1
|
Fan S, Wei J, Xu X, Yan R, Li Q, Liu Y, Huang Y, Wang Y, Fan G, Zhang L. Treatment of chromium-containing sludge using sintering and ironmaking combined technology: A risk-reducing strategy for environmental impact. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 359:120986. [PMID: 38696849 DOI: 10.1016/j.jenvman.2024.120986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 04/03/2024] [Accepted: 04/20/2024] [Indexed: 05/04/2024]
Abstract
The efficient, safe and eco-friendly disposal of the chromium-containing sludge (CCS) has attracted an increasing concern. In this study, Co-processing of CCS was developed via employing sintering and ironmaking combined technology for its harmless disposal and resource utilization. Crystalline phase and valence state transformation of chromium (Cr), technical feasibility assessment, leaching risk, characteristics of sintered products, and pollutant release during CCS co-processing were investigated through a series of laboratory-scale sintering pot experiments and large scale industrial trials. The results showed that the content of Cr(VI) in sintered products first increased then decreased with increasing temperature ranges of 300 °C-800 °C, and reached a maximum of 2189.64 mg/kg at 500 °C. 99.99% of Cr(VI) can be reduced to Cr(III) at above 1000 °C, which was attributed to the transformation of the Cr(VI)-containing crystalline phases (such as, MgCrO4 and CaCrO4) to the (Mg, Fe2+)(Cr, Al, Fe3+)2O4. The industrial trial results showed that adding 0.5 wt‰ CCS to sintering feed did not have adverse effects on the properties of the sintered ore and the plant's operating stability. The tumbler index of sinter was above 78% and the leaching concentrations of TCr (0.069 mg/L) was significantly lower than the Chinese National Standard of 1.0 mg/L (GB5085.3-2007). The TCr contents of sintering dust and blast furnace gas (BFG) scrubbing water were less than 0.19 wt‰ and 0.11 mg/L, respectively, which was far below the regulatory limit (1.5 mg/L, GB13456-2012). The mass balance evaluation results indicated that at least 89.9% of the Cr in the CCS migrated into the molten iron in the blast furnace (BF), which became a useful supplement to the molten iron. This study provided a new perspective strategy for the safe disposal and resource utilization of CCS in iron and steel industry.
Collapse
Affiliation(s)
- Shengxuan Fan
- School of Chemistry and Environmental Engineering, Wuhan Polytechnic University, Wuhan, 430023, China
| | - Jinchao Wei
- Zhongye Changtian International Engineering Co., Ltd., Changsha, 410205, China; National Engineering Research Center of Sintering and Pelletizing Equipment System, Changsha, 410205, China
| | - Xiaorong Xu
- School of Chemistry and Environmental Engineering, Wuhan Polytechnic University, Wuhan, 430023, China
| | - Ran Yan
- School of Chemistry and Environmental Engineering, Wuhan Polytechnic University, Wuhan, 430023, China
| | - Qian Li
- Zhongye Changtian International Engineering Co., Ltd., Changsha, 410205, China; National Engineering Research Center of Sintering and Pelletizing Equipment System, Changsha, 410205, China
| | - Ying Liu
- R&D Center of Wuhan Iron and Steel Company, Wuhan, 430080, China
| | - Yanjun Huang
- School of Chemistry and Environmental Engineering, Wuhan Polytechnic University, Wuhan, 430023, China
| | - Yi Wang
- School of Chemistry and Environmental Engineering, Wuhan Polytechnic University, Wuhan, 430023, China.
| | - Guozhi Fan
- School of Chemistry and Environmental Engineering, Wuhan Polytechnic University, Wuhan, 430023, China
| | - Lei Zhang
- School of Chemistry and Environmental Engineering, Wuhan Polytechnic University, Wuhan, 430023, China.
| |
Collapse
|
2
|
Shen D, Bao Q, Qiu J, Gu F, Wu Z, Wu M, Guo W, Long Y. Effect of calcium oxide on chromium solidification during the melting of hazardous waste incineration fly ash. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 317:115475. [PMID: 35662047 DOI: 10.1016/j.jenvman.2022.115475] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 05/29/2022] [Accepted: 05/31/2022] [Indexed: 06/15/2023]
Abstract
Thermal treatment technology considerably affects the harmlessness of fly ash (FA), but highly toxic heavy metals, such as Cr, attract considerable attention. In this study, we investigated the influence of CaO dosage at 600°C-1200 °C on the curing effect of Cr during FA thermal treatment based on the combination effect of CaO. Static, dynamic, and continuous sequential leachings were performed for the sintered products. Results showed that the leaching concentration of Cr decreased by approximately 91% when CaO dosage was 8.57%, and the difference in the residual state was the main reason for the difference in the leaching behavior of Cr. The proportion of the residual state in the sintered products increased from 35.16% to 64.01%. The transition between Cr2O3, Cr5O12, and CaCr2O4 is the fundamental reason for the leaching behavior of Cr and the change in the residual state. This study provides a scientific basis for preventing and controlling heavy metal pollution and optimizing environmental supervision in the FA thermal treatment process.
Collapse
Affiliation(s)
- Dongsheng Shen
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310012, China; Instrumental Analysis Center of Zhejiang Gongshang University, Hangzhou, 310018, China
| | - Qiqi Bao
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310012, China
| | - Junjian Qiu
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310012, China
| | - Foquan Gu
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310012, China
| | - Zixiao Wu
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310012, China
| | - Minjin Wu
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310012, China
| | - Wenxin Guo
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310012, China
| | - Yuyang Long
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310012, China; Instrumental Analysis Center of Zhejiang Gongshang University, Hangzhou, 310018, China.
