Municipal Solid Waste Incineration Ash Research Articles

Caracterização e incorporação de cinza de resíduo sólido urbano em cerâmica vermelha

Resumo Este trabalho tem por objetivo avaliar o efeito da incorporação de cinza de resíduo sólido urbano nas propriedades físicas e mecânicas da cerâmica vermelha. Foram preparados corpos de prova por prensagem uniaxial a 20 MPa para queima a 750 °C, com incorporações de resíduo (70% de cinza de fundo e 30% de cinza volante) de até 20% em massa em argila caulinítica da região de Campos dos Goytacazes, RJ. As matérias-primas foram submetidas à análise química, mineralógica, física e morfológica. As propriedades físicas e mecânicas avaliadas nos corpos de prova foram: absorção de água, retração linear e tensão de ruptura à flexão. Os resultados sugerem a incorporação de quantidades em torno de 5% em massa de cinzas na argila para não prejudicar o comportamento mecânico da cerâmica, bem como evitar o aparecimento de porosidade aberta excessiva, podendo ser esta uma destinação final ambientalmente adequada para as cinzas de resíduo sólido urbano.

Improving durability of reinforced concrete structures by recycling wet‐ground MSWI bottom ash

Municipal solid waste incineration (MSWI) generates high amounts of bottom ash that, after grinding, could be used as mineral addition for concrete. Wet grinding of the bottom ash can prevent the risk of deleterious expansion due to hydrogen evolution, associated to the presence of metallic aluminium. The pozzolanic behavior of the bottom ash may improve concrete resistance to the penetration of aggressive species. Advantages of recycling wet‐ground MSWI bottom ashes may even be higher when self‐compacting concrete (SCC) is used, which requires large quantity of fine powders (usually more than 500 kg/m3) to prevent segregation of the fresh mix. This paper describes the results of a research aimed at investigating the use of wet‐ground MSWI bottom ashes as mineral additions for the production of self‐compacting concrete. Several types of mineral additions (MSWI bottom ash, coal fly ash, and ground limestone) were used in replacement of 15, 30, and 45% of Portland cement. The results showed that the MSWI ash, added to the mix as a fine slurry obtained by wet‐grinding, led to the production of SCC concrete with compressive strength and resistance to chloride and carbonation similar, or even better, than those of concrete with same amount of coal fly ash.

쓰레기 소각재 용융슬래그 미분말을 혼입한 모르타르의 압축강도 특성에 대한 연구

In order to investigate the feasibility of municipal solid waste incineration ash melted slag powder as admixture, an experimental study was performed on cement mortar with municipal solid waste incineration ash melted slag powder. Fresh mortar properties and strength properties with various municipal solid waste incineration ash melted slag powder replacement ratios were estimated. There replacement ratio adopted in this study was 0, 10, 20, 30, 40, 50%. After then flow properties was considered as properties of fresh mortar. And compressive strength was determined 3, 7, 14, 28, 56 days for the hardened mortar specimens. According to the test results, the flow of mortar was increased with in replacement amount of municipal solid waste incineration ash melted slag powder. Furthermore, compressive strength at early age was decreased, whereas the compressive strength at the age of 28, 56day was increased.

Cesium sorption/desorption characteristics of sodium bentonite affected by major cations in leachate from MSW incinerator ash

Cesium sorption/desorption characteristics of sodium bentonite affected by major cations in leachate from MSW incinerator ash

Spatial Variation of Shear Wave Velocity of Waste Materials from Surface Wave Measurements

The mechanical properties of waste materials are, typically, believed to be more variable than natural soils; however, detailed investigations into the variability of these materials is generally unavailable. The shear wave velocity and its variation with depth and laterally for five different waste types has been measured and analyzed at 26 locations. Shear wave velocity measurements were performed using the multichannel analysis of surface waves (MASW) and microtremor analysis method (MAM) techniques. Statistical analyses were performed for these locations as well as locations available in the literature. Waste types tested include municipal solid waste (MSW) in Subtitle D landfills in Michigan, MSW in a bioreactor landfill, MSW incineration ash, hazardous waste, construction and demolition waste, and municipal water treatment sludge. An empirical shear wave velocity model with depth is calibrated for each of the various waste types. Spatial variability of shear wave velocity is quantified using the coefficient of variation (COV) as a function of depth. The COV of the shear wave velocity of these waste types was found to be similar to values reported in the literature for soil and rock sites.

