In thermophilic digestion systems, sludge stabilization may be adversely impacted by high concentrations of ammonia nitrogen or the rapid accumulation of fatty acids; however, few studies have focused on the mitigation of the inhibition of reactive oxygen species (ROS). In this study, fulvic acids or tea polyphenols were introduced to a thermophilic digestion system and the effects of ROS scavengers on sludge stabilization were investigated. As fulvic acids or tea polyphenols were added to sludge, they reacted with metal cations, such as Cu2+ and Zn2+, to form stable complexes that enabled active metal ions to be transported into cells to enhance the oxidase activities. Therefore, the digestion systems presented a lower O2•- content compared with that of a control group with no additive. Both fulvic acids and tea polyphenols mitigated the adverse effects of the ROS and enhanced the reduction of volatile solids (VS), however, fulvic acids better facilitated the sludge stabilization. The optimal dosage was 0.3% of the total solids as fulvic acids were added to the sludge every 48 h. The VS reduction in the digester reached 38.2% at 14 d, which was clearly higher than that in the control group. The pathway of ROS scavengers affecting sludge stabilization was proposed, and it may be helpful to gain deeper insight into the characteristics of thermophilic digestion processes as well as the mechanism of sludge stabilization.

中文翻译：

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活性氧清除剂对嗜热微需氧消化的稳定作用。

在高温消化系统中，高浓度的氨氮或脂肪酸的快速积累可能会对污泥的稳定性产生不利影响。然而，很少有研究集中在减轻活性氧（ROS）的抑制上。在这项研究中，黄腐酸或茶多酚被引入到高温消化系统中，并研究了ROS清除剂对污泥稳定性的影响。当黄腐酸或茶多酚添加到污泥中时，它们会与金属阳离子（例如Cu2 +和Zn2 +）反应，形成稳定的络合物，使活性金属离子能够转运到细胞中，从而增强氧化酶的活性。因此，与不含添加剂的对照组相比，消化系统的O2•-含量较低。富里酸和茶多酚都减轻了ROS的不利影响，并增加了挥发性固体（VS）的减少，但是，富里酸更好地促进了污泥的稳定。最佳剂量是每48小时将黄腐酸加到污泥中的总固体量的0.3％。消化器的VS降低在14天达到38.2％，明显高于对照组。提出了ROS清除剂影响污泥稳定化的途径，可能有助于深入了解嗜热消化过程的特征以及污泥稳定化的机理。每48小时将3％的总黄腐酸固体含量添加到污泥中。消化器中的VS降低在14 d时达到38.2％，明显高于对照组。提出了ROS清除剂影响污泥稳定化的途径，可能有助于深入了解嗜热消化过程的特征以及污泥稳定化的机理。每48小时将3％的总黄腐酸固体含量添加到污泥中。消化器的VS降低在14天达到38.2％，明显高于对照组。提出了ROS清除剂影响污泥稳定化的途径，可能有助于深入了解嗜热消化过程的特征以及污泥稳定化的机理。