Study On The Advanced Treatment And Combined Treatment Process Of Phenol/acetone Production Wastewater

The production of phenol and acetone discharges a high concentration of wastewater,which is strongly alkaline and contains a large amount of refractory organic matter.After pretreatment,the salt concentration is high,which is adverse to biological treatment.In this study,the bioreactor and continuous-flow Fenton oxidation were combined into a biologicaltreatment-Fenton-oxidation process to carry out the pilot study of phenol/acetone wastewater treatment,and the main conclusions were as follows.With the bioreactor,coventional activated sludge from industrial park wastewater treatment plant were used as inoculant.After one month of acclimation through salinity increase step by step,the activated sludge could adapt the high salinity of the wastewater.The chemical oxygen demand(COD)in wastewater could be reduced from 2000~2400mg/L to below 180mg/L and the effluent COD was mainly soluble COD.The semi-volatile organic compounds that can be extracted with dichloromethane and aromatic compounds detected by three dimensional fluorescent spectrums could be removed significantly.After one month of stop operation,Bioreactor could recovery to normal level in one week,which could meet the maintenance requirement of the phenol/acetone installation.Main families in the bioreactor were Acidobacteria Subgroup 4 Unknown Family,Anaerolineaceae,Xanthomonadales Incertae Sedis,Saprospiraceae,Nitrosomonadaceae,etc.,which were siginificantly different from those of inoculated sludge.The batch test of Fenton-flocculation was carried out to treat the biological effluent of phenol/acetone wastewater with COD of 140~170 mg/L.The biological effluent was treated by Fenton oxidation first,and then PAM was added to promote the settling of Fenton sludge.The results indicated that under the optimized conditions(Fe SO4·7H2O 1g/L,30% hydrogen peroxide solution 1m L/L,reaction time of 60 min.p H adjustion to about 7 after the reaction),dosage of 4mg/L PAM could significantly improve the sedimentation of Fenton sludge.The Fenton oxidation process was verified and optimized by continuous-flow Fenton reactor.Hydrogen peroxide dosage,ferrous sulfate dosage and wastewater p H had significant effects on the treatment efficiency.When hydrogen peroxide dosage was 1m L/L(30% hydrogen peroxide solution),Fe SO4·7H2O dosage was 1g/L,the retention time was 60 min or more,effluent COD could meet Emission standard of pollutants for petroleum chemistry industry(GB 31571-2015).The semi-volatile organic compounds detected in the biological effluent were removed effectively.The continuous experiment of the biological-treatment-Fenton-oxidation process was carried out to verify the stability of the combined process.When the influent COD was 2100~2450mg/L,the combined treatment of biological treatment and Fenton oxidation was carried out under the optimized conditions(biological treatment reactor temperature 20 ~ 30 ?,HRT = 48h;Fenton treatment Fe2SO4·7H2O dosage 1g/L,30% H2O2 dosage 1m L/L,HRT = 60min),the average COD removal rate of biological treatment was 92.15%,the average removal rate of Fenton oxidation was 73.81%,and the effluent was stable to COD special emission limit(50mg/L)in Emission standard of pollutants for petroleum chemistry industry(GB 31571-2015).The total cost of the process per m3 wastewater was ?13.96,including ?8.00 for neutralization,?2.41 for biological treatment and ?3.55 for advanced treatment.