| Coagulants such as alum, [Al2(SO4)3X14H2O], ferric chloride [FeCl3], or ferric sulfate [Fe2(SO4)3] are commonly used to remove particulate and dissolved constituents from water supplies in the production of drinking water. The resulting waste product, called water-treatment residuals (WTR), contains precipitated Al and Fe oxyhydroxides resulting in a strong affinity for anionic species. Recent research has focused on using WTR as cost-effective materials to reduce soluble phosphorus (P) in soils, runoff, and land-applied organic wastes (manures and biosolids). Studies show P adsorption by WTR to be fast and nearly irreversible, suggesting long-term stable immobilization of WTR-bound P. Because excessive WTR application can induce P deficiency in crops,... |
