【作者】 昌盛；

【导师】 李建政；

【作者基本信息】 哈尔滨工业大学 ， 环境科学与工程， 2012， 博士

【摘要】 利用有机废水进行发酵制氢能起到污水治理和能源回收的双重功效，因而受到空前关注。厌氧发酵制氢技术以其底物利用范围广、反应条件温和、产氢速率高和稳定性好等优势，被认为是最具发展前景的生物制氢技术。针对目前厌氧发酵制氢反应器存在的污泥流失、反应器产氢效能不够理想等限制其工业化进程的关键技术问题，本论文在优化设计厌氧接触式发酵制氢反应器(ACR)的基础上，围绕“ACR发酵制氢反应器的运行调控和产氢效能”开展了深入研究，确立了ACR发酵制氢系统乙醇型发酵的定向启动条件、运行控制参数和提高系统产氢效能的调控策略，从微生物生态学角度揭示了发酵产氢微生物顶极群落形成的机制，并研究了系统中同型产乙酸耗氢作用的控制方法，进一步提高了ACR发酵制氢反应器的产氢效能。试制的ACR发酵制氢反应装置，由一个连续流搅拌槽式反应器(CSTR)与一个固-液-气三相分离器串联而成。污泥回流技术的采用，使反应系统具有了更高的生物持有能力，为提高反应器的比产氢速率(HPR)奠定了基础。以啤酒废水处理厂二沉池的污泥为种泥，在进水化学需氧量(COD)浓度5000mg/L、水力停留时间(HRT)6h、温度35oC等条件下，反应器可在55d内形成稳定的乙醇型发酵。在OLR28-44kgCOD/m~3·d内，随着进水COD的增加，ACR系统内Ethanoligenens harbinense YUAN-3为代表的发酵产氢菌得到逐步富集，产氢速率也随之增加，在OLR为44kgCOD/m~3·d时， HPR达到了3.51±0.45m~3/m~3·d。种泥的微生物群落结构特征，对发酵制氢系统的启动进程及顶极微生物群落的结构和代谢特征起着决定性作用。研究表明，以啤酒废水处理厂二沉池污泥、产酸发酵厌氧污泥和生活污水排放沟底泥为接种物启动的ACR系统，虽然在HRT8h、COD5000mg/L条件下均能形成产氢性能良好的乙醇型发酵，但在群落结构上的差异使系统的产氢性能呈现显著差别。分子生物学研究表明，以产酸发酵厌氧污泥启动的反应系统在达到稳定运行后，其生物多样性最好，而以生活污水排放沟底泥启动的系统最差；但在以生活污水排放沟底泥启动的系统中富集了更多的以E. harbinense YUAN-3为代表的发酵产氢菌，因而表现出更强的产氢效能，其产氢速率和污泥比产氢速率分别为14.0L/d和11.1mmolH2/g VSS·d。尽管污水处理剩余污泥启动ACR制氢系统的效果不如生活污水排放沟的底泥，但其来源广泛且易得。通过适当的预处理，提高其发酵产氢微生物的丰度和活性后，可成为一个比较理想的规模化发酵制氢系统启动的种泥来源。试验结果表明，对于剩余活性污泥，不同的预处理方法最终形成的微生物群落和发酵类型存在显著差异，其中，经酸预处理的的污泥系统最终形成的是丁酸型发酵体系，获得的最大氢气转化率(HY)为1.82mol H2/mol-glucose；对于厌氧颗粒污泥，各种预处理方法和未经预处理的污泥发酵体系，均呈丁酸型发酵；经氯仿预处理的污泥发酵体系显示出更高的产氢效能，HY可达1.96molH2/mol-glucose。以未经处理、经热预处理和经曝气预处理的剩余活性污泥启动ACR发酵制氢系统，在HRT8h、COD5000mg/L条件下均能形成稳定的发酵产氢微生物体系，但以曝气预处理污泥启动的反应系统中的发酵产氢菌种最为丰富，高效发酵产氢菌E. harbinense YUAN-3占据绝对优势，使系统表现出了较其他两套系统更好的产氢性能，产氢速率达到了16L/d。发酵生物制氢系统启动种泥的微生物群落结构，无论是在序批式或连续流培养过程中，均会发生群落演替。不同来源的种泥，以及不同预处理方法获取的接种物，构建了具有不同微生物组成的初始微生物群落，这一初始微生物群落的结构特征，直接决定了乙醇型发酵或丁酸型发酵顶极群落的最终形成。初始污泥负荷率F/M、pH和进水碳氮比(简记为COD/N，其中N以总氮计)等控制参数对ACR系统的产氢性能影响很大。在初始F/M为1.5kgCOD/kgVSS·d、进水COD5000mg/L、COD/N200、HRT8h和pH4.3-4.5等条件下，ACR发酵制氢氢系统可在14d内启动成功并达到稳定的乙醇型发酵。通过响应面法(RSM)优化获得的最佳OLR为63kgCOD/m~3·d，其中COD为11.3g/L，HRT为4.3h，在此条件下获得的HPR和HY分别达到了5.8m~3/m~3·d和1.78molH2/mol-glucose。与一体化的CSTR发酵制氢反应器相比，ACR制氢反应器拥有更高的生物持量，因而可在更高的有机负荷下运行，获得更大的比产氢速率，是一种高效的发酵制氢反应设备。在以混合微生物体系为基础的发酵制氢反应系统中，常会有同型产乙酸菌的滋生，其耗氢作用严重影响了反应器的产氢效能，而氯仿(CHCl3)的投加则可有效抑制耗氢的同型产乙酸作用，显著提高系统的产氢效能。研究表明，以啤酒废水处理厂二沉池污泥启动的ACR发酵制氢系统，存在大量的耗氢同型产乙酸菌，系统产氢效能低下，投加0.1%(V/V)剂量的CHCl3后，系统中以Eubacterium limosum和Eubacterium sp.SA11为代表的同型产乙酸菌迅速消失，而产氢能力较强的哈尔滨产氢产乙醇菌E.harbinense则大量富集，系统活性污泥的比产氢速率从11.7mlH2/gVSS·d迅速增加并稳定在113.8mlH2/gVSS·d，基质的氢气转化率也从0.14molH2/mol-glucose跃升到了1.07molH2/mol-glucose。更多还原

【Abstract】 Biological hydrogen production from organic wastewater has dual effect ofwastewater treatment and energy recovery. In current, this research subject hasreceived increasingly attention. Among different biological processes for hydrogenproduction, anaerobic fermentation is the most commercially feasible H2biologicalproduction method because of its potential of direct use of wastewater streams andorganic wastes and its high production rate Considering the key problems of thecurrent anaerobic fermentative hydrogen production process and the operationalcontrol methods, a new process entitled “anaerobic contact