Case background: 1. Design capacity: 30m3/h2. Water Properties: Source: the bottom water drained from Crude Oil Storage Tank.Feed Water Characteristics:(before treatment)High oil content; High degree of mineralization; High total hardness.Thread Water Characteristics:(after treatment) The water property shall meet all the standard of client’s requirement.Water disposal after treatment:As the client's requirements, the treated water will be send to evaporation pond, re-injected back into the borehole or reuse after sterilization.Technical Treatment Process Selection:Compare the original waste water with the treated water, we find that the original waste water is with high oil content, high degree of mineralization and high total hardness. So the key points of this waste water treatment process are: remove oil, reduce hardness and desalination.Remove oil: According to the original waste water property and our analysis, our proposal is using second level gravity oil remove and pressure filtering.Reduce Hardness: According to our analysis, the Lime Softening and Na-ion exchange reactor system will suitable for this job.Desalination: According to our analysis, we choose mechanical evaporation compression process (MVC) for the desalting process. Project Proposal:Firstly, the waste water shall be treated by follow the three steps(remove oil, reduce hardness and desalination) as we propose, then the water come out will meet all the standard of the client’s requirement. According to the Client’s requirements, the treated water will run into the evaporation pond through pipeline, be re-injected back into borehole through pumps or reuse after sterilization.