Agronomic effects of land application of water treatment sludges

Economic, regulatory, and legal constraints on alternative disposal methods are raising interest in land application of water treatment sludges. Understanding the agronomic and environmental issues is essential before a land-based disposal program is implemented. Water treatment sludges may favorably modify the pH and water-holding capacity of soils but generally have little fertilizer value. Supplemental phosphorus (P) fertilizer will usually be needed to offset the strong P-binding capacity of these sludges. Heavy metal concentrations can be limited in sludges primarily by controlling the purity of the coagulant chemicals. This paper discusses these issues.