| The wastewater of pharmaceutical industry park from the upstream pharmaceutical enterprises after biological treatment has poor biodegradability.The wastewater was pretreated by four more mature treatment methods: Fe-C micro-electrolysis,ozone oxidation,coagulation sedimentation and Fenton oxidation.The best pretreatment process was determined by the experiments,to reduce COD concentration and improve the wastewater biodegradability.According to the pretreatment experiment,the Fenton oxidation showed the best performance: When the influent COD was 280 mg·L-1,the effluent COD was 120 mg·L-1 and the removal rate was about 60%.The B/C ratio of wastewater increased from 0.10 to 0.45.After pretreatment by Fenton oxidation,the wastewater was treated by the MBR system.The influence of hydraulic retention time,dissolved oxygen and MLSS was investigated in the MBR system.The results indicated that when MLSS was 6000mg·L-1,DO was 2.5mg·L-1,HRT was 18 h,and influent COD concentration was 110~120mg·L-1 for MBR system,the effluent COD concentration was50~60mg·L-1 and the COD removal rate was about 50%.Then ozone oxidation was used to treat the wastewater further after MBR treatment,to ensure the effluent meet the requirements of the first level A standard in the "pollutant discharge standard of urban sewage treatment plant"(GB18918-2002).When the ozone dosage was 20 mg·L-1,pH was7.5~8,influent COD concentration was 50~60mg·L-1and the contact time was 0.5h in ozonation treatment,the effluent COD concentration was 36~46mg·L-1,being lower than50 mg·L-1.The effluent COD concentration has met the requirements of the first level A standard in the "pollutant discharge standard of urban sewage treatment plant"(GB18918-2002).According to the parameters determined by the above experiments,a project with treatment capacity of 50,000 t·d-1 was designed,including main treatment units and equipments.The design study providing reference for similar pharmaceutical industry park Sewage treatment plant. |
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