Stabilization and separation of heavy metals in incineration fly ash during the hydrothermal treatment process

Hu, Yuyan; Zhang, Pengfei; Li, Jianping; Chen, Dezhen

doi:10.1016/j.jhazmat.2015.06.002

Cited by 88 publications

(30 citation statements)

References 32 publications

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“…Currently, investigations on the degradation of dioxins in fly ash through thermal degradation, mechanochemical treatment, hydrothermal treatment as well as catalytic hydrodechlorination technique have also been studied. To some extent a reduction of the toxicity of dioxins has been realized (Hu et al, 2015;Weidemann et al, 2015;Wang et al, 2016a;Wang et al, 2016b;Mao et al, 2017). However, most of these techniques may be not suitable for HSWI fly ash treatment due to its special characteristics (Wei et al, 2017a).…”

Section: Introductionmentioning

confidence: 99%

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

Liu

Wei

et al. 2017

Aerosol Air Qual. Res.

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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.

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Section: Introductionmentioning

confidence: 99%

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

Liu

Wei

et al. 2017

Aerosol Air Qual. Res.

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“…However, as heating proceeded, the connection area between adjacent particles extended and particles combined more firmly, and the number of open pores declined dramatically [17, 28]. After thermal treatment, compact particle clusters came into being.…”

Section: Resultsmentioning

confidence: 99%

Stabilization of lead in incineration fly ash by moderate thermal treatment with sodium hydroxide addition

et al. 2017

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Municipal solid waste (MSW) incineration fly ash (IFA) can be potentially reused as a substitute for some raw materials, but treatment for detoxification is indispensable owing to high contents of heavy metals in fly ash. In the present work, due to excessive leaching concentration of lead (Pb), a moderate thermal treatment with sodium hydroxide (NaOH) addition was employed to stabilize Pb in IFA. The moderate thermal treatment was performed under relatively low temperature ranging from 300 to 500°C and at retention time from 1 to 3 h with NaOH addition in a range of 1 to 9%. Leaching results showed that leaching concentrations of Pb in IFA leachates decreased below the standard for hazardous waste identification (5 mg/L) in China under all treatment scenarios. With the increase of temperature, retention time and the amount of NaOH, the concentration of Pb were further suppressed in IFA leachates. Especially, at 500°C for 3 h with 9% NaOH addition, the concentration of Pb dropped to 0.18 mg/L, which was below the standard for sanitary landfill (0.25 mg/L) in China. In thermal process, needle-like crystallites melted to form granules and clumps with compacter structure and less pores. After the thermal treatment, water-soluble and exchangeable fractions of Pb significantly decreased. Therefore, the thermal treatment coupled with NaOH could be applied to realize the environmentally sound management of MSW IFA.

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“…After the hydrothermal treatment (HT), the autoclave was cooled to atmospheric conditions. Then, the suspension was immediately separated into the liquid phase and solid phase via vacuum filtrating (Hu et al, 2015). The solid ash cake products (referred to as hydrothermally treated fly ash, "HT product") was dried at 105°C for 24 hours, then ground and stored before testing (Jin et al, 2013).…”

Section: Hydrothermal Processmentioning

confidence: 99%

Seed-induced Hydrothermal Synthesis of Tobermorite from Municipal Solid Waste Incinerator Fly Ash

Shi¹,

Zhang²,

Li³

2017

JRST

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Resource recovery of municipal solid waste (MSW) incinerator fly ash is widely concerned. Tobermorite, an important but rare naturally mineral, could not be directly hydrothermal synthesized from it owing to its high content of Ca but low concentration of Si and Al. The selected external silicon-aluminum additives including coal fly ash (Cfa), bentonite, kaolin and diatomite were solely or combined added. With the addition of 30% mass composite additive in which the ratio of quality for Cfa and diatomite is 1:1, tobermorite could be synthesized most effectively in 48h at 150°C, mainly attributing to the proper element proportion adjusted by additives. Tobermorite seed added could not only promote the large formation of tobermorite, but also inhibit the production of hibschite and kaotoite. Since Ca/(Si + al) = 1.20 and al/(Si + al) = 0.20, addition of 30% mass of composite additive and 3% mass of tobermorite seed would be the recommended technological parameter.

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Stabilization and separation of heavy metals in incineration fly ash during the hydrothermal treatment process

Cited by 88 publications

References 32 publications

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

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

Stabilization of lead in incineration fly ash by moderate thermal treatment with sodium hydroxide addition

Seed-induced Hydrothermal Synthesis of Tobermorite from Municipal Solid Waste Incinerator Fly Ash

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