Potential reduction in nutrient leachability from sewage sludge applied in land reclamation

The paper deals with the release of nutrients and organic carbon from sewage sludge applied in land reclamation within BREF/IPPC recommendations for tailings and waste rock management. The contents of Ntotal and Ptotal in the sludge leachate exceed the pollution standards of permissible surface water pollution according to Government Decree 229/2007 Coll. Adding 10% of kaolinite and bentonite significantly decreases the leachability of Ptotal; the adsorption efficiency reached 83% in kaolinite and 88% in bentonite. During oneweek stabilization of sludge there was a substantial decomposition of organic compounds, which resulted in a rise in the contents of Ntotal and dissolved organic carbon in the leachate. The content of Ntotal in the leachate increased by a half, in the dissolved organic carbon (DOC) it rose by 2/3. At higher concentrations of Ntotal and DOC in the leachate the efficiency of adsorption of kaolinite and bentonite is higher. The effect of additives on the base of clay minerals did not manifest in the form of reduced ecotoxicity of the sludge leachate.