Municipal Waste Incineration Fly Ash Research Articles

Investigation of waste alkali-activated cementing material using municipal solid waste incineration fly ash and dravite as precursors: Mechanisms, performance, and on-site application

The proper treatment of municipal solid waste incineration fly ash (MSWIFA) is a crucial concern due to its hazardous nature and potential environmental harm. To address this issue, this study innovatively utilized dravite and black liquor to solidify MSWIFA. The semi-dry pressing method was employed, resulting in the production of waste alkali-activated cementing material (WACM). This material demonstrated impressive compressive and flexural strength, reaching 45.89 MPa and 6.55 MPa respectively, and effectively solidified heavy metal ions (Pb, Cr, Cu, Cd, and Zn). The leaching concentrations of these ions decreased from 27.15, 10.36, 8.94, 7.00, and 104.4 mg/L to 0.13, 1.05, 0.29, 0.06, and 12.28 mg/L, respectively. The strength of WACM increased by 3 times compared to conventionally produced materials. Furthermore, WACM exhibited excellent long-term performance, with acceptable heavy metal leaching and minimal mechanical degradation. Experimental and theoretical analyses revealed the heavy metal solidification mechanisms, including chemical binding, ion substitution and physical encapsulation. Finally, the on-site application of WACM confirmed its feasibility in meeting both environmental and strength requirements.

Characterization and stabilization of incineration fly ash from a new multi-source hazardous waste co-disposal system: field-scale study on solidification and stabilization.

The multi-source hazardous waste co-disposal system, a recent innovation in the industry, offers an efficient approach for hazardous waste disposal. The incineration fly ash (HFA) produced by this system exhibits characteristics distinct from those of typical incineration fly ash, necessitating the use of adjusted disposal methods. This study examined the physicochemical properties, heavy metal content, heavy metal leaching concentration, and dioxin content of HFA generated by the new co-disposal system and compared them with those of conventional municipal waste incineration fly ash. This study investigated the solidification and stabilization of HFA disposal using the organic agent sodium diethyl dithiocarbamate combined with cement on a field scale. The findings revealed significant differences in the structure, composition, and dioxin content of HFA and FA; HFA contained substantially lower levels of dioxins than FA did. Concerning the heavy metal content and leaching; HFA exhibited an unusually high concentration of zinc, surpassing the permitted emission limits, making zinc content a critical consideration in HFA disposal. After stabilization and disposal, the heavy metal leaching and dioxin content of HFA can meet landfill disposal emission standards when a 1% concentration of 10% sodium diethyldithiocarbamate (DDTC) and 150% silicate cement were employed. These results offer valuable insights into the disposal of fly ash resulting from incineration of mixed hazardous waste.

Application of ultrafine bubbles for enhanced carbonation of municipal solid waste incineration ash during direct aqueous carbonation

Municipal solid waste incineration fly ash was selected as the alkaline Ca-bearing solid waste, and a series of direct aqueous carbonation experiments using 10% CO2 gas were conducted to showcase the capability of ultrafine bubbles (UFBs) in enhancing carbonation efficiency. Results from the experiments, conducted using a one-pass water flow system, revealed that carbonation without UFBs increased the CO2 content of the ash from 59 to 200 mgCO2/g (an increase of 141 mgCO2/g), while the presence of UFBs elevated it to 237 mgCO2/g (an increase of 178 mgCO2/g). Consequently, the introduction of UFBs led to a 26% increase in CO2 content in ash [(178−141) / 141]. This improvement was primarily attributed to the enhanced carbonation efficiency for particles ≥ 46 µm. The positive impact of UFBs was more evident (62% increase in CO2 content in ash) in experiments using a water circulation system, where carbonation proceeded at a faster rate compared to the one-pass water flow system. In terms of the mechanism, X-ray diffraction and scanning electron microscopy analyses indicated that UFBs facilitated the removal of CaCO3 deposition, which inhibited Ca(OH)2 dissolution. To the best of our knowledge, this study is the first to demonstrate the favorable influence of UFBs on fly ash carbonation efficiency.

