In this report the effect of process failure modes on aromatic and polynucl
ear aromatic compounds during the lab-scale incineration of municipal sludg
e is examined. The thermal, temporal, and fuel-oxidant mixing failure modes
were tested. They were respectively simulated by holding the primary therm
al exposure at 400 degrees C and varying the afterburning between 500 and 1
100 degrees C, the afterburning residence time between 1 and 3 s, and the c
ombustion oxygen using almost stoichiometric (30%) and large excess (160%),
Results indicate that the thermal failure mode is the most important facto
r controlling the number of compounds emitted at an afterburning temperatur
e below 700 degrees C, At higher temperatures the number and amounts of aro
matic and polynuclear aromatic compounds emitted are controlled by the fuel
-oxidant mixing failure. It was found that, when fuel oxidant mixing failur
e was active, the formation of 20 aromatic and polynuclear aromatic compoun
ds was observed even at an afterburning temperature as high as 1100 degrees
C while, when it was not active, at 900 degrees C no emission of organics
was detected.