A Study On Treatment Of Dyeing And Printing Wastewater By Alternate Period Electro-coagulation

The treatment of dyeing and printing wastewater has been a difficult point in the field of wastewater treatment owing to characteristics of enormous water demand quantity, strong color, high concentration of COD, low biodegradability, widely varied quantity, and serious damage to environment etc. But the treatment of dyeing and printing wastewater by electrochemistry method has some significant advantages, such as small equipments, small floor space for its equipment, amenability to automation, no additional chemicals and secondary pollution etc. However the electrochemistry method has some shortcomings, such as large of power consumption and liable blunt on anode etc. In order to solve those questions, this paper has done a study on the treatment effect of dyeing and printing wastewater and the law of treatment, using self-designed alternate period power supply and thinking about the function between Cathode and anode. At the same time, this paper analyses the power consumption of dealing with unit mass of dye and further research the reaction mechanism of this process.Through the sigle factor experiment analysing, we can got:reaction time, reaction voltage, plate spacing, the electrolyte concentration, alternating period, dye concentration, stirring speed and the pH value had effects on the treatment results, and effect of the electrolyte concentration is significant among these factors. Thinking about the decolorize rate and COD removal efficiency of reactive black KN-B, we can got the optimal reaction conditions:reaction time is 30min, reaction voltage is 10V, plate spacing is 1.0cm, the electrolyte concentration is O.Olmol/L, alternating period is 10s, dye concentration is 200mg/L, stirring speed is 1000r/min, the pH value is 5.The results of analyzing reaction mechanism show that treatment of dyeing and printing wastewater by electro-coagulation are the combined effect of electrolysis oxidization and deoxidization, electric floating and flocculation of the metal ions. Among those effects the flocculation of the metal ions is significant, about 47.64%. Using to alternant period can effectively prevent electrode blunt and can protect the electrode. Meanwhile the treatment of dyeing and printing wastewater by electro-coagulation can effectively save energy and effectively overcome defect of large power in consumption previous electrochemistry method. Therefore electro-coagulation method with alternating period is a feasible, effective and new treatment method of dyeing and printing wastewater.