Study Of Microwave-assisted Catalytic Oxidation For Treatment Of Printed Circuit Board Organic Wastewater

With the development of the electronics industry, the printed circuit board production has been developed very quickly in recent years. Throughout the processes of printed circuit board, the stripping wastewater has been piped with the characteristics of hard to be handled and dangerous to the environment. Because it was difficult to be treated to the emission stander by biological and physical-chemical processes, the wastewater became the most difficult problem that the PCB factories had to solve. By taking the printed circuit board stripping wastewater as the subject, this paper used microwave assisted catalytic oxidation to treat the wastewater, and he results showed that this method could achieve good effect.This paper first studied the influencing factors on the treated effect under microwave heating ozone oxidation by changing microwave power, pH value, gas flow rate and the reation time. As a result, under such a condition of pH value of 6.0, gas flow rate of 400 ml/ min, the concentration of ozone of 0.55 mg/L, microwave power of 500 W, the processing time of 25 minutes, that the COD removal rate could reach to 10.3 percent. The data showed that wastewater treated result was not good under microwave heating ozone oxidation without catalyzer.Then, in order to improve the treated effect, catalyzer was added in the original experiment. And the bamboo activated carbon made by microwave irradiation was the perferred one. In the experiments under microwe--bamboo activated carbon--ozone catalytic oxidation, several factors as the catalyst amount, the concentrations of ozone, the gas flow rate, the microwave power, pH value, and the reaction time were studied on treated effect, and these six factors'orthogonal experimentes were taken. The poor analysis showed that the relationshipes between primary and secondary factors were the amount of catalyst> pH value> heating time> ozone concentration> microwave power> air velocity, the treated wastewater COD removal rate under the best condition (the amount of catalyst 1.5 g, pH of 6.0, heating time of 15 minutes, ozone concentration of 0.55 mg/L, 400 W of microwave power, gas flow rate of 400 ml/min) could reach to 85.0 percent, with the treated wastewater COD value of 135 mg/L, which was still unable to meet the state wastewater discharge stander.Finally, the bamboo activated carbon was modified, and whose surface loaded metal was used as the catalyzer in the wastewater treated experiments under microwe--modified bamboo activated carbon--ozone catalytic oxidation. As a result, the modified bamboo activated carbon had good reuseful performance. On the 10th reuse time, the COD removal rate still could reach to 88.2 percent. The data also indicated that the modified bamboo activated carbon was more suitable to be the catalyzer in the experiment than bamboo activated carbon. When 1.0 g the catalyzer was used, pH value of 6.0, gas flow rate of 400 ml/min, the concentration of ozone 0.55 mg/L, microwave power of 500W, the processing time of 25 minutes, the COD removal rate could reach to 95.6 percent, and the treated wastewater COD value was decreased to 39 mg/L, which could meet the first wastewater discharge stander.