| 'China is not only a country with water resource shortage but also a country with serious surface-water pollution. Industrial wastewater is one of important factors influencing surface water environment. And refinery wastewater is one of industrial wastewaters, which is produced in the process of refining crude oil, processing and oil washing and so on. In recent years, China's petrochemical industry got rapid development, following the rising of refinery effluent emissions year by year. Refinery waste water can be used as reclaimed water after certain process treatment, which can not only improve the utilization rate of water resources, but also saving a lot of water. And mitigate the paradox of water shortage effectively.In this paper, the sewage treatment and reuse process of the company's first sewage treatment plant after transformation were researched at refining department of PetroChina Ningxia Petrochemical Company. And then, study on the wastewater treatment process and its properties of the second sewage treatment plant. Results are as follows:1) The main discharge-standard treatment process applied A/O2 after modification in the first wastewater treatment plant of PetroChina Ningxia Petrochemical Company. Operation shows that the process runs stably and pollutants removal effect is significant. After A/O2 process treatment, CODCr≤80mg/L, NH3-N≤10mg/L, petroleum<5mg/L, sulfide<0.3mg/L, volatile phenols<0.1 mg/L. Pollution indexes meet the requirements of the national emission standards. The removal efficiency of the process to CODCr are basically over 92%, to NH3-N are over 85%, to sulfide not below 89%, to petroleum and volatile phenols were both higher than 99%. In the process, for higher treatment effect, DO in section A must be controlled in the state of less than 0.5mg/L, DO in section O1 and O2 should be kept in 3mg/L, temperature should be between 20-30℃, pH should be between 6.5-8, C:N:P is 100:5:1. The process can remove CODr, nitrogen and phosphorus simultaneously.The deep-treatment's applied BAF+multi-media filter+multilocular biological activated carbon filter. Its removal efficiency to CODCr and petroleum are over 60%and 45%respectively. Effluent water quality is stable. Petroleum is low the requirement of national emission standards and can totally meet the requirement of circulating cooling water of refining department. When BAF process, multi-media filter, multilocular biological activated carbon filter were combined in the deep-treatment of finery wastewater, SS, CODCr, BOD5, nitrogen and phosphorus can be removed effectively. With biological oxidation and removal of suspended solids combined in the same reactor is biggest advantage of it. It also can save the follow-up sedimentation tanks.2) The second sewage treatment plant took advanced treatment technology, which was the A/O+BAF+dual-membrane process. The process can adapt to changes of refinery wastewater quality and quantity. It has short water residence time and can save space occupied. At the same time, it can also resistance to shock load, was low investment, low energy consumption, and saving operating cost. Because application of the reuse device, high-quality recycled water could be recycled so that plant water consumption was reduced. And then the purpose of water conservation could be achieved. Those provide practical experience for Crafts choice of finery wastewater plants.
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