| |
Collapse
|
3
|
Zhan X, Wang L, Wang L, Gong J, Wang X, Song X, Xu T. Co-sintering MSWI fly ash with electrolytic manganese residue and coal fly ash for lightweight ceramisite. CHEMOSPHERE 2021; 263:127914. [PMID: 32822940 DOI: 10.1016/j.chemosphere.2020.127914] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 07/28/2020] [Accepted: 08/03/2020] [Indexed: 06/11/2023]
Abstract
The MSWI fly ash (FA) is classified as hazardous waste and electrolytic manganese residue (EMR) as the harmful industrial waste. FA, water-washed FA (WFA), EMR and coal fly ash (CFA) were co-recycled to form lightweight MFCE ceramisites. The effects of FA, WFA and mixed MSWI fly ash on ceramisites were discussed. The approach to mixing FA and WFA increased the recycling amount of MSWI fly ash. The optimal mixture of 34.5% EMR, 24.1% CFA, 20.7% FA and 20.7% WFA sintered at 1160 °C for 12 min with a procedural heating rate (10 °C/min) and belonged to Class 800 artificial lightweight aggregate (GB/T 17431.1-2010); the quantity of MSWI fly ash in ceramisite was as high as 41.4%. Volatilization rates of Cd, Pb, Cu, Zn, Mn and Cr for ceramisite were higher 75.0, 24.2, 62.7, 133, 343 and 764% than FA respectively, attributed to the co-existence of chlorides and sulfates. The remained Zn, Cu, Pb, Mn and Cr were exchanged with Mg2+/Ca2+/Al3+ of diopside and wollastonite to form residual fractions. Our findings provided a feasibility method of co-recycling MSWI fly ash and electrolytic manganese residue to produce green lightweight aggregates.
Collapse
Affiliation(s)
- Xinyuan Zhan
- Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, 400044, PR China; College of Environment and Ecology, Chongqing University, Chongqing, 400044, PR China
| | - Li'ao Wang
- Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, 400044, PR China; College of Environment and Ecology, Chongqing University, Chongqing, 400044, PR China.
| | - Lei Wang
- Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, 400044, PR China
| | - Jian Gong
- Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, 400044, PR China; College of Environment and Ecology, Chongqing University, Chongqing, 400044, PR China
| | - Xiang Wang
- Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, 400044, PR China; College of Environment and Ecology, Chongqing University, Chongqing, 400044, PR China
| | - Xue Song
- College of Chemistry, Chemical and Environmental Engineering, Henan University of Technology, Zhengzhou, 450001, PR China
| | - Tengtun Xu
- College of Environment and Resources, Chongqing Technology and Business University, Chongqing, 400067, PR China
| |
Collapse
|
4
|
Abstract
Incineration has gained popularity over landfill as a key solution for the reduction of massively increasing volumes of municipal solid waste (MSW) generation worldwide and in particular China. However, it is not the end solution. The disposal of the incineration residues, which are enriched with a wide range of heavy metals and soluble salts, has become a challenge for the environmental managers. The aim of this study was to review the increasing urbanization and its repercussion on waste generation in China; waste management options were compared for possible environmentally friendly considerations. Treatment techniques of incineration fly ash were discussed to determine the effectiveness of obtaining environmentally stable material, and, finally, possible applications of incineration fly ash for utilization were discussed based on identifying the processing suitability, performance and environmental impact of incineration fly ash for its applications.
Collapse
|
5
|
Lane DJ, Sippula O, Peräniemi S, Jokiniemi J. Detoxification of wood-combustion ashes containing Cr and Cd by thermal treatment. JOURNAL OF HAZARDOUS MATERIALS 2020; 400:123315. [PMID: 32947715 DOI: 10.1016/j.jhazmat.2020.123315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 06/22/2020] [Accepted: 06/23/2020] [Indexed: 06/11/2023]
Abstract
This study assesses the potential of thermal processing for detoxification of wood-combustion ashes that contain high levels of Cr and Cd. Thermal treatment (1000 °C) of bottom ash and fly ash in an oxidising gas (air) atmosphere resulted in: low volatilisation of Cd and most other heavy metals, oxidation of Cr in the ashes to Cr (VI), and, in the case of the fly ash, significantly increased leaching of Cr and Mo. Thermal treatment in a nitrogen atmosphere resulted in local reducing conditions due to oxidation of ash-derived carbon to CO (g). Thermal treatments in this atmosphere and in a reducing atmosphere consisting of 10 % H2 and the balance N2 detoxified the ashes in at least two ways: (i) by substantially removing Cd, Pb, Bi, Tl, and, in the case of the fly ash, Zn from the ashes by volatilisation; and (ii) by thermal reduction of Cr (VI) in the ashes. There was at least a 100-fold reduction in the leaching of total Cr from both the bottom ash and the fly ash following the thermal treatments in reducing conditions. Chromium only leached from the detoxified bottom ash to a significant extent in acidic conditions (pH < 4).
Collapse
Affiliation(s)
- Daniel J Lane
- Fine Particle and Aerosol Technology Laboratory, Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland.
| | - Olli Sippula
- Fine Particle and Aerosol Technology Laboratory, Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland; Department of Chemistry, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland
| | - Sirpa Peräniemi
- School of Pharmacy, University of Eastern Finland, FI-70211 Kuopio, Finland
| | - Jorma Jokiniemi
- Fine Particle and Aerosol Technology Laboratory, Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland
| |
Collapse
|
6
|
Yang Y, Ma H, Chen X, Zhu C, Li X. Effect of incineration temperature on chromium speciation in real chromium-rich tannery sludge under air atmosphere. ENVIRONMENTAL RESEARCH 2020; 183:109159. [PMID: 32028182 DOI: 10.1016/j.envres.2020.109159] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 01/17/2020] [Accepted: 01/20/2020] [Indexed: 06/10/2023]
Abstract
As a hazardous waste, the disposal of chromium enriched tannery sludge has attracted increasing public concern due to its potential adverse risks towards the environment. And incineration is considered to be an effective method to stabilize heavy metals, like Cr, in solid phase during tannery sludge treatment. In this study, real chromium enriched tannery sludge without pre-treatment was incinerated at 300°C-1200 °C under air atmosphere to investigate the transformation of chromium speciation. Here detailed thermal behavior, phase transformation and chromium speciation were characterized by TG-DSC, XRD and XPS, respectively. Experimental results show that content of Cr(VI) increases gradually with the increase of temperature from 300 °C to 500 °C and reaches a maximal level of 46% total Cr at 500 °C, with different Cr(VI) species of CaCrO4, MgCrO4 and Cr5O12. However, the content of Cr(VI) decreases gradually with the further increase of temperature, with only about 5% Cr(VI) at high temperature of 1200 °C, due to formation of Cr(III) species of Cr2O3 crystallite and MgCr2O4 spinel. Besides, a growing number of hexagonally shaped flake-like crystallite Cr2O3 can be discovered from characterization results of XRD and SEM. Finally, the reduction of CaCrO4 to Cr2O3 in the presence of SiO2 is thermodynamically feasible over 700 °C, indicating possible transformation of Cr(VI) to Cr(III) through controlled incineration temperature.