Aging effects on the mechanical property of waste mixture in coastal landfill sites

Coastal landfill sites not only offer an option for disposal but also create a new land space after the completion of landfilling. To perform proper design on settlement, stability, and/or bearing capacity at landfill sites, the geotechnical properties of the waste layer such as deformation and shear strength should be investigated. This research is focused on the mechanical properties of waste mixture sampled at a coastal landfill site including municipal solid waste incinerator ash, slag, soil and others, to provide useful information on geotechnical properties in utilizing coastal landfill sites after their closure. A series of triaxial consolidated undrained compression tests (CU) and hydraulic conductivity tests were carried out on the reconstituted waste samples before and after being cured in simulated leachate water in coastal landfill sites for different periods, to understand the aging effects on mechanical properties of waste mixture. It was shown that while curing results in an increase in the peak strength and deformation modulus, the residual strength was not affected by the curing periods. Scanning electron microscope observations and X-ray diffraction analysis on the waste samples after curing confirmed that the formation of ettringite and hydration products had a densification effect on the microstructure. The higher peak shear strength and lower hydraulic conductivity of the waste samples were attributed to this effect.

Leaching optimization of municipal solid waste incineration ash for resource recovery: A case study of Cu, Zn, Pb and Cd

Ash from municipal solid waste incineration (MSWI) may be quite cumbersome to handle. Some ash fractions contain organic pollutants, such as dioxins, as well as toxic metals. Additionally, some of the metals have a high value and are considered as critical to the industry. Recovery of copper, zinc and lead from MSWI ashes, for example, will not only provide valuable metals that would otherwise be landfilled but also give an ash residue with lower concentrations of toxic metals.In this work, fly ash and bottom ash from an MSWI facility was used for the study and optimization of metal leaching using different solutions (nitric acid, hydrochloric acid and sulfuric acid) and parameters (temperature, controlled pH value, leaching time, and liquid/solid ratio). It was found that hydrochloric acid is relatively efficient in solubilizing copper (68.2±6.3%) and zinc (80.8±5.3%) from the fly ash in less than 24h at 20°C. Efficient leaching of cadmium and lead (over 92% and 90% respectively) was also achieved. Bottom ash from the same combustion unit was also characterized and leached using acid. The metal yields were moderate and the leachates had a tendency to form a gelatinous precipitate, which indicates that the solutions were actually over-saturated with respect to some components. This gel formation will cause problems for further metal purification processes, e.g. solvent extraction.

Investigation on the side effects of municipal solid waste incineration ashes when used as mineral addition in cement-based material

The main focus of this study is the characterisation of the municipal solid waste incineration (MSWI) ashes and their influence on engineering properties of cement paste when part of Portland cement is replaced with ground MSWI ashes. Petrographic examinations were performed in order to identify chemical composition of ashes and to determine their contents. To evaluate the main side effect of ashes when used in cement, the creation of network of bubbles due to the presence of aluminium, ashes, and aluminium powder were submerged in high pH solution and the evolution of hydrogen gas was measured. Cement paste cylinders were cast with various amounts of mineral additions and their strength and durability were investigated. Analysis on the measured data demonstrated that the use of ashes as cement replacement has both beneficial and detrimental effects on the strength and durability caused by the filler effect and hydrogen gas development, respectively.

