高温浓缩厌氧污泥活性保存机理解析

Successful development of anaerobic digesters involves the startup of new digesters, which requires establishment of suitable environment and microbial populations needed to achieve the desired performance. However, the enrichment process of microbs can take considerable time as the methanogenic populations and activities are low, also the costs for storing and transporting of the sludge are very expensive. The research showed that thermophilic condensed anaerobic sludge kept high methanogenic activity during the sludge was stored up to four months. Therefore, positive theoretical exploration can be achieved by optimizing the stored temperature condition and further improving the recovery metabolic rate of the condensed sludge. This research will break through the bottleneck of low-efficiency start-up of thermophilic anaerobic reactor. Also, it has great theoretical value and application prospect to drive the development of biogas industrialization. Based on the previous results, this study is to investigate the effect of stored temperature on the methanogenic activity, to clarify the biodegradability and metabolic pathways of various substrates and to reveal the synergistic effect of fermentation bacteria and methanogens. One case study designed in this research will improve the development of new technology on the start-up of biogas project by using thermophilic condensed sludge as seed sludge for 20L lab-scale reactor’s start-up.

厌氧反应器启动过程耗时长、花费高，且菌泥供应源不足，从某种程度上限制了沼气工程的产业化发展。目前已发现，高温厌氧浓缩污泥在贮存过程中对产甲烷活性具有较强的保存能力。因此，优化高温厌氧污泥浓缩及贮存条件，最大程度保存其产甲烷活性，并进一步提高活性恢复速率，可为突破高温厌氧反应器难以快速低耗启动瓶颈进行积极的理论探索，对推进沼气产业化发展及相关新技术开发具有重大的理论价值和应用前景。本研究在明确贮存时间对高温浓缩污泥产气活性影响较小的基础上，开展不同贮存温度下高温浓缩污泥的产甲烷活性测定；通过浓缩污泥对不同发酵底物的降解性能研究，确定其主要微生物的代谢途径；通过对浓缩污泥活性恢复过程中污泥团粒结构显微观察及微生物群落动态解析，揭示发酵型细菌和产甲烷古菌的生长规律和二者之间的协同作用机理；并以高温浓缩污泥为菌源，开展20L小型厌氧反应器启动实例研究，以推动浓缩污泥启动沼气工程的技术研发。

厌氧反应器启动过程耗时长、花费高，且菌泥供应源不足，从某种程度上限制了沼气工程的产业化发展。目前已发现，高温厌氧浓缩污泥在贮存过程中对产甲烷活性具有较强的保存能力。因此，优化高温厌氧污泥浓缩及贮存条件，最大程度保存其产甲烷活性，并进一步提高活性恢复速率，可为突破高温厌氧反应器难以快速低耗启动瓶颈进行积极的理论探索，对推进沼气产业化发展及相关新技术开发具有重大的理论价值和应用前景。研究结果表明：.（1）不同菌源高温厌氧污泥产甲烷活性研究表明，以餐厨垃圾为发酵底物且底物与种泥添加比（S/I Ratio）为1:1条件下，原始种泥经过离心浓缩处理或进一步真空旋转蒸发浓缩处理后，厌氧消化最大甲烷产气速率（Rm）均有不同程度的降低。沼气工厂厌氧反应器原始污泥的甲烷累积产气量明显高于市政污水处理厂污泥，其CS甲烷累积产气量为412.2 mL/g VS substrate，比相应原始污泥提高了7.0%，但沼气工厂菌源CES因厌氧反应初期挥发性脂肪酸的积累而导致厌氧发酵失败。.（2）批试浓缩污泥活性恢复实验结果表明，第一阶段发酵贮存浓缩污泥活性有所损失，与接种原始污泥反应器发酵效果相比，产甲烷活性达到原始污泥活性的79.93%-90.39%；第二阶段发酵累积甲烷产量比原始污泥增加了1.11%-29.97%；第三阶段发酵累积甲烷产量比原始污泥增加了3.33%-30.43%。贮存浓缩污泥经过一个阶段批式反应后，其活性可以得到有效恢复，实现厌氧反应器快速启动。贮存浓缩污泥厌氧发酵三阶段下各处理优势菌群均为Methanosaeta，在各反应器内乙酸产甲烷途径占主体。.（3）连续厌氧发酵实例验证揭示了贮存浓缩污泥和贮存原始污泥在不同有机负荷率下连续厌氧发酵活性恢复效果。从反应器各阶段产气特征判断，10 g VS/L和20 g VS/L负荷启动的反应器产气效率高于5 g VS/L负荷启动的反应器。属水平下，浓缩污泥样品古菌优势菌群是Methanosarcina，而原始贮存污泥样品古菌优势菌群是Methanosaeta；在门水平下不同反应器细菌分布以Firmicutes和Bacteroidetes为主；目水平下不同反应器内Clostridiales和Bacteroidales为两大优势菌群。