The O <sub> 3 </ Sub> / U.s. And A Combination Of Biological Degradation Of Organic Phosphorus Pesticide Wastewater

It is always difficult to dispose organophosphorus pesticides wastewater which is characterized as high concentration of chemical oxygen demand, complicated com-position, high toxicity for biotic systems, biorecalcitrant, Ultrasound/Ozone, as a potential method for wastewater treatment, is one of the advanced oxidation processes with high oxidant ability, no secondary pollution and noselectivity when completely mineralizing varies pollutants to inorganic ions. But the operational costs of AOPs treatment are relatively high compared to those of biological treatments, which are at present, the cheapest and the most environmental friendly. So there are more potential advantages of the coupled process than of the single process in the non-biodegradable organic wastewater treatment field.In this paper, the effect of coupled Ultrasound/Ozone-biological system for the degradation of parathion pesticides was studied. The research mainly includes three parts: ozonation,Ultrasound/Ozone and coupled Ultrasound/Ozone-biological system which were carried out to degrade the parathion pesticide wastewater, respectively. Influence aspects, such as ozone inflow, pH value, the initial concentration of wastewater and the reaction time were investigated. The comparison of three methods was also carried out.Firstly, for ozonation, the removal of COD increases with the increasing of ozone inflow but there is a maximum value. The maximum removal rate of COD of the parathion pesticide wastewater is 54.4 percent when the pH value is equal to about 10.22. The removal rate of COD increases with increasing reaction time and reaches a maximum after 60minutes. The removal rate of COD decreases with the increasing of initial concentration of the parathion pesticide wastewater. Secondly, for ultrasound enhancement ozonation, the removal of COD increases with the increasing of ozone inflow, but the removal efficiency will not varied with the change of ozone inflow when the inflow reaches a certain quality(such as 400mg/h). The removal rate of COD of wastewater is 65.8 percent when the pH value is equal to about 10.22. The removal rate of COD of wastewater decreased with increasing of the initial concentration of the parathion pesticide wastewater. And there is little effect on the degradation of the parathion pesticide wastewater by ultrasound alone (the frequency is 59 kHz). The removal efficiency of pesticide wastewater is contrasted on ozonation and ultrasound Ultrasound/Ozone. It shows that the degradation reaction is more quickly when the ultrasound is added. When the other conditions are the same, the removal rate of pesticide wastewater is only 46.9 percent with ozonation while the rate is 65.3percent by Ultrasound/Ozone.At last, it was investigated that Ultrasound/Ozone time influenced on the biological treatment, and the optimum Ultrasound/Ozone time were acquired. The results show that the high concentrations of COD 1221.5 mg/L for parathion pesticide wastewater, Ultrasound/Ozone 20 min, then to conduct the follow-up of biological processes, the total removal of COD of wastewater is 79.9 percent. Meanwhile, the experimental results also demonstrate that it is possible to combine Ultrasound/Ozone with conventional biological treatment for the remedy of wastewater containing generally non-biodegradable organophosphorus pesticides.