A Study On The Degradation Of Organophosphorus Pesticides By Hydrolysis And Ozonation

In this paper,the characteristics of organic phosphorus wastewater and its the treatment methods are introduced.The focus of this work puts on the degradation of organophosphorus pesticides by hydrolysis and ozone-based advanced oxidation techniques.The effect of different reaction conditions on the hydrolysis of organic phosphorus was explored.(Ti???catalyzed O₃/H₂O₂ was used to study oxidation of organophosphorus pesticides by hydroxyl radicals under acidic conditions.The toxicity of organophosphorus wastewater after treatment was also tested.First,organic phosphorus wastewater was treated by hydrolysis.It was found that hydrolysis of organophosphorus proceeded better under acidic condition than alkaline conditions,And the higher the temperature,the higher the hydrolysis efficiency.The addition of KMnO₄ could promote the release of organic phosphorus.Orthogonal experimental results showed the optimized parameters for hydrolysis of organophosphorus pesticides are listed as the following:temperature 80°C,pH 3,the best time for 9 hours.Struvite stone was synthesized using the treated organic phosphorus wastewater as P source.Second,the degradation of methyl parathion?abbreviated as MP?was carried out using ozone-based advanced oxidation technology.The results of the ozonation treatment of MP in different pH conditions indicated that although MP could be degraded within 5 min,phosphorus release rate of MP and COD removal efficiency under alkaline solution were greatly better than those in acidic solution.O₃/Ti???/H₂O₂ treatment also had higher COD removal and organic phosphorus release efficiency at pH 3.3.The rate constants of MP with ozone and?OH radicals were determined to be 31.98 L??mol?s?^-1 and 7.488×10⁹ L??mol?s?^-1 by the relative method.The results of the activated sludge test showed that the oxidative reaction of hydroxyl radicals could significantly improve the biodegradability of MP-containing wastewater.Finally,the degradation of methamidophos?MMD?by the ozone and ozone-based advanced oxidation technology,MMD is not a aromatic compound with a double-bond.The results indicated that MMD could be completely degraded in 5min in different pH conditions.At pH 3.3,the O₃/Ti???/H₂O₂ treatment also had higher COD removal rate and organic phosphorus release efficiency.The results of activated sludge test shown that pretreatment could increase the biodegradability of MMD-containing wastewater.Based on the above analysis,organic phosphorus wastewater could be degraded by hydrolysis,but the release rate of organic phosphorus was not good.To effectively degrade organophosphorus compounds,it is necessary to use advanced oxidation techniques.These results are significant for the effective pretreatment of organophosphorus wastewater.