Experimental Study On The Pretreatment Of Sudden Aniline Pollution In Water And Engineering Emergency Disposal

In the explosion accident of a chemical industrial park in Jiangsu in 2019,the concentration of aniline compoundsin the heavily polluted river reached 50⁷0mg/L and COD_Cr was about 600mg/L,which exceeded the bearing capacity of the original sewage treatment system in the park.Therefore,pretreatment was needed to meet the water quality requirements of the original sewage treatment system.This paper is divided into two parts:pretreatment experiment and practical engineering emergency response.Three methods,including chlorine dioxide oxidation method,ozone oxidation method and Fenton oxidation method,were selected in the pilot test of pretreatment,and were compared and analyzed to select appropriate methods to guide the implementation of emergency disposal.The main work is as follows:The removal of aniline compounds and CODcr from polluted river water by chlorine dioxide oxidation process was studied.The influence of initial pH,chlorine dioxide dosage and reaction time on the treatment effect was studied by single factor experiment.On the basis of single factor experiment,the orthogonal experiment was carried out.The experimental results showed that:The treatment effect was best when the initial pH was5,the dosage of ClO₂ was(COD_Cr)/?ClO₂?mass ratio 3:1,and the reaction time was 90 min,of which the aniline compounds and CODcr decreased to2.11mg/l and 279mg/L respectively at room temperature,and the removal rates were 96.5%and 54.5%.The removal of aniline and CODcr from polluted river water by ozonation was studied.The influence of initial pH,ozone dosage and reaction time on the treatment effect was studied by single factor experiments.The experimental results showed that:The treatment effect was best when the initial pH was 9,the dosage of O₃ was(COD_Cr)/?O₃?mass ratio 10:6,and the reaction time was 60 min,of which the removal efficiency of aniline and CODcr decreased to 0.67mg/l and 370mg/L respectively,and the removal rates were 96.5%and 37.2%.The removal of anilines and CODcr from polluted river water by Fenton oxidation method was studied.Based on single factor experiment,orthogonal experiment was carried out to study the treatment effects of initial pH,?H₂O₂?/(Fe²⁺)molar ratio,H₂O₂ and Fe²⁺dosages and reaction time of polluted water.The experimental results show that:The treatment effect was best when the reaction time was 60 min,initial pH was 5,the?H₂O₂?/(Fe²⁺)molar ratio was 8:1,and the dosage of H₂O₂ was(COD_Cr)/?H₂O₂?mass ratio 1:2,and the concentration of aniline compounds was not detected and the removal rate over 99.9%,the concentration of COD_Cr was reduced to 119 mg/L and the removal rate is 79.6%.Considering the treatment effect,process conditions and treatment cost of the three treatment methods,Fenton oxidation method was selected to guide the emergency treatment of field engineering.The main structures were transformed accordingly and the emergency disposal plans which were designed according to the actual conditions were as follows:ferrous sulfate solution and 27.5%hydrogen peroxide were added on both sides of the modified Fenton oxidation sedimentation tank,and the roots blower is used to aerate and stir?air water ratio 5:1?.The operation parameters of emergency disposal are as follows:dosing quantity of the ferrous sulfate heptahydrate was 1.7 kg/m³ and 27.5%hydrogen peroxide solution was 5.5L/m³,and aeration stirring time wasincreased to 3h.The concentration of aniline compounds was reduced to 0.30⁰.75mg/L and the concentration of COD_Cr was reduced to 264³25mg/L in the effluent after operation,meeting the water quality requirements of the original treatment system in the park.