Recycling Of Bottom Ash Research Articles

Assessing effects of waste coal bottom ash on construction cost of reinforced concrete structures considering experimental data

In this study, it has been examined whether the bottom ash (BA) released to the nature as waste material from the thermal power plant can be used in reinforced concrete structures (RCS) and how much cost reduction will be caused in construction technology if BA is used in RCS. For this purpose, coal BA produced by Turkey-Zonguldak Cates power plant is mixed in different ratios into the concrete mixture of the beams. The different coal bottom ash ratio (BAR) is used instead of aggregate in the mixture. The beams created for 5 different BARs are subjected to tests and it is observed that the beam with the most critical bending is the beam with 75% coal BA. This BAR is applied to bearing elements of finite element model (FEM) and then current cost of the building and the construction cost used 75% coal BAR are compared with each other. It has been observed that when 75% coal BAR is used instead of aggregate in RCSs, there is a 40% reduction in construction costs. This result is of great importance both for the recycling of BA and for revealing that BA reduces construction costs.

Recycling of bottom ash from biomass combustion in porcelain stoneware tiles: Effects on technological properties, phase evolution and microstructure

This work aims to evaluate the use of bottom biomass ash as an alternative raw material in porcelain stoneware bodies. For this purpose, ash coming from a biomass thermoelectric power plant in Emilia-Romagna (Italy) was selected and its chemical, mineralogical and thermal properties determined. Data indicated its technological role as a flux, so it was introduced in a porcelain stoneware batch in partial replacement of feldspars and experimented at laboratory scale. A bottleneck, relative to the rheological behavior of the slips, was overcome by a slight deflocculant increase. The powder compacts were fired from 1000° to 1220 °C in order to follow the evolution of the technological properties, phase composition (XRPD-Rietveld) and microstructure (SEM). The introduction of ash allowed to lower the firing temperature by 20 °C, while keeping the technological properties comparable with those of the benchmark. Moreover, the mineralogical and microstructural data revealed different sintering kinetics.

Municipal solid waste incineration bottom ash recycling in concrete: Preliminary approach with Oporto wastes

The present research explored the feasibility of using dry finely ground bottom ash (GBA) from municipal solid waste incineration as SCM for concrete mixtures in cooperation with a local waste management company, LIPOR. A first study was performed using GBA as a sole partial replacement for Portland cement in paste and mortar specimens. GBA showed both beneficial and detrimental effects on paste/mortar mixtures. In terms of fresh properties, water demand on paste and workability on mortar containing GBA as cement replacement kept the same as reference specimens paste/mortars. Setting time was not affected by GBA incorporation, and ASR expansion was mitigated. The disadvantageous effect, namely, mechanical strength loss on GBA mortar, was mainly due to metallic aluminium, found on the main oxide composition and SEM of GBA, which is associated with hydrogen gas evolution. Thus, the amount of aluminium content remaining in MIBA should be analysed even after the ageing process.

Effects of enhanced metal recovery on the recycling potential of MSWI bottom ash fractions in various legal frameworks.

In recent years, complex new bottom ash treatment processes for enhanced metal recovery have been implemented in Switzerland, producing residual bottom ash fractions with various qualities. This study focusses on three different treatment processes by characterizing all arising fractions in detail. Thereby the factors influencing the composition of these fractions are identified and their recycling potential in Switzerland is investigated. However, high legislative requirements on total contents of heavy metals represent a high barrier for bottom ash recycling in Switzerland. Therefore, the recycling potential is further evaluated based on the waste legislation applied in the Netherlands, where recycling of bottom ash has a long tradition. There, threshold values for bottom ash recycling are based on leachate concentrations and not on total contents as in Switzerland. However, Swiss Waste Legislation also knows threshold values based on leachate concentrations for certain waste materials. The leaching tests applied in these two countries, however, are different. The comparison of both leaching tests reveals that the setup and conditions, especially the considered pH range, significantly influence the leaching of heavy metals. With emphasis on problematic pollutants, the possibilities for new applications of these fractions are evaluated based on Swiss and Dutch legal threshold values. The comparison within the legal frameworks of these two countries allows recognizing opportunities and risks related to bottom ash recycling.

