Study On Emulsion Wastewater Treatment With Pulsed Current Electroflotation Method

Electroflotation is a simple process that floats polltants to the surface of a water body by tiny bubbles of hydrogen and oxygen gases generated from water electrolysis. It shows good performences on pollutants removal rate, without secondary pollutants, small units. To overcome the major problems of high electricity consumption and electrode passivation, pulsed current electroflotation was introduced to treat wastewater.The removal of COD from linear incision machine tool emulsion wastewater was investigated by a pulsed current elelctroflotation method. Operating variables including the current density(i), electrolysis duration(T), electrode spacing(d) and pH were considered in order to determine their effects on the COD removal efficiency. The key factors affecting the COD removal efficiency during the electroflotation process are as follows: pH value> electrolysis duration(T)> electrode spacing(d)> current density(i). The optimum Operating condition is 35min of electroflotation treatment with 277.78A·m^-2 of current density, 2.5cm of electrode spacing and 5 of pH value.Emulsion wastewater containing various types of pollutants like surfactant, additives and COD with high-concentration, which is discharged from mechanical processing industry, is a typical emulsion wastewater that is difficultly biodegraded and may induce heavy contamination. Conventional methods of physical and chemical or chemical only are hard to treat emulsion wastewater efficiently.Comparison of correlation coefficient-R, F-test value-F, surplus sum of squares-Q and residuals from regression equations(confidence level is 0.95) including linear polynomial, purequadratic polynomial, quadratic polynomial and cubic polynomial, an empirical model of quadratic polynomial was created from the experimental data by the means of regression analysis.The experimental results show that electroflotation is found effective in treating emulsion wastwater, with the advantages of less flocculant dose (30～50 percent of coagulant consumption), smaller sludge volume, less energy consumption and treatment time.