Collapse
Affiliation(s)
- Yonglin Yang
- School of Environmental Science and Engineering, Shaanxi University of Science & Technology, Xi'an, 710021, PR China; School of Chemical Engineering, Shenmu Vocational & Technical College, Shenmu, 719300, PR China
| | - Hongrui Ma
- School of Environmental Science and Engineering, Shaanxi University of Science & Technology, Xi'an, 710021, PR China.
| | - Xiangping Chen
- School of Environmental Science and Engineering, Shaanxi University of Science & Technology, Xi'an, 710021, PR China.
| | - Chao Zhu
- School of Environmental Science and Engineering, Shaanxi University of Science & Technology, Xi'an, 710021, PR China
| | - Xiaojie Li
- School of Chemistry and Chemical Engineering, Shaanxi University of Science & Technology, Xi'an, 710021, PR China
| |
Collapse
|
7
|
Kirkelund GM, Jensen PE. Electrodialytic treatment of Greenlandic municipal solid waste incineration fly ash. WASTE MANAGEMENT (NEW YORK, N.Y.) 2018; 80:241-251. [PMID: 30455005 DOI: 10.1016/j.wasman.2018.09.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 08/13/2018] [Accepted: 09/11/2018] [Indexed: 06/09/2023]
Abstract
In Greenland, fly ash could contribute as a local resource in construction as a substitute for cement in concrete or clay in bricks, if the toxicity of the ash is reduced. In this study, fly ash from three different Greenlandic waste incinerators were collected and subjected to electrodialytic treatment for removal of heavy metals with the aim of enabling reuse of the fly ashes. Seven electrodialytic experiments treating up to 2.5 kg of fly ash in a 10 L suspension were made. The heavy metal removal was mostly dependent on the initial concentration in the fly ash. Heavy metal leaching was examined before and after treatment and revealed overall a significant reduction in leaching of Cd, Cr, Cu, Pb and Zn; however, Cr and Pb leaching were above Danish guideline levels for reuse purposes. Hg leaching was also reduced to below Danish guideline levels, although only investigated for one fly ash. Hexavalent Cr was not the dominant speciation of Cr in the fly ashes. Ettringite formed during electrodialytic treatment in the fly ash suspensions at pH above 12. The total concentration of eligible components for reuse such as CaO, SiO2 and Al2O3, increased during the electrodialytic treatment.
Collapse
Affiliation(s)
- Gunvor M Kirkelund
- Department of Civil Engineering, Technical University of Denmark, 2800 Lyngby, Denmark.
| | - Pernille E Jensen
- Department of Civil Engineering, Technical University of Denmark, 2800 Lyngby, Denmark
| |
Collapse
|
8
|
Chen W, Kirkelund GM, Jensen PE, Ottosen LM. Comparison of different MSWI fly ash treatment processes on the thermal behavior of As, Cr, Pb and Zn in the ash. WASTE MANAGEMENT (NEW YORK, N.Y.) 2017; 68:240-251. [PMID: 28757224 DOI: 10.1016/j.wasman.2017.07.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 05/26/2017] [Accepted: 07/11/2017] [Indexed: 06/07/2023]
Abstract
To reduce heavy metal leaching and stabilize municipal solid waste incineration (MSWI) fly ash, different methods and combination of methods were tested: water washing, electrodialytic separation and thermal treatment at 1000°C. A comparison of heavy metal concentration and leaching levels of As, Cr, Pb and Zn for the different untreated and treated ashes was made. The results showed that minimizing leaching to meet the limiting values of the all the studied heavy metals can be obtained at the same time by combining water washing, electrodialytic separation and thermal treatment. The ash subjected to this combination had lower Cr than the ash solely subjected to thermal treatment or subjected to water washing prior to thermal treatment. The electrodialytic separation (EDS) of the washed ash lowered pH from alkaline to acidic, which resulted in elevated leaching of Cd and Zn, while the Cr leaching was reduced. Up to 58.6% of Zn and 5.5% of Pb were extracted by EDS compared to less than 0.6% extraction by water washing. During thermal treatment of the EDS treated ash, the ash was re-alkalized. Due to solidification and possibly evaporation, most heavy elements left in the thermally treated ash were stabilized and immobilized. However, leaching of As and/or Cr was still problematic and did not meet the limit value for the thermally treated ash being recycled in construction work. The removal of Ca and decomposition of Ca oxides and minerals during EDS was linked to the leaching patterns of As and Cr after thermal treatment.
