Study On Treatment Of Dye Wastewater With Electrocoagulation Method

The dye wastewater is of great quantity, heavy toxicity, higher concentration, complicated constituents, high salt content, and great variety of pH, which has become one of the problems of industrial wasterwater treatment. Due to its inherent simplicity of design and operation, together with the growing need for small-scale cost effective water treatment systems, the electrocoagulation (EC) technology has received a renewed interest for industrial applications, and reviews about the perspectives and possibilities of the EC technology for water treatment have increased recently. In this study, the treatment of simulated wastewater of reactive brilliant blue X-BR (RBB X-BR) has been researched using two kinds of EC devices. One includes iron plate and aluminum plate as the electrods and the powe is periodic reversing. The iron anode and iron cathode with the common DC power supply will be used in the traditional EC method. The influence on degradation effect of color and CODcr has been investigated respectivey through controlling different reaction conditions in the obove two EC methods. Futhermore, the reaction mechanism will be analysed emphatically.Results show that the treatment effct has been influenced to different degree under different reaction conditions, including reaction time, reaction voltage, stirring speed, reversing period, initial dye concentration, electrolyte concentration, plate distance, and the initial pHof dye wastewater. The details are as follows:for the periodic reversing method, electrolysis time35mins, electrolysis voltage9V, stirring speed750r/min, reversing period11s, initial dye concentration1200mg/L, electrolyte concentration0.0045mol/L, plate distance0.6cm, and no adjustment of initial pH. Under these conditions the dye decoloration rate of99.42%, COD removal rate of93.03%. For the traditional EC method, electrolysis time30mins, electrolysis voltage9V, stirring speed750r/min, initial dye concentration9000mg/L, no extra electrolyte concentration, plate distance1.0cm, and no adjustment of initial pH as well and under these conditions the dye decoloration rate is99.66%, COD removal rate of95.18%. The periodic reversing method is more suitable for the treatment of dye wastewaterof low concentrations (300～1200mg/L), rather than apply to the treatment of lower and high concentration dye wastewater (<300mg/L or>1200mg/L). The traditional EC method can continuously adapt to changes in a wide range of concentrations of dye wastewater, especially for the treatment of high and higher concentrations of dye wastewater (1000～9000mg/L). We also found that periodical reversing method can effectively reduce the corrosion of electrods and prevent electrodes blunt, moreover, the power consumption is lower when dealing with the wastewater of low concentration of RBB X-BR, comparing with the traditional EC. The results of analyzing reaction mechanism show that treatment of dye wastewater by electrocoagulation are the combined effect of electrolysis oxidization and deoxidization, electric floatation and flocculation of the metal ions. Iron ions play an important role in the process of electrocoagulation.