pH对发酵系统的产甲烷活性抑制及产氢强化

为抑制厌氧发酵系统的产甲烷活性,强化其发酵产氢性能,采用逐级降低pH的调控方法,探讨连续流搅拌槽式反应器(CSTR)从具有显著甲烷发酵特征的厌氧发酵系统向发酵产氢系统转变的运行特征．在进水COD 7 000 mg／L、水力停留时间(HRT) 8 h条件下,发酵体系在pH 由65～72降低到60～65时,虽然发酵气中的甲烷体积分数逐渐减少乃至消失,但氢气体积分数一直在3％以下;当pH下降到40～50时,系统中的产酸发酵作用得到了进一步强化,挥发性发酵产物总量平均为2 052 mg／L,呈现为典型的乙醇型发酵,发酵气产量平均为26 L／d,其氢气体积分数稳定在45％左右,活性污泥的比产氢率达167 L／(g·d)．

Enhancement of the fermentative hydrogen production in a continuous-flow stirred tank reactor by decreasing pH to inhibit methanogenesis

To develop a feasible method for inhibiting methanogenesis while enhancing fermentative hydrogen production in anaerobic organic wastewater fermentation process,a continuous-flow stirred tank reactor(CSTR) a methane production feature was introduced and used as the base-line condition.The CSTR was operated at(35±1) ℃ with an influent COD 7 000 mg/L and a hydraulic retention time(HRT) 8 h throughout the performance test.When the pH in the CSTR decreased from 6.5-7.2 to 6.0-6.5,the methane yield decreased remarkably and could not be inspected in the biogas at last,while the percentage of hydrogen in biogas kept at a low level less than 3%.When the CSTR operated with a lower pH 4.0-5.0,the acidogenesis was further enhanced with a total organic intermediate of 2 052 mg/L,dominated by ethanol and acetic acid,indicating a typical ethanol-type fermentation established in the CSTR.During the ethanol-type fermentation process,a biogas yield of 26 L/d was obtained with a hydrogen percentage about 45%.The specific hydrogen producing rate of the anaerobic activated sludge reached at 1.67 L/(g·d) averagely.