The efficiency of common sludge electro-dewatering (EDW) is restrained by the following issues: 1, the near-anode sludge dries out quickly, causing a rapid increase in electrical resistance; 2, the pH at anode decreases by the accumulation of H+ from the electrolysis of moisture, resulting in a decrease in Zeta potential (ζ). Alleviating the negative impact of these problems is the key to improving the dewatering efficiency of EDW. Therefore, in this study, calcium oxide (CaO) was used for near-anode sludge modification to increase its pH and electrical conductivity. With increasing CaO dosage, pH rose from 6.0 to 12.2, electrical conductivity increased from 368 ± 16 μS/cm to 6285 ± 21 μS/cm and the ζ declined from -15.3 ± 0.6 mV to -8.8 ± 0.4 mV. The EDW tests were conducted at 30 V and 25.5 kPa. The results indicate near-anode sludge modification with CaO weighing 3%-5% mass of raw sludge (mu(RS)) improved the EDW effect, while the energy consumption increased slightly. When 3%-5% mu(RS) of CaO was added, the final moisture content of sludge was 54.5%-44.3%, below that of the blank group (no CaO added), which was 57.9%; the time to obtain target moisture content (60%) was 910 s-590 s, lower than the blank group's 1060 s; and the energy consumption to obtain target moisture content was 0.233 kW h/kg H2O-0.271 kW h/kg H2O, higher than the blank group's 0.157 kW h/kg H2O. A quantitative criterion (KsiEDW) was adopted to assess the feasibility of EDW. Economically and energetically, the experiment with 4% mu(RS) of CaO added for near-anode modification was the optimal condition in this research, due to its second smallest KsiEDW, the best sludge reduction effect (67.2%), lower final moisture content (46.2%) and less time (640 s) to obtain target moisture content. The results show some mechanisms of EDW and provide experience for practical application.

中文翻译：

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污水污泥的电脱水：不同剂量氧化钙对近阳极污泥的改性作用。

普通污泥电脱水（EDW）的效率受到以下问题的限制：1，阳极附近的污泥很快变干，导致电阻迅速增加；如图2所示，阳极上的pH由于水分电解引起的H +的积累而降低，导致Zeta电位（ζ）降低。减轻这些问题的负面影响是提高EDW脱水效率的关键。因此，在这项研究中，氧化钙（CaO）用于近阳极污泥改性，以增加其pH和电导率。随着CaO剂量的增加，pH从6.0上升到12.2，电导率从368±16μS/ cm增加到6285±21μS/ cm，ζ从-15.3±0.6 mV下降到-8.8±0.4 mV。EDW测试在30 V和25.5 kPa下进行。结果表明，CaO占原污泥质量的3％-5％（mu（RS））修饰近阳极污泥可改善EDW效果，而能耗则略有增加。当添加3％-5％mu（RS）的CaO时，污泥的最终含水量为54.5％-44.3％，低于空白组（未添加CaO）的57.9％；获得目标水分含量（60％）的时间为910 s-590 s，低于空白组的1060 s。获得目标含水量的能耗为0.233 kW h / kg H2O-0.271 kW h / kg H2O，高于空白组的0.157 kW h / kg H2O。采用定量标准（KsiEDW）来评估EDW的可行性。从经济和精力上考虑，添加4％mu（RS）CaO进行近阳极改性的实验是该研究的最佳条件，因为它的KsiEDW最小，最佳的污泥减少效果（67.2％），较低的最终水分含量（46.2％）和更少的时间（640 s）获得目标水分含量。结果表明了EDW的一些机理，为实际应用提供了经验。