Study On The Treatment Of Aniline Pesticide Wastewater With Fenton-Anaerobic Reactor-BAF Process

Nitrobenzene monoamine pesticide is the general designation of lots of pesticidevariety,including dibutalin,trifluralin,pendimethalin trifluralin,which is mainly used as a herbicide.In its production and purification process,a large amount of high COD concentrations,high-SS,chroma,high salinity and bio-inhibitory wastewater are discharged.According to the properties of such wastewater,we used advanced oxidation-anaerobic-aerobic combined process to treat the nitrobenzene pesticide wastewater.Take COD,SS,chroma as the key indicators to the treatment effect on processing unit and combined process.Pretreatment section inspected the Fenton's dosage,initial reaction pH,reaction time and other techniques and operating conditions.It was found that nitrobenzene oxidation Fenton monoamine pesticide wastewater,the treatment had obvious effect.COD removal rate reached 78%and above,there was a marked improvement in color which was from deep brown into pale yellow.Through several single factor experiments,it was identified that Fenton's reagent dosage and optimal reaction conditions;pH = 4,H₂O₂ dosage of 20 mL/L,FeSO₄·7 H₂O dosage 1 g/L,stirring for 30 minutes,static response for 2 hours.Pretreated wastewater by Fenton reagent and comprehensive wastewater were mixed into biochemical unit.Anaerobic sewage sludge seeded anaerobic reactor and operated in a low organic load.Start-up period,COD volume loading increased from 0.8 kgCOD/(m³Â·d)to 1.5 kgCOD /(m³Â·d)above,and completed within one month.The biodegradability of effulent wastewater was significantly improved,meanwhile the COD and color decreased.During normal operation of reactor,study on the in-fluent COD,the effluent COD concentration and volume loading could be found reactor COD volumetric loading changed with the charge of COD concentration changes,the removal of COD had significantly positive correlation with COD volume loading.When influent COD＞350mg/L,the effullent COD from anaerobic reactor was less than 200mg/L and COD removal rate was above 50 per cent.When influent concentration was 300 mg / L,COD removal efficiency significantly decreased,the effluent COD was close to 250 mg/L, minimum removal was only 15%to 20%.When the HRT=12h,the effluent water quality through BIOFOR aerobic degradation could meet the first discharge standard(GB8978-1996),effluent COD＜100mg/L,SS＜70mg/L,color＜50,pH=6～9.