Design And Application Of Wastewater Treatment Project In Oil And Grease Processing Industry

With the rapid development of China’s economy,the scale of oil industry processing in China has been expanded year by year,and now it has become the first scale in the world.Environmental protection requirements are also increasingly strict.The upgrading of national and local standards,new and old sewage treatment stations of oil and grease enterprises will also face the upgrading of standards.It is an urgent problem for all oil and grease processing enterprises to combine a process that can meet the requirements of new standards,and also meet the needs of stable operation and cost reduction.The traditional wastewater treatment method of oil processing industry is relatively simple,and its discharge standard requirements are relatively simple and loose,and the effluent can meet the general standard requirements.However,for the production line,it is required that the hydration,degumming and soap removal are complete,the wastewater discharge standard is relatively strict,and the solid waste control is more and more strict,so the sludge treatment cost is higher and higher,As a result,the whole sewage treatment cost increases.In this paper,combined with the actual situation of the new project,referring to the requirements of the project EIA documents,through the investigation and study of several existing sewage station projects,it is found that the squeezing wastewater in the oil processing wastewater is easier to be treated,the difficulty of refining wastewater treatment is the key,the treatment of COD_Crand ammonia nitrogen is less difficult,and the biodegradability is better,which can meet the more stringent standard requirements,The difficulty lies in the treatment of total phosphorus in refining wastewater and the stabilization of biochemical indexes.Firstly,for the treatment of total phosphorus in refining wastewater,the effects of physicochemical treatment and biochemical treatment methods and soap content were explored.The physicochemical treatment method is demulsification and soap removal process.The soap containing hydrated phospholipids is converted into oil containing non hydrated phospholipids and then separated.Part of the remaining soluble phosphorus is removed by coagulation precipitation process;The upper limit of phosphorus removal capacity of biochemical system and the standard of phosphorus content in influent water were set.The activated sludge process with nitrogen and phosphorus removal capacity was selected.The phosphorus entering biochemical system was reduced to below 0.5 mg/L as much as possible by using the high-efficiency phosphorus release and absorption capacity of microorganism,and then micro phosphorus removal was carried out by coagulation sedimentation process to make it reach the standard stably.Secondly,aiming at the problem of the stable discharge of biochemical indexes,we should improve the conventional process and choose the ideal physicochemical treatment process on the basis of meeting the influent standard of biochemical system;The stability of the front-end physicochemical treatment effluent can ensure the normal operation of the biochemical system.In this paper,acid demulsification is used to remove soap and oil,and the soap and oil in the wastewater are treated first.At this time,the COD_Crtreatment efficiency can reach more than 90%,which can meet the requirements of the biochemical system,It can solve the problem of stable emission.Combined with the requirements of the above two aspects,this paper combines a new process,so that each link can meet the treatment of more indicators as much as possible.In the physical and chemical treatment process,soap removal,COD_Crremoval and phosphorus removal are combined.In the biochemical treatment process,activated sludge process which can remove both nitrogen and phosphorus is selected.Micro phosphorus is treated through the high-efficiency phosphorus release and absorption capacity of microorganisms;According to the strict treatment standard,the biological contact oxidation process and coagulation sedimentation process can be added in the follow-up process to avoid the biochemical problems of sludge bulking and difficult cultivation of microorganisms in the follow-up biochemical system caused by unbalanced or too low nutrients in the effluent from the front-end activated sludge process;Better guarantee the system’s stable emission,meet the needs of production.