Diisobutylamine mediated CO2 mineralization and CaCO3 production from municipal solid waste incineration fly ash as raw ingredient and regeneration reagent

The CO2 mineralization technology involving Ca leaching and subsequent mineralization has emerged in recent years. It is still plagued by slow mineralization rate and frequent pH swings, requiring the consumption of exogenous substances. In this study, a leaching-mineralization-regeneration process for CO2 sequestration and CaCO3 production from municipal solid waste incineration fly ash (MSWIFA) mediated by diisobutylamine was proposed. Ca could be effectively extracted into the leaching solution with a concentration of 37420 mg/L from fly ash while heavy metals could be left in the leached residue. Diisobutylamine, acted as an H+ extractant and a crystal form regulator, was mixed with 1-octnaol to form a novel extraction system. When diisobutylamine/1-octanol/leaching solution ratio was at 1:2:3, almost full precipitation of Ca and a high CaCO3 yield of 282.4 g/kgfly ash was achieved. The crystal form of the CaCO3 product was confirmed by scanning electron microscope to be spherical and identified by X-ray diffraction as vaterite. The product purity (99.1 %) met the standard requirement (HG/T 2226–2019) for industrial use. Fly ash acted as a regenerant and was able to fully regenerate the extraction system. The mineralization performance of the regenerated extraction system remained relatively stable in multiple cycles of mineralization-regeneration process. Given the fundamental nature of this research, it would provide a potential route for future CO2 mineralization and Ca-containing waste utilization.

Leaching behavior and comprehensive toxicity evaluation of heavy metals in MSWI fly ash from grate and fluidized bed incinerators using various leaching methods: A comparative study

Municipal solid waste incineration fly ash (MSWI FA) is a kind of hazardous waste that contains a substantial amount of heavy metals. To facilitate the appropriate treatment of MSWI FA, the leaching behavior of heavy metals was evaluated in MSWI FA from various sources using different leaching methods. Nine kinds of MSWI FA were investigated using three kinds of batch leaching tests (TCLP, HJ/T 300, and EN12457-2). The chemical form distributions of heavy metals in MSWI FA were obtained by sequential extraction procedures (SEPs) and the environmental risk posed by MSWI FA was comprehensively evaluated. The results showed that the grate and fluidized bed MSWI FA performed differently in various leaching methods, which was mainly dependent on the leachate pH and the chemical form distributions of the heavy metals. In addition, the BCR SEP was more suitable for the fractionation of heavy metals and the environmental risk assessment of MSWI FA when compared with Tessier's SEP. The overall pollution toxicity index allowed a comprehensive risk assessment specific to the leaching environment, thereby offering valuable guidelines for the stabilization or resource-based treatment of MSWI FA.

Synthesis of layered double hydroxides from municipal solid waste incineration fly ash for heavy metal adsorption

The process of urbanization has resulted in a continuous growth of the production of municipal solid waste, consequently leading to the increase of municipal solid waste incineration fly ash (MSWI FA) over time. This has prompted the need for effective disposal and value-added utilization strategies for MSWI FA. In this study, a hydrothermal method was employed to synthesize CaAl layered double hydroxides (LDHs) using MSWI FA as the raw material. The main objective was to investigate how different synthesis parameters affect the crystallinity of the layered bimetallic hydroxides. Subsequently, the synthesized LDHs were characterized using various techniques such as BET, SEM, XRD, FT-IR, and XPS. The results revealed the presence of calcium and aluminum cations in the interlayer region of the synthesized material, with chloride ions, sulfate ions, and acetate ions being the predominant anions. Moreover, the formation of LDHs presents an effective approach for the self-purification of leachates derived from MSWI FA. The LDHs exhibited excellent adsorption capacity for Cd2+ and Cu2+ in wastewater, with maximum values of 730 mg·g−1 and 446 mg·g−1, respectively. The adsorption mechanisms involved isomorphous substitution, complexation, as well as the precipitation of hydroxides or interlayer anions. This method presents a novel approach for effectively utilizing MSWI FA to produce environmentally friendly value-added adsorbents.

