The adsorption characteristics of activated alumina treated with aluminum sulfate were studied to develop a new removal process for low concentration phosphorus in the waters of rivers and lakes. The equilibrium study showed that the adsorption capacity was enhanced about 1.7-fold by treating with aluminum sulfate. The effective intraparticle diffusion coefficients, determined by the Boyd's method based on batch runs, were hardly affected by such a low phosphorus concentration as observed in the water of rivers and lakes under investigation. The temperature dependence of the intraparticle diffusion coefficients based on the concentration in solid showed the activation energy of 29.7kJ·mol−1, which was a little higher than that in usual pore diffusion. The maximum continuous operation term (regeneration cycle) of the present phosphorus adsorption system was estimated. Under the conditions of influent phosphorus concentration of 0.1 g·m−3, removal extent of 90%, particle size of 2 × 10−3m, temperature of 298K and space velocity of 1.39 × 10−3s−1 (5h−1), the present removal system remained effective for about 500 days.