Pilot Test On Catalytic Destruction Of UPOPs In Flue Gas From Typical Municipal Waste Incineratorin China

Unintentionally produced persistent organic pollutants(UPOPs)listed in the Stockholm Convention which has been in effect in China need to be eliminated globally.UPOPs include polychlorinated dibenzo-p-dioxins and polychlorinateddibenzofurans(known as dioxin,PCDD/Fs),polychlorinated biphenyls(PCBs),pentachlorobenzene(Pe CBz)and Hexachlorobenzene(Hx CBz)(known as non-dioxin UPOPs).Municipal Waste Incinerators(MWIs)has been recognized as a major source of UPOPs.Considering the fact that incineration is becoming more and morepopular in waste disposal,the emission control of UPOPs is now a very challenging task for China.The emission characterization of UPOPs in flue gas from MWI need more studies.On the other hand,activated carbon injection whichis currently the predominant technology for UPOPs emission reductiononly transfers UPOPs from flue gas to the solid residues.Moreover,the synergetic removal of multiple UPOPs in real flue gas has not well investigated.Catalytic destruction has been identified as a promising alternative technology of UPOPs control,with the advantage of decomposition instead of transfer to residues.So far catalytic destruction has not been adopted in Chinese incinerators.One important reason is the absence of local demonstration.So it is neccssary to conduct related demonstration research.In this study,stack gas samples,raw gas and fly ash samples were collected from six MWIs in China.The emission factors as well as emission pattern of non-dioxin UPOPs were reported.The removal efficiencies of UPOPs byactivated carbon injection were evaluated.The mass concentration of Pe CBz and Hx CBz were much higher than PCDD/Fs.The stack gas emission factors of PCDD/Fs,dl-PCBs,Pe CBz,and Hx CBz were 3.15 ?g/t(45.6 ng TEQ/t),0.372?g/t(4.52 ng TEQ/t),144 ?g/t,84.7 ?g/t,respectively.The activated carbon injection cannot completely ensure the emission of PCDD/Fs meet the national standard.In addition,it is inferior to the removal of non-dioxin UPOPs.Especially for Hx CBz,the averageremoval efficiency was only 57.5%.A pilot-scale selective catalytic oxidation system for UPOPs removal was designed in this study.Thesystem was composed of the reactor,a preheater and control system,and so on.Flue gas before treated by activated carbon from MWI is taking as the research object.The gas processing capacity is designed as1550 Nm3/h.The operation temperature ranges from 100 to 350?.It is obvious that the the remove efficiencies of UPOPs by developedcatalyst(L-CAT)was much better than commercial catalyst(C-CAT),because the former has larger specific surface area and higher surface labile oxygen content.The emission of PCDD/Fs can meet the national emission standard at 3 layers of L-CAT.At the same time,the removal efficiencies of Pe CBz and Hx CBz can be up to 81.2%,and 71.7%,respectively.For the 28 days running,the system can sustainably guarantee the PCDD/Fs meet the national emission limit,meanwhile,still can remove Pe CBz and Hx CBzeffectively.The preliminarycalculation on the investment and operation cost of catalytic destruction technology showed that it has goodapplication prospect.