Collapse
Affiliation(s)
- Wan Chen
- Department of Civil Engineering, Technical University of Denmark, Denmark.
| | - Gunvor M Kirkelund
- Department of Civil Engineering, Technical University of Denmark, Denmark
| | - Pernille E Jensen
- Department of Civil Engineering, Technical University of Denmark, Denmark
| | - Lisbeth M Ottosen
- Department of Civil Engineering, Technical University of Denmark, Denmark
| |
Collapse
|
9
|
Mao L, Gao B, Deng N, Liu L, Cui H. Oxidation behavior of Cr(III) during thermal treatment of chromium hydroxide in the presence of alkali and alkaline earth metal chlorides. CHEMOSPHERE 2016; 145:1-9. [PMID: 26650573 DOI: 10.1016/j.chemosphere.2015.11.053] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 10/29/2015] [Accepted: 11/16/2015] [Indexed: 06/05/2023]
Abstract
The oxidation behavior of Cr(III) during the thermal treatment of chromium hydroxide in the presence of alkali and alkaline earth metal chlorides (NaCl, KCl, MgCl2, and CaCl2) was investigated. The amounts of Cr(III) oxidized at various temperatures and heating times were determined, and the Cr-containing species in the residues were characterized. During the transformation of chromium hydroxide to Cr2O3 at 300 °C approximately 5% of the Cr(III) was oxidized to form intermediate compounds containing Cr(VI) (i.e., CrO3), but these intermediates were reduced to Cr2O3 when the temperature was above 400 °C. Alkali and alkaline earth metals significantly promoted the oxidation of Cr(III) during the thermal drying process. Two pathways were involved in the influences the alkali and alkaline earth metals had on the formation of Cr(VI). In pathway I, the alkali and alkaline earth metals were found to act as electron transfer agents and to interfere with the dehydration process, causing more intermediate Cr(VI)-containing compounds (which were identified as being CrO3 and Cr5O12) to be formed. The reduction of intermediate compounds to Cr2O3 was also found to be hindered in pathway I. In pathway II, the alkali and alkaline earth metals were found to contribute to the oxidation of Cr(III) to form chromates. The results showed that the presence of alkali and alkaline earth metals significantly increases the degree to which Cr(III) is oxidized during the thermal drying of chromium-containing sludge.
Collapse
Affiliation(s)
- Linqiang Mao
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046, PR China
| | - Bingying Gao
- College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, PR China
| | - Ning Deng
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046, PR China
| | - Lu Liu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046, PR China
| | - Hao Cui
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046, PR China.
| |
Collapse
|
10
|
Yu J, Qiao Y, Jin L, Ma C, Paterson N, Sun L. Removal of toxic and alkali/alkaline earth metals during co-thermal treatment of two types of MSWI fly ashes in China. WASTE MANAGEMENT (NEW YORK, N.Y.) 2015; 46:287-297. [PMID: 26303652 DOI: 10.1016/j.wasman.2015.08.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2015] [Revised: 08/04/2015] [Accepted: 08/05/2015] [Indexed: 06/04/2023]
Abstract
This study aims to vaporize heavy metals and alkali/alkaline earth metals from two different types of fly ashes by thermal treatment method. Fly ash from a fluidized bed incinerator (HK fly ash) was mixed with one from a grate incinerator (HS fly ash) in various proportions and thermally treated under different temperatures. The melting of HS fly ash was avoided when treated with HK fly ash. Alkali/alkaline earth metals in HS fly ash served as Cl-donors to promote the vaporization of heavy metals during thermal treatment. With temperature increasing from 800 to 900°C, significant amounts of Cl, Na and K were vaporized. Up to 1000°C in air, less than 3% of Cl and Na and less than 5% of K were retained in ash. Under all conditions, Cd can be vaporized effectively. The vaporization of Pb was mildly improved when treated with HS fly ash, while the effect became less pronounced above 900°C. Alkali/alkaline earth metals can promote Cu vaporization by forming copper chlorides. Comparatively, Zn vaporization was low and only slightly improved by HS fly ash. The low vaporization of Zn could be caused by the formation of Zn2SiO4, ZnFe2O4 and ZnAl2O4. Under all conditions, less than 20% of Cr was vaporized. In a reductive atmosphere, the vaporization of Cd and Pb were as high as that in oxidative atmosphere. However, the vaporization of Zn was accelerated and that of Cu was hindered because the formation of Zn2SiO4, ZnFe2O4 and ZnAl2O4 and copper chloride was depressed in reductive atmosphere.
Collapse
Affiliation(s)
- Jie Yu
- State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, 430074 Wuhan, Hubei, China
| | - Yu Qiao
- State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, 430074 Wuhan, Hubei, China.
| | - Limei Jin
- State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, 430074 Wuhan, Hubei, China
| | - Chuan Ma
- State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, 430074 Wuhan, Hubei, China
| | - Nigel Paterson
- Department of Chemical Engineering, Imperial College London, London SW7 2AZ, United Kingdom
| | - Lushi Sun
- State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, 430074 Wuhan, Hubei, China
| |
Collapse
|
11
|
Mao L, Gao B, Deng N, Zhai J, Zhao Y, Li Q, Cui H. The role of temperature on Cr(VI) formation and reduction during heating of chromium-containing sludge in the presence of CaO. CHEMOSPHERE 2015; 138:197-204. [PMID: 26072117 DOI: 10.1016/j.chemosphere.2015.05.097] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 05/14/2015] [Accepted: 05/27/2015] [Indexed: 06/04/2023]
Abstract
In this study, the temperature dependence of Cr(VI) formation and reduction in the presence of CaO was examined during the thermal treatment of sludge that contains chromium. thermogravimetry-differential scanning calorimetry and X-ray diffractometry were used to characterize the thermal behavior and phase transformation, respectively. Na2CO3 leaching procedure was employed to determine the amount of Cr(VI). The result showed that CaO promoted Cr(III) oxidation, however, its influence is very dependent on heating temperature, with the extent of the effect varying with temperature. From 200-400 °C, the presence of CaO facilitated formation of intermediate product Cr2O3+x containing Cr(VI) during dehydration of chromium hydrate, while Cr2O3+x would decompose as temperature over 400 °C, accompanied by part of Cr(VI) being reduced to Cr(III). From 500 to 900 °C, Cr(III) reacted with CaO to form a leachable CaCrO4 product. This product was stable and a prolonged heating time did not reduce the amount of Cr(VI) significantly. At 1000-1200 °C, part of CaCrO4 was reduced to Ca(CrO2)2 in 1h. While extended heating time above 1h resulted in the Ca(CrO2)2 being oxidized reversibly to CaCrO4 at 1200 °C. Since CaCrO4 is thermodynamically less stable over 1000 °C, MgO could induce CaCrO4 to be reduced into MgCr2O4 at around 900 °C, lower than that for the reduction from CaCrO4 into Ca(CrO2)2. It suggested that adding MgO might be a potential approach for inhibiting Cr(VI) formation during heating sludge containing chromium.
