Abstract
ABSTRACTFlotation has been proven to successfully remove most polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) and carbon constituents from hospital solid waste incinerator (HSWI) fly ash. The resultant froths contain large quantities of carbon constituents that can reburn in the incinerator. In this paper, the reburning behavior of froths at temperatures from 800°C to 1200°C was compared with that of HSWI fly ash. Results showed that the destruction efficiency of PCDD/Fs was higher in the froths than in the fly ash at the same reburning temperature. The destruction efficiencies of PCDD/Fs in the froths exceeded 98% at temperatures higher than 1000°C. The volatilization ratio of Pb, Zn, and Cu was lower in the froths than in the fly ash. Furthermore, reburning of the froths can achieve energy recovery of the carbon constituents. Therefore, flotation followed by reburning treatment in a combustion chamber could be a suitable process for the detoxification and reutilization of HSWI fly ash.
Highlights
The centralized incineration treatment of hospital solid waste is prominent in China
This study mainly investigated the effect of flotation on hospital solid waste incinerator (HSWI) fly ash characteristics, polychlorinated dibenzofurans (PCDD/Fs) decomposition, and the volatilization behavior of heavy metals during reburning
This study investigated the effect of flotation on the reburning behavior of fly ash
Summary
The centralized incineration treatment of hospital solid waste is prominent in China. Due to small-scale incinerator, incomplete incineration and high chlorine content in the waste feed, some toxic persistent organic pollutants are generated such as polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), polycyclic aromatic hydrocarbons (PAHs), chlorobenzenes (CBs), chlorophenols (CPs) and polychlorinated biphenyls (PCBs), etc. The PCDD/F emission factors of hospital solid waste incinerator (HSWI) were about 1–2 orders higher than those of municipal solid waste incinerator (MSWI) (Lee et al, 2003; Cheruiyot et al, 2016). A rotary kiln is the main type of incinerator used because it has the advantages of adequate mixing and continuous operation. In facilities that use rotary kilns, the primary and secondary combustion chambers are operated at temperatures of 800°C and 1200°C, respectively (Gao et al, 2009). At the end of the incinerator, a large amount of powder activated carbon (PAC) is injected into the exhaust gas to ensure that the concentration of PCDD/Fs in the flue gas remains lower
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