Abstract: According to the characteristics of the fresh water and the reused wastewater as well as the working conditions of circulating water system, an environmental friendly low-phosphorus treatment technology was developed. The technology was applied in the circulating water system of the refinery units for three months as the industrial experiments. The results showed that the average corrosion rate and the average adhesion rate of carbon steel test tube were 0.032 1 mm/a and 4.187 5 mg/(cm².month), respectively. The proportion of the reused wastewater in all make-up water was promoted to 77.23%. The mass concentration of phosphorus introduced by the water treatment agents was decreased by 70%. This treatment technology has shown remarkable economic and social benefits.

Key words: wastewater recycling, low phosphorus water treatment agent, corrosion, scale