The role of temperature and CaCl2 in activated sludge dewatering under hydrothermal treatment.
The role of temperature and CaCl2 in activated sludge dewatering under hydrothermal treatment.
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DOI：
10.1016/j.watres.2013.11.034
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发表时间：
2014-03
期刊：
影响因子：
12.8
通讯作者：
Jie Yu;Minhui Guo;Xinhua Xu;Baohong Guan
中科院分区：
文献类型：
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作者：
Jie Yu;Minhui Guo;Xinhua Xu;Baohong Guan
脱水是活性污泥处置的重要环节。在水热处理条件下，当温度从100℃升高到200℃，阈值温度为130℃时，活性污泥的脱水性能先恶化后改善。氯化钙辅助水热处理改善了活性污泥的脱水性能，消除了低至20 mg/g干固体(DS)的阈值温度。当温度和CaCl2用量增加到60 mg/g DS时，脱水性能持续改善。结果表明，在160℃以下，生物大分子增溶引起的电荷中和作用主导了脱水性的演变，而在较高温度下，水结合组分的分解起着更重要的作用。可溶性蛋白质和多糖的相对分子质量的变化表明，在水热处理过程中，CaCl2与污泥成分相互作用，改变了污泥成分。通过CaCl2将可溶的生物聚合物整合到絮体基质中，形成致密的絮体结构，从而改善了絮体的脱水性能。这项工作揭示了与脱水性能相关的絮体组成和结构的变化，并对水热处理中温度和CaCl2在活性污泥脱水中的作用提供了新的理解。
Dewatering is important for activated sludge disposal. The dewaterability of activated sludge was first deteriorated and then ameliorated when the temperature was raised from 100 to 200 °C with a threshold temperature of 130 °C under hydrothermal treatment. Calcium chloride assisted hydrothermal treatment to improve the dewaterability of activated sludge, and eliminated the threshold temperature at as less as 20 mg/g dry solid (DS). An increase in temperature and dosage of CaCl2till 60 mg/g DS allowed a continuous improvement of dewaterability. It is found that the charge neutralization resulted from biopolymers solubilization dominated the dewaterability evolution below 160 °C, while the decomposition of water-binding components played a more important role at higher temperatures. The variation of molecular weight of soluble protein and polysaccharides implies that CaCl2interacted with the component of sludge and altered the constituent during the hydrothermal treatment. The integration of soluble biopolymers into the floc matrix by CaCl2contributed to the compacted floc structure and thus improved the dewaterability. This work presents an insight into the floc variation in both the composition and structure associated with the dewaterability and offers a new understanding to the role of temperature and CaCl2in hydrothermal treatment on activated sludge dewatering.