Improvement of desalinization performance in reclaimed land through recycling of bottom ash and oyster shells

Reclaimed land and coastal soils have characteristics of poor drainage and high salinity because they are adjacent to the ocean. As salty soil hinders growth of crops, it is necessary to improve drainage performance and desalinize the soil for efficient use of reclaimed land. Bottom ash and oyster shells are produced in significant amounts as by-products and wastes in Korea each year and, if left unattended, can cause environmental problems. Because these materials are large in size, particle size distribution and permeability of the soil can be improved by mixing of such ash and shells. Carbonate, a main component of oyster shell, is known to promote granulation of soil particles and can affect the grain size distribution of the soil. In addition, bottom ash has a porous structure that can improve permeability when it is mixed with soil. Therefore, several experiments and numerical analyses were performed in this study on use of bottom ash and oyster shells as soil improvement materials and drainage materials to improve the desalinization efficiency of reclaimed land. Permeability was improved by about 2.7 times at a 20% mixing ratio and by about 5.5 times at a 40% mixing ratio of oyster shell, and bottom ash was most suitable and effective when used as a material for the drainage layer. Desalinization efficiency was highest when mixing oyster shells at a 40% ratio and using bottom ash for drainage, which increased the efficiency by approximately 2.6 times over 10 days. In conclusion, reuse of bottom ash and oyster shell could improve the efficiency of reclaimed land use.

Recycling of bottom ash derived from combustion of cattle manure and its adsorption behaviors for Cd(II), Cu(II), Pb(II), and Ni(II).

Bottom ash generated by the combustion of cattle manure (BA-CCM) was investigated as an adsorbent for the removal of heavy metals such as Cd(II), Cu(II), Pb(II), and Ni(II) from aqueous solutions. When cattle manure was used as fuel, the thermal efficiency of the boiler was 88.7%, and the CO and CO2 concentrations in the exhaust gas were 2.3ppm and 12.1%, respectively. The percentage of remaining solids was 31wt.% after combustion at 900°C. X-ray fluorescence analyses showed that the elemental composition of the BA-CCM was mainly CaO (43.3%), SiO2 (15.8%), CO2 (13.0%), and P2O5 (10.3%). The kinetic adsorption of Cd(II), Cu(II), Pb(II), and Ni(II) by BA-CCM reached equilibrium after 12h, and the pseudo-second-order model fitted the experimental data well. The maximum amount of Cd(II), Cu(II), Pb(II), and Ni(II) adsorbed by the bottom ash was 5.4, 72.6, 88.2, and 24.6mg/g, respectively. The equilibrium adsorption of metals onto BA-CCM was well-described by the Freundlich model. Thermodynamic analysis showed that the adsorption onto the bottom ash was endothermic and that the Gibbs free energy decreased as the temperature increased. The presence of cations such as Na+, Ca2+, and Al3+ was found to reduce the amount of metals adsorbed onto the BA-CCM, and Cd(II) adsorption was found to be more dependent on ionic strength than adsorption of Cu(II), Pb(II), and Ni(II). This study demonstrates the feasibility of producing heat energy by burning cattle manure and removing heavy metals from aqueous solutions using the generated bottom ash as an adsorbent.

Analysis of Current Status and Regulatory Promotion for Incineration Bottom Ash Recycling in Taiwan

Incineration is the most important technology for treating municipal solid waste (MSW) and industrial waste in Taiwan. Currently, there are 24 large-scale MSW incineration plants operated to generate about 1.2 million metric tons of residual ash (mostly bottom ash) based on approximately 6.5 million metric tons of waste incinerated yearly. To reduce the depletion of non-renewable resources under the circular economy principle, the recycling of MSW incineration bottom ash (IBA) as recycled aggregate in concrete and construction applications has been progressed in recent years around the world. According to the official database, the trend analysis of MSW generation and treatment, electricity power and IBA generation from the MSW incineration plants over the past decade (2010–2019) was performed in this work. It showed an increased power generation, growing from 0.485 kWh/kg in 2010 to 0.530 kWh/kg in 2019. In 2019, 2738 GWh of power was sold to Taipower (one of the state-owned companies in Taiwan) for electricity grid connection, gaining income of about NT$ 5,089,383,000 (≈US$ 172,520,000) at an average rate of 1.86 NT$/kWh (0.063 US$/kWh). On the other hand, the ratios of incineration bottom ash (IBA) generation to refuse incinerated indicated a decreasing trend due to the increased operation efficiencies of MSW incineration plants. Based on the revised regulations implemented on 18 May 2020, the regulatory measures for promoting IBA recycling in Taiwan were promulgated to valorize it for the production of recycled aggregate under rigorous requirements for prevent it from polluting the environment.

