Laboratoire de Transformations Intégrées de la Matière Renouvelable, Université de Technologie de Compiègne, BP 20529, 60205 Compiègne Cedex, France.
Water Res. 2011 Mar;45(6):2167-80. doi: 10.1016/j.watres.2011.01.001. Epub 2011 Jan 13.
This paper deals with the influence of pH, salt and polyelectrolytes on the electro-dewatering (EOD) of agro-industrial sludge at 3% w/w of dry matter. Initially, a selection of polyelectrolyte types and doses was carried out for mechanical dewatering tests. Subsequent EOD tests were carried out in a laboratory two sided filter press at constant electric current density of 80 A/m(2) and at pressure of 5 bar. It was found that whatever was the initial value of pH, salt content or polyelectrolyte type, the EOD progressed always towards the same equilibrium point at around 50% w/w of dry matter. EOD rate and energy input was not affected by the presence of polyelectrolyte whatever was its charge density and molecular weight. However, EOD rate and specific energy consumption and repartition of liquid at anode and cathode sides were strongly influenced by the salt content (adjusted by Na(2)SO(4)) or by the initial pH (adjusted with H(2)SO(4) or NaOH). EOD performed better at lower salt content and at slightly acid pH. In optimum conditions, the process (EOD) required 2 h to reach dry matter of 40% w/w with specific energy consumption of 0.25 k Wh/kg of water removed for the treatment of conditioned sludge. For comparison, compression without electric field at 5 bar required 11 h to reach 22% w/w of dry matter. This work emphasizes and demonstrates that the electrolytic hydroxide and hydronium ions formed at the electrodes have considerable influence in the course of EOD.
本文研究了 pH 值、盐和聚电解质对 3%干物质农业工业污泥的电脱水 (EOD) 的影响。首先，进行了聚电解质类型和剂量的选择，以进行机械脱水测试。随后在实验室双面压滤机中进行了后续的 EOD 测试，电流密度为 80 A/m(2)，压力为 5 bar。结果发现，无论初始 pH 值、盐含量或聚电解质类型如何，EOD 总是朝着大约 50%干物质的相同平衡点进行。无论聚电解质的电荷密度和分子量如何，EOD 速率和能量输入都不受其存在的影响。然而，EOD 速率和比能量消耗以及液体在阳极和阴极侧的分布强烈受到盐含量（用 Na(2)SO(4)调节）或初始 pH 值（用 H(2)SO(4)或 NaOH 调节）的影响。在较低的盐含量和略酸性的 pH 值下，EOD 表现更好。在最佳条件下，该过程（EOD）需要 2 小时才能达到 40%干物质的水平，处理调理污泥的比能量消耗为 0.25 kWh/kg 去除的水。相比之下，在 5 bar 下没有电场的压缩需要 11 小时才能达到 22%的干物质。这项工作强调并证明了在 EOD 过程中，电极上形成的电解氢氧化物和氢离子具有相当大的影响。
