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The effect of sludge chemistry on freeze-thaw conditioning of activated sludge.

机译：污泥化学性质对活性污泥冻融条件的影响。

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摘要

Sludge dewatering is a difficult and expensive process in water and wastewater treatment. Mechanical techniques, such as centrifuges and filters, are difficult to operate and maintain, and drying beds require large land areas. All dewatering operations require expensive chemicals for sludge conditioning. Freeze-thaw technology, which is an alternative method of sludge conditioning has gained considerable popularity during the last decade. Particularly in cold regions, where freeze-thaw can be achieved by taking advantage of the natural climatic conditions, freeze-thaw conditioning has emerged as an effective and low-cost method of assisting sludge dewatering.; Freeze-thaw conditioning works very well for alum sludge, however it does not work as well for activated sludge. Apparently, the organic, inorganic, and biological constituents of activated sludge, which are not found in alum sludge, hinder the freezing process. With activated sludge, the improvements achieved after freeze-thaw conditioning are temporary and reversible. If, however, the sludge chemistry and the floc structure of activated sludge are changed prior to freezing, it may be possible to improve the results of freeze-thaw conditioning.; In this study, the sludge chemistry and floc structure were changed by removing and adding extracellular polymers and cations to the sludge matrix, and by employing other methods such as elutriating the sludge, varying the freezing temperature, and storing the sludge under aerobic and anaerobic conditions. Cations were removed by dilution, chelation and ion exchange processes, and extracellular polymers were removed by NaOH, EDTA and EGTA extraction, heating, blending, and centrifuging. The concentration of extracellular polymers was quantified by measuring protein and carbohydrate concentrations. The concentration of the cations was determined by using a direct coupled plasma (DCP) spectrometer. The results of this study show that high protein, carbohydrate, and cation concentrations present in activated sludge hinder complete freezing of sludge, thereby decrease the dewaterability, settleability, and compactibility of sludge after freeze-thaw conditioning. Removal of extracellular polymers and cations from sludge matrix improves the outcome of freeze-thaw conditioning. In a treatment plant, the effectiveness of freeze-thaw conditioning can be significantly increased simply by employing dilution and elutriation during the treatment process.
机译：在水和废水处理中，污泥脱水是困难且昂贵的过程。机械技术（例如离心机和过滤器）难以操作和维护，并且干燥床需要大面积土地。所有脱水操作都需要昂贵的化学物质来处理污泥。在过去的十年中，冻融技术是污泥处理的一种替代方法，已广受欢迎。特别是在寒冷地区，利用自然气候条件可以实现冻融，冻融处理已成为一种帮助污泥脱水的有效且低成本的方法。冻融调节对明矾污泥效果很好，但是对活性污泥效果不佳。显然，明矾污泥中未发现的活性污泥的有机，无机和生物成分阻碍了冷冻过程。对于活性污泥，冻融调节后获得的改善是暂时且可逆的。但是，如果在冷冻之前改变了污泥的化学性质和活性污泥的絮凝结构，则可能会改善冻融条件。在这项研究中，通过去除污泥基质中的细胞外聚合物和阳离子并添加污泥，改变絮凝温度，在好氧和厌氧条件下存储污泥等其他方法，改变了污泥的化学性质和絮凝结构。 。通过稀释，螯合和离子交换过程除去阳离子，并通过NaOH，EDTA和EGTA萃取，加热，混合和离心除去细胞外聚合物。通过测量蛋白质和碳水化合物的浓度来量化细胞外聚合物的浓度。通过使用直接耦合等离子体（DCP）光谱仪确定阳离子的浓度。这项研究的结果表明，活性污泥中存在的高蛋白，碳水化合物和阳离子浓度会阻碍污泥的完全冻结，从而降低冻融条件后污泥的脱水性，沉降性和可压缩性。从污泥基质中去除细胞外聚合物和阳离子可改善冻融条件。在处理厂中，只需在处理过程中采用稀释和淘洗，即可大大提高冻融调节的效率。

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  • 作者

    Ormeci, Banu.;

  • 作者单位

    Duke University.;

  • 授予单位 Duke University.;
  • 学科 Engineering Environmental.
  • 学位 Ph.D.
  • 年度 2000
  • 页码 244 p.
  • 总页数 244
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 环境污染及其防治;
  • 关键词

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