In previous work we have shown that recycling pre-sonciated drinking water treatment sludge (DWTS) could improve coagulated water quality. Here, the removal of naturally occurring organic matter of source water was further optimized using response surface methodology (RSM) with Box-Behnken Design (BBD). The four variables, i.e., volumetric recycling ratio of DWTS, energy density, ultra-sonication time and duty cycle in an experimental jar test of ultrasound assisted flocculation-coagulation were optimized. All the variables showed a significant effect on dissolved organic carbon (DOC) removal of source water (p < 0.05), of which the duty cycle had a stronger effect on the removal performance compared to the other independent variables. The predicted optimal DOC removal rate was 36.94%, and this matched well the observed performance of 36.54 ± 0.56%, obtained by ultra-sonicating the sludge prior to recycling using a power input of 1.015W/mL, an ultra-sonciation time of 9min50sec, and a duty cycle of 80%, while the volumetric recycling ratio of DWTS was 5.8%. The natural organic matter fractions in the coagulated water samples indicated that recycling sonicated DWTS that had been washed prior to recycling in order to remove solubilzied extracellulaer polymers could enhance removal of hydrophobic acids and 3-30 kDa fractions, but this treatment increased the presence of substances with molecular weight <3 kDa. Humic-like substances were effectively removed while tyrosine-like substances could be enriched. Sludge samples (raw DWTS, sonicated DWTS, sludge formed by recycling raw DWTS, and sludge formed by recycling sonicated DWTS without solubilzied extracellular organics) were characterized by XRF, X-ray diffraction patterns and FE-SEM-EDS to reveal possible physical characteristics that could be related to the DOC removal performance.

在以前的工作中，我们表明，回收预处理的饮用水处理污泥（DWTS）可以改善凝结水的质量。在这里，使用Box-Behnken Design（BBD）的响应面方法（RSM）进一步优化了去除源水中天然存在的有机物的过程。优化了超声波辅助絮凝-混凝的实验罐试验中DWTS的体积循环比，能量密度，超声处理时间和占空比这四个变量。所有变量均显示出对溶解有机碳（DOC）去除源水的显着影响（p<0.05），其中占空比与其他自变量相比对去除性能的影响更大。预测的最佳DOC去除率为36.94％，这与观察到的36.54±0.56％的性能非常吻合，该性能是通过使用1.015W / mL的功率输入对污泥进行超声处理再回收之前获得的，超声时间为9min50sec ，占空比为80％，而DWTS的体积回收率为5.8％。凝结水样品中的天然有机物馏分表明，在回收前已进行洗涤以去除溶解的胞外聚合物的回收超声DWTS可以增强对疏水酸和3-30 kDa馏分的去除，但是这种处理增加了物质的存在分子量<3 kDa。有效地去除了腐殖质样物质，同时可以丰富酪氨酸样物质。通过XRF，X射线衍射图和FE-SEM-EDS对污泥样品（原始DWTS，超声DWTS，通过回收原始DWTS形成的污泥以及通过在不溶解细胞外有机物的情况下通过回收DWTS形成的污泥）进行表征，以揭示可能的物理特征可能与DOC去除性能有关。