Recycling of bottom ash and fly ash wastes in eco-friendly clay brick production

The use of waste-based materials in the construction industry has received significant attention in recent years to develop environmentally-friendly construction materials. This paper presents an experimental study on the properties of bricks containing clay, fly ash (FA), and bottom ash (BA). A total of 12 batches of bricks were manufactured and experimental tests were conducted at two firing temperature of 950 and 1050 °C to determine the apparent porosity, water absorption, apparent specific gravity, bulk density, compressive strength, and thermal conductivity. Microstructural analysis was undertaken to describe the reasons for the obtained experimental results. The results show that the bricks fired at 1050 °C exhibit slightly lower apparent porosity and water absorption but slightly higher bulk density and thermal conductivity than those fired at 950 °C. The results also show that an increase in the FA content leads to an increase in the apparent porosity and water absorption but a decrease in bulk density and thermal conductivity of the bricks. BA content does not have any significant influence of the properties of the bricks. It is also shown that bricks containing 5% FA, 5% BA, and 10% BA exhibit a similar compressive strength to those containing only clay. The leaching results show that the leaching of heavy metals from fired bricks is significantly lower than that of the limit concentrations. The leaching concentrations of the samples show that the heavy metals were immobilized in the ceramic structures of all fired bricks. These highly promising findings suggest that up to 30% replacement of wastes with ashes can provide bricks to reduce the environmental impact of abundant waste products and conserve non-renewable natural resources.

Contribution to closing the loop on waste materials: valorization of bottom ash from waste-to-energy plants under a life cycle approach

Incineration has undergone several technology improvements, reducing air emissions and increasing the efficiency of energy and material recovery; however, there is still a long way to go. To analyze the environmental impacts of waste incineration, this study assessed 15 waste fractions that compose municipal waste in Spain, which are grouped as non-inert materials (plastics, paper, cardboard and organic matter), unburned materials (glass and Al) and ferrous materials. Additionally, this paper evaluates the valorization of bottom ash (BA) to produce steel, aluminum and cement in these recycled/recoverable waste fractions. The results depend on the input waste composition and the heating value (HHV) and showed that ferrous and unburned materials had the worst environmental performance due to the null HHV. The valorization of BA in steel, Al and cement production significantly reduced the environmental impact and the consumption of resources. BA recycling for secondary steel and Al production would improve the environmental performance of the combustion of unburned materials and ferrous materials, whereas the use of BA in cement production diminished the consumption of NR for non-inert materials. This is of great interest for organic matter and PC, waste with a low energy production and high heavy metal and sulfur content.

A Study on Char Gasification Characteristics for Recycling of Bottom Ash Emitted by Waste Gasification Plant

A Study on Char Gasification Characteristics for Recycling of Bottom Ash Emitted by Waste Gasification Plant

Impact of co-landfill proportion of bottom ash and municipal solid waste composition on the leachate characteristics during the acidogenesis phase

Incineration has become an important municipal solid waste (MSW) treatment strategy, and generates a large amount of bottom ash (BA). Although some BA is reused, much BA and pretreatment residues from BA recycling are disposed in landfill. When BA and MSW are co-landfilled together, acid neutralization capacity and alkaline earth metal dissolution of BA, as well as different components of MSW may change environmental conditions within the landfill, so the degradation of organic matter and the physical and chemical properties of leachate would be affected. In this study, the effect of co-landfilled BA and MSW on the leachate characteristics during the hydrolysis and acidogenesis phase was studied using different BA/MSW ratios and MSW compositions. The results showed that the co-landfill system increased leachate pH, electric conductivity and alkalinity. For MSW with a high content of degradable components, the release and degradation of total organic carbon (TOC) and volatile fatty acids (VFA) from MSW were promoted when the BA ratio by wet weight was less than 50%, and the biodegradability of leachate was improved. When the BA ratio exceeded 50%, the degradation of organic matters was inhibited. For MSW with low content of degradable components, when the proportion of BA was less than 20%, the release and degradation of TOC and VFA from MSW were promoted and alkalinity increased. When the BA ratio exceeded 20%, the degradation of organic matters was inhibited. The 50% BA ratio could improve the bio-treatability of leachate indicated by the leachate pH and C/N ratio. However, BA inhibited the release of nitrogen (TN and NH4+-N) at all BA ratios and MSW compositions. At the same time, the addition of BA increased the risk of leachate collection system clogging due to the dissolution and re-precipitation of alkaline earth metals contained in BA.

