Pilot Test On Advanced Treatment Of Printing And Dyeing Wastewater By Ozonation

Printing and dyeing wastewater secondary effluent contains toxic and harmful substance, which is difficult to biodegrade. For this reason, state and regions establish the increasingly stringent sewage discharge standards. In order to meet these standards, enterprises have to take advanced treatment for reusing wastewater.The paper choose the printing and dyeing wastewater secondrary effluent to be investigated, CODcr of this wastewater is between 120mg/L to 160mg/L, several treating processes including ozonation alone,homogeneous catalytic ozonation and the ozonation cooperated with H₂O₂,UV have been studied on the treatment effect.In the study of ozonation alone, the ozonation alone technology can generate a limited amount of ?OH, whether raising water pH value or increasing the ozone dosage, resulting in the CODcr removal rate is not high.In heterogeneous catalytic ozonation, Al2O3–supported manganese oxides were prepared using impregnation method. As for the 500mL wastewater whose initial pH value is 4.0, On the condition that ozone dosage of 57.6mg, catalyst dosage of 30g, catalyst particle size of 2mm 3mm, the removal rate of CODcr in catalytic ozonation is 15.5% higher than the removal rate of CODcr in ozonation alone; with the initial pH value of effluent rises, the catalytic activity of catalyst lower. The main route of catalytic ozonation is to produce ?OH. Manganese will dissolve out in the acid effluent, resulting in the catalyst life is numbered.In the ozonation cooperated with H₂O₂,UV. As for the 500mL wastewater whose initial pH value is 6.8, On the condition that ozone dosage of 48mg, 0.1mL H₂O₂ add in reactor before reaction, UV lighting tube for 10w, the removal rate of CODcr in O3/H₂O₂,O3/UV,O3/H₂O₂/UV is higher than the removal rate of CODcr in ozonation alone, 7.9%,10.4%,17.3% respectively. As for O₃/H₂O₂ process, with the initial pH value of effluent rises, the optimum dosage of H₂O₂ lower. The removal rate of CODcr in most time by pre-adding is higher than imtemittent adding.