Department of Engineering Sciences, University of Agder, Grimstad, Norway; Norwegian Institute for Sustainability Research, Fredrikstad 1672, Norway E-mail:
Department of Engineering Sciences, University of Agder, Grimstad, Norway.
Water Sci Technol. 2023 Nov;88(10):2547-2565. doi: 10.2166/wst.2023.363.
Particles are a concern regarding tunneling wastewater, but gaps remain in understanding metal(loid)s content and coagulation efficiency. In this research, characterization of the wastewaters before and after treatment was investigated by chemical analysis and various techniques for particle characterization. Then, laboratory work was conducted to evaluate effectiveness of sedimentation and use of coagulants to remove particles and particle-associated contaminants. Both natural (chitosan) and chemical coagulants (ferric chloride sulfates and polyaluminium chloride solution), were applied in a jar test system. The results indicated that short-time sedimentation alone substantially reduced the particle content and particle-associated pollutants, including metal(loid)s, while subsequent chemical coagulation was required to comply with discharge limits. The optimum dosages of chitosan, PIX, and PAX for water 1 after pre-treatment (15 min sedimentation) were 1 mg/L, 3 mg Fe/L, and 3 mg Al/L, respectively, while a dosage of 2 mg Al/L gave the best results in water 3. Furthermore, chemical coagulation significantly decreased the volume density of particles in the diameter range of 1-100 μm, showing that coagulants are efficient for the removal of smaller particles not removed by conventional sedimentation.
颗粒是隧道废水的一个关注点，但对于金属（类）物质含量和混凝效率的理解仍存在差距。在这项研究中，通过化学分析和各种颗粒特性分析技术对处理前后的废水进行了表征。然后，进行了实验室工作以评估沉淀和使用混凝剂去除颗粒和颗粒相关污染物的效果。天然（壳聚糖）和化学混凝剂（硫酸铁氯化物和聚氯化铝溶液）都在 Jar 测试系统中进行了应用。结果表明，单独进行短时间沉淀可以大大降低颗粒含量和颗粒相关污染物，包括金属（类）物质，而随后需要进行化学混凝才能符合排放限值。对于预处理后的水 1（15 分钟沉淀），壳聚糖、PIX 和 PAX 的最佳剂量分别为 1mg/L、3mgFe/L 和 3mgAl/L，而水 3 的最佳结果是 2mgAl/L。此外，化学混凝显著降低了直径在 1-100μm 范围内的颗粒的体积密度，表明混凝剂对于去除常规沉淀无法去除的较小颗粒是有效的。