미연소 섬유분에 의한 도시 쓰레기 소각재 혼입 시멘트 복합재료의 성능감소

Abstract The negative effects of unburned fabric in municipal solid waste incinerator (MSWI) ash on the performances of cement com-posite were investigated. The chemical and physical characteristics of MSWI ash powder containing high volume of unburnedfabric were analyzed. The workability and compressive strength of mortar-type cement composites with the ash powder wereevaluated. The workability of the cement composites was decreased mainly by unburned fabric in the ash, while the compressivestrength was decreased by MSWI ash itself. From the experimental results, the critical limits for both MSWI ash and their pow-der containing unburned fabric in the cement composites should be limited from standpoint of the workability of the composite. Key words : Municipal solid waste incinerator (MSWI) ash, unburned fabric, cement composites, workability, strength · Received : April 6, 2015 · 1st Revised : May 11, 2015 · 2nd Revised : May 26, 2015 · Accepted : June 29, 2015Corresponding Author : Hyeong-Ki Kim (E-mail : hyeongki@chosun.ac.kr)School of Architecture, Chosun University, 1st Engineering Building, Room #9108, 309 Pilmun-daero, Dong-gu, Gwangju,501-759 KoreaⓒThe Korean Institute of Resources Recycling. All rights reserved. This is an open-access article distributed under the termsof the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/), which permitsunrestricted non-commercial use, distribution and reproduction in any medium, provided the original work is properly cited.

Pre-treatment of municipal solid waste incineration (MSWI) bottom ash for utilisation in cement mortar

The removal of elemental aluminium, sulphate and harmful organics from two types of MSWI ash samples, the sand sized (0.1–2mm) fraction of MSWI bottom ash from a grate furnace (SF), and boiler and fly ash from a fluidized bed incinerator (BFA), were done to use as fine aggregates in preparation of cement mortar. Results indicate that the chemical treatment by 0.25M Na2CO3 solution can dissolve the Al and the sulphate bearing minerals from the BFA and therefore enhance its quality to use as a fine aggregate in cement mortar preparation. On the other hand, heat treatment at about 675°C before Na2CO3 treatment is necessary to improve the quality of SF for using as a fine aggregate. The compressive strengths of mortars improve significantly due to the partial replacement of sand by heat and Na2CO3 treated ash samples. The proposed treatment methods slightly change the toxic element leaching behaviours of the ash samples. The concentrations of toxic elements in the leachates generated from the treated ash samples as well as the leachates generated from the mortars containing these ash samples are well within the regulatory limits.

Contemporary practices and findings essential to the development of effective MSWI ash reuse policy in the United States

Abstract Municipal solid waste incineration (MSWI) in the United States generates a significant amount (∼6.6 million mtons) of ash annually, yet the utilization of this ash in beneficial use applications is nearly non-existent. In some European and Asian nations, policy regulates the use of MSWI bottom ash in construction with an accepted degree of environmental and human health risk. Both federal and state-level solid waste policy in the United States largely does not address ash reuse. U.S. MSWI industry practices have been adapted to avoid hazardous waste generation and primarily practice ash disposal in monofills. Numerous case studies and laboratory experiments have characterized MSWI ashes with regard to the potential environmental contaminants and have demonstrated the efficacy of bottom ash in specific reuse scenarios. In reviewing these studies, and by analyzing the reuse policy in several nations, the authors identify key aspects of effective MSWI ash reuse. These are discussed within the framework of available data and information, and examples are provided. Moving toward the sustainable management of resources such as MSWI bottom ash will require U.S. state-level policy to address the conditions under which ashes may or may not be reused. Suggestions on practices (often already occurring in many other areas of the world) to facilitate the reuse of MSWI ashes are provided.

Waste heat generation: A comprehensive review

A comprehensive review of heat generation in various types of wastes and of the thermal regime of waste containment facilities is provided in this paper. Municipal solid waste (MSW), MSW incineration ash, and mining wastes were included in the analysis. Spatial and temporal variations of waste temperatures, thermal gradients, thermal properties of wastes, average temperature differentials, and heat generation values are provided. Heat generation was influenced by climatic conditions, mean annual earth temperatures, waste temperatures at the time of placement, cover conditions, and inherent heat generation potential of the specific wastes. Time to onset of heat generation varied between months and years, whereas timelines for overall duration of heat generation varied between years and decades. For MSW, measured waste temperatures were as high as 60–90°C and as low as −6°C. MSW incinerator ash temperatures varied between 5 and 87°C. Mining waste temperatures were in the range of −25 to 65°C. In the wastes analyzed, upward heat flow toward the surface was more prominent than downward heat flow toward the subsurface. Thermal gradients generally were higher for MSW and incinerator ash and lower for mining waste. Based on thermal properties, MSW had insulative qualities (low thermal conductivity), while mining wastes typically were relatively conductive (high thermal conductivity) with ash having intermediate qualities. Heat generation values ranged from −8.6 to 83.1MJ/m3 and from 0.6 to 72.6MJ/m3 for MSW and mining waste, respectively and was 72.6MJ/m3 for ash waste. Conductive thermal losses were determined to range from 13 to 1111MJ/m3yr. The data and analysis provided in this review paper can be used in the investigation of heat generation and thermal regime of a wide range of wastes and waste containment facilities located in different climatic regions.