reactor (ACR)” wasdeveloped in this thesis. The present study attempted to investigate the performanceand control strategy of fermentative hydrogen production in ACR. The operationconditions and methods for establishing ethanol-type fermentation and acceleratingstart-up of ACR were highlighted in this study. Moreover, the mechanism of theformation of climax microbial community of the fermentative hydrogen productionwas revealed from the perspective of microbial ecology. At last, the significance ofhydrogen sink by homoacetogenesis was evaluated and the method of inhibition ofhomoacetogens was investigated， which was aimed to improve the hydrogenproduction capability of ACR.The novel invented hydrogen production process was comparised with acontinuous flow stirred tank reactor (CSTR) and a settler. The system had a bettercapability of holding higher biomass concentration since the sludge was recoveriedinto CSTR from the sedimentation tank, which promises that the ACR system couldoperate at high organic loading rate (OLR) and exhibit an excellent hydrogenproduction. In order to explore the feasibility of using this novel ACR system foranaerobic fermentative hydrogen production, the reactor was started-up with thechemical oxygen demand (COD) of5000mg/L and hydraulic retention time (HRT)of6h at35oC for the first time. The seed sludge used in this section was taken froma secondary sedimentation tank of a local beer wastewater treatment plant. Theresult showed that an ethanol-type fermentation type was established and the systemcould reach steady-state after55days of operation. After the reactor achievedsteady-state, the performance of ACR under OLR ranged from28to44kgCOD/m~3·d was evaluated. It showed that the Ethanoligenens harbinense YUAN-3turned to be more abundance as the influent COD increased, and the specifichydrogen production rate (SHPR) increased to3.51±0.45m~3/m~3·d when OLR wasincreased to44kgCOD/m~3·d.The characteristics of the microbial commnnity of the seed play a decisive role in the start-up proceeding of the fermentative hydrogen productiong systems and themetabolic pathway of the climax microflora. The results showed that ethanol-typefermentation occurred in all the three reactors seeded with different inoculums. Theseed sludge were collected from secondary sedimentation tank of a local beerwastewater treatment plant (R1), anaerobic acidogenic reactor (R2) and sewagesludge (R3), respectively. The reactors were operated under indentical conditions(HRT8h,COD5000mg/L). The results of molecular biology analysis showed thatthe species of microorganisms of R2was the most, followed by R1and R3, but theEthanolgenesis harbinense Yuan-3was most predominant in R3reaction system.Thus, the R3system gave both the highest hydrogen production rate of14.0L/d andspecific hydrogen production of sludge of11.1mmol H2/g VSS·d.When used the untreated, heat-shock and the aeration treated excess activatedsludge as seed sludge for starting up the ACR system, all the reactors could