Operation Control And Characteristics Of Fermentative Hydrogen Production In Anaerobic Contact Reactor

Because hydrogen was non-poisonous, non-polluting and possessed largecombustion value, it was recognized as a perfect alternative of fossil fuel.Biological hydrogen production from anaerobic fermentation process had beenattracted increasing global attention, because it was environment friendly andenergy-saving. To achieve bio-hydrogen industrial production, it was significant toselect the suitable reactor and the appropriate fermentation type. The present studyintended to observe and study the operation characteristics of fermentativehydrogen production in an anaerobic contact reactor (ACR) during starting andrunning period, and compared the hydrogen production capability of ethanol-typefermentation and butyric acid-type fermentation with different organic loading rate(OLR).ACR could hold more biomass concentration because of sludge backflow,which made ACR displayed an outstanding hydrogen production. The both sameACRs, ACT I and ACR II, were started up at a hydraulic retention time of12h andan influent chemical oxygen demand (COD) of5000mg/L. The pH was controlledat5.6~6.0. But the sludge backflow cell of ACR II was paused. The results showedthat the ACR II reached steady butyric acid-type fermentation much faster than ACTI. The hydrogen-producing efficiency was higher for ACT I than for ACR II,indicating its better ability to maintain biomass. The hydrogen production rate andspecific hydrogen production rate of the sludge were9L/d and0.15L/(g·d),respectively, for the steady ACT I, which was2.05and1.15times of correspondingvalues of ACR II system, respectively.The OLR was the vital factor which affected the hydrogen production. Thepaper studied the effect of OLR on hydrogen production in ethanol-type and butyricacid-type fermentation by shortening HRT and increasing the fluent COD. Theresults showed that the specific hydrogen production rate of ethanol-typefermentation was0.14L/(g·d),0.12L/(g·d) and0.08L/(g·d) at HRT8h,6h and4h, respectively, with the same influenct COD5000mg/L. When the influenct CODwas5000mg/L, HRT was8h,6h, the type of butyric acid-type fermentation wasnot changed, but when HRT was4h, the butyric acid-type fermentation wasunstable and converted to mingle acids-type fermentation. The specific hydrogenproduction rate was0.14L/(g·d),0.12L/(g·d),0.08L/(g·d), respectively. Thespecific hydrogen production rate of ethanol-tpye fermentation at8h,6h,4h was 2.05,3.43,4.81times of corresponding values of butyric acid-type fermentation,respectively. When HRT was6h, the influenct COD was5000mg/L,8000mg/L,12000mg/L,15000mg/L, respective ly, the specific hydrogen production rate ofethanol-type fermentation was0.63L/(g·d),0.69L/(g·d),0.77L/(g·d),0.65L/(g d), respectively. When HRT was8h, the influenct COD was5000mg/L,8000mg/L,15000mg/L,20000mg/L, respective ly, the specific hydrogen production rate ofbutyric acid-type fermentation was0.19L/(g·d),0.13L/(g·d),0.17L/(g·d),0.16L/(g·d). The results indicated that when the OLR was high, the capability ofhydrogen producion in ethanol-type fermentation was better than in butyricacid-type fermentation.