Lee Eunyoung, Min Kyung Jin, Park Ki Young
Department of Civil, Environmental and Plant Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul, 05029, Korea.
Department of Tech Center for Research Facilities, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul, 05029, Korea.
Sci Rep. 2025 Jun 5;15(1):19845. doi: 10.1038/s41598-025-04919-z.
This study investigates the effects of sludge recycling on anaerobic digestion (AD) performance and microbial community dynamics during food waste leachate treatment. Three reactors with varying solid retention times (SRTs) were operated: a control without sludge recycling (SRT = 20 days) and two experimental setups with SRTs of 40 and 80 days achieved through sludge return. Increasing SRT improved methane production and volatile solids reduction compared to the control, with reductions of 81.0-90.2% at the highest SRT. However, extended SRTs resulted in the accumulation of recalcitrant compounds, such as humic substances, and elevated hydrogen sulfide production due to the increased abundance of sulfate-reducing bacteria (SRB). Microbial analysis showed that higher SRTs enhanced methanogenic diversity, including acetoclastic, hydrogenotrophic, and methylotrophic pathways, while promoting the coexistence of key methanogens such as Methanosaeta, Methanobrevibacter, and Methanoculleus. Although humic substances and SRB abundance increased with higher SRT, methane production remained stable, indicating limited actual inhibition under the studied conditions. Additionally, ATP and specific methanogenic activity tests indicated higher microbial activity at longer SRTs. These findings emphasize the impact of increasing SRT on AD performance, highlighting both benefits in methane yield and challenges in managing inhibitory by-products. Further research should optimize SRT to balance microbial activity, efficiency, and stability in AD processes.
本研究调查了污泥循环利用对食物垃圾渗滤液处理过程中厌氧消化（AD）性能及微生物群落动态的影响。运行了三个具有不同固体停留时间（SRT）的反应器：一个不进行污泥循环的对照反应器（SRT = 20天），以及通过污泥回流实现SRT分别为40天和80天的两个实验装置。与对照相比，增加SRT提高了甲烷产量和挥发性固体减少量，在最高SRT时减少量达到81.0 - 90.2%。然而，延长SRT导致难降解化合物（如腐殖质）的积累，并且由于硫酸盐还原菌（SRB）丰度增加导致硫化氢产量升高。微生物分析表明，较高的SRT增强了产甲烷多样性，包括乙酸裂解、氢营养和甲基营养途径，同时促进了关键产甲烷菌如甲烷八叠球菌、甲烷短杆菌和甲烷袋状菌的共存。尽管腐殖质和SRB丰度随着SRT升高而增加，但甲烷产量保持稳定，表明在所研究的条件下实际抑制作用有限。此外，ATP和特定产甲烷活性测试表明，在较长SRT时微生物活性更高。这些发现强调了增加SRT对AD性能的影响，突出了甲烷产量方面的益处以及管理抑制性副产物方面的挑战。进一步的研究应优化SRT，以平衡AD过程中的微生物活性、效率和稳定性。
