微生物电解产氢促进剩余污泥产甲烷研究

CORC > 生态环境研究中心 > 中国科学院生态环境研究中心 > 中国科学院环境生物技术重点实验室

题名	微生物电解产氢促进剩余污泥产甲烷研究
作者	刘文宗
学位类别	博士后
答辩日期	2013-07
授予单位	中国科学院研究生院
授予地点	北京
导师	庄国强 ; 王爱杰
关键词	剩余污泥微生物电解生物制氢能源回收 waste activated sludge microbial electrolysis cell (MEC) bio-hydrogen production energy recycling
其他题名	Methane production from waste activated sludge enhanced by microbial electrolysis
学位专业	环境科学与工程
中文摘要	当前我国正面临城市污泥产生量激增、污泥的处理处置问题日益突出的问题，目前污泥厌氧消化技术在实现污泥的减量化、污泥稳定上技术成熟，前景良好，而且产生的沼气通过发电、产能等途径还可以补偿污水厂能耗。但是，污泥厌氧消化工艺在实际运行中存在运行处理效能低下问题。在现有工艺优势条件下，进一步提高污泥处理效率和增加能源回收效益是当前工艺发展应用的最根本目标。在博士后入站工作期间主要围绕污水处理厂剩余污泥的处置和资源化问题，通过选择更有效的污泥预处理方式定向获得更高的挥发酸产量，借助微生物电解新技术进一步提高污泥发酵液中挥发酸的转化能力和能源气体回收效率。研究提出了引入微生物电化学系统与污泥厌氧消化处理工艺相耦合的新思路，探所污泥发酵液中有机小分子在微生物电解体系中的氢气转化效率，通过比较不同预处理条件、外加辅助电压和电极空间布置等关键参数对污泥处理能量回收效益影响的分析，优化污泥预处理条件和微生物电解产能耦合体系。为了降低污泥发酵液的电解质性能对微生物电解过程的限制和优化预处理过程的试剂选择，研究了不同缓冲介质体系对氢气转化率的影响，发现磷酸盐缓冲体系、碳酸氢盐体系和氯化钠体系使发酵液的电导率提高，并能有效增加了微生物电催化体系的电子传递能力，从而提高了COD 的去除速率和氢气收率。通过不同的化学添加剂对污泥发酵产酸分析发现，物理化学条件（酸，碱，超声）能够促进挥发酸的产量但是后期产甲烷会导致挥发酸的消耗；生物添加剂条件（SDS，鼠李糖脂）促进挥发酸的产量更加明显，但是后期对产甲烷过程存在抑制使挥发酸可以持续积累。针对提高剩余污泥发酵液在微生物电解产能体系中的能量收益，碱性条件下双频超声波预处理方法对污泥进行破碎提高污泥水解效率和挥发酸产量十分有效，而且对后续微生物电解产氢工艺优化调节和效能提高可控性最佳。选择双频超声对剩余污泥预处理10 min，pH 为10 的初始条件下进行产酸发酵，处理时间缩短为3 d，挥发酸最大积累量达到7000 mg COD/L。从剩余污泥的投入与资源化产出衡量，可以达到10 mmol H2/g VSS。通过辅助电压优化，0.8V 时生物能与投入电能的对大能量收益最高，达到169.07±0.84%，最高氢气产率为1.14±0.02 m3/m3/d，最高氢气转化率7.03±0.13 mg H2/g VSS。与同期相关研究在没有污泥预处理情况下相比，微生物电解产氢所需的辅助电压从2V 降低到0.8V，而产氢结果则从96 mL H2/g COD 提高到0.98-1.2 L H2/g COD，氢气转化率提高了10 倍。通过对比直接换水、氮气除氧、阳极生物膜空气曝露以及鼓吹空气4 种方式，发现对生物膜进行10min 的空气曝露处理程度对甲烷抑制有较好效果，对阳极生物膜鼓吹空气10min 后比完全厌氧条件下的氢气产量增加60%，氢气产量从0.8 m3/m3 reactor/d 提高到1.3 m3/m3 reactor/d。针对传统的产甲烷菌代谢途径难以转化C3 以上挥发酸，而尝试通过微生物催化电解以电子回收方式转化这些非适产甲烷底物为氢气，可以变相促进产甲烷过程，新型工艺将生物催化电解系统与厌氧体系耦合稳定后甲烷产率达到68.9 ml/天，比厌氧发酵过程高3 倍。耦合体系最终累计甲烷产量达到958ml，是厌氧发酵过程高2 倍。研究工作针对目前污泥厌氧处理技术中改进预处理方法、提高有机质转化效率、改善能量回收效益三个方面的目标，通过生物电极产生的电子传递过程以加速有机质到能源产品的转移速率，从而增强污泥中潜在生物质的利用，提高污泥处置过程的能量收益。研究表明微生物电化学技术在污泥资源化中具有可行性，并有很大应用潜力。
英文摘要	Nowadays energy consumption and environmental pollution is a pair of paradoxical problems in the world. We are confronted an increasing energy requirement and an inevitable environmental damage from fossil energy utilization. Municipal waste activated sludge (WAS) is increasing hugely in China and many problems are challenging traditional treatment method in WAS disposal. Nowadays, anaerobic digestion is commonly accepted as a promising and useful technology for energy recycling and electricity production. However, there are still much room to improve treatment efficiency on organic transfer and energy recovery. Targeting at higher efficiency of organic removal and energy conversion from WAS treatement, a novel system coupling anaerobic digestion with microbial electrolysis cell (AD-MEC) was proposed for WAS treatment. Small molecular organics (VFAs) was converted efficiently to reductive hydrogen by MEC, and the system energy efficiency was improved by optimizing WAS pretreatment method, applied voltage and electrode spatial structure. The electrolyte capacity of WAS fermentation liquid affected MEC efficiency and then determined