Stabilization/Solidification of Noncombustible Industrial Waste by Asphalt Emulsions

Abstract

A procedure for stabilization/solidification of loose waste from the manufacture of Ni and Cd electrodes, which represents a nonutilizable and noncombustible hazardous waste, has been worked out. The procedure comprises solidifying the waste by means of an anionic slow-setting aqueous-asphalt emulsion with subsequent formation of an asphalt coating on the surface of solidified waste by spraying with an anionic rapid-setting aqueous-asphalt emulsion. This asphalt coating represents a secondary barrier against leaching of pollutants into the environment. Results of leachability tests with water (Czech Republic regulations) as well as with acetic acid (toxicity characteristic leaching procedure test, EPA) are evidence of the successful stabilization of given waste. Values of determined leachability parameters of test specimens prepared from stabilized waste are very favorable and, in addition, virtually the same as those of blank test. This demonstrates, in a convincing manner, efficiency of the developed stabilization/solidification procedure. Results have also shown the toxicity characteristic leaching procedure test is indispensable for the assessment of toxic metals leachability. Performed tests have shown a marked drop in ecotoxicity from relatively high toxicity of untreated waste leachate to low toxicity of stabilized waste leachate.