College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, China; Shanxi Academy of Advanced Research and Innovation, Taiyuan 030024, China.
College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, China.
Water Res. 2024 Jul 1;258:121772. doi: 10.1016/j.watres.2024.121772. Epub 2024 May 13.
Nitrate photolysis has become an efficient, low-cost and promising technology for emerging contaminants removal, while its performance and mechanism for waste activated sludge (WAS) treatment is still unknown. This study innovatively introduced nitrate photolysis for WAS disintegration, and investigated the effect of nitrate addition (150-375 mg N/L) for short-chain fatty acids (SCFAs) production during anaerobic fermentation (AF). The results showed that nitrate photolysis significantly promoted the SCFAs production from WAS, and peaked at 280.7 mg/g VSS with 7-d fermentation with 150 mg N/L addition (150N-UV), which increased by 8.8-35.0 % and 10.7-23.3 % compared with other photolysis groups and sole nitrate groups. Effective release of the soluble organics was observed in the nitrate photolysis groups during AF, especially soluble proteins, reaching 1505.4 mg COD/L at 9 d in 150N-UV group, promoted by 7.0∼15.7 % than nitrate/nitrate photolysis groups. The model compounds simulation experiment further demonstrated the positive effect of nitrate photolysis on organics hydrolysis and SCFAs accumulation. The result of the radical capture and quenching verified the reactive oxygen species contributed more compared with reactive nitrogen species. Functional group analysis confirmed the effective bioconversion of the macromolecular organics during the fermentation. Moreover, the nitrate photolysis enhanced the enrichment of the functional consortia, including anaerobic fermentation bacteria (AFB), e.g., Fnoticella, Romboutsia, Gracilibacter and Sedimentibacter, and nitrate reducing bacteria (NRB), e.g., Acinerobacter and Ahniella. The macrogenetic analysis further revealed that glycolysis, amino acid metabolism, acetate metabolism and nitrogen metabolism were the dominating metabolic pathways during fermentation, and the abundance of the relevant genes were enhanced in 150N-UV group.
硝酸盐光解已成为一种高效、低成本且有前景的新兴污染物去除技术，但其用于处理废活性污泥（WAS）的性能和机制仍不清楚。本研究创新性地将硝酸盐光解引入到 WAS 解体中，并研究了添加硝酸盐（150-375 mg N/L）对厌氧发酵（AF）中短链脂肪酸（SCFAs）生成的影响。结果表明，硝酸盐光解可显著促进 WAS 中 SCFAs 的生成，在 150 mg N/L 加标（150N-UV）、7 天发酵时达到峰值 280.7 mg/g VSS，比其他光解组和单独硝酸盐组分别增加了 8.8-35.0%和 10.7-23.3%。在 AF 过程中，硝酸盐光解组中观察到可溶性有机物的有效释放，特别是可溶性蛋白质，在 150N-UV 组中 9 天时达到 1505.4 mg COD/L，比硝酸盐/硝酸盐光解组高 7.0∼15.7%。模型化合物模拟实验进一步证明了硝酸盐光解对有机物水解和 SCFAs 积累的积极作用。自由基捕获和淬灭实验的结果证实，与氮反应活性物质相比，活性氧物质的贡献更大。功能基团分析证实了发酵过程中大分子有机物的有效生物转化。此外，硝酸盐光解增强了功能菌群的富集，包括厌氧发酵细菌（AFB），如 Fnoticella、Romboutsia、Gracilibacter 和 Sedimentibacter，以及硝酸盐还原菌（NRB），如 Acinerobacter 和 Ahniella。宏基因组分析进一步表明，在发酵过程中，糖酵解、氨基酸代谢、乙酸盐代谢和氮代谢是主要的代谢途径，相关基因的丰度在 150N-UV 组中得到增强。