Collapse
Affiliation(s)
- Linqiang Mao
- State Key Laboratory of Pollution Control and Resource Reuse, and School of the Environment, Nanjing University, Nanjing 210046, PR China
| | - Bingying Gao
- College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, PR China
| | - Ning Deng
- State Key Laboratory of Pollution Control and Resource Reuse, and School of the Environment, Nanjing University, Nanjing 210046, PR China
| | - Jianping Zhai
- State Key Laboratory of Pollution Control and Resource Reuse, and School of the Environment, Nanjing University, Nanjing 210046, PR China
| | - Yongbin Zhao
- National Institute of Clean-and-low-carbon Energy (NICE), Beijing 102209, PR China
| | - Qin Li
- State Key Laboratory of Pollution Control and Resource Reuse, and School of the Environment, Nanjing University, Nanjing 210046, PR China
| | - Hao Cui
- State Key Laboratory of Pollution Control and Resource Reuse, and School of the Environment, Nanjing University, Nanjing 210046, PR China.
| |
Collapse
|
12
|
Yu J, Qiao Y, Sun L, Jin L, Wang W, Ma C. Detoxification of ashes from a fluidized bed waste incinerator. CHEMOSPHERE 2015; 134:346-354. [PMID: 25973859 DOI: 10.1016/j.chemosphere.2015.04.045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Revised: 04/08/2015] [Accepted: 04/19/2015] [Indexed: 06/04/2023]
Abstract
This paper was to test and control the toxicity of bottom and fly ashes from a circulated fluidized bed (CFB) incinerator. Bottom and fly ashes were firstly subject to TCLP test. Even though leachates of most particle size of bottom ash were below regulatory limit, the leachates of finer bottom ash may exceed the regulatory limit. Therefore, finer bottom ash should be separated and treated before landfilled directly or used as cement replacement. Due to high amounts of leached heavy metals, thermal treatment of fly ash was carried out to remove heavy metals. The influence of temperature, residence time, metal chloride and gas velocity were studied. In all conditions, Cd can be well removed. Pb can be almost completely removed with MgCl2 addition at 1000°C in 1h. The removal of Zn and Cu was accelerated significantly by MgCl2 and higher temperature separately. At optimum conditions, more than 90% of Cu and 95% of Zn could be removed, while a maximum 20% of Cr was removed due to the existence or formation of CaCr2O4, MgCr2O4 and K2Cr2O4 in raw or treated fly ashes.
Collapse
Affiliation(s)
- Jie Yu
- State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, 430074 Wuhan, Hubei, China
| | - Yu Qiao
- State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, 430074 Wuhan, Hubei, China.
| | - Lushi Sun
- State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, 430074 Wuhan, Hubei, China.
| | - Limei Jin
- State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, 430074 Wuhan, Hubei, China
| | - Wenxia Wang
- State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, 430074 Wuhan, Hubei, China
| | - Chuan Ma
- State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, 430074 Wuhan, Hubei, China
| |
Collapse
|
13
|
Lindberg D, Molin C, Hupa M. Thermal treatment of solid residues from WtE units: a review. WASTE MANAGEMENT (NEW YORK, N.Y.) 2015; 37:82-94. [PMID: 25592372 DOI: 10.1016/j.wasman.2014.12.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 12/03/2014] [Accepted: 12/04/2014] [Indexed: 05/26/2023]
Abstract
Thermal treatment methods of bottom ash, fly ash and various types of APC (air pollution control) residues from waste-to-energy plants can be used to obtain environmentally stable material. The thermal treatment processes are meant to reduce the leachability of harmful residue constituents, destroy toxic organic compounds, reduce residue volume, and produce material suitable for utilization. Fly ash and APC residues often have high levels of soluble salts, particularly chlorides, metals such as cadmium, lead, copper and zinc, and trace levels of organic pollutants such as dioxins and furans. Different thermal treatment methods can be used to either decompose or stabilize harmful elements and compounds in the ash, or separate them from the ash to get a material that can be safely stored or used as products or raw materials. In the present paper, thermal treatment methods, such as sintering, vitrification, and melting have been reviewed. In addition to a review of the scientific literature, a survey has been made of the extensive patent literature in the field.
Collapse
Affiliation(s)
- Daniel Lindberg
- Åbo Akademi University, Process Chemistry Centre, Piispankatu 8, FI-20500 Turku, Finland.
| | - Camilla Molin
- Åbo Akademi University, Process Chemistry Centre, Piispankatu 8, FI-20500 Turku, Finland.
| | - Mikko Hupa
- Åbo Akademi University, Process Chemistry Centre, Piispankatu 8, FI-20500 Turku, Finland.
| |
Collapse
|
14
|
Kavouras P, Pantazopoulou E, Varitis S, Vourlias G, Chrissafis K, Dimitrakopulos GP, Mitrakas M, Zouboulis AI, Karakostas T, Xenidis A. Incineration of tannery sludge under oxic and anoxic conditions: study of chromium speciation. JOURNAL OF HAZARDOUS MATERIALS 2014; 283:672-679. [PMID: 25464309 DOI: 10.1016/j.jhazmat.2014.09.066] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 09/19/2014] [Accepted: 09/27/2014] [Indexed: 06/04/2023]
Abstract
A tannery sludge, produced from physico-chemical treatment of tannery wastewaters, was incinerated without any pre-treatment process under oxic and anoxic conditions, by controlling the abundance of oxygen. Incineration in oxic conditions was performed at the temperature range from 300°C to 1200°C for duration of 2h, while in anoxic conditions at the temperature range from 400°C to 600°C and varying durations. Incineration under oxic conditions at 500°C resulted in almost total oxidation of Cr(III) to Cr(VI), with CaCrO4 to be the crystalline phase containing Cr(VI). At higher temperatures a part of Cr(VI) was reduced, mainly due to the formation of MgCr2O4. At 1200°C approximately 30% of Cr(VI) was reduced to Cr(III). Incineration under anoxic conditions substantially reduced the extent of oxidation of Cr(III) to Cr(VI). Increase of temperature and duration of incineration lead to increase of Cr(VI) content, while no chromium containing crystalline phase was detected.
