| At present, there are about more than 420 billion cubic metres wastewater discharged into the rivers and lakes around the world each year, and the 5500 billion cubic metres fresh water has been polluted. It does great harm to human health for water pollution, and about one billion people drink unclean water in developing countries(From the fourth World Water Forum). Therefore, it has become one of major issues needed to be solved among the contemporary environmental governance for wastewater comprehensive treatment. The plasma water treatment technology, has become a research hotspot in recent years, due to its no additives, no secondary pollution and rapid response with organic pollutants. But it exists a common feature about the small amount of the plasma water treatment per unit time in large scale application, seriously affecting its industrialization.Based on this, to induce the generation of H2O2 and O3 simultaneously, this paper attempts to increase the humidity of gas used to dielectric barrier discharge(DBD). Then H2O2 and O3 will be put into wastewater simultaneously to generate ?OH through their synergistic reaction, so as to improve the degradation capacity of wastewater, finally realizing industrialization development of the plasma water treatment device. In this paper, the main research work are carried out as follows:(1) Based on single DBD, a set of plasma water treatment prototype have been designed and made in this paper. A method is used to test the ?OH production by optical emission spectrum at different humidity of argon gas under the single DBD device. It is proved that ?OH and H2O2(?OH+?OHâ†'H2O2) can be generated in this way. It has been studied the change rules of OH(A2Σ+) output induced by water under different experimental conditions such as voltage, power supply, electrode and flow rate. The experimental results show that OH(A2Σ+) output reaches the maximum when the smooth electrode is drived by the pulsed power supply, and the voltage, the flow rate is equal to 10 k V, 200L/h respectively.(2) In order to further increase the humidity of discharge gas, ultrasonic atomization device is introduced to set up a double DBD water treatment prototype, looking forward to get more H2O2, O3 and other active substances. It has been investigated the mechanism of generation of H2O2 and O3 along with their yield maximization conditions by double DBD device. The generating of H2O2 and O3 affecting by several factors, such as air cooling, atomization amount, applied voltage, p H value and Electrical Conductivity(EC), have been studied in detail. It is concluded that the highest H2O2 output, up to 12.7162mg/h, is in the experimental condition include atomization amount, voltage applied, EC and p H value should be equal to 0.8, 34 k V, 9999, 6.78 respectively in the case of not forcing air cooling. And when the setup is forced air cooling and atomization amount, electrode voltage, EC, p H value are separately equal to 0.2, 34 k V, 2501, 10, which is very favorable for O3 production, up to 2.8510g/h.(3) 30mg/L methylene blue and 60mg/L acid fuchsine have been degradated by single and double DBD water treatment prototype respectively. On the one hand, it mainly focuses on the decolorization rate of methylene blue affected by different experimental conditions, such as voltage, power supply, electrode, flow rate and humidity, under the single DBD device. And the related degradation mechanism has been discussed. On the other hand, both the decolorization rate and degradation mechanism of acid fuchsine have also been discussed under different experimental conditions such as air cooling, atomization amount, applied voltage, p H value and EC when double DBD device is used. The results show that the decolorization rate of methylene blue solution reaches the maximum, as high as 97.33% after six minutes treatment, when the voltage is equal to 11 k V, the humidity is equal to 5%, the flow rate is equal to 500L/h, and the smooth electrode is drived by the pulsed power supply.While when the atomization amount, voltage applied, EC and p H value is equal to 0.4,34 k V, 09,6.78 respectively in the case of forcing air cooling, the decolorization rate of acid fuchsine reaches the maximum, up to 97.06% after sixteen minutes treatment.Based on the above experiment, the generation of H2O2 and O3 can be induced by increasing the humidity of discharge gas simultaneously, then put into wastewater, improving the efficiency of degradation, which verifies the feasibility of the proposed schemes. |
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