Sustainability assessment and prioritisation of bottom ash management in Macao.

In Macao, about 7200 t yr-1 of bottom ash (BA) is generated and conventionally landfilled with construction waste. Because the properties of BA are similar to those of natural aggregates, it is suitable to be recycled as construction material. However, pre-treatment processes for BA reuse may require more resource input and may generate additional environmental impacts. Life cycle assessment, multi-media transport model analysis, cost-benefit analysis and the analytical hierarchy process were conducted to evaluate the impacts of current and potential BA management scenarios regarding environmental, economic, social and regulatory aspects. The five analysed scenarios are as follows: (0) BA buried with construction and demolition waste (current system); (1) pre-treated BA used to replace 25% of the natural aggregate in asphalt concrete; (2) pre-treated BA used to replace 25% of the natural aggregate in cement concrete; (3) pre-treated BA used to replace 25% of cement in cement concrete; and (4) pre-treated BA sent to China, blended with municipal solid waste for landfill. The results reveal the following ranking of the scenarios: 3 > 2 > 0 > 1 > 4. Scenario 3 shows the best conditions for BA recycling, because the quantity of cement concrete output is the highest and this brings the greatest economic benefits. Our use of integrated analysis provides multi-aspect investigations for BA management systems, particularly in accounting for site-specific characteristics. This approach is suitable for application in other non-western regions.

Recycling of MSWI Bottom Ash: A Review of Chemical Barriers, Engineering Applications and Treatment Technologies

Bottom ash from municipal solid waste incineration is an underutilized secondary resource, which currently gains large attention due to increased landfill costs and the push towards a circular economy. Due to the high concentrations and mobility of pollutants, bottom ash cannot readily replace virgin construction materials. Over the last decade, many research efforts have addressed these issues in view of newly developed engineering applications. However, the required quality of bottom ash varies for each application. In this review we focus on the ternary relationship between engineering applications, chemical barriers/limitations and treatment technologies for municipal solid waste incinerator bottom ash. For each intended engineering application [loose (bulk) construction aggregates; sand, aggregate or cement replacement in concrete; raw material for cement or ceramics] the appropriate treatment technologies are selected to overcome identified chemical barriers. This allows future top-down design decisions, starting from the most promising engineering application of bottom ash. The main chemical barrier for bottom ash recycling as loose construction aggregates is the leaching of heavy metals and/or metalloids. This can be overcome by size separation, carbonation, mild heat treatment or by using mineral additives. In structured concrete, the presence of metallic aluminum or zinc causes early cracking and a high chloride concentration causes corrosion of reinforcement steel. Therefore, recent developments in wet/semi-dry separations facilitated enhanced eddy current separation to remove non-ferrous metals. The washing of bottom ash to remove chloride, is to date the sole technology to prepare bottom ash as raw material for cement kilns. Finally, when bottom ash is used as feedstock for ceramics production, recent knowledge was generated to allow for selecting thermal process parameters in such a way that leaching of both heavy metals and metalloids is minimized.

Assessment of the Physicochemical Characteristics of Bottom Ash Recycling from the Municipal Solid Waste Incineration

Assessment of the Physicochemical Characteristics of Bottom Ash Recycling from the Municipal Solid Waste Incineration

Characterization of chlorine and heavy metals for the potential recycling of bottom ash from municipal solid waste incinerators as cement additives

Bottom ash is an inevitable by-product from municipal solid waste (MSW) incineration plants. Recycling it as additives for cement production is a promising disposal method. However, the heavy metals and chlorine are the main limiting factors because of the potential environmental risks and corrosion of cement kilns. Therefore, investigating heavy metal and chlorine characteristics of bottom ash is the significant prerequisite of its reuse in cement industries. In this study, a correlative analysis was conducted to evaluate the effect of the MSW components and collection mode on the heavy metal and chlorine characteristics in bottom ash. The chemical speciation of insoluble chlorine was also investigated by synchrotron X-ray diffraction analysis. The results showed that industrial waste was the main source of heavy metals, especially Cr and Pb, in bottom ash. The higher contents of plastics and kitchen waste lead to the higher chlorine level (0.6 wt.%–0.7 wt.%) of the bottom ash. The insoluble chlorine in the MSW incineration bottom ash existed primarily as AlOCl, which was produced under the high temperature (1250°C) in incinerators. Open image in new window

Immobilization of antimony in waste-to-energy bottom ash by addition of calcium and iron containing additives

