This study aimed to improve the productivity of dark fermentative hydrogen production from organic waste. An anaerobic sequencing batch reactor was used for hydrogen fermentation and it was fed with food waste (VS 4.4 ± 0.2% containing 27 g carbohydrate-COD/L) at various CO 2 sparging rates (40-120 L/L/d), hydraulic retention times (HRTs; 18-42 h), and solid retention times (SRTs; 18-160 h). CO 2 sparging increased the H 2 productivity by 5-36% at all the examined conditions, confirming the benefit of the replacement of headspace gas by CO 2. The maximum H 2 production was obtained by CO 2 sparging at 80 L/L/d, resulting in the H 2 productivity of 3.18 L H 2/L/d and the H 2 yield of 97.3 mL H 2/g VS added. Increase of n-butyrate and isopropanol yields were concurrent with the enhanced H 2 yield by CO 2 sparging. Acidogenic efficiency, the sum of H 2, organic acid, and alcohol, in the CO 2-sparged reactor ranged from 47.9 to 56.0%, which was comparable to conventional acidogenesis. Thermodynamic analysis confirmed that both CO 2 sparging and CO 2 removal were beneficial for H 2-producing reactions, but CO 2 sparing has more profound effect than CO 2 removal on inhibiting H 2-consuming reactions.
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Fuel Technology
- Condensed Matter Physics
- Energy Engineering and Power Technology