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首页> 外文期刊>Journal of Residuals Science & Technology >Moisture Removal Mechanism of Sludge Conditioning by Freeze-Thaw Process
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Moisture Removal Mechanism of Sludge Conditioning by Freeze-Thaw Process

机译：冻融法处理污泥的水分去除机理

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The purpose of this study is to investigate the effects of sludge floc size and solids content on freeze-thaw conditioning and to enhance our understanding of the freeze-thaw conditioning mechanism. Digested activated sludge and an unidirectional freezing apparatus were used to perform the experiment. The results indicated that if sludges of small floc size was frozen at low speed, i.e, 10 mm/h, floc migration and aggregation occurred with the formation of ice front causing dehydration. This resulted in increasing floc compactness and narrowing the particle size distribution (PSD). For sludges composed of large floc, the floc were easily destroyed by the migrating ice front resulting in a smaller mean floc diameter and PSD than sludges composed of small floc. At low freezing speed, development of ice front for sludge with high solid concentration is slower than that of sludge with low solid concentration. When high freezing speed was employed to freeze sludge, floc destruction by ice front was more obvious, and the compactness of particle layer was lower than that caused by low freezing speed. Furthermore, under high freezing speed sludge with high solid concentration was easily entrapped by the ice crystal, and floc diameter was increased. However, gross migration of sludge was not found under this condition. Based on the experimental results, a modified model for the sludge freeze conditioning is proposed with the consideration of the effect of floc size and solids concentration. In addition, pretreatment to increase the solid concentration and decrease floc size before freeze-thaw conditioning are recommended to enhance the efficiency of this technique.
机译：这项研究的目的是调查污泥絮凝物的大小和固体含量对冻融调节的影响，并加深我们对冻融调节机理的理解。用消化的活性污泥和单向冷冻装置进行实验。结果表明，如果将絮凝体小的污泥低速冷冻，即10 mm / h，絮凝物的迁移和聚集就会形成冰面，从而引起脱水。这导致絮凝物致密性增加，并且粒度分布（PSD）变窄。对于由大絮状物组成的污泥，絮凝物很容易被迁移的冰锋破坏，从而导致平均絮凝物直径和PSD比由小絮状物组成的污泥小。在低速下，高固体浓度污泥的冰锋发展速度要慢于低固体浓度污泥的冰锋发展。当采用高冷冻速度冷冻污泥时，冰锋对絮凝物的破坏更为明显，且颗粒层的致密性低于低冷冻速度造成的。此外，在高冷冻速度下，具有高固体浓度的污泥容易被冰晶截留，并且絮状物直径增加。但是，在这种情况下未发现污泥的总迁移。基于实验结果，提出了一种考虑污泥粒径和固体浓度影响的污泥冷冻调节模型。另外，建议进行预处理以增加固体浓度并减小絮凝物的尺寸，然后再进行冻融处理，以提高该技术的效率。

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