Burning clarifier sludge in fluidised bed furnace - with additive to encapsulate heavy metal content

摘要

Process for disposal of clarified sludge comprises burning the sludge in a whirling bed furnace together with an additive to bind the heavy metals present in the sludge by encapsulating the solid particles of heavy metal so that they sink in the whirling bed as agglomerated particles. Pref. the sludge is burned at 600-1000 deg.C, esp. 830-870 deg.C. The additive for encapsulating the heavy metal particles may be added to the sludge prior to burning or during the burning, e.g. where the additive is introduced continuously during the burning. The additive is pref. in powder or dust form and is esp. a silicic acid and metal oxide contg. material, esp. glass. The sludge may be dewatered prior to burning and the additive may be heated before it is introduced into the combustion process. Pref. the combustion residues are removed continuously from the process. USE/ADVANTAGE - Allows disposal of clarifier sludge from treatment of urban waste water by burning in a fluidised bed furnace such that the heavy metal content becomes encapsulated and is recovered as combsution residues in the form of agglomerated particles which are easy to dispose of. The process overcomes problems of previous processes and avoids environmental pollution.