The Research Of Reaching Standard Emission Of Saline Wastewater For An Oil Refinery

In April 2015,Environmental Protection Department made more rigorous emission standard of pollutants for petroleum refining industry.During the period of sole treatment of saline wastewater for an oil refinery,the indicators such as oil content,COD,NH₄-N and TN failed to reach the discharge standard.This paper presented“source control,process intensification and reasonable addition”new ideas for the reaching standard emission of saline wastewater,providing data support and modification opinions for the technical renovation and actual operation results of existing saline wastewater treatment system.Founding in the survey of saline wastewater treatment system,the large fluctuation of water quality and quantity of electric desalting water,low oil pollutants removal rate of physico-chemical treatment system and short biochemical treatment system are main causes of saline wastewater treatment being not up to standard.Aiming at the problems of saline wastewater,such as high oil content and large fluctuation of oil content,this paper presented the oil removal technology of static precipitation for electric desalting water of reversely washing and demulsifying removal oil technology of ozone strengthening flotation.?1?Oil removal technology of static precipitation for electric desalting water of reversely washing:added homogeneous precipitation tank,and transformed the original electric desalting water treatment technology into from sewage pipeline,precipitation tank,tank within tank,oilseparating tank,to flotation tank.?2?Demulsifying removal oil technology of ozone strengthening flotation:when effluent oil content is 25⁶0mg/L in the primary flotation,COD concentration is 700¹000mg/L,pH value is 6.5,cationic flocculant-PAM is 1mg/L and reaction time is 1h,the best additive quantity of ozone is 30mg/L,the average of effluent oil content is below12mg/L,oil removal rate is over 60%,and removal COD is more than 60mg/L.After saline wastewater of refinery was processed by the latest modification saline wastewater treatment system“ozone strengthening flotation,anaerobic biological bed,moving bed biofilm reactor,anoxic/oxic,secondary sedimentation tank,and biological aerated filter”,oil content,NH₄⁺-N and TN of effluent wastewater could reach emissions requirements of emission standard of pollutants for petroleum refining industry“GB31570-2015”,but effluent COD could not reach completely discharge standard.The paper suggested that explores the optimum operation parameters of each processing units in detail to ensure effluent COD can reach absolutely discharge standard.