[混凝法去除五价砷及絮体回流强化效果的中试研究]

[Pilot study on pentavalent arsenic removal by coagulation and the strengthening effect of flocs recycling].

作者信息

Yao Juan-Juan, Gao Nai-Yun, Xia Sheng-Ji, Chen Bei-Bei

机构信息

State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China.

出版信息

Huan Jing Ke Xue. 2009 Jun 15;30(6):1663-8.

PMID:19662848

Abstract

The pilot and bench scale studies on pentavalent arsenic removal by coagulation and the strengthening effect of flocs recycling were performed. The results show that above 95% As (V) in the raw water exists in the form of dissolved As (V). Furthermore, the removal efficiencies of dissolved arsenic and total arsenic by mixing, first flocculation, second flocculation, sedimentation, filtration units were 87.92%, 6.18%, 2.38%, 1.55%, 1.23% and 1.10%, 1.83%, 2.20%, 86.42%, 7.38% respectively. Therefore, conversion rate of dissolved As(V) into particulate As(V) and the settlement performance of flocs were strongly dependent on the coagulation effect, which determined the As(V) removal efficiency in the whole system. Flocs have a strong adsorption capacity for As(V) and the adsorption obeys a second order reaction kinetics and well fits the modified Freundlich model. Flocs recycling can obviously promoted the As(V) removal by enhanced coagulation and reduce the dosage of coagulant with recycling point set at rapid mixed site and recycling ratio at 50%.

摘要

进行了关于通过混凝去除五价砷以及絮体循环强化效果的中试和小型试验研究。结果表明，原水中95%以上的五价砷以溶解态五价砷的形式存在。此外，混合、一次絮凝、二次絮凝、沉淀、过滤单元对溶解态砷和总砷的去除效率分别为87.92%、6.18%、2.38%、1.55%、1.23%和1.10%、1.83%、2.20%、86.42%、7.38%。因此，溶解态五价砷向颗粒态五价砷的转化率以及絮体的沉降性能强烈依赖于混凝效果，这决定了整个系统中五价砷的去除效率。絮体对五价砷具有很强的吸附能力，吸附遵循二级反应动力学，且很好地符合修正的弗伦德利希模型。将絮体循环点设置在快速混合处且循环比为50%时，絮体循环可通过强化混凝明显促进五价砷的去除，并减少混凝剂用量。