Abstract: In November 2002, a new facility at the Liaohe Oilfield in Liaoning Province, China was commissioned to treat 20,000 m3/day of produced wastewater. The aim of the process is to provide water quality which is suitable as feed water for the high pressure, once-through steam generators. The performance during the first 8 months of operation has been demonstrated. Due to the unique composition of the influent water and very strict treatment requirements, this process has been designed to overcome significant challenges . The process includes flow regulation tanks, skim tanks, DAF units, clarifiers, walnut shell filters, micromedia filters and WAC ion exchange softeners. In this paper the configuration of the system will be described. Emphasis has been placed on the new technology and equipment involved. Operating problems and the results of the more significant experiments and equipment trials will also be reviewed.