ABSTRACT In order to eradicate the chances of sea and land pollution, Arabian Oil Company have introduced wastewater treatment facilities and disposal well injection system, where this system will treat different kinds of oily contaminated industrial wastewater and produce a quality of water which can be readily disposed of into a chosen subsurface formation. With all the difficulties that would have been expected for treating different kinds of incompatible wastewater, the system have been started up and put into service successfully since October 1979.