choose of chemical agents for WAS pretreatment. Three different chemical salts were used to improve hydrogen production from fermentation liquid. The conductivity was increased by phosphate, bicarbonate and sodium chloride. The COD removal and hydrogen recovery were increased when electron transferring was enhanced in the system. Chemical additives, such as acids and alkaline, were successfully enhanced VFAs production from waste sludge. But VFAs were not accumulated to a quite high level and were consumed shortly becuased of methane production following. While some surfactants, such as SDS and rhamnolipid, increased VFAs substantially and maintained their accumulation by inhibiting methanogens. Targeting at efficiency improvement of the coupling system of waste sludge treatment and energy conversion, it was proved that WAS was pretreated effectivly by bi-frequency ultrasonic and alkaline, and the highest SCFAs were accumulated to 7000 COD mg/L at 3rd day. Highest H2 yield was 1.2 mL H2/mg COD at 2-fold dilution with 155% energy efficiency. Based on sludge input and energy output, hydrogen production was up to 10 mmol H2/g VSS. The hightest energy efficienywas 169.07±0.84% when 0.8 V was applied. The highest hydrogen production rate was 1.14±0.02 m3/m3/d and coversion efficiency was 7.03±0.13 mg H2/g VSS. Compared to unpretreated sludge, the COD conversion was increased from 96 mL H2/g COD to 0.98-1.2 L H2/g COD but electricity input was reduced from 2 V to 0.8 V in the coupling system, which was 10 times increased on hydrogen conversion. It was found that hydrogen production can be further increased when anode biofilm was exposed to air for 10mins before sludge fermentation liquid was added. Compared to anaerobic operation, hydrogen yield increased by 60% from 0.8 m3/m3 reactor/d to 1.3 m3/m3 reactor/d. In order to improve complex carbon conversion from sludge directly to energy, microbial electrolysis was coupled into anaerobic digestion process for higer hydrogen and methane collection. The results proved that the highest VFAs accumulation was increased from5200 mg COD/L in AD reactor to 6500 mg COD/L in BES-AD reactor from 3rd to 10th day. Methane generation was detected on 4th day in all reactors. The methane production rate was 68.9 ml/day, which was significantly improved compared to 21.3 ml/day of AD after operated 12 days. The highest methane yield of the reactor with electrodes reached 958 mL at 24 d, which is almost double higher than that of the control without electrodes and applied voltage (517 mL). It was proved that microbial electrolysis enhanced methane yield 2 times higher than traditional anaerobic digestion process. This work shows a possibility of cascade utilization of waste activated sludge, and energy recovery is promisingly improved in the novel system coupling anaerobic digestion with microbial electrolysis cell (AD-MEC).
公开日期	2014-07-07
内容类型	学位论文
源URL	[http://ir.rcees.ac.cn/handle/311016/7561]
专题	生态环境研究中心_中国科学院环境生物技术重点实验室
推荐引用方式 GB/T 7714	刘文宗. 微生物电解产氢促进剩余污泥产甲烷研究[D]. 北京. 中国科学院研究生院. 2013.