Collapse
Affiliation(s)
- P Kavouras
- School of Physics, Section of Solid State Physics, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece.
| | - E Pantazopoulou
- Division of Chemical Technology, Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece
| | - S Varitis
- School of Physics, Section of Solid State Physics, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - G Vourlias
- School of Physics, Section of Applied Physics, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - K Chrissafis
- School of Physics, Section of Solid State Physics, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - G P Dimitrakopulos
- School of Physics, Section of Solid State Physics, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - M Mitrakas
- Department of Chemical Engineering, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - A I Zouboulis
- Division of Chemical Technology, Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece
| | - Th Karakostas
- School of Physics, Section of Solid State Physics, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - A Xenidis
- School of Mining Engineering and Metallurgy, National Technical University of Athens, Zografou Campus, Athens 15780, Greece
| |
Collapse
|
15
|
Verbinnen B, Billen P, Van Coninckxloo M, Vandecasteele C. Heating temperature dependence of Cr(III) oxidation in the presence of alkali and alkaline earth salts and subsequent Cr(VI) leaching behavior. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:5858-5863. [PMID: 23635007 DOI: 10.1021/es4001455] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In this paper, the temperature dependence of Cr(III) oxidation in high temperature processes and the subsequent Cr(VI) leaching was studied using synthetic mixtures. It was experimentally shown that in the presence of alkali and alkaline earth salts, oxidation of Cr(III) takes place, consistent with thermodynamic calculations. Heating of synthetic mixtures of Cr2O3 and Na, K, or Ca salts led to elevated leaching of Cr(VI); in the presence of Na, more than 80% of the initial Cr(III) amount was converted to Cr(VI) at 600-800 °C. Kinetic experiments allowed explanation of the increase in Cr(VI) leaching for increasing temperatures up to 600-800 °C. After reaching a maximum in Cr(VI) leaching at temperatures around 600-800 °C, the leaching decreased again, which could be explained by the formation of a glassy phase that prevents leaching of the formed Cr(VI). By way of illustration, Cr(VI) formation and leaching was evaluated for a case study, the fabrication of ceramic material from contaminated sludge. Based on the proposed reaction mechanisms, countermeasures to prevent Cr oxidation (addition of NH4H2PO4, heating under inert atmosphere) were proposed and successfully tested for synthetic mixtures and for the case study.
Collapse
Affiliation(s)
- Bram Verbinnen
- ProcESS, Process Engineering for Sustainable Systems, Department of Chemical Engineering, KU Leuven, W. De Croylaan 46, B-3001 Leuven, Belgium.
| | | | | | | |
Collapse
|
16
|
Hernandez AB, Ferrasse JH, Chaurand P, Saveyn H, Borschneck D, Roche N. Mineralogy and leachability of gasified sewage sludge solid residues. JOURNAL OF HAZARDOUS MATERIALS 2011; 191:219-227. [PMID: 21592652 DOI: 10.1016/j.jhazmat.2011.04.070] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Revised: 04/10/2011] [Accepted: 04/16/2011] [Indexed: 05/30/2023]
Abstract
Gasification of sewage sludge produces combustible gases as well as tar and a solid residue as by-products. This must be taken into account when determining the optimal thermal conditions for the gasification process. In this study, the influence of temperature, heating atmosphere and residence time on the characteristics of the gasified sewage sludge residues is investigated. ICP-AES analyses reveal that the major chemical elements in the char residues are phosphorus, calcium, iron and silicon. Heavy metals such as copper, zinc, chromium, nickel and lead are also present at relatively high levels - from 50 to more than 1000 mg/kg of dry matter. The major mineral phases' identification - before and after heating - as well as their morphology and approximate chemistry (XRD and SEM-EDX) demonstrate that a number of transformations take place during gasification. These are influenced by the reactor's temperature and the oxidative degree of its internal atmosphere. The copper-, zinc- and chromium-bearing phases are studied using chemometric tools, showing that the distribution of those metals among the mineral phases is considerably different. Finally, batch-leaching tests reveal that metals retained in the residue are significantly stabilized after thermal treatment to a higher or lower extent, depending on the thermal conditions applied.
Collapse
Affiliation(s)
- Ana Belén Hernandez
- M2P2, Laboratoire de Mécanique, Modélisation et Procédés Propres, CNRS-Aix-Marseille University, UMR 6181, Aix-en-Provence, France
| | | | | | | | | | | |
Collapse
|
17
|
Furlani E, Tonello G, Maschio S. Recycling of steel slag and glass cullet from energy saving lamps by fast firing production of ceramics. WASTE MANAGEMENT (NEW YORK, N.Y.) 2010; 30:1714-1719. [PMID: 20400283 DOI: 10.1016/j.wasman.2010.03.030] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2009] [Revised: 03/22/2010] [Accepted: 03/23/2010] [Indexed: 05/29/2023]
Abstract
The paper reports on some experimental results obtained from the production of ceramics containing steel slag and glass cullet from exhaust energy saving lamps mixed in different proportions. Blending of components was done by attrition milling. Pressed powders were fast fired (50 min, cold to cold) in air up to several temperatures in the range 1000-1140 degrees C. The sintering behaviour was studied by shrinkage and water absorption measurements. Density, strength and hardness of the fired bodies were determined and XRD were examined. The fired samples were finally tested in acidic environment in order to evaluate their elution behaviour and consequently their possible environmental compatibility. It is observed that the composition containing 60 wt.% of steel slag and 40 wt.% of glass cullet displayed the best overall behaviour.
