Assessment of PCDD/Fs Emission during Industrial-Organic-Solid-Waste Incineration Process in a Fluidized-Bed Incinerator

This study was conducted in a fluidized-bed incineration plant, evaluating the formation, emission and flux of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from industrial-organic-solid-waste (IW) incineration. The results revealed that both the total (or I-TEQ) concentrations of toxic and 136 total PCDD/Fs in flue gas (FG), fly ash (FA) and bottom ash (BA)were ramped up to a higher level than those during municipal-solid-waste (MSW) incineration. A possible explanation was the chlorine (Cl) content of IW. However, the emitted PCDD/Fs in FG (FA/BA) still fulfilled the criteria. Subsequently, similar distribution patterns of PCDD/F isomers were observed in subsystems, indicating a unified formation-pathway. De novo synthesis was detected as the dominant formation-pathway of PCDD/Fs, while high-temperature and precursor syntheses were excluded. DD/DF chlorination formed PCDD/Fs to some extent. Furthermore, the mass flow chart indicated that PCDD/Fs output in primary FG was significantly strengthened (>1000 times) by de novo synthesis, from 1.25 mu g I-TEQ/h to 1.67 mg I-TEQ/h. With effective cleaning by APCS, 99.6% of PCDD/Fs in FG were purified. PCDD/Fs in the gas phase were finally emitted at a discharge rate of 7.25 mu g I-TEQ/h. However, accumulated FA took most PCDD/Fs into the environment (>99%), reaching 3.56 mg I-TEQ/h.

Automated summary

This study was conducted to evaluate the formation, emission, and flux of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from industrial-organic-solid-waste incineration in a fluidized-bed plant. The results showed that the concentrations of toxic and total PCDD/Fs in flue gas, fly ash, and bottom ash were higher compared to municipal-solid-waste incineration, possibly due to the higher chlorine content in industrial waste. However, the emitted PCDD/Fs still met the criteria. De novo synthesis was found to be the dominant formation pathway, while high-temperature and precursor syntheses were excluded. Chlorination of DD/DF contributed to the formation of PCDD/Fs to some extent. The purification process reduced 99.6% of PCDD/Fs in the flue gas, resulting in a discharge rate of 7.25 μg I-TEQ/h of PCDD/Fs in the gas phase, while most of the PCDD/Fs (over 99%) were accumulated in the fly ash, with a discharge rate of 3.56 mg I-TEQ/h into the environment.