Recycle Option for Municipal Solid Waste Incineration Fly Ash (MSWIFA) as a Partial Replacement for Cement in Mortars Containing Calcium Sulfoaluminate Cement (CSA) and Portland Cement to Save the Environment and Natural Resources.

Reduction of emissions, energy consumption, and use of substitutes for natural resources is an element of sustainable development and the circular economy. Cement production is a process with a high carbon footprint; therefore, minimizing the use of this material has a significant impact on reducing environmental costs. A substitute for cement is municipal solid waste incineration fly ash (MSWIFA). The article presents a method of making an eco-concrete with the use of municipal solid waste incineration hazardous fly ash. The use of secondary waste for the production of building materials additionally contributes to achieving climate neutrality established by the European Union and China. The article analyzes the physicochemical properties of various MSWIFAs, the amount and leachability of heavy metals, and selected elements from MSWIFA and concrete properties. The technical properties of mortars containing MSWIFA were investigated. Consistency is not affected by MSWIFA content, although the workability time is prolonged. Air entraining admixture efficiency is lowered, but the effect lasts longer. The initial setting time is prolonged, and the flexural and compressive strengths are decreased in early terms because of the zinc presence in MSWIFA. MSWIFA does not influence the water demand, volume stability of mortars, or microstructure of cement's hydration products.

Co-disposal kinetics and characteristics of sewage sludge and municipal solid waste incineration fly ash

Sewage sludge (SS) and municipal solid waste incineration fly ash (MSWIFA) have characteristics of high yield, scattered distribution, and strong harm. Co-disposal of SS and MSWIFA in the existing cement kilns is a prospective way to deal with these two types of solid waste. In this study, the pyrolysis kinetic, thermogravimetric analysis, heat and mass transfer characteristics and pollutant release during SS and MSWIFA co-disposal were investigated through a series of experiments and simulations. In the experiment, pulverized coal (PC) was used as fuel to imitate the real environment of a cement kiln. According to the results, the interaction of the two solid wastes was observed mainly during the devolatilization and combustion periods. At an average blending ratio (60%) and 25 ℃/min heating rate, the blend actual mass loss rate has the largest difference compared to the linearly calculated mass loss rate (0.74%/min), with higher comprehensive combustion characteristic index (3.54), and the blends have better overall heat transfer, internally converging to 350 K. Meanwhile, when SS proportion in PC-SS-MSWIFA is between 20% and 30%, the emission concentration of SO2 and NO was low, and it has good environmental benefits. This research aims to offer theoretical support for the co-disposal of SS and MSWIFA.

Mechanism study of Cu(II) adsorption from acidic wastewater by ultrasonic-modified municipal solid waste incineration fly ash

Mechanism study of Cu(II) adsorption from acidic wastewater by ultrasonic-modified municipal solid waste incineration fly ash

Fate of Cl and chlorination mechanism during municipal solid waste incineration fly ash reutilization using thermal treatment: a review.

Safe and sustainable treatment of municipal solid waste incineration fly ash (MSWI FA) is urgently needed worldwide because of its high heavy metals, dioxin, and chlorine (Cl) contents. Thermal treatment is widely considered as a promising method for treating MSWI FA owing to its high toxic content removal efficiency and resource recovery; however, residual Cl is a concurrent critical problem faced during reutilisation of thermal treatment products. This review summarises the innovative thermal treatment methods of MSWI FA, such as those employed in production of cement, lightweight aggregates, glass slag, and metal alloys. The characteristics of Cl in MSWI FA, removal rate, transformation of water-soluble Cl into water-insoluble Cl, and the effect of different influencing factors such as temperature, composition, superheated steam, and mechanical pressure were analysed. The volatilization and decomposition of NaCl, KCl and CaClOH dominates Cl removal; however, the degradation of organic Cl and heavy metal chlorination volatilization process that generate HCl and heavy metal chlorides, respectively, also contributed to Cl removal. To promote the reutilisation of MSWI FA-based products, the leaching behaviour of residual Cl in products obtained by different thermal treatments was investigated.