reachsteady-state and estabilish stable fermentative hydrogen producing microorganismin the systems under HRT of8h and COD of5000mg/L. Experimental resultsshowed that the species of microorganisms and the quantity of Ethanoligenensharbinense were the largest in the microbial community in the reactor which wasinoculated the sludge treated by aeration. As result, the hydrogen production ratewas the largest (16L/d) than the other two systems which inoculated the untreatedand heat-shock treated sludge. The results of the above experiments indicated thatthe microbial community would both change in the batch and continuous-flowfermentation hydrogen production system. The seed inocula collected from differentsources and the inoculated sludge treated by various pretreatment methods haddifferent original microbial community and the results indicated that the topmicrobial community of ethanol-type fermentation and butyrate-type fermentationwas directly dependent on the initial microbial community structure of theinoculums.The initial start-up sludge loading rate, pH and influent COD/N has indenpentsignificant influence on the performance of fermentative hydrogen production ofACR. The results found that the ACR could reach steady-state with ethanol-typefermentation only after14days of operation when the initial F/M ratio, COD, pH,influent COD/N and HRT was controlled at1.5gCOD/gVSS·d,5000mg/L,4.3-4.5,200and8h, respectively. On this basis, the influent COD and HRT of ACR systemwere further optimized for hydrogen production by response surface methodology.The result showed that the highest HPR of5.8m~3/m~3·d of the hydrogen productionreactor system was achieved when the OLR was63kgCOD/m~3·d, i.e. COD andHRT was controlled at11.3g/L and4.3h, respectively. As compared to the CSTR(with inner separator), the ACR had a better capability of holding bioamass and it isa promising bioprocess for fermentative hydrogen production. The hydrogen production could be influenced by the homoacetogenesis in thehydrogen production system by anaerobic mixed microflora. While, the activity ofhomoacetogenes could be inhibited by chloroform. The hydrogen production couldbe improved when adding chloroform into the the hydrogen production system.Experimental results showed that the role of hydrogen consumption byhomoacetogenesis significantly affect the hydrogen production, when used theinoculum that was collected from a local beer wastewater treatment plant. It foundthat the Eubacterium limosum and Eubacterium sp. SA11which were classified tohomoacetogens were disappeared in the profile of microbial community, while theEthanoligenens harbinense YUAN-3were enriched after additing0.1%(v/v)chloroform into the fermentative hydrogen system. The result showed that thespecific hydrogen production of the sludge was increased from11.7ml H2/gVSS·dto113.8ml H2/gVSS·d as the homoacetogenesis was inhibited by chloroform. Thehydrogen yield was increased from0.14molH2/mol-glucose to1.07molH2/mol-glucose simultaneously.更多还原