Prevention of PCDD formation in MSW incinerators by inhibition of catalytic activity of fly ash produced

Abstract

It has been observed that polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) can form from various precursors by catalytic activity of municipal incinerator fly ash between 200 and 400 °C. Study of the effect of temperature on PCDD formation shows that tetra- to octachlorodibenzo-p-dioxins form in greater amounts at 300°C. The catalytic activity of fly ash for formation of PCDD appears to be associated with various metals present. The catalytic reactions of fly ash to form PCDD and PCDF from various precursors at different temperatures can be inhibited using certain chemical reagents. Organic and inorganic basic compounds were tested as inhibitors in the laboratory experiments. Separation, identification and quantitation of dioxins and other compounds formed from precursors and with inhibitors on fly ash were carried out using GC-FID, GC-ECD and GC-MS techniques. Advantages and disadvantages of various inhibitors will be discussed as a technology to prevent PCDD and PCDF formation in MSW incinerators.