Study And Application On Treatment Of Pesticide Wastewater By Combined Process Of Multi Effect Evaporation-Mrico-electrolysis-Fenton-VTBR-Fenton Technology

Pesticide wastewater is the general name of the pesticide production wastewater.It is a comprehensive wastewater,which mainly originates from production and processing processes of herbicides,insecticides,fungicides,and other pesticides,and which contains a lot of refractory organic pollutants generated during these processes,and which contains large amounts of suspended pollutants,has relatively higher colourity and salinity,and possesses very strong biological toxicity.Aiming at the characteristics of this kind of wastewater,the conventional water treatment processes have poor treatment effects and high treatment costs.In this paper,the comprehensive treatment is explored by conducting effective combination of multiple-effect evaporation,Fe-C micro electrolysis-Fenton oxidation,VTBR,deep oxidation treatment technologies through experimental investigations.The reasonable combination of the wastewater treatment process is conducted on the basis of salinity change,CODcr removal rate,B/C change,treatment costs,etc.The optimal operation controlling parameters of the processes are determined,so that the scientific data bases are provided for the engineering designs.Through production and operation commissioning of the engineering designs,the feasibility of the combination technology for the wastewater treatment of Kuaida Agrochemical has been effectively proved,and meanwhile,it provide theoretical references for the treatment of the similar wastewater.In this paper,it has been proven by experiments that organic amine salts can be effectively retained through aiming at the water quality characteristics of pesticide production wastewater of Kuaida Company,adopting the desalting technology of the multiple-effect evaporation,and carrying out desalting by evaporating under acidic conditions.Compared with the conventional evaporation technologies,the total nitrogen content in the evaporated liquid drops from 400 mg/L to 140 mg/L,and the ammonia nitrogen load in the downstream sections is reduced.Through experiments,the optimal initial pH,the chemical dosage,the reaction residence time,and so on are explored respectively for pretreating the pesticide production wastewater with the combination technology of O₃ oxidation,O₃/UV catalytic oxidation,micro electrolysis,Fenton oxidation,and micro electrolysis-Fenton oxidation.The feasibility and efficiency of pretreating pesticide wastewater with the micro electrolysis-Fenton oxidation combined process are proven by taking into account of COD removal rate,B/C changes,and treatment operating cost,and other aspects.They provide references and scientific data bases for the industrialized treatment of pesticide wastewater.Under the condition of initial pH of 3,hydrogen peroxide solution dosage of 10 mL/L,the highest CODcr removal efficiency can reach 51.7%,and the B/C of wastewater can be increased to0.37,and the wastewater treatment cost per ton is 11.47 Yuan/Ton.It has been determined by experimental researches that the domestication time of biochemical VTBR process is about 60 days,and the removal rate can reach more than 80%,and it meet the demand of engineering design.It has been proven by the experiment researches:For the pesticide production wastewater of Kuaida Company,when the salinity exceeds 20,000 mg/L,it will cause larger inhibition on the removal ability of microorganism,and the CODcr removal rate is reduced from 85.4%to below 60%.The feasibility adopting Fenton oxidation technology to serve as the advanced oxidation treatment technology of such wastewater is explored through experiments.Meanwhile,the linear relationship between the Fenton oxidation chemical dosage and CODcr removal quantity is researched for the Fenton oxidation serving as the final advanced treatment.It is obtained that the mass ratio of the hydrogen peroxide solution dosage and the CODcr removal quantity is about 2:1.In this paper,it has eventually been proven that:After the multiple-effect evaporation-micro electrolysis-Fenton oxidation-VTBR-Fenton oxidation combined process is adopted to treat the pesticide production wastewater of Kuaida Company,the CODcr removal rate of the wastewater can reach more than 98.3%,and various water quality indicators of the effluent water meet the requirements of emission standards.In addition,this process design is put into production and operation,and the engineering project has been being stably operated,and the effluent water comes up to the standards.