Experimental Study On Pretreatment Of Methyl Orange Dye Wastewater

Dye wastewater has the characteristics of large water quantity,high color,high COD,complicated composition,toxic and harmful substances,poor biodegradability and difficult handling.It belongs to industrial wastewater that difficult to treat.The treatment of dye wastewater is still the hot and difficult research of water treatment research at home and abroad.In this paper,methyl orange was used as the treatment object.Methyl orange has a typical azo dye structure.The COD removal rate and decolorization rate were used as the treatment indexes.The effect of the electrocoagulation method on the simulated wastewater of methyl orange was studied by using the iron plate as the electrode.The significance order of each influencing factor was determined,and the optimum values of the factors were determined according to the order.Then the effect of ultrasonic method on the treatment of simulated wastewater from methyl orange was studied.The significance order of each influencing factor was determined,and the optimum values of each factor were determined according to the order.Finally,the two methods were combined into the electrocoagulation-ultrasonic combination method,and the significance order of each influencing factor was determined.The optimum values of each factor under the experimental conditions were determined according to this order.The results of electrocoagulation test showed that the order of significance of the five main influencing factors was:electrolysis time>electrolysis voltage>electrode spacing>initial pH>initial concentration.Under the experimental conditions,the optimum experimental conditions were as follows:electrolysis time 30 min,electrolysis voltage 20V,iron electrode spacing 1cm,initial pH=5,initial concentration 200mg/L or so,under this condition the decolorization rate up to 98.45%,COD removal rate of up to 65.09%.The results of ultrasonography showed that the four main influencing factors were:Ultrasound power>Initial pH>Initial concentration>Ultrasound time.Under the experimental conditions,the optimum experimental conditions were as follows:ultrasonic power 420W,initial pH control of about 5,initial concentration 200mg/L,ultrasonic time 240min,the decolorization rate was up to 10.25%under this condition,COD removal rate was the highest Up to 7.97%.The results of electrocoagulation-ultrasonography showed that the order of significance of the four major influencing factors was:treatment time>initial concentration>electrolyte NaCl concentration>initial pH.Under the experimental conditions,the optimum test conditions were as follows:the treatment time was 20min,the initial concentration was about 200mg/L,the concentration of electrolyte was 1.5g/L,the initial pH was controlled at 5-6,and the decolorization rate was 99.85%,COD removal rate of up to 68.89%.The comparison of the experimental results shows that the electrocoagulation-ultrasonic combination method has a higher effect on the methyl orange dye wastewater than the individual electrocoagulation method and the ultrasonic method.