Study On The Treatment Of Wastewater From The Production Of 2-Nitro-4-Anisole By Lime Coagulation

There are a great variety of dye intermediates.The wastewater with high Chroma and toxicity from the production of dye intermediates is complex and difficult to deal with.Treating this kind of water is of concern among the whole industry.2-nitro-4-Acetylamino-methyl-phenoxide(AMA)is one of the dye intermediates.A large number of by-products,mainly 2-nitro-4-methoxyaniline and3-nitro-4-methoxyaniline,are produced in the process.At the same time wastewater also contains a lot of sulfuric acid and acetic acid,resulting in a high acidity.This project takes the wastewater of a dyeing factory as the research object.In this paper,the production wastewater of 2-nitro-4-acetylaminoanisole was pretreated by lime coagulation method,and the coagulation treatment after Fenton reaction was carried out.Single factor experiments,orthogonal experiments and response surface experiments were used to study the effects of calcium oxide particle size,reaction agitation intensity and sedimentation time on the removal efficiency of pollutants in pretreatment.The effects of pH,coagulants such as polyaluminium chloride(PAC)and polyacrylamide(PAM)on sedimentation and removal were also investigated,in order to obtain the best conditions of the pretreatment and deep coagulation process of the wastewater,improve the treatment effect and reduce the processing cost.In the pretreat experiment,the optimum reaction conditions were as follows: the diameter of calcium oxide was 200 mesh,the stirring intensity was 1100 r /min,and the precipitation time was 90 min.The concentration of 2-nitro-4-methoxyaniline was reduced from 446 mg/L to 240.4 mg/L,and the removal rate was 46.1%.The concentration of 3-nitro-4-methoxy-aniline dropped to 1149 mg/L,with the removal rate of 14.1%.The color dropped to 7461 times,the removal rate of 17.1%.In the Fenton effluent coagulation treatment experiment,the optimum reaction conditions were as follows: the dosage of PAC was 1.15g/L,the dosage of PAM was0.018g/L,and pH was7,2-nitro-4-methoxyaniline and 3-nitro-4-methoxyaniline concentrations were reduced to 25.38 mg/L and 36.41 mg/L,respectively.The removal rates of 2-nitro-4-methoxyaniline and 3-nitro-4-methoxyaniline were 74.1%and 64.3%,respectively.