The Design Of Hydrogen Production Reactor Based On PLC And The Start-up Of Dark Fermentation Hydrogen Production

Hydrogen is expected an ideal fuel in the future because of it is clean, pollution-free property. Based on the continuous flow test of mixed microfiora and molecular microbiology technology, this experiment studied the start-up of fermentation biohydrogen production reactors and microbial community succession during start-up of ethanol type fermentation. These researchs are helpful for the improving of hydrogen production capacity on cell level and it's application.Based on PLC technology, this researche established reactors for biohydrogen production. The reactor system consist of sludge domestication system, pH measure system, culture medium container, momentum system and adjuster, warning system, biohydrogen production reactors, PLC control system and accessorye quipments.The dark fermentation reactor was used for biohydrogen production using sludge from hot spring as seed bacteria and molasses as substrate. The factors affecting the start-up of dark fermentation reactor including organic loading rate (OLR) and hydraulic retention time (HRT) were studied. The results showed that organic loading rate (OLR) and hydraulic retention time (HRT) were key parameters for start-up. A strategy controlling OLR and HRT was obtained as: the initial ORL of 6.0 kgCOD/m~3·d, pH value was not controlled, biomass was 30gVSS/L and using OLR stepwise manner for reactor start-up, it was found that when HRT was controlled at 9h during start-up process, butyrate type fermentation was formed, when HRT was controlled at 6h during start-up process, ethanol type fermentation was formed.Microbial community succession during the dark fermentation reactor start-up was investigated using molecular microbiogy technology. It showed that the experimental condition made microbial diversity decrease gradually, microbial similarity increase gradually, succession speed accelerate fast at the beginning, then slow down gradually, till the stable microbial community structure established. The microbial community structure and climax community were variational with operation. Based on DGGE profiles, significant microbial population shifts took place in the first 16 d, but a longer period up to 28d was required to establish a microbial community with stable metabolic activity for ethanol type fermentation.