Recovery of Cadmium from Wastewater by Crystallization of Cadmium Carbonate in a Fluidized Bed Pellet Reactor

• Main Authors: Cheng-Che Chen, 陳政澤
• Other Authors: D.H. Tseng
• Format: Others
• Language: zh-TW
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/88190145351102743233

碩士 === 國立中央大學 === 環境工程研究所 === 83 === The purpose of this study is to develop a laboratory scale of fluidized bed reactor for removing and recovery of cadmium from wastewater by the theory of crystallization. By measuring quartz-sands physical characterization and fluidized bed hydraulic analysis to find out the nature of equipment for the basis of next crystallization experiment. The target metal of cadmium is selected due to itshigh toxicity. The studies also investigate the various operation limit to determine the optimal conditions for recovery of cadmium carbonate by crystallization in a fluidized bed reactor. From the experiment results, in this case of quartz-sands physical experiment and paper almost similar result could be found. However, because of the reaction time is so shortthat the physical characterization of the pellets make no difference. According to hydraulic view, the principal limit that influences the hydraulic of fluidized bed characterization is the surface velocity. As the surface velocity is increased, Reynolds number, expansion ratio, porous ratio, pressure drop, energy dispersion and the velocity gradient as increased, surface area as decreased , that results are same with paper. Nevertheless the height of fixed bed, particle size of quartz-sands and glass-pears in distributor have no obvious influence with the hydraulic characterization of fluidized bed. Finally, the results of crystallize experiment showed that the optimal operation conditions of cadmium carbonate including effluent pH operated between 9.0 and 9.5, the treatment loading can be achieved to 5.00 kg-Cd/m2 h, the influent concentration ratio of CT/Cd is from 1.3 to 6.0 mmol/mmol, the hydraulic loading is more than 49.67 m/h, the fixed bed depth is the more than 60 cm, and quartz-sands size between 0.2 and 0.4 mm. st effluent quality and crystallize efficiency.