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; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
Water Res. 2024 May 1;254:121393. doi: 10.1016/j.watres.2024.121393. Epub 2024 Feb 27.
The addition of exogenous materials is a commonly reported method for promoting the anaerobic digestion (AD) of sludge. However, most exogenous materials are nano-sized and their use encounters problems relating to a need for continuous replenishment, uncontrollability and non-recyclability. Here, magnetic porous microspheres (MPMs), which can be controlled by magnetic forces, were prepared and used to enhance the methanogenesis of sludge. It was observed that the MPMs were spherical particles with diameters of approximately 100 µm and had a stable macroporous hybrid structure of magnetic cores and polymeric shells. Furthermore, the MPMs had good magnetic properties and a strong solid-liquid interfacial electron transfer ability, suggesting that MPMs are excellent carriers for methanogenic consortia. Experimental results showed that the addition of MPMs increased methane production and the proportion of methane in biogas from AD by 100.0 % and 21.2 %, respectively, indicating the MPMs notably enhanced the methanogenesis of sludge. Analyses of variations in key enzyme activities and electron transfer in sludge samples with and without MPMs in AD revealed that the MPMs significantly enhanced the activities of key enzymes involved in hydrolysis, acidification and methanation. This was achieved mainly by enhancing the extracellular electron transfer to strengthen the proton motive force on the cell membrane, which provides more energy generation for methanogenic metabolism. A careful examination of the variations in the morphology, pore structure and magnetism of the MPMs before and after AD revealed that the MPMs increased the prevalence of many highly active anaerobes, and that this did not weaken the magnetic performance. The microbial community structure and metatranscriptomic analysis further indicated that the acetotrophic methanogens (i.e., Methanosaeta) were mainly in a free state and that CO-reducing methanogens (i.e., Methanolinea and Methanobacterium) mainly adhered to the MPMs. The above synergistic metabolism led to efficient methanogenesis, which indicates that the MPMs optimised the spatial ecological niche of methanogenic consortia. These findings provide an important reference for the development of magnetic porous materials promoting AD.
添加外源物质是促进污泥厌氧消化（AD）的常用方法。然而，大多数外源物质是纳米级的，其使用存在需要不断补充、不可控和不可回收等问题。在这里，制备了可以通过磁力控制的磁性多孔微球（MPMs），并将其用于增强污泥的产甲烷作用。结果观察到，MPMs 是直径约为 100 µm 的球形颗粒，具有稳定的磁性核和聚合物壳的大孔混合结构。此外，MPMs 具有良好的磁性和较强的固液界面电子传递能力，表明 MPMs 是产甲烷菌群的优良载体。实验结果表明，添加 MPMs 可分别使 AD 中甲烷产量和沼气中甲烷的比例提高 100.0%和 21.2%，表明 MPMs 显著增强了污泥的产甲烷作用。对 AD 中添加和不添加 MPMs 的污泥样品中关键酶活性和电子传递的变化进行分析表明，MPMs 显著增强了水解、酸化和产甲烷过程中关键酶的活性。这主要是通过增强细胞外电子传递来增强细胞膜上的质子动力势，为产甲烷代谢提供更多的能量产生。仔细检查 AD 前后 MPMs 的形态、孔结构和磁性的变化表明，MPMs 增加了许多高活性厌氧菌的流行程度，并且这并没有削弱其磁性性能。微生物群落结构和宏转录组分析进一步表明，乙酸营养型产甲烷菌（即 Methanosaeta）主要处于游离状态，而 CO 还原产甲烷菌（即 Methanolinea 和 Methanobacterium）主要附着在 MPMs 上。这种协同代谢导致了高效的产甲烷作用，这表明 MPMs 优化了产甲烷菌群的空间生态位。这些发现为促进 AD 的磁性多孔材料的发展提供了重要参考。
