Revealing the Underlying Mechanisms of How Initial pH Affects Waste Activated Sludge Solubilization and Dewaterability in Freezing and Thawing Process,ACS Sustainable Chemistry & Engineering

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Revealing the Underlying Mechanisms of How Initial pH Affects Waste Activated Sludge Solubilization and Dewaterability in Freezing and Thawing Process
ACS Sustainable Chemistry & Engineering ( IF 7.1 ) Pub Date : 2018-10-05 00:00:00 , DOI: 10.1021/acssuschemeng.8b04427
Xuran Liu _{1,

2} , Qiuxiang Xu _{1,

2} , Dongbo Wang _{1,

2} , Qi Yang _{1,

2} , Yanxin Wu _{1,

2} , Jingnan Yang _{1,

2} , Jilai Gong _{1,

2} , Jun Ye ₃ , Yifu Li _{1,

2} , Qilin Wang ₄ , Yiwen Liu ₄ , Bing-Jie Ni ₄ , Guangming Zeng _{1,

2} , Xiaoming Li _{1,

2}

Affiliation

In this study, the effect of initial pH ranging from 3 to 11 on waste activated sludge solubilization and dewaterability in the freezing and thawing (F/T) process was investigated. Experimental results showed that alkaline conditions enhanced the solubilization of sludge in F/T treatment, whereas acidic conditions improved the dewaterability of sludge. Optimum solubilization with organic substances being 189.7 mg COD/g VSS occurred at initial pH 10, which was 12.9 times higher and more biodegradable than the control. Optimal dewaterability performance was achieved at initial pH 4, with capillary suction time and specific resistance to filterability reduction being reached to 85.4% and 87.8%, respectively. It was found that F/T treatment at initial alkaline condition also obtained good dewatering performance, and F/T treatment at initial acidic condition acquired fine solubilization too. Mechanism explorations exhibited that the OH^– and freezing had synergetic effects on the degradation of extracellular polymeric substances (EPS) to enhance sludge solubilization, and OH^– can be concentrated to a much higher level in the liquid-like boundary region upon freezing, which further strengthened this effects. The H⁺ and freezing also showed synergetic effects on the protonation of functional groups of EPS and flocculation of the colloidal sludge to improve sludge dewaterability. This study clearly reveals the role and mechanisms of initial pH on the F/T process aiming at solubilization and dewaterability of sludge, and might provide supports for the application of F/T-based strategy in field situations in the future.

中文翻译：

揭示初始pH如何影响冷冻和融化过程中废物活化污泥的增溶和脱水性的潜在机理

在这项研究中，研究了初始pH在3至11之间对冷冻和融化（F / T）过程中废料活性污泥的增溶性和脱水性的影响。实验结果表明，碱性条件提高了污泥在F / T处理中的溶解度，而酸性条件提高了污泥的脱水能力。在初始pH 10时，有机物的最佳溶解度为189.7 mg COD / g VSS，比对照高12.9倍，并且可生物降解性更高。最佳pH值是在初始pH 4时达到的，脱水性能最佳，毛细管抽吸时间和滤过性降低的比电阻分别达到85.4％和87.8％。发现在初始碱性条件下进行F / T处理也获得了良好的脱水性能，初始酸性条件下的F / T处理也获得了良好的增溶作用。机制探索表明，OH^-和冻结上的胞外聚合物（EPS）的降解有协同效应，以增强污泥增溶，并且OH ^-可根据冷冻，这进一步加强了这一效应被集中到在液体状边界区域高得多的水平。H ⁺和冻结也对EPS的官能团的质子化和胶体污泥的絮凝产生协同作用，从而提高了污泥的脱水性。这项研究清楚地揭示了初始pH在F / T过程中的作用和机理，其目的在于污泥的增溶和脱水，并可能为将来基于F / T的策略在野外应用提供支持。

更新日期：2018-10-05

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