Start-Up And Operation Of EGSB Biohydrogen Production Reactor Using Sugarbeet And Brown Sugar As Substrates

Hydrogen energy is an ideal solution to the global energy crises and environmental degradation.The current industrial hydrogen production technology has many disadvantages and unsustainability, which cause the utilization rate of hydrogen energy still very low. Fermentative biohydrogen production has an enormous potential to the large scale industrial production, but still need us to pay great attention to raise the production rate and find cheap raw materials. Sugarbeet is a cash crop with high sucrose content which had low price and been grown widely. It is theoretically fit for being the substrate of fermentative hydrogen production. This study chose sugarbeet as substrate for biohydrogen production using an expanded granular sludge bed reactor (EGSB).Brown sugar was also selected as a comparing fermentative substrate.In the experiment which substrate was brown sugar, COD was increased from 2000 to 8 000 mg/L gradually, the starting HRT was 6h.When the COD was increased at the level of 8 000 mg/L, the HRT began to shorten to 4h,3h and 2h,each kept for 7d.A maximum hydrogen production rate of 5.73 L/(L·d) was achieved, when hydrogen content was 48.44%, HRT was 2h, pH was 4.36 and OLR was 97.2 kg COD/(m3·d). The average hydrogen content of biogas during the experiment was 41.27%, and the pH range was 4.23～4.55.In the steady operation period, the dominant liquid end products were ethanol and acetic acid, which represented ethanol-type fermentation.Because of the technical problem in the bench scale study, water extract of sugarbeet was used as substrate instead of sugarbeet pulp.The same OLR control strategy which has been used in former study was employed here. The system was stable within 56d operation and Ethanol-type fermentation was formed.When the COD was around 8000 mg/L,HRT was 6h, 4h,3h and 2h, the maximum hydrogen production rates were 3.80,4.63,4.92 and 5.54 L/(L-d), respectively. pH range was 3.46-3.86.The maximum hydrogen production rate during this experiment was 5.54 L/(L·d), when hydrogen content was 49.63%,HRT was 2h, pH was 3.57 and OLR was 97.9 kg COD/(m3·d).The results of the two experiments verified the feasibility of fermentative hydrogen production from sugarbeet, but the hydrogen production rate and utilization rate of substrate were still improvable. It was also need to pay more attention to the feeding form of sugarbeet.