In a circulation treatment system and method for treating a fountain solution the amounts of BOD, COD, n-hexane and SS are reduced in the fountain solution to recycle the fountain solution without draining it off. Circulation passages are connected to a vessel of a dampening section of an offset rotary press via communication passages, and circulate a fountain solution by introducing the fountain solution in the vessel from an introducing port and discharging the fountain solution from a discharging port. In the course of the circulation passages is a line pump for forcibly circulating the fountain solution, a potential absorption filtering device using an absorbing effect of a zeta potential, and an activated carbon filtering device using an absorbing effect of activated carbon. Fine particles of ink, paper, oil or similar materials contained in the fountain solution are first absorbed and removed by the potential absorption filtering device and then the fountain solution is decolorized and deodorized by the activated carbon filtering device.