Collapse
Affiliation(s)
- E Furlani
- Università di Udine, Dipartimento di Scienze e Tecnologie Chimiche, Via del Cotonificio 108, 33100 Udine, Italy.
| | | | | |
Collapse
|
18
|
Maschio S, Furlani E, Tonello G, Faraone N, Aneggi E, Minichelli D, Fedrizzi L, Bachiorrini A, Bruckner S. Fast firing of tiles containing paper mill sludge, glass cullet and clay. WASTE MANAGEMENT (NEW YORK, N.Y.) 2009; 29:2880-2885. [PMID: 19608400 DOI: 10.1016/j.wasman.2009.06.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Revised: 04/16/2009] [Accepted: 06/10/2009] [Indexed: 05/28/2023]
Abstract
The paper describes results obtained in the development of a previous research. We study here, in fast firing, the sintering behaviour and measure some properties of tiles containing a mixture of 60 wt% of paper mill sludge and 40 wt% of glass cullet. The behaviour of this material is compared to those displayed by materials obtained by the same mixture added with 10, 20 and 30 wt% of a natural red clay. In parallel, the same properties are measured also on a reference blend, which is presently used to produce commercial tiles. We show that powders containing 60 wt% of paper sludge and 40 wt% of glass cullet to which 30 wt% of clay is added give rise to materials that display a stable sintering process and have good hardness and strength and therefore could be used for the industrial production of tiles.
Collapse
Affiliation(s)
- S Maschio
- Università di Udine, Dipartimento di Scienze e Tecnologie Chimiche, Via del Cotonificio 108, Udine 33100, Italy.
| | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Liu Y, Zheng L, Li X, Xie S. SEM/EDS and XRD characterization of raw and washed MSWI fly ash sintered at different temperatures. JOURNAL OF HAZARDOUS MATERIALS 2009; 162:161-173. [PMID: 18555594 DOI: 10.1016/j.jhazmat.2008.05.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2007] [Revised: 03/27/2008] [Accepted: 05/05/2008] [Indexed: 05/26/2023]
Abstract
The disposal of fly ash generated during municipal solid waste incineration (MSWI) may pose a significant risk to the environment due to the possible leaching of hazardous pollutants, such as toxic metals. Sintering technology attracted more attention than the vitrification process because of its low energy needed. Generally, a preliminary washing treatment of raw fly ash with water was necessary for this sintering technology. This study investigated the composition and morphology of raw fly ash (RFA) and washed fly ash (WFA) at different sintering temperatures, and examined the newly formed minerals during sintering. Toxicity characteristic leaching procedure (TCLP) tests were carried out to investigate the effect of the washing treatment and sintering process on the leaching performance of heavy metals in fly ash. Results showed that, with an increase of sintering temperature more complex aluminosilicates were formed; the incorporation of Mg, Fe and Pb into the aluminosilicates occurred during the sintering process at higher temperatures (800 and 900 degrees C). The washing treatment reduced the leachable concentration of Cd, Pb and Ni, but increased that of Cr. A CaCrO(4) compound was considered as a potential soluble species.
Collapse
Affiliation(s)
- Yangsheng Liu
- College of Environmental Science and Engineering, Peking University, Beijing 100871, China.
| | | | | | | |
Collapse
|
20
|
Chiang KY, Tsai CC, Wang KS. Comparison of leaching characteristics of heavy metals in APC residue from an MSW incinerator using various extraction methods. WASTE MANAGEMENT (NEW YORK, N.Y.) 2009; 29:277-284. [PMID: 18571915 DOI: 10.1016/j.wasman.2008.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2007] [Revised: 02/14/2008] [Accepted: 04/21/2008] [Indexed: 05/26/2023]
Abstract
This study investigates four extraction methods (water extraction, toxicity characteristics leaching procedure (TCLP), modified TCLP with pH control, and sequential chemical extraction (SCE)), each representing different liquid-to-solid (L/S) ratios, pH controls, and types of leachant, and their effects on the leaching concentration of heavy metals in municipal solid waste (MSW) incinerator air pollution control (APC) residue. The results indicated that for extraction with distilled water, the heavy metal leaching concentration (mg/l) decreased with L/S ratio, but the amount of heavy metal released (AHMR), defined as the leached amount of heavy metals to the weight of the tested sample (mg/kg), increased with an increase in L/S ratio, in the range of 2-100. The results also showed that both the leaching concentration and the amount of released metals were strongly pH-dependent in the TCLP and modified TCLP tests. In the case of pHs lower than 6.5, the leaching concentrations of Cd, Pb, Cu, Zn, and Cr decreased with an increase in pH. As pH increased higher than 6.5, Cr and Zn were almost insoluble. Meanwhile, Cd and Cu also showed a similar trend but at pHs of 8.5 and 7.5, respectively. Due to the nature of amphoteric elements, in the case of pHs higher than 7, the Pb leaching concentration increased with increasing pH. In modified TCLP tests with the pH value controlled at the same level as in the SCE test, the heavy metal speciation approached the extractable carbonate bound fraction by the SCE. Both amounts of targeted metals leached from the SCE and modified TCLP tests were much higher than those for the regular TCLP and water extraction tests.
Collapse
Affiliation(s)
- Kung-Yuh Chiang
- Department of Environmental Engineering and Science, Feng-Chia University, 100 Wen-Hwa Road, Tai-Chung 407, Taiwan, ROC.
| | | | | |
Collapse
|
21
|
Wang Q, Tian S, Wang Q, Huang Q, Yang J. Melting characteristics during the vitrification of MSWI fly ash with a pilot-scale diesel oil furnace. JOURNAL OF HAZARDOUS MATERIALS 2008; 160:376-381. [PMID: 18439755 DOI: 10.1016/j.jhazmat.2008.03.043] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2007] [Revised: 12/11/2007] [Accepted: 03/04/2008] [Indexed: 05/26/2023]
Abstract
Treatment of municipal solid waste incineration (MSWI) fly ash is becoming an important issue in China. A pilot-scale experiment was carried out to treat MSWI fly ash by using a diesel oil furnace (DOF) for more than 6 months. The effects of melting temperature on volume reduction, weight loss, compositional changes, and toxicity of leach water for molten slag have been investigated and reported. Results indicated that the volume reduction fraction of raw fly ash (RFA) and washed-fly ash (WFA) was 75-80% and the weight loss fraction was 23.8-30% at 1260-1350 degrees C. During the vitrification, CaO, A12O3, and SiO2 percentages in fly ash increased as the temperature increased, especially for SiO2, which was caused by both the decomposition of carbonates or sulfates and the volatilization of metal chlorides because the main components in secondary fly ash collected from fabric filter bags were NaCl and KCl. The leaching concentrations of heavy metals in molten slag were lower than the standard values of TCLP. The releasing levels of dioxin and other pollutants (such as SO2, HCl, CO, NOx, etc.) in flue gas were all lower than the Chinese standard.
