| abstract |
Water discharged from a circulating cooling water system is treated by a water recovery system including a clarification equipment and an RO membrane, and treated water is returned to the circulating cooling water system. A dispersant is added to the circulating cooling water system for dispersing scale components. The dispersant includes a polymer having a carboxyl group and having a weight average molecular weight of 5,000 or less, and permeates through the clarification equipment. The polymer having a carboxyl group and having a weight average molecular weight of 5,000 or less permeates through the clarification equipment, and performs as a scale dispersing agent for the RO membrane, preventing precipitation of scale. Since the polymer intrinsically has an anticorrosion effect, it becomes unnecessary to add a phosphoric acid compound to the cooling water system as an anticorrosion agent, or the required amount of the compound to be added can be reduced. |