Microwave-assisted hydrothermal synthesis of autoclaved bricks from municipal solid waste incineration fly ash and coal fly ash (MSWIFA) and its carbon emission

In this study, the feasibility of manufacturing low-carbon autoclaved municipal solid waste incineration fly ash and coal fly ash (MSWI-FA) bricks from MSWI fly ash and coal FA with microwave-assisted hydrothermal synthesis was investigated. To facilitate the experiment, block samples were prepared. The effects of microwave pre-treating parameters on the performance of block samples were investigated. Mechanisms of microwave pre-treating were studied. The effects of microwave pre-treating were further investigated by micro-analyses of synthesized block samples. Environmental impacts were discussed from heavy metal solidification/stabilization and CO2 emission. The results showed that the optimal microwave parameters were 30 min and 385 W. With microwave pre-treating, Al-substituted tobermorite crystallites were generated in raw material mixtures. For block samples, more Al-substituted tobermorite crystals were observed, and lower total pore volume and pore diameter were found. The solidification/stabilization rates of Cu, Pb, and Zn increased by 163.20%, 24.89%, and 78.77%, respectively, and CO2 emission could be reduced up to 53.40%.

Performance of sustainable ternary blended cement containing municipal solid waste incineration fly ash coupled with slag, coal fly ash or metakaolin

Developing low-clinker cements can effectively reduce carbon footprint of the cement industry. Additionally, more sustainable methods over landfilling are needed to tackle the increasing annual generation of municipal solid waste incineration fly ash (IFA). In this study, carbonated-washed IFA coupled with slag (SG), coal fly ash (CFA) or metakaolin (MK) were used to substitute 60 % of Portland cement to form ternary blended cement. Performance of the blended cements was investigated and compared with pure Portland cement in terms of hydration kinetics, binding capacity, hydration mechanisms, pore characteristics, microstructure, and leaching toxicity. Results indicated that in the blended cement systems, ettringite was stabilized by the formation of hemicarboaluminate as a result of the reaction between calcium carbonate in the IFA and aluminate in SG, CFA and MK. The SG displayed the best synergy with IFA, refining pore structure through pozzolanic reaction and increased formation of ettringite and hemicarboaluminate. For an optimal 40 % SG+20 % IFA blended cement, the mortar compressive strength reached 90 % of that for pure Portland cement at 90 days. Although CFA had abundant aluminate, its low reactivity restrained the performance of the blended cement, resulting in poorer pore structure and lower compressive strength. The MK had abundant reactive silicate and aluminate, but the rapid consumption of calcium hydroxide by the pozzolanic reaction and hemicarboaluminate formation restrained further reaction, limiting the performance of the blended cement at the later stage. Besides, the heavy metal leachability and dioxin level in the produced mortar satisfy the prerequisites to be categorized as nonhazardous according to HJ 1134. This study demonstrated the promising potential of the blended cements to simultaneously divert IFA from landfills and reduce the clinker content of cement.

