I have looked at the other ...

I have looked at the other responses you have recd and none of them have suggested Electro-coagulation which is the technology developed by my research company to deal with "Frac" water out of the oil field.  This is a technology that utilizes consumable electrodes that we supply to you and we can maintain the system or train your personnel how to replace the electrodes.  I have numerous articles on this technology on the internet.  You can call me at 916-877-1553 to talk more about how to use this in your situation.  When the oil is in the water the technology removes it with an electric current and the oil comes out looking like small pieces of pepper.  We also remove up to 98% of the other contaminants in the water including metals.