Methodology for the removal of inorganic components from urban wastes, industrial wastes and sludges from sewage treatment plants

摘要

A methodology for the removal of the harmful components of ash from urban/industrial wastes and sludges from the sewage treatment plants is invented. The harmful components are alkaline metals, chlorine, sulphur, zinc, lead, and chromium. They are removed before the thermochemical conversion and therefore the corrosion problems, scaling/deposition, ash agglomeration, dioxin and furan emissions, alkaline metal, chlorine, sulphur emissions are minimized if not diminished. The emissions of heavy metals such as zinc, lead, copper, and chromium are reduced. The removal is achieved with prepyrolysis/pregasification at 250-320° C. for 5 min to 2 h of urban/industrial wastes and sludges from the sewage treatment plants. Then the prepyrolyzed/pregasified sample is washed with a 0.5%-5% weight basis aqueous calcium acetate and/or magnesium acetate and/or aluminum acetate solution. These acetate salts can be mixed in a proportion of 0% to 100% to form an active salt which is used for the preparation of the aqueous solution.