Sludge incineration tests on circulating fluidised bed furnace

Results of sludge incineration tests on a demonstrative fluidised bed furna ce are reported and discussed. They show that particulate, heavy metals and acidic compounds in the emissions can be easily controlled both when sludg e is spiked with chlorinated hydrocarbons up to a chlorine concentration in the feed of 5%, and when the afterburner is switched off. As for organic m icropollutants, polynuclear aromatic hydrocarbons (PAH) were much lower tha n the Italian limits of 10 mug/m(3) (no limits are at present considered in the European Directives). Dioxins (PCDDs) and furans (PCDFs) in some tests exceeded the limit of 0.1 ng/m(3) (TE) but the concentrations in the fly a shes were much lower, thus evidencing a possible presence of contaminants i n gas phase. PAHs and PCDD/PCDFs were not depending on the afterburning ope ration, the presence of organic chlorine in the feed sludge and the copper addition to sewage sludge.