Water Treatment Residuals for Immobilizing Phosphorus in Surface and Ground Waters.

Water treatment residuals (WTRs) are environmentally benign byproducts from purification of water supplies for potable or industrial uses.  Because Al and Fe salts are commonly used to remove turbidity and color from source waters, WTRs contain reactive hydrous Al and Fe oxides with P-fixing properties.  Methods employing WTRs to reduce P loss from agricultural land include: (1) incorporation into soils with excessive soil test P, (2) Co-blending with nutrient sources, and (3) buffers or barriers to intercept P in surface or ground water flows.  Effective application rates and methods remain an area of intense research.  Large-scale implementation of WTRs for controlling off-site P losses to sensitive water bodies is hindered by state regulations, inability of P indices to credit their use, and insufficient supplies of locally available WTRs.