Application of sewage sludge and other amendments to coal refuse material iii. effects on percolate water composition

The effects of sewage sludge, lime, and gypsum on the chemical composition of percolate from acidic coal refuse material was studied at a Fulton County, IL, land reclamation site. Treatments consisted of a control, 542 dry Mg ha⁻¹ anaerobically digested sewage sludge, 89.6 Mg ha⁻¹ lime, 112 Mg ha⁻¹ gypsum, and combinations of these amendments. The chemical composition of the percolate collected monthly (1976 to 1980) from suction lysimeters at a 1-m depth reflected the treatments applied to the coal refuse material. Percolate pH, NH⁺₄-N and [NO⁻₃ + NO⁻₂]-N levels were lowest in either the gypsum or control treatments and highest in the sewage sludge treatment. Percolate SO₄ levels were lowest in either the control or sludge-amended treatments and highest in the gypsum-amended treatments. Levels of NH⁺₄-N and [NO⁻₃ + NO⁻₂]-N in percolating waters from the sludge-amended treatments declined with time, while P levels remained at 5 yr) reclamation, the effectiveness of the sludge and sludge + lime treatments would be better maintained by applying more sludge (1050 Mg ha⁻¹) and (900 to 1350 Mg ha⁻¹) + lime (134 to 189 Mg ha⁻¹) initially. The factor of two difference between the theoretical and actual amounts of lime and sewage sludge needed in the field suggests that an added safety factor of one and a half to two for application of these amendments is desirable for long-term reclamation of coal refuse material. Contribution of the Res. and Development Dep., The Metropolitan Sanitary District of Greater Chicago, Chicago, IL 60611.