尿泡粪在高温间歇真空厌氧发酵过程中重金属相平衡迁移规律研究

In view of higher treatment difficulty of livestock waste due to application of large amount of copper and zinc in large-scale pig industy, which cause the higher content of heavy metals in feces, and exceeding the standard seriously for heavy metals in wastewater. The experimental results showed that the content of heavy metal, ammonia nitrogen and chemical oxygen demand (COD) decreased significantly compared with normal temperature anaerobic fermentation during thermophilic intermittent vacuum anaerobic fermentation, and heavy metal in solid residue can be passivated by microwave assisted high temperature aerobic pyrolysis. However, the mechanism of equilibrium migration of heavy during in urine immersion feces thermophilic intermittent vacuum anaerobic fermentation need to be further studied to further strengthen this advantage. This project intend to research on the variation mechanism of substrate components， including nitrogen sources (protein, amino acid, heterocyclic nitrogenous substance, humic acid, uric acid, and ammonia nitrogen), organic acid substance, aluminosilicate and alkaline-earth metals, and the influence of above variation on the phase equilibrium migration of Cu, Zn, Pd, Cd between liquid and solid phase, during thermophilic intermittent vacuum anaerobic fermentation, seeking new path to ease the burden of biogas slurry. In addition, to monitor the dynamic and variation feature, efficiency of acid and biogas production of acidogenic bacteria, methanogenic bacteria, which will provide a scientific basis for the perfect combination of harmless and resource utilization of urine immersed feces.

规模化养猪业铜锌用量大，粪污重金属含量高，沼液中重金属严重超标，加大了治理难度。项目组采用高温间歇真空发酵处理尿泡粪，表明沼液中重金属含量、氨氮含量和COD均较常温厌氧发酵显著下降，而沼渣重金属上升可以采用微波辅助高温有氧裂解实现玻璃化钝化。但是对影响尿泡粪高温间歇真空发酵过程中重金属相平衡移动的机理还需要深入研究，以便进一步强化这一优势。本项目拟采用对比试验深入研究高温间歇真空发酵过程中底物组分中含氮物质（蛋白质、氨基酸、杂环含氮物质、腐植酸、尿酸、尿素、氨氮）和有机酸类物质、以及硅铝酸盐和碱土金属含量变化规律及其对重金属铜、锌、铅、镉在沼液和沼渣两项中迁移和平衡移动规律的影响,为减轻沼液治理难度寻找新途径。监测发酵过程中产酸菌群、和甲烷菌群动态及其产酸产气效率的变化特征，为实现尿泡粪无害化和资源化利用的完美结合提供科学基础。

对于尿泡粪中氮源组成及其含量、碳源组成及其含量、重金属形态及含量、碱土金属成分及含量、微生物菌群种属、pH值进行分析。通过人工控制影响高温间歇真空厌氧发酵效率的主要因素及底物的处理方式，探明尿泡粪中重金属在厌氧发酵前后形态及含量的变化，对比厌氧发酵前后微生物菌群、总酸组成及含量的变化。.结果显示，在厌氧发酵温度37 ℃的条件下，CH4累积产量分别是20 ℃及55 ℃条件下的1.06及24倍。并且随着接种比逐渐提高，甲烷累积产量逐渐增加，其对于P在固液两相中的迁移规律也有重要影响。此外，厌氧发酵对于氮素形态分布也有重要影响。不同预处理的稻草对于重金属迁移的影响不同，其中碱处理和超声波相结合的预处理方式能显著提高甲烷产率，且能够有效降低厌氧发酵后沼液中的Cu、Zn含量。通过对于沼液中微生物的分析发现，沼液中土著微生物对于重金属迁移具有重要影响。其原理在于微生物分泌大量胞外聚合物将更多的铜锌吸附、蓄积、沉淀、螯合和固定于胞外最外层聚合物之上，有效地减缓其进入胞内的进程。基于尿泡粪中重金属迁移规律的研究，探究了不同种类的吸附材料对于尿泡粪中的重金属迁移规律的影响：吸附材料膨润土沸石对Cu(Ⅱ)及Zn(Ⅱ)的最大吸附容量分别为16.39 mg/g及12.72 mg/g。羟基磷灰石、磷酸钙和物理酸钠水合物能够快速去除Cu和Zn。负载Fe3O4的磁性生物炭对水溶液中铜的平衡吸附量是原始稻草秸秆生物炭的5倍以上。本研究形成的结论将为实现尿泡粪无害化和资源化利用的结合提供科学基础。