Methodology for evaluation of hazards from solid waste and landfill generated leachate

Abstract: A methodology based on an analytical protocol for evaluation of hazards from landfill leachate and solid waste is described. A dynamic analytical protocol, the LAQUA protocol, including measurements of inorganic and water-quality parameters, polar and non-polar organic marker compounds, and toxicity, was constructed. An acute toxicity test, using the brackish water crustacean Artemia salina as test organism, was developed. The methodology was applied to authentic problems such as investigation of different treatment techniques for landfill leachate, evaluation of leaching tests and characterization of solid wastes, and an investigation of a filter material aimed for leachate treatment. Investigated treatment methods comprised in all cases pre-treatment by aeration combined with sedimentation, followed by one of: bioremediation, ozonation, chemical oxidation by Fenton’s reagent, or geo-bed filters. Evaluated filter materials were mixtures of natural or residual waste products. A combination of pre-treatment followed by a geo-bed filter containing a mixture of peat and carbon-containing ash gave an efficient simultaneous removal of metals and organic pollutants. The performance of two leaching tests for characterization of solid waste, the up-flow percolation test (SIS-CEN/TS 14405:2004) and the batch test (SS-EN 12457 -3), was investigated. Solid waste materials (sludge from street gutters and fragmented metallic waste) were characterized using leaching tests and the hazards of the materials were evaluated in the eluate, obtained at specific liquid-to-solid ratios (L/S). The L/S 2 and L/S 10 values were compared with limit values included in the waste acceptance criteria (WAC). The analyses were extended towards specific organic compounds, such as individual phenolic compounds and polychlorinated biphenyls (PCB). Organic compounds were found in eluates from both types of tests, showing the possibility to use these methods to evaluate the leaching of such compounds from waste materials. The use of authentic leachate as leachant, leads to increased concentrations of heavy metals in the eluate, compared to the prescribed use of demineralised water as leachant. Generally good agreement was found between the results of the two leaching methods. A strategy based on batch tests is described for investigation of a filter material for leachate treatment. Batch tests gave suitable information about the leaching from new and used material, and showed high removal efficiencies of metals and non-polar organic compounds. However, for investigation of removal of polar organic markers (e.g. phenolic compounds) a batch test is not sufficient and should be supplemented by a column test.