An LC3-type binder produced with marine clay and municipal waste incineration fly ash

Marine clay and municipal waste incineration ash are two major wastes in Singapore. The low reactivity of marine clay and high chloride (Cl) content in incineration fly ash (IFA) limit their application as supplementary cementitious materials. In this study, these wastes are synergistically used to prepare an LC3-type binder. The compressive strength of the proposed binder is comparable to or higher than the OPC references at 7 and 28 days. Pore-filling AFm crystals are ubiquitous in the hardened paste, which are characterized as hemicarbo-AFm and (Cl-, CO32-)-AFm when IFA was and was not subjected to Cl-removal treatment, respectively. A significant conversion of AFt to AFm is observed during the first 28 days. The leaching of Cl and certain heavy metals are reduced compared with the case of IFA-OPC binary binder. This work broadens the concept of LC3 binder system, and may inspire circulation of wastes in Singapore for construction practice.

Geopolymerization of MSWI fly ash and coal fly ash for efficient solidification of heavy metals: Insights into stabilization mechanisms and long-term leaching behavior

High levels of heavy metals (HMs) are present in municipal solid waste incineration fly ash (MSWI-FA), which requires proper management before landfilling. The aim of this study is to investigate the feasibility of co-disposal of MSWI-FA and coal fly ash (Coal-FA) using geopolymerization technology to solidify heavy metals and to analyze the long-term leaching behavior of heavy metals (HMs). The active silicon, aluminum, and calcium present in MSWI-FA and Coal-FA are essential for the synthesis of geopolymers. The geopolymer with 20 wt% MSWI-FA (M20) achieved the maximum compressive strength of 25.73 MPa, mainly due to the formation of C-A-S-H gels. Heavy metals were effectively immobilized and met the limits of GB18598–2019. The compressive strength of M20 was decreased by 1.6% in sulphuric acid-nitric acid leaching solution for 64 days, but decreased by 57.4% in the acetic acid leaching solution. The geopolymer was more stable in the acid rain environment, resulting in less leaching of heavy metals. The bulk diffusion model (BDM) and Finite Element Method (FEM) could satisfactorily describe the leaching behavior of HMs. The results provide valuable guidance for future waste management practices and the development of solidification processes for MSWI-FA.

Facile preparation of vaterite dominated incineration fly ash (IFA) by slurry carbonation and its performance as supplementary cementitious material

Municipal solid waste incineration fly ash (IFA) can be treated by slurry carbonation and adopted as a supplementary cementitious material (SCM) to reduce the carbon emission of the cement industry. However, effects of control parameters of carbonation on the mineralogy and morphology of the treated IFA require further investigation. In this work, the control parameters were sequentially optimized, aiming at producing more chemically active vaterite during carbonation. The vaterite dominated IFA was subsequently used as an SCM and its performance was studied and compared with limestone (pure calcite). Results indicated that precipitation of vaterite was favored under lower temperature and higher water-ash ratio conditions. CO2 flow rate has relatively smaller impact on the mineralogy of the treated IFA, but a higher rate led to agglomeration of vaterite particles. Under the optimized condition, vaterite dominated IFA containing 60% vaterite and 10% calcite was obtained. For the blended cement, its early hydration was suppressed by calcium sulfite (CaSO3) in the IFA, but the additional sulfate (CaSO4) accelerated the ettringite formation. The vaterite calcium carbonate in the treated IFA stabilized ettringite and reacted with aluminate phases to form hemicarbonate, refining the pore structure. However, hemicarbonate formation was limited by availability of aluminum that was consumed to form ettringite. Compared to limestone, the vaterite dominated IFA behaved better performance as an SCM, and the Porland cement can be substituted by 20% without compromising the 3-day and 28-day compressive strength. Toxicity leaching tests indicated only Pb exceeded regulatory limits in raw IFA, while Pb leaching in mortar samples was greatly declined below 1% of the limit.