The leaching of Sb from waste-to-energy (WtE) bottom ash (BA) often exceeds the Dutch limit value of 0.32mgkg−1 for recycling of BA in open construction applications. From the immobilization mechanisms described in the literature, it could be concluded that both Ca and Fe play an important role in the immobilization of Sb in WtE BA. Therefore, Ca and Fe containing compounds were added to the samples of the sand fraction of WtE BA, which in contrast to the granulate fraction is not recyclable to date, and the effect on the Sb leaching was studied by means of batch leaching tests. Results showed that addition of 0.5 and 2.5% CaO, 5% CaCl2, 2.5% Fe2(SO4)3 and 1% FeCl3 decreased the Sb leaching from 0.62±0.02mgkgDM−1 to 0.20±0.02, 0.083±0.044, 0.25±0.01, 0.27±0.002 and 0.29±0.02mgkgDM−1, respectively. Due to the increase in pH from 11.41 to 12.53 when 2.5% CaO was added, Pb and Zn leaching increased and exceeded the respective leaching limits. Addition of 5% CaCO3 had almost no effect on the Sb leaching, as evidenced by the resulting 0.53mgkgDM−1 leaching concentration. This paper shows a complementary enhancement of the effect of Ca and Fe, by comparing the aforementioned Sb leaching results with those of WtE BA with combined addition of 2.5% CaO or 5% CaCl2 with 2.5% Fe2(SO4)3 or 1% FeCl3. These lab scale results suggest that formation of romeites with a high Ca content and formation of iron antimonate (tripuhyite) with a very low solubility are the main immobilization mechanisms of Sb in WtE BA. Besides the pure compounds and their mixtures, also addition of 10% of two Ca and Fe containing residues of the steel industry, hereafter referred to as R1 and R2, was effective in decreasing the Sb leaching from WtE BA below the Dutch limit value for reuse in open construction applications. To evaluate the long term effect of the additives, pilot plots of WtE BA with 10% of R1 and 5% and 10% of R2 were built and samples were submitted to leaching tests at regular intervals over time. The Sb leaching from untreated WtE BA was just below or above the Dutch limit value. The Sb leaching from the pilot plots of BA with additives first remained stable around 0.13mgkg−1 but had a tendency to slightly increase after 6months, indicating the need for further research on the effect of weathering, and more specifically of carbonation, on Sb leaching from WtE BA.

Use of bottom ash from olive pomace combustion in the production of eco-friendly fired clay bricks

Olive pomace bottom ash was used to replace different amounts (10–50wt%) of clay in brick manufacturing. The aim of this study is both studying bricks properties and showing a new way of olive pomace bottom ash recycling. Properties of waste bricks were compared to conventional products following standard procedures in order to determine the maximum waste percentage. The amount of olive pomace bottom ash is limited to 20wt%, obtaining bricks with superior engineering properties when 10wt% of waste is added. Adding higher amount of waste (30–50wt%) resulted in bricks with water absorption and compressive strength values on the edge of meeting those established by standards. Therefore, the addition of 10 and 20wt% of olive pomace bottom ash produced bricks with a bulk density of 1635 and 1527kg/m3 and a compressive strength of 33.9MPa and 14.2MPa, respectively. Fired bricks fulfil standards requirements for clay masonry units, offering, at the same time, better thermal insulation of buildings due to a reduction in thermal conductivity of 14.4% and 16.8% respectively, compared to control bricks (only clay).

Recyclability of bottom ash mixed with dredged soils according to the transportation distance and mixing ratio through the estimation of CO2 emissions

Bottom ash and dredged soils can be used as construction materials because they are similar in physical characteristics to natural aggregates. However, whenever such byproducts as bottom ash and dredged soils are used, the energy efficiency of recycling is offset to a certain degree by emissions from transportation. The objective of this study is to analyze the environmental efficiency of recycling bottom ash and dredged soils through the estimation of CO2 emissions, considering both transportation distance and the mixing ratio. Agricultural reservoirs were selected as the final destinations of these recycled materials. This analysis demonstrated that using 100% bottom ash emits less CO2 than using natural aggregates when the ash is transported less than 35.15 km. This breakeven distance increases exponentially with the mass fraction of admixed dredged soil. However, admixture with natural soils does not affect the breakeven distance. Using the breakeven distances, the effective area with which it is efficient to recycle bottom ash was delineated. When dredged soil is admixed to a mass fraction of 70%, the effective area covers most of South Korea. In addition, 100% bottom ash was efficient in 1622 reservoirs (9.45%) in terms of CO2 emissions, and the mixture with 30% bottom ash and 70% dredged soils is efficient in 98.83% of all of the reservoirs in Korea. Bottom ash is most useful for reducing CO2 emissions when it is mixed with dredged soils, which are a byproduct of construction found on-site. This result is meaningful because bottom ash and dredged soils are complementary in their physical characteristics, and they need to be mixed before use as construction materials. The recycling of bottom ash becomes even more attractive with anticipated improvements in fuel efficiency.

