Study On Start-up And Bioaugmentation Of Continuous Biohydrogen Production System

Hydrogen is expected to become an ideal fuel in the future because it is clean, pollution-free. As a high energy carrier, hydrogen can be stored and transported easily. Based on the continuous flow test of mixed microflora, this research involved start-up of biohydrogen production reactor and the enhancement start-up of butyrate type fermentation. The start-up strategy of UASB biohydrogen production reactor was put forward, which would establish high efficient hydrogen producing population in a short time.An up-flow anaerobic sludge blanket (UASB) reactor was used for biohydrogen production. The seed sludge was taken from Xiamen sewage processing plant. Molasses was used as substrate. Emphasis was placed on assessing the factors affecting the UASB reactor start-up process, which includes organic loading rate (OLR), hydraulic retention time (HRT) and pH value. The bioaugmentation technology was introduced into the UASB biohydrogen production reactor. During the start-up process, Klebsiella oxytoca HP1 was put in the reactor intermittently and the hydrogen production capacity was investigated.The results of the effect of the initial OLR on the UASB reactor suggests that ethanol type fermentation was established when the initial OLR was controlled at 6.0 kgCOD·m^-3·d^-1. The rate of conversion of molasses was increased by the hydrogen producing microbial community at HRT of 9 h and the hydrogen production capacity of the UASB reactor increased evidently. When pH value was controlled at about 5.5±0.1, the maximal hydrogen production rate was obtained as 3.94 L·d^-1.High efficient hydrogen producing bacteria Klebsiella oxytoca HP1 was used to enhance the UASB reactor start-up process for ten days and its inoculation was 3% of total seeding sludge. The results demonstrated that, the hydrogen production rate of the reactor with bacteria dosing was 25 % higher than that without augmentation. Acetate and butyrate were the main volatile fatty acids (VFA) products and their content was 10% higher than that without augmentation. Compared with the normal start-up process, the start-up time of the reactor with dosing bacteria cells shorted 5 days. Bacteria dosing during reactor start-up not only improved microbial community structure and increased operational stability but also shortened start-up time. Bacteria dosing was a good way for reactor start-up.