硫酸盐还原菌介导的种间氢转移强化剩余污泥产甲烷及互营调控机制

Waste activated sludge (WAS) represents a significant amount of embedded energy. How to accomplish these energy recovery potential is a breakthrough to achieve the beneficial cycle of energy consumption by wastewater treatment and energy recovery from WAS digestion. To prevent the restricted hydrolysis and the inhibited syntrophic acetogenesis by hydrogen-accumulation and thermodynamics in the traditional WAS anaerobic digestion (AD), aiming to enhance the methane production from the metabolism of carbon-rich organics in WAS, here, the applicant proposes an innovative methane production process enhanced by sulfate reducting bacteria (SRB)-mediated interspecies hydrogen transfer (IHT). In order to accelerate the hydrolysis rate and provide electron acceptor for SRB, peroxysulphate (S2O82-) pre-oxidation will be used to disintegrate the microbe cells in WAS. The pattern of embedded energy release and optimizing match strategy of S2O82- reduzate and SRB metabolic will be disclosed. Aiming to relieve the thermodynamic inhibition of syntrophic acetogenesis by hydrogen-producing acetogen (HPA), syntrophism association of SRB and HPA will be built to improve the acetate conversion from C3-C5 VFAs. The mechanism of IHT, synchronization metabolism and syntrophism regulation between SRB and HPA will be further elucidated. Moreover, the ecological relationship of SRB, HPA and aceticlastic methanogenic bacteria (AMB) and controllable construction strategy of functional microorganisms will be proposed. This research will provide theoretical and technical basis for the application of IHT-AD technology for enhancing energy recovery from WAS.

剩余污泥内含非常可观的嵌入式能源，如何充分发挥其厌氧消化产甲烷潜力是实现“污水处理耗能-污泥消化产能”良性循环的突破口。申请者以促进污泥中碳代谢产甲烷为目标，针对传统污泥厌氧消化水解过程受限、产氢产乙酸过程受氢累积和热力学限制的难点问题，创新性的提出硫酸盐还原菌（SRB）介导的种间氢转移强化污泥产甲烷研究思路。本课题拟重点研究过硫酸盐预氧化污泥溶胞方法，提升水解过程速率，为SRB代谢提供电子供体，并揭示嵌入式能源释放及其与SRB代谢优化匹配规律；构建SRB与产氢产乙酸菌（HPA）互营联合体系，促进C3-C5脂肪酸转化为乙酸，明确其种间氢转移和同步代谢-互营调控机制；同时，解读新型污泥产甲烷体系中功能微生物群落结构，探究SRB、HPA和食乙酸产甲烷菌的互生互作关系，加速污泥“厌氧生物链”的碳代谢循环，从而增强污泥中嵌入式能源转化回收效能，为推动新型产甲烷技术的实际应用提供理论依据和技术基础。

课题围绕申请书内容，针对传统剩余污泥（WAS）厌氧消化水解受限、产氢产乙酸受氢累积和热力学限制的难点问题，对硫酸盐自由基（过硫酸盐（S2O82-，PDS）、高铁酸钾/亚硫酸盐（FeO46+-SO32-））预氧化污泥溶胞及硫酸盐还原菌（SRB）介导种间氢转移强化污泥产甲烷进行了深入研究。设计并优化了运行参数和条件，深入解析硫酸盐自由基强化厌氧产酸机制，剖析SRB和产氢产乙酸菌（HPA）强化产甲烷机理，探究SRB、HPA和食乙酸产甲烷菌（AMB）互作关系。研究成果达预期目标，具体如下：1）采用多菌源驯化不完全脂肪酸氧化型 SRB，筛选的丙酸、丁酸和戊酸型SRB对硫酸盐还原率达 48%、56%和 38%，高通量分析表明主要的SRB包括Desulfovibrio和Anaerofilum等；筛选了以丙酸和丁酸为底物的HPA混合菌群，其利用率分别达35.8%和40.9%；2）研究四种PDS激发方式（二价铁、零价铁、热和紫外）对污泥溶胞效能，热活化PDS预处理溶胞效果最好，且 Heat_PDS+SRB 体系乙酸产量最大，即促进C3-C5转化为乙酸最有效；3）用高铁酸钾（PF）、Na2SO3及PF+Na2SO3预处理WAS，得出PF+Na2SO3可有效促进污泥产酸，EPR表明硫酸根和羟基自由基发挥主要作用。XPS表明SRB在PF+Na2SO3强化产酸体系中能将约40%的SO42-转化为HS-/S2-，79% Fe(VI)转化为Fe(III)，对污泥有絮凝作用。同时确定了PF和Na2SO3的最佳产酸比例为2:3；4）解析了S2O82-和FeO46+-SO32-预处理协同SRB体系的微生物群落，以PF+Na2SO3+SRB为例，富集了多种SRB，如Rhodobacter、Desulfobulbus、Desulfovibrio、Desulfotomaculum和Desulforhabdus等，Desulfovibrio作为不完全氧化SRB，与Morganella、Bacteroides、Rhodobacter和Klebsiella呈正相关。表明发酵菌、产酸菌和SRB间可能存在共生关系；5）构建新型产甲烷体系，探究 SRB、HPA和AMB的互作关系，优化了SRB和HPA的投加比例。甲烷产量随HPA和SRB增加而增大，考虑到经济环保性，确定1:1:100（HPA:SRB:WAS）为最佳比例。