UTILIZATION OF WATER TREATMENT RESIDUAL MATERIAL TO BIND INORGANIC PHOSPHORUS

The U.S. livestock industry in many states has large confined animal populations in limited geographic areas. This trend has resulted in a concentration of manure production and the possibility of over-application of manure to soils. Over-application of manure may result in an accumulation of soil phosphorus (P) much higher than crop P nutrient requirements. Incidental losses of P from fields with excess soil P concentrations into water bodies have raised environmental concerns about decreased water quality. P losses have been reduced from manure-treated fields using water treatment residual (WTR) material. Water treatment residual material consists of river sediments (silts and clays) that have been flocculated using alum [Al2(SO4)3] during drinking water purification processes. Alum-treated WTR material can effectively bind P because it contains Al-oxides. Our objective was to determine the inorganic-P sorption characteristics of WTR material and WTR material mixed with a Norfolk soil. The P sorption data were fitted to a Langmuir equation to determine P sorption maxima (Pmax) values. The WTR material had a high Pmax value of 215 mg P g−1. In contrast, the unamended Norfolk soil had a relatively low Pmax value of