Collapse
Affiliation(s)
- Qi Wang
- Chinese Research Academy of Environmental Science, Beijing 100012, China.
| | | | | | | | | |
Collapse
|
22
|
Erdem M, Ozverdi A. Leaching behavior of chromium in chrome shaving generated in tanning process and its stabilization. JOURNAL OF HAZARDOUS MATERIALS 2008; 156:51-55. [PMID: 18206298 DOI: 10.1016/j.jhazmat.2007.11.111] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2007] [Revised: 08/18/2007] [Accepted: 11/29/2007] [Indexed: 05/25/2023]
Abstract
In this study, leaching properties and pollution potential of chromium in chrome shaving (CS), which is a solid residue of leather industry, containing 2.27% Cr were investigated and thermal stabilization procedure was applied to the CS for chromium immobilization. For this purpose, firstly, effects of the liquid/solid ratio, contact time, pH and sequential extraction on the leaching behavior of chromium in the CS were studied. It was determined that the CS-caused chromium pollution is a hazardous material for environment. Thermal stabilization procedure was applied to the CS in the temperature range of 250-500 degrees C for the chromium immobilization. Effective stabilization of chromium in the CS was achieved by heating of CS at 350 degrees C under CO(2) atmosphere. Leaching experiments were also carried out with the samples obtained from the stabilization process and the results compared with that of the CS. Also, TCLP test method was applied to the samples to determine pollution potentials and discharge situations of the CS and its stabilization products. While the chromium concentrations in the test solutions of all samples stabilized thermally at above 350 degrees C were below the USEPA regulatory limit of 5 mg/l, the concentration of chromium leached out from the CS was 30-fold bigger than the USEPA regulatory limit.
Collapse
Affiliation(s)
- Mehmet Erdem
- Department of Environmental Engineering, Firat University, Elaziğ, Turkey.
| | | |
Collapse
|
23
|
Chou JD, Wey MY, Chang SH. Emission of Pb and PAHs from thermally co-treated MSWI fly ash and bottom ash process. JOURNAL OF HAZARDOUS MATERIALS 2008; 150:27-36. [PMID: 17521803 DOI: 10.1016/j.jhazmat.2007.04.041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2006] [Revised: 04/12/2007] [Accepted: 04/17/2007] [Indexed: 05/15/2023]
Abstract
Municipal solid waste incinerator (MSWI) fly ash was regarded as a hazardous material because concentrations of TCLP leaching solution exceeded regulations. Previous studies have investigated the characteristics of thermally treated slag. However, the emissions of pollutant during the thermal treatment of MSWI fly ash have seldom been addressed. The main objective of this study was to evaluate the emission of Pb and PAHs from thermally co-treated MSWI fly and bottom ash process. The experimental parameters included the form of pretreatment, the proportion of bottom ash (bottom ash/fly ash, B/F=0, 0.1 and 1) and the retention time. The toxicity of thermally treated slag was also analyzed. The results indicated that (1) Pb emission occurred only in the solid phase and that PAHs were emitted from both solid and gas phases during thermal treatment process. (2) Washing pretreatment reduced not only the TCLP leaching concentration of Pb (from 15.75 to 1.67 mg/L), but also the emission of PAHs from the solid phase during thermal treatment process. (3) Adding bottom ash reduced the TCLP leaching concentration of thermally treated slag. (4) The concentration of Pb emission increased with retention time. (5) The thermal treatment reduced the toxicity of raw fly ash effectively, the inhibition ratio of raw fly ash and thermal treated slag were 98.71 and 18.35%, respectively.
Collapse
Affiliation(s)
- Jing-Dong Chou
- Department of Environmental Engineering, National Chung-Hsing University, Taichung 402, Taiwan, ROC
| | | | | |
Collapse
|
24
|
Bethanis S, Cheeseman CR, Sollars CJ. Effect of sintering temperature on the properties and leaching of incinerator bottom ash. WASTE MANAGEMENT & RESEARCH : THE JOURNAL OF THE INTERNATIONAL SOLID WASTES AND PUBLIC CLEANSING ASSOCIATION, ISWA 2004; 22:255-264. [PMID: 15462333 DOI: 10.1177/0734242x04045426] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The fine particle size fraction of municipal solid waste incinerator bottom ash is often problematic because reuse applications for this material are limited. In these experiments incinerator bottom ash with a particle size of less than 8 mm was processed using conventional ceramic production techniques involving wet milling, drying, compacting and sintering. The effect of sintering temperature on the sintered density, microstructure, acid neutralization capacity (ANC) and the release of metal ions as a function of leachate pH are reported. Sintering at 1080 degrees C produced samples with maximum density. This material contained diopside (CaMgSi2O6), clinoenstatite (Mg2Si2O6) and wollastonite (CaSiO3) as the major crystalline phases. The acid neutralization capacity of sintered samples is significantly lower than milled bottom ash, and further reduces as the sintering temperature increases. This is associated with reduced leaching of Ca from sintered ash samples under all leachate pH conditions. Heavy metals present in the incinerator bottom ash included Cr, Cu, Ni, Zn, Cd and Pb. Sintering under optimum conditions reduced the leachable fraction of these metals under aggressive acid conditions (leachate pH 3) by factors ranging from 90% for Ni to greater than 99% for Cr, Cd, Zn and Pb.
Collapse
Affiliation(s)
- Sophia Bethanis
- Centre for Environmental Control and Waste Management, Department of Civil and Environmental Engineering, Imperial College of Science, Technology and Medicine, London, UK
| | | | | |
Collapse
|