INVESTIGATION OF INCINERATION CHARACTERISTICS OF WASTE-WATER TREATMENT-PLANT SLUDGE

Incineration is an important disposal method for the large volumes of sludge produced by industrial and municipal waste water treatment. Thi s paper describes analytical methods developed for examining industria l sludge incineration processes and the dependence of potential produc ts of incomplete combustion (PICs) on the sludge composition. A surrog ate sludge was developed from peat, calcium and iron salts, and a wast e water-treatment polymer suspension to simulate incineration characte ristics of the real sludge while allowing for controlled variation of its composition. Experiments were conducted under both oxidative and p yrolysis conditions, in reactor systems ranging from microscale up to bench scale with on-line analytical instrumentation. The organic produ cts emitted from the surrogate were quite similar to those of the slud ge, with the exception of products from certain synthetic polymers. Si gnificant quantities of aromatic hydrocarbons were emitted from the co mbustion of the cellulosic and lignin fractions of the material even w ithout the presence of those specific compounds in the original waste. The presence of the metal salts and the additional water they retaine d significantly affected the peak hydrocarbon concentration by delayin g the onset of emissions and lengthening their duration. The amount of polystyrene and polymethylmethacrylate in the real sludge made their decomposition products important potential PICs, which would need furt her combustion.