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Application and mechanism of a novel flocculation reagent for mechanical dewatering: A case study on slurry separation in a large-diameter slurry shield
Tunnelling and Underground Space Technology ( IF 6.7 ) Pub Date : 2025-01-21 , DOI: 10.1016/j.tust.2025.106413
Jian Zhang, Guoping Ren, Tugen Feng, Yu Liang, Yihao Yin

A novel C-type flocculation reagent was developed to address the high water content of sludge and the environmental pollution caused by wastewater discharge during mechanical dewatering in the Zhanjiang Bay undersea tunnel. Microscopic parameters, such as particle size and zeta potential, were analyzed to elucidate the flocculation and dewatering mechanisms of the C-type reagent. The applicability of the C-type reagent was further validated in a field test and compared to that of conventional reagents. The results showed that the C-type reagent reduced the water content of the sludge by approximately 20 % and decreased the turbidity of the supernatant by approximately 79 %. The C-type reagent demonstrated enhanced bridging and charge neutralization activity, which facilitated the aggregation of fine particles (<10 μm) into larger particles (>50 μm), ultimately enhancing the efficiency of flocculation. The C-type reagent also facilitated the formation of a calcium drainage channel skeleton with enhanced water permeability and reduced the slurry viscosity to improve the efficiency of mechanical dewatering. These effects enhanced the pore size distribution of the slurry to a range of 346 to 8656 nm, which was approximately 15 % to 41 % greater than the overall pore size of the original slurry. Onsite utilization of 0.5 % C-type reagent enhanced the solid content of the sludge by 35.7 % compared with that obtained with the original reagent, resulting in a 20 % reduction in cost. Moreover, the sludge meets the sewage standards for indicators such as pH and thus qualifies for direct discharge. The findings of this study offer valuable insights for the selection of environmentally friendly and efficient reagents in the context of combined flocculation–mechanical dewatering.

中文翻译:


新型絮凝剂在机械脱水中的应用及机理——以大直径渣浆盾构中浆料分离为例



针对湛江湾海底隧道机械脱水时污泥含水率高和废水排放造成的环境污染,开发了一种新型 C 型絮凝剂。分析微观参数,如粒径和 zeta 电位,以阐明 C 型试剂的絮凝和脱水机制。C 型试剂的适用性在现场测试中进一步验证,并与常规试剂进行了比较。结果表明,C 型试剂使污泥的含水量降低了约 20%,上清液的浑浊度降低了约 79%。C 型试剂表现出增强的桥接和电荷中和活性,这有利于细颗粒 (<10 μm) 聚集成更大的颗粒 (>50 μm),最终提高絮凝效率。C 型试剂还促进了钙排水通道骨架的形成,增强了透水性,并降低了浆料粘度,从而提高了机械脱水的效率。这些效应将浆料的孔径分布提高到 346 至 8656 nm 的范围,这比原始浆料的总孔径大约 15 % 至 41 %。现场使用 0.5% C 型试剂使污泥的固体含量比使用原始试剂获得的固体含量提高了 35.7%,从而使成本降低了 20%。此外,污泥符合 pH 值等指标的污水标准,因此有资格直接排放。本研究的结果为在絮凝-机械脱水联合背景下选择环保和高效的试剂提供了有价值的见解。
更新日期:2025-01-21
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