title: Water softening by induced crystallization in fluidized bed.
abstract: 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 60L/hr, a fixed-bed height of 0.5m, pH value of 9.5, quartz sand nuclear diameter of 0.2-0.4mm, and a reflux ratio of 60%, the effluent concentration of calcium hardness was reduced to 60mg/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.
authors.affiliation: School of Civil and Environment Engineering, Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, Beijing 100083, China. Electronic address: yuefangchen@vip.sina.com.
authors.forename: Yuefang
authors.initials: Y
authors.lastname: Chen
authors.affiliation: School of Civil and Environment Engineering, Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, Beijing 100083, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Fan
authors.affiliation: School of Civil and Environment Engineering, Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, Beijing 100083, China.
authors.forename: Danfeng
authors.initials: D
authors.lastname: An
authors.affiliation: School of Civil and Environment Engineering, Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, Beijing 100083, China.
authors.forename: Yujie
authors.initials: Y
authors.lastname: Cheng
authors.affiliation: School of Civil and Environment Engineering, Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, Beijing 100083, China.
authors.forename: Hazel
authors.initials: H
authors.lastname: Tan
mesh_terms: D019149:Bioreactors; D002119:Calcium Carbonate; D003460:Crystallization / Q000379:methods; D012822:Silicon Dioxide; D014865:Waste Disposal, Fluid / Q000379:methods*; D014880:Water Softening
chemical_list: D012822:Silicon Dioxide; D002119:Calcium Carbonate
keywords: Fluidized bed; Hardness; Induced crystallization; Quartz sand; Softening capability