State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China.
State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China.
Water Res. 2017 Dec 1;126:329-341. doi: 10.1016/j.watres.2017.09.046. Epub 2017 Sep 26.
The anaerobic conversion of sewage sludge to methane-rich biogas is an important bioenergy strategy that has been hindered by low conversion efficiency. The poorly understood mechanism of the influence of the key structural component in sludge is responsible for this. The influence of organic-binding metals (OBM), which account for a substantial proportion of metals in sludge, on biogas conversion of both sewage sludge and model sludge were explored in this study. It is observed that the net cumulative methane production of sludge decreased by 23% with the increase of OBM content, implying the crucial role of the OBM in anaerobic sludge digestion. Experimental results showed that the apparent activation energy of sludge organic solubilisation and the median particle size of sludge particulates increased with increasing OBM content, whereas the surface binding sites for enzymes decreased, indicating that the stability of the sludge floc was reinforced by the effect of OBM. Further analyses of the sludge structure revealed that a high OBM content (>2.5% total solids in the present study) compacted the sludge organic matter, restricted the molecular mobility and deteriorated the depolymerisation of the biopolymers by bridging and hydrogen-bonding interactions. This suggests that as a result of the effect of OBM, the hydrolysis and acidification of sludge particulate could be inhibited, resulting in poor biogas conversion. Moreover, it was further authenticated by the results from biochemical methane potential assay process. These findings can deepen the understanding of the role of OBM in sludge for biogas conversion and are important for the improvement of anaerobic sludge digestion.
污水污泥厌氧转化为富含甲烷的沼气是一种重要的生物能源策略，但由于转化效率低而受到阻碍。造成这种情况的原因是对污泥中关键结构成分影响的机制了解甚少。本研究探索了有机结合金属（OBM）对污水污泥和模型污泥沼气转化的影响，OBM 占污泥中金属的很大一部分。研究发现，随着 OBM 含量的增加，污泥的净累积甲烷产量减少了 23%，这表明 OBM 在厌氧污泥消化中起着至关重要的作用。实验结果表明，污泥有机溶解的表观活化能和污泥颗粒的中值粒径随着 OBM 含量的增加而增加，而酶的表面结合位点减少，这表明 OBM 的作用增强了污泥絮体的稳定性。对污泥结构的进一步分析表明，高 OBM 含量（本研究中总固体的 2.5%以上）使污泥有机物压实，限制了分子的流动性，并通过桥接和氢键相互作用恶化了生物聚合物的解聚。这表明，由于 OBM 的作用，污泥颗粒的水解和酸化可能受到抑制，导致沼气转化不良。此外，生化甲烷潜力测定过程的结果进一步证实了这一点。这些发现可以加深对 OBM 在污泥沼气转化中的作用的理解，对提高厌氧污泥消化效率具有重要意义。