Effect of chemical treatment of MSWI bottom ash for its use in concrete

In this paper, municipal solid waste incineration (MSWI) bottom ash was characterised before and after chemical treatment and the effect of ash addition on the performance of concrete as a partial replacement of fine aggregate was evaluated. The chemical treatment aimed to eliminate the side effect of MSWI ash – the creation of a network of bubbles – which can eventually lead to a significant reduction of the overall performance of concrete. Petrographic examinations, energy dispersive X-ray spectroscopy and X-ray diffraction, were carried out to chemically characterise the MSWI bottom ash. The mechanical performance of the ash-combined concrete was evaluated by measuring its compressive strength. Analysis of the measured data demonstrates that the chemical treatment successfully transformed metallic aluminium in the ash into a stable form and hence expansion of the concrete due to hydrogen gas evolution was no longer detected in the concrete containing treated ash. Consequently, compared with specimens with untreated ash, concrete specimens with treated bottom ash showed improved performance.

Sintering characteristics of CaO-rich municipal solid waste incineration fly ash through the addition of Si/Al-rich ash residues

Thermal treatment is a promising technology for the fast disposal of hazardous municipal solid waste incineration (MSWI) fly ash in China. However, fly ash produced in grate incinerator (GFA) is rich in CaO and chlorides, which promote the formation of toxic hexavalent chromium [Cr(VI)] and ash agglomeration during the thermal process, inhibiting the thermal disposal of GFA. In this study, sintering characteristics of CaO-rich GFA were improved by adding Si/Al-rich MSWI ash residues. According to the results, ash agglomeration was well suppressed during thermal treatment of the mixed ash. Si/Al/Fe-compounds competed with un-oxidized Cr-compounds to react with CaO and suppressed Cr(VI) formation. Meanwhile, chlorides in GFA facilitated heavy metal volatilization from added ashes to the secondary fly ash, favoring the recovery of these metals. Ca-aluminosilicates was found as the main mineral phase in the thermally treated mixed ash, which has attractive potential for applications. The formation of the aluminosilicates made the heavy metals that remained in the treated mixed ash more stable than the thermally treated single ash.

Mechanism of chromium oxidation by alkali and alkaline earth metals during municipal solid waste incineration

The influence of alkali and alkaline earth metals on the formation of hexavalent chromium (Cr(VI)) during municipal solid waste (MSW) incineration has drawn much attention due to the high toxicity of Cr(VI). In the present work, the distribution of Cr(VI) in MSW incineration ash residues sampled from various plants was measured. The results show that the oxidation of chromium in combustion process is determined by the content of free CaO (f-CaO) in the MSW and is facilitated by alkali metal compounds at lower temperatures in the flue gas cooling process. In some cases, the content of f-CaO is low during MSW incineration, and the oxidation of Cr2O3 in the case of low mole ratio of Ca and Cr was investigated. The mixture of CaO and Cr2O3 was heated at temperatures ranging from 973 to 1373K and the oxidation of Cr2O3 was detected by determining the consumption of oxygen in the carrier gas using an online mass spectrometer. According to the results, more chromium is oxidized in the thermally treated mixture at 1173K than at higher temperatures. At 1173K, part of chromium is oxidized to form CaCrO4 and the unoxidized chromium remains in the form of Cr2O3. In contrast, Cr2O3 is prior to form Ca3(CrO4)2 at higher temperatures and the unoxidized chromium is mostly transformed into CaCr2O4. Compared with Cr2O3, CaCr2O4 is more easily oxidized by CaO or K2CO3, indicating that more Cr(VI) would be formed during MSW incineration when trivalent chromium (Cr(III)) is transformed into CaCr2O4. Measures should be taken to suppress the formation of CaCr2O4 such as the control of the operating temperature and CaO addition.

