken design (BBD)

photo-fermentative biohydrogen performance; BBD response surface; mixing; kinetics analysis; energy conversion efficiency.

To better investigation the effect of mixing on photo-fermentative biohydrogen performance of agricultural waste. In this paper, corn cob was selected as the substrate. Experiments under different substrate concentrations, mixing rates and light intensity were conducted. The interaction between the three factors was investigated by using BBD response surface method and the photo-fermentative biohydrogen performance was optimized. The cumulative hydrogen production was taken as the assessment index. Reducing sugar concentrations (RSC), pH, oxidation reduction potential (ORP), hydrogen production rate, cumulative hydrogen yield were monitored. Gompertz model was adopted to analyze the kinetic parameters. Moreover, the energy conversion efficiency was calculated. Results showed that hydrogen production capacity was stronger when the mixing condition was added. The optimal conditions were concluded by single factor experiment that the light intensity was 6000 Lux, substrate concentration was 55.56g TS/L and mixing rate was 150 rpm. The BBD response surface showed the maximum hydrogen production was 564.515 mL when the light intensity was 6000 Lux, the mixing rate was 144.18 rpm, and the substrate concentration was 58.06g TS/L. The optimum conditions predicted by the model were verified by experiments, and the cumulative hydrogen production was 534.03 mL. The relative error between the experimental value and the predicted value is only 5.4%.