Alum control of internal phosphorus loading in a municipal river sediment

Precipitation and inactivation of phosphorus(P) by the addition of aluminum (AI) is a widely applied sediment restoration measure. Laboratory experiment with sediment from municipal river was conducted to evaluate the effects of poly-aluminum chloride with different adding means. Adding poly-aluminum chloride doesn´t remarkably influence pH. At the same time Al³⁺ concentration is less than 50 ug·L^-1. Spraying poly-aluminum chloride also can prohibit phosphorus release from sediment. But disturbance (wind, storms, etc) will destroy alum floc layer. The restoring effect will be weakened by disturbance. It can restrain phosphorus release from sediment for long time by means of injecting poly-aluminum chloride into sediment. Injection means is one of the best scheme.