College of Environmental Science and Engineering, Beijing Key Lab for Source Control Technology of Water Pollution, Beijing Forestry University, Beijing, 100083, China; Xiong'an Institute of Eco-Environment, Hebei University, Baoding, 071002, China.
College of Environmental Science and Engineering, Beijing Key Lab for Source Control Technology of Water Pollution, Beijing Forestry University, Beijing, 100083, China.
Water Res. 2019 May 15;155:245-254. doi: 10.1016/j.watres.2019.02.047. Epub 2019 Feb 26.
A moderate Mn(Ⅶ) oxidation-in situ Fe(Ⅲ) coagulation (Mn(Ⅶ)-Fe(Ⅱ)) conditioning strategy was proposed to improve sludge filterability and release the water bound in extracellular polymeric substances (EPS). During Mn(Ⅶ)-Fe(Ⅱ) conditioning, flocs disintegration and cell disruption, macro and micro physicochemical properties of activated sludge, especially of EPS, were investigated. Relationships between protein molecular structures in EPS fractions of three layers and sludge dewaterability were also determined. Besides, factor analysis was used to explain the variances of "functional" protein secondary structures, which may have an important effect on sludge dewaterability. Results showed that sludge filterability (CST/CST) increased by 2.40 times and partial bound water was released at 2 min oxidation of 120 mg/g KMnO with subsequent FeCl termination at equivalent molar ratio of 1:3. During this strategy, EPS wrapping on cells surface was disintegrated, and a limited influence occurred on cells. It was also found that CST and bound water content were strongly correlated with aggregated strands, random coil and β-turn percentages in slime (R >-0.82, p < 0.05). Moreover, the dewaterability also presented strong negative correlations with aggregated strands, β-sheet and β-turn in TB-EPS (R >-0.78, p < 0.05). This suggested that unfolding and despiralization of slime protein and moderate weakening rigidity of tightly bound EPS (TB-EPS) protein were beneficial for improvement of sludge dewaterability. In addition, the strong correlation between percentages of "functional" protein secondary structures and factor 1 score (R > 0.85, p < 0.05) demonstrated that EPS migration, rather than only EPS disintegration, may have a key impact on the formation of some protein secondary structures in slime and TB-EPS. The observed protein secondary structures, which may affect sludge dewaterability, were probably derived from inner EPS.
提出了一种适度 Mn(Ⅶ)氧化原位 Fe(Ⅲ)混凝（Mn(Ⅶ)-Fe(Ⅱ)）调理策略，以改善污泥的过滤性能并释放细胞外聚合物物质（EPS）中结合的水分。在 Mn(Ⅶ)-Fe(Ⅱ)调理过程中，研究了絮体的解体和细胞的破裂，以及活性污泥的宏观和微观物理化学性质，尤其是 EPS。还确定了 EPS 三个层中蛋白质分子结构与污泥脱水性能之间的关系。此外，还使用因子分析来解释“功能”蛋白质二级结构的方差，这可能对污泥脱水性能有重要影响。结果表明，在 120mg/g KMnO4 氧化 2min 后，用等摩尔比 1:3 的 FeCl3 终止氧化，污泥过滤性能（CST/CST）提高了 2.40 倍，部分结合水被释放。在此策略中，细胞表面的 EPS 包裹被破坏，对细胞的影响有限。还发现 CST 和结合水含量与污泥中聚集链、无规卷曲和β-转角的百分比呈强相关（R>-0.82，p<0.05）。此外，脱水性能与 TB-EPS 中聚集链、β-折叠和β-转角也呈现出很强的负相关（R>-0.78，p<0.05）。这表明，污泥蛋白的展开和去螺旋化以及紧密结合 EPS（TB-EPS）蛋白的适度弱化刚性有利于改善污泥的脱水性能。此外，“功能”蛋白质二级结构百分比与因子 1 得分之间的强相关性（R>0.85，p<0.05）表明，EPS 的迁移，而不仅仅是 EPS 的解体，可能对污泥中一些蛋白质二级结构的形成有关键影响。观察到的可能影响污泥脱水性能的蛋白质二级结构可能源自内部 EPS。