화력발전소 매립 석탄재의 분쇄가 지오폴리머의 강도에 미치는 영향

Abstract Bottom ash from coal fired power plants is not widely used due to a broad range of particle sizes and a high carbon contentfor producing geopolymers. The effect of mechanical activation on compressive strength of bottom ash- based geopolymers wasexamined by rod and planetary-ball milling to encourage full-fledged recycling of bottom ash, the main component of pond ash.The amount of amorphous component in the milled ash samples did not change significantly after the mechanical activation. Itis presumably because needle-shaped mullite crystals, which is a major crystalline phase and grown in a glassy matrix, possesshigh strength and toughness, and therefore, they could endure external shocks and remain almost intact. Milling operation, how-ever, decreased the particle size and improved the homogeneity of ash, thereby leading to increase reactivity of milled ash withalkali activators. Rod milling produced a relatively narrow particle size distribution of the milled ash particles; however, it was · Received : July 16, 2014 · 1st Revised : September 1, 2014 · 2nd Revised : October 24, 2014 · Accepted : November 6, 2014Corresponding Author : Sujeong Lee (E-mail : crystal2@kigam.re.kr)Mineral Resources Research Division, Korea Institute of Geoscience & Mineral Resources, 124 Gwahang-no, Yuseong-gu,Daejeon, 305-350 KoreaTel : +82-42-868-3125 / Fax : +82-42-868-3418ⓒ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.

생활폐기물 성상변화에 따른 소각시설 바닥재의 특성 변화와 시멘트 클링커 원료로 재활용 가능성 평가

생활폐기물 소각시설에서 발생하는 바닥재는 높은 염소함량과 불순물 때문에 재활용에 한계가 있다. 하지만 종량제봉투의 도입과 음식물폐기물의 직매립 금지, 생산자책임제도의 도입 등 다양한 제도의 개선을 통해 성상이 변화되고 있다. 최근의 생활폐기물은 수분함량과 염소함량이 낮고 발열량이 높은 특성을 보이는데 이는 음식물폐기물의 분리배출, 폐기물의 전처리를 통한 불연물의 분리, 염소 등이 함유된 PVC 분리 등에 기인한 것으로 볼 수 있다. 본 연구의 목적은 이러한 제도, 특히 음식물폐기물의 분리배출 등의 정책 도입에 따른 생활폐기물 소각시설의 바닥재 성상변화 특성을 분석하고 이를 토대로 바닥재의 재활용 가능성을 평가하는 것이다. 바닥재에 함유된 다양한 성분 중 시멘트 클링커의 주요 성분인 CaO는 2001년 26.7%에서 2006년 34.0%로 증가하였고, 염소성분은 2001년 1.84%에서 2006년 0.00655%로 큰 폭으로 감소하였는데 이는 석탄 화력발전소에서 발생하는 비산재의 특성에 근접하는 것으로서 시멘트 클링커의 원료물질 등 재활용 가능성을 가지게 된 것으로 판단할 수 있다. Recycling of bottom ash from municipal solid waste (MSW) incinerator has been strictly limited due to its composition of high level chlorine and other unfavorable substances. The composition of MSW has been, however, changed after the introduction of garbage-bag sales system, extended producer responsibility (EPR) policy and the prohibition of direct landfill of food waste. Recent waste shows reduced moisture and chlorine content, increased calorific value due to the separation of food waste, incombustible materials and PVC. The main purpose of this study is to investigate the trend of composition changes of MSW incinerator bottom ash and to compare the analytical results with those before the separation system was introduced. CaO content of bottom ash, one of the major component of cement clinker, increased from 26.7% in 2001 to 34.0% in 2006. The chlorine content showed a dramatic decrease from 1.84% in 2001 to 0.00655% in 2006, which is closely compatible with that of the fly ash of coal-utilizing thermal power plants, which is mainly due to the changes of MSW composition. It is eventually considered that there is a possibility of utilizing the incinerator bottom ash as a raw material of cement clinker feed substances.