Treatment Of Pesticide Wastewater By Potassium Persulfate Oxidation Technology

The pesticide wastewater produced during the production and use of pesticides is a serious hazard to the ecological environment and human safety.The hydroxyl radicals generated by the conventional advanced oxidation method have certain limitations,while the sulfate radicals have the advantages of strong oxidation and long half-life,so the new peroxynitrite oxidation method is attracting attention.In this paper,the effects of different activation methods to activate potassium persulfate for pesticide wastewater treatment were investigated with trichlorfon and bifenthrin as the research objects.The main findings and results are as follows:（1）Thermal activation of potassium persulfate was used to degrade trichlorfon simulated wastewater（COD=700 mg/L）,and the effects of different factors on the degradation rate and related kinetics were discussed.Both increasing the amount of potassium persulfate and decreasing the p H could promote the thermal activation,and the reaction rate increased significantly with the increase of temperature.The degradation rate reached 80%when the reaction temperature was 80℃at a potassium persulfate addition of 13.5 g/L until 3 h.The effect of Fe²⁺was investigated on the basis of thermal activation.When the concentration of Fe²⁺was 1 mmol/L,the reaction temperature was 80℃,and the reaction rate reached 98.8%when the reaction reached 3 h.（2）Thermal activation,Fe⁰/thermal combined activation and Al⁰/thermal combined activation of potassium persulfate were used to degrade trichlorfon simulated wastewater（COD=3600 mg/L）,and the effects of different factors were discussed.Fe⁰/thermal combined activation and Al⁰/thermal combined activation were significantly better than thermal activation.Al⁰/thermal combined activation was more effective and the reaction rate was greater in the early stage of the reaction;however,the reaction rate was slower in the later stage,resulting in a lower final degradation rate than Fe⁰/thermal combined activation.（3）Firstly,chemical flocculation was used to treat bifenthrin simulated wastewater.The results showed that increasing p H to 12 or decreasing p H to 2 could promote flocculation,while the effects of temperature and PAC/PAM dosage were relatively small.Then Fe⁰/thermal combined activation of potassium persulfate was used to treat the post-flocculation wastewater,and the results showed that the alkaline environment was unfavorable to degradation,and increasing the amount of iron powder could improve the reaction rate.The higher the temperature,the greater the reaction rate.The degradation rate reached 96.6%at the reaction temperature of 80℃,zero-valent iron dosage of 1 mmol/L and the reaction up to 4 h.