Study Of Organophosphorus Pesticide Wastewaters By Plasma

It is still a problem to treat the organophosphorus pesticide wastewater effectively, which is characterized as high concentration of organic matter, high toxicity for biotic systems, biorecalcitrant etc. Furthermore, the available methods could not be satisfied to the environmental pollution control engineering by means of their higher costs, lead to secondary pollution, long-term processes and low efficiency. The financial support for this work was provided by the National Key Technology R&D Program (No. 2006BAC11B06) and the Environmental Science and Technology Plan of Jiangsu Province (No. 2000, 21.19). Two typical pesticide wastewaters containing dichlorvos and triazophos were degraded using plasma produced by ionization discharge, respectively.The dichlorvos and triazophos were degraded in a simulated natural environment and using plasma. And it could provide some valuable references on the following correlation studies.The effects of the initial wastewater concentration, light, temperature and pH value the natural degradation of organophosphorus pesticide wastewaters had been discussed, respectively. The result shows that: the degradation of organophosphorus pesticide wastewater declined with increase of initial concentration; intensity of light irradiation enhanced the pesticide degradation; the degradation efficiency rose dramatically at high temperature; alkaline condition could accelerated the reaction.Considering some main parameters, such as initial concentration, temperature, pH value, oxygen flow and intensity of light irradiation, the tendency of the degeneration of the organophosphorus pesticides had been determined. Finally the optimizing condition and impact of the factors were obtained by orthogonal experiments. The degradation efficiency declined as pesticide primary concentration increased. But the temperature had different effect on the degradation that the degradation efficiency of triazophos did not change significantly in the range of 25 degree Centigrade to 35 degree Centigrade. Generally, alkaline condition advantaged the pesticide degradation and the degradation efficiency increased with pH value increased. The dichlorvos had been almost entirely degraded in 12 minutes at the pH value about 11; and the degradation efficiency slightly decreased at the pH value above 11. When the pH value was about 10, the degradation efficiency of triazophos would up to 100% in 12 minutes; and the degradation efficiency would appear less obviously decline at pH value above 10. With the increase of oxygen flow, the degradation efficiency of dichlorvos and triazophos showed a downward trend; and the degradation efficiency pronounced upward trend with the increase of intensity of light irradiation. Under a certain level conditions, pH value had the significant effect on the degradation efficiency, followed by the temperature, concentration, intensity of light irradiation; and the less impact of the degradation efficiency was oxygen flow.As a conclusion, plasma technology is an effective method for the treatment of organic phosphorus pesticide wastewater.