不同pH下糖蜜废水的厌氧产酸发酵类型及微生物群落结构解析

为寻求厌氧产酸发酵反应器的适宜控制参数和微生物学机制,以ACR(厌氧接触式发酵制氢反应器)为试验平台,通过分阶段调控反应器的pH,考察不同pH下ACR系统的产酸发酵类型和产氢性能,并采用聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)技术对微生物群落结构进行了解析.以糖蜜废水为基质,以城市污水厂剩余污泥为种泥,在污泥接种量(以MLVSS计)为3.58 g/L、进水ρ(COD_Cr)为5 000 mg/L、HRT为12 h条件下,分别考察了系统在pH为6.0～6.5、5.5～6.0、5.0～5.5、4.5～5.0条件下的运行特性.结果表明,在pH为4.5～5.0时,系统中以Ethanoligenens harbinense YUAN-3为代表的产氢菌群占优,呈现典型的乙醇型发酵特征,活性污泥表现出的产氢性能最佳,其氢气转化率和污泥的比产氢速率分别为1.9 mol/mol和7.8 mmol/(g·d).在pH为5.5～6.5、5.0～5.5的条件下,Clostridium tyrobutyricum strain A1-3、Propionibacterium sp.B2M2分别成为优势菌群,系统分别呈现出丁酸型发酵、混合酸发酵类型.研究显示,随着pH的改变,系统内的产酸发酵菌群随之发生更迭,在不同pH控制水平下形成不同的顶级微生物群落结构,进而使得系统呈现出不同发酵类型和产氢性能. 

Analysis of the Dynamics of the Microbial Community and Changing of Acidic Fermentation Type of an Anaerobic Reactor Treating Refinery Molasses Wastewater under Different Controlled pH Levels

Abstract:In order to seek suitable controlling parameters for anaerobic fermentative acid production in an anaerobic contact reactor(ACR),the acidic fermentation type and the performance of biohydrogen production of an anaerobic reactor treating refinery molasses wastewater under different pH levels was investigated,and the microbial community was analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE).The diluted molasses wastewater was used as a substrate,and the excess sludge from a municipal wastewater treatment plant was used as seed sludge.The ACR was started after inoculated sludge(3.58 g/L) at the influent COD_Cr 5 000 mg/L under HRT of 12 h,and biohydrogen production was studied under four different controlled pH values(6.0-6.5,5.5-6.0,5.0-5.5,4.5-5.0).The results indicated that the Ethanoligenens harbinense YUAN-3 was dominant in the reactor under pH of 4.5-5.0,which indicated that a typical ethanol fermentation type was established in ACR.And simultaneously,the hydrogen yield(1.9 mol/mol) and specific hydrogen production rate(7.8 mmol/(g·d)) peaked at this controlled pH value.The ACR exhibited butyric acid fermentation type and mixed acid fermentation type within the pH at range of 5.5-6.5 and 5.0-5.5,respectively.The profiles of PCR-DGGE indicated that the Clostridium tyrobutyricum strain A1-3 and Propionibacterium sp.B2M2 were dominant as the pH was controlled at 5.5-6.5 and 5.0-5.5,respectively.The results showed that the acidic fermentative bacteria were shifted as the pH changed,and a different microbial community was established under each controlled pH value,which suggested that both the fermentation type and hydrogen production capability were obviously different.