Pozzolanic reaction of a mortar made with cement and slag vitrified from a MSWI ash-mix and LED sludge

Fly ash and scrubber ash that were generated by incinerators were mixed to produce municipal solid waste incinerator (MSWI) ash mix based on the proportions of the produced ash. In addition, 50 wt.% sludge produced during the manufacturing process of light emitting diodes (LEDs) was mixed into the MSWI ash mix, which was then melted to create MSWI-LED slag. This slag was used to replace 0, 5, 10, 20, and 30 wt.% cement and then the 5×5×5cm3 slag-blended cement mortar (SBCM) specimens were molded. Analyses of compressive strength and other properties were conducted. The results showed that the SBCM specimen at 1–7days of age possessed a compressive strength close to or slightly higher than that of a ordinary Portland cement mortar (OPCM) specimen, whereas that at 14–90days had a compressive strength 6–36% greater than that of OPCM specimens. The specimens were analyzed using X-ray diffraction (XRD), thermogravimetric and differential thermal analyses (TG/DTAs), and nuclear magnetic resonance (NMR). The results showed that the pozzolanic reaction in the slag increased compressive strength. Moreover, this study conducted a toxicity characteristic leaching procedure (TCLP) and investigated initial and final setting times and the fluidity of the specimens. The results indicated that MWSI-LED slag prevented heavy metal leaching, increased the compressive strength of specimens of different ages, shortened the initial and final setting times, and only slightly reduced fluidity. Replacing part of the cement in mortar with this slag facilitates waste recycling, enhances environmental protection, and meets the demand for sustainable development.

도시쓰레기 소각재 슬래그로 제조된 지오폴리머의 특성

본 연구에서는 도시 쓰레기 소각재 슬래그에 알칼리 활성화제로서 NaOH를 첨가하여 지오폴리머를 합성하고 그 물성을 평가하였다. 특히 NaOH의 몰농도, 원료의 입도 그리고 액체/고체 비율이 제조된 지오폴리머의 압축강도에 미치는 영향을 조사하였다. 원료의 입도가 미세할수록 합성된 지오폴리머의 강도는 증가하였으며, 액체/고체 비율의 최적 값은 0.13으로 나타났다. 합성된 지오폴리머의 압축강도는 첨가된 NaOH의 몰농도가 증가함에 따라 함께 증가하는 경향을 나타내었으나, 20 M 이상의 농도에서는 일정 값에 수렴하였다. 20 M 이상의 NaOH 농도로 제조된 지오폴리머에는 sodium aluminum silicate 및 sodium aluminum silicate hydrate 형태의 2종류 zeolite 결정상이 생성되었다. 20 M NaOH 및 <TEX>$70^{\circ}C$</TEX> 양생조건으로 제조된 시편에서 가장 높은 압축강도, 163 MPa이 발현되었으며, 이것은 고농도의 NaOH가 지오폴리머 반응 및 치밀한 미세구조 형성을 촉진시켰기 때문인 것으로 사료된다. 본 연구에서 제조된 고강도의 지오폴리머는 향후, 도시쓰레기 소각재 슬래그의 재활용율 제고는 물론 시멘트 대체 분야 발전에 일조할 것으로 기대된다. In this research, the geopolymer was fabricated using municipal solid waste incineration ash (denoted as MSWIA) slag and alkali activator, NaOH and its properties were analyzed. Particularly, the effects of NaOH molarity, particle size of MSWIA, and liquid/solids ratio on the compressive strength of geopolymers were investigated. The compressive strength of geopolymers fabricated increased with finer grain size of MSWIA, and optimum value of the liquid/solids ratio was identified as 0.13. As the molarity of the NaOH increased, the compressive strength of geopolymers was increased. Even more the 20 M of NaOH, but the strength was not increased. The calcium aluminum silicate and calcium aluminum silicate hydrate zeolites were generated in the geopolymer fabricated with more than 20 M of NaOH, with some unreacted silica and unknown crystals remained. The highest compressive strength, 163 MPa, of geopolymer was appeared at conditions of curing temperature <TEX>$70^{\circ}C$</TEX>, and 20 M of NaOH, indicating that the high concentration of NaOH accelerates the geopolymer reaction and dense microstructure. The high-strength geopolymer fabricated in the present study is expected to contribute significantly to develop the field of cement alternative substances and to improve the recycling rate of MSWIA slag.

