Water softening by induced crystallization in fluidized bed

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• 作者：Yuefang Chen ; ^{yuefangchen@vip.sina.com} ; Rong Fan ; Danfeng An ; Yujie Cheng ; Hazel Tan
• 关键词：Fluidized bed ; Induced crystallization ; Hardness ; Softening capability ; Quartz sand
• 刊名：Journal of Environmental Sciences
• 出版年：2016
• 出版时间：December 2016
• 年：2016
• 卷：50
• 期：Complete
• 页码：109-116
• 全文大小：975 K
• 卷排序：50

文摘

Fluidized bed and induced crystallization technology were combined to design a new type of induced crystallization fluidized bed reactor. The added particulate matter served as crystal nucleus to induce crystallization so that the insoluble material, which was in a saturated state, could precipitate on its surface. In this study, by filling the fluidized bed with quartz sand and by adjusting water pH, precipitation of calcium carbonate was induced on the surface of quartz sand, and the removal of water hardness was achieved. With a reactor influent flow of 60 L/hr, a fixed-bed height of 0.5 m, pH value of 9.5, quartz sand nuclear diameter of 0.2–0.4 mm, and a reflux ratio of 60%, the effluent concentration of calcium hardness was reduced to 60 mg/L and 86.6% removal efficiency was achieved. The resulting effluent reached the quality standard set for circulating cooling water. Majority of the material on the surface of quartz sand was calculated to be calcium carbonate based on energy spectrum analysis and moisture content was around 15.994%. With the low moisture content, dewatering treatment is no longer required and this results to cost savings on total water treatment process.