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Treatment of printing and dyeing wastewater by the device of high gradient magnetic separation (HGMS) developed by author was tested. The results showed that printing and dyeing wastewater contained varied chemical composition and whose initial concentration of chromaticity and COD were 800 and 565mg/L respectively can be well cleaned by Fenton oxidation-magnetic seed coagulation-HGMS. The removal rate of chromaticity and COD was up to 92.6% and 79.5% respectively. The effluent can meet the national drainage criterion. The optimum technological parameters are as follows: pH=6, [FeSO 4 ·7H 2 O]=250mg/L, [H 2 O 2 ]=1.3ml/L, [PAM]=0.75 mg/L, dose of magnetic particle W=150mg/L,current intensity I=8A, current velocity U=2.420L/min, packing density of stainless steel wire R=1.00%-1.43%. Recovery rate of magnetic particle was up to 90% by regenerated technique of chemistry in combination with physics.

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Abstract.The Fe-Co-Ce composite catalysts were prepared by co-precipitation method, and the effect of calcination temperature and calcination time on the performances of the Fe-Co-Ce composite catalysts were investigated. The results indicated that the optimum calcination temperature and calcination time of the Fe-Co-Ce composite catalysts were 450 °C and 7 h, respectively. Using the catalysts which prepared under the optimum calcination conditions catalytic wet oxidation of methyl orange simulated wastewater, after 90 min, the COD, COD removal rate, absorbance, decolorization rate and pH of the methyl orange simulated wastewater were 737.7, 70.5%, 0.348, 95.3%, and 5.31, respectively. According to the analyses of the SEM, FTIR, and TG-DTA curves, the components of the catalysts which prepared under the optimum calcination conditions distributed evenly, and the chemical compositions of the catalysts including C-O, -OH, and H-O-H, showing a good thermal stability.