Treatment of 2-phenylamino-3-methyl-6-di-n-butylaminofluoran production effluent by combination of biological treatments and Fenton's oxidation
Treatment of 2-phenylamino-3-methyl-6-di-n-butylaminofluoran production effluent by combination of biological treatments and Fenton’s oxidation

High strength refractory organic stream is produced during the production of 2-phenylamino-3-methyl-6-di-n-butylaminofluoran (One Dye Black 2,abbr.ODB 2),a novel heat-sensitive material with a promising market.In this study,a combination of acidification- precipitation,primary biological treatment,Fenton's oxidation and another biological treatment was successfully used for the removal of COD from 18000-25000 mg/L to below 200 mg/L from the ODB 2 production wastewater in a pilot experiment.A COD removal of 70%-80% was achieved by acidification-precipitation under a pH of 2.5-3.0.The first step biodegradation permitted an average COD removal of 70% under an hydraulic residence time (HRT) of 30 h.By batch tests,the optimum conditions of Fenton's oxidation were acquired as:Fe~(2 ) dose 6.0 mmol/L;H_2O_2 dose 3000 mg/L;and reaction time 6 h.The second step biological treatment could ensure an effluent COD below 200 mg/L under an HRT of 10 h following the Fenton's treatment.