Dear Oksana, Now probable ...

Dear Oksana,

Now probable you are aware of the solution. Most of the earlier answers are close to the correct solution. First step will be to get the testing report of the wastewater sample if available. Generally these wastes are characterized by high COD and low COD to BOD ratio meaning that the wastes are less biodegradable. I will suggest treatment plant comprising Oil and grease separator (followed by DAF if emulsified oil is present), Equalization tank, Clariflocculator, Biological treatment like activated sludge process followed by tertiary treatment in the form of pressure sand filter, activated carbon filter and chlorination. The degree of treatment also depends on whether you want to dispose the treated waste in sea or reuse it. I hope you are satisfied with the answer.