Effects of Surfactants on the Removal of Carbonaceous Matter and Dioxins from Weathered Incineration Fly Ash

Abstract

Our previous study demonstrated flotation to be effective in removing carbonaceous matter and dioxins from fresh fly ash in medical waste incinerators (MWIs). However, flotation of weathered fly ash seems to be difficult because of the oxidation of the ash surface and the presence of hydrophilic unburned carbon. Three types of surfactants namely nonionic Tween 80, anionic sodium dodecyl sulfate (SDS) and cationic CTAB were employed at different doses to improve flotation performance. Results indicated that Tween 80 exhibited superior decarburization performance compared with SDS and CTAB. The effect of surfactants on dioxin removal was found to correspond to the carbon removal from MWI fly ash. The optimal removal yields (90.6% of carbonaceous matter and 88.6% of dioxins) were obtained when 5% (w/w) Tween 80 was added. However, an excessive dose might cause the dissolution of dioxins.

Effects of Sulfur and Calcium Compounds on Dioxin Reduction in a Fluidized Bed Combustor

“…6(a) shows that the most prevalent congeners in the ash were 1,2,3,4,6,7,.4%), OCDD (12.9-17.3%), and OCDF (9.1- 13.5%). HxCDF and HpCDF were the two dominant homologs, results which were similar to those of Liu et al (2017). From the viewpoint of the contribution to the total I-TEQ values (as shown in Fig.…”

Experimental Investigation of the Decarburization Behavior of Medical Waste Incinerator Fly Ash (MWIFA)

“…The concentrations of dioxins and their congeners in the froths and the tailings were analyzed using the method of isotope dilution high resolution gas chromatography-high resolution mass spectrometry (HRGC-HRMS, MS-800D UltraFOCUS, Tokyo, Japan). The details of dioxin analytic method were given previously [23]. The total toxic equivalent (TEQ) of dioxin of each congener was obtained on the basis of the international toxic equivalency factors.…”

Characteristics and Treatment Methods of Medical Waste Incinerator Fly Ash: A Review

“…Recently, flotation of fresh MWIFA was systematically investigated. Liu found approximately 90% of carbon constituents and dioxins in MWIFA could be enriched and then separated as froths by flotation [12,54,153]. A novel process for the successive removal of dioxins and recovery of heavy metals from MWIFA was also developed by Wei [42].…”

“…After flotation, dioxin content in the tailings was significantly reduced to approximately 1.55 ng I-TEQ/g, which meets the standard of landfill site of municipal solid waste (3 ng I-TEQ/g). The volume and toxicity of the tailings decreased greatly, which might be landfill disposed [153]. Therefore, flotation is one of the promising alternatives for MWIFA treatment.…”