Assessment of mobility and bioavailability of contaminants in MSW incineration ash with aquatic and terrestrial bioassays

Incineration of municipal solid waste (MSW) is a waste treatment method which can be sustainable in terms of waste volume reduction as well as a source of renewable energy. In the process fly and bottom ash is generated as a waste material. The ash residue may vary greatly in composition depending on the type of waste incinerated and it can contain elevated levels of harmful contaminants such as heavy metals. In this study, the ecotoxicity of a weathered, untreated incineration bottom ash was characterized as defined by the H14 criterion of the EU Waste Framework Directive by means of an elemental analysis, leaching tests followed by a chemical analysis and a combination of aquatic and solid-phase bioassays. The experiments were conducted to assess the mobility and bioavailability of ash contaminants. A combination of aquatic and terrestrial bioassays was used to determine potentially adverse acute effects of exposure to the solid ash and aqueous ash leachates. The results from the study showed that the bottom ash from a municipal waste incineration plant in mid-Sweden contained levels of metals such as Cu, Pb and Zn, which exceeded the Swedish EPA limit values for inert wastes. The chemical analysis of the ash leachates showed high concentrations of particularly Cr. The leachate concentration of Cr exceeded the limit value for L/S 10 leaching for inert wastes. Filtration of leachates prior to analysis may have underestimated the leachability of complex-forming metals such as Cu and Pb. The germination test of solid ash and ash leachates using T. repens showed a higher inhibition of seedling emergence of seeds exposed to the solid ash than the seeds exposed to ash leachates. This indicated a relatively low mobility of toxicants from the solid ash into the leachates, although some metals exceeded the L/S 10 leaching limit values for inert wastes. The Microtox® toxicity test showed only a very low toxic response to the ash leachate exposure, while the D. magna immobility test showed a moderately high toxic effect of the ash leachates. Overall, the results from this study showed an ecotoxic effect of the solid MSW bottom ash and the corresponding ash leachates. The material may therefore pose an environmental risk if used in construction applications. However, as the testing of the solid ash was rather limited and the ash leachate showed an unusually high leaching of Cr, further assessments are required in order to conclusively characterize the bottom ash studied herein as hazardous according to the H14 criterion.

Porous materials produced from incineration ash using thermal plasma technology

This study presents a novel thermal plasma melting technique for neutralizing and recycling municipal solid waste incinerator (MSWI) ash residues. MSWI ash residues were converted into water-quenched vitrified slag using plasma vitrification, which is environmentally benign. Slag is adopted as a raw material in producing porous materials for architectural and decorative applications, eliminating the problem of its disposal. Porous materials are produced using water-quenched vitrified slag with Portland cement and foaming agent. The true density, bulk density, porosity and water absorption ratio of the foamed specimens are studied here by varying the size of the slag particles, the water-to-solid ratio, and the ratio of the weights of the core materials, including the water-quenched vitrified slag and cement. The thermal conductivity and flexural strength of porous panels are also determined. The experimental results show the bulk density and the porosity of the porous materials are 0.9–1.2gcm−3 and 50–60%, respectively, and the pore structure has a closed form. The thermal conductivity of the porous material is 0.1946Wm−1K−1. Therefore, the slag composite materials are lightweight and thermal insulators having considerable potential for building applications.

Applicability of Municipal Solid Waste Incineration Ash on Base Layers of Pavements

AbstractThis study presents the characteristics of municipal solid waste (MSW) incineration ash obtained from an electric energy generation plant and evaluates the MSW ash applicability in base road pavement layers through the mixture of ash with a nonlateritic regional clay soil. Chemical, physical, and mechanical tests and the mechanistic-empirical design for a typical pavement structure were carried out on the pure soil and also in the soil mixture with the addition of different ash content (20 and 40%). Fly ash reduced the expansion of the material, showing an increase in the California bearing ratio (CBR) and resilient modulus value. The results are satisfactory, depending on the content and type of ash used, highlighting the positive work of MSW fly ash for its use in base road pavement layers.