Mitigating heavy metal volatilization during thermal treatment of MSWI fly ash by using iron(III) sulfate as a chlorine depleting agent

In the thermal treatment of municipal solid waste incineration fly ash (FA), the presence of chlorides leads to the pronounced volatilization of heavy metals at high temperature, making heavy metals stabilization challenging. Conventional washing processes struggle to remove chlorides completely, and even minor residual chlorides can lead to significant heavy metal volatilization. This study innovatively applied iron(III) sulfate as a chlorine depleting agent, which can form FeCl3 (boiling point 316 °C) and volatilize to remove the residual chlorides at below 500 °C, thus preventing the chlorination and volatilization of heavy metals at 600–1000 °C. Using water-washed FA to produce lightweight aggregate (LWA) preparation, after adding iron(III) sulfate, the volatilization rates of Pb and Cd at 1140 °C decreased to 5.4% and 9.3%, respectively, a reduction of 82.8% and 84.1% compared to before its addition. The LWA met standard requirements in both performance and heavy metal leaching toxicity. The mechanism was further studied through thermodynamic equilibrium calculations and heating experiments of pure chemicals. This study presents novel approaches and insights for suppressing the volatilization of heavy metals in FA at high temperature, thereby promoting the advancement of thermal treatment techniques and the safe, resourceful disposal of FA.

Use of municipal solid waste incineration fly ash as a supplementary cementitious material: CO2 mineralization coupled with mechanochemical pretreatment

The use of municipal solid waste incineration fly ash, commonly referred to as “fly ash”, as a supplementary cementitious material (SCM), has been explored to mitigate the CO2 emissions resulting from cement production. Nevertheless, the incorporation of fly ash as an SCM in mortar has been shown to weaken its compressive strength and increase the risk of heavy metal leaching. In light of these challenges, this study aims to comprehensively evaluate the influence of CO2 pressure, temperature, and residual water/binder ratio on the CO2 uptake and compressive strength of mortar when combined with fly ash. Additionally, this study systematically examines the feasibility of mechanochemical pretreatment, which enhances the homogenization of fly ash and augments the density of the mortar's microstructure. The results indicate that the use of mechanochemical pretreatment leads to a notable 43.6% increase in 28-day compressive strength and diminishes the leaching of As, Ba, Ni, Pb, Se, and Zn by 17.9-77.8%. Finally, a reaction kinetics model is proposed to elucidate the CO2 sequestration process under varying conditions. These findings offer valuable guidance for incorporating fly ash as an SCM and CO2 sequestrator in mortar.

Effect of particle size of NanoSiO2 on cement-based stabilization/solidification of municipal solid waste incineration fly ash

As a part of by-product generated during the incineration, the municipal solid waste incineration fly ash (MFA) is a secondary pollutant. The ordinary Portland cement (OPC)-based stabilization/solidification (S/S) is a prevalent and robust technique for the treatment of MFA, which can not only effectively dispose the MFA, but also decrease the demand of OPC and reduce the greenhouse gas emissions. However, when MFA was directly utilized to partly replace the cement with a replacement ratio of 15%, the MFA-OPC based composites exhibited inferior mechanical properties. The nano silica (NS) was considered to be introduced to compensate for the strength loss caused by the MFA. In this research, the NS with varying dosages and particle sizes were integrated into the MFA-OPC composites and in total seven groups of the composites were prepared. The mechanical properties of the composites were examined and the results indicated that the composites containing 2 wt% 100 nm NS presented relatively superior mechanical properties. The incorporation of NS could increase the compressive strength of MFA-OPC composites by 37.5% at later age. Then, thermodynamic modelling and the micro-structural analysis including hydration heat, XRD, TG, MIP and SEM were coupling applied to probe into the NS modification mechanism. Experimental results indicated that the addition of NS enhanced the strength of OPC containing MFA at both early and later ages via pozzolanic reaction, hydration acceleration and micro filling effects. Overall considering the macro performance improvement and microstructure modification effect, the 2 wt% NS with particle size of 100 nm was recommended to be utilized. Therefore, this study expands the emerging application of NS and demonstrates that NS-augmented binders can ensure low-carbon and high-performance S/S of hazardous materials.

Immobilization mechanisms of heavy metals by utilizing natural cow bone waste for municipal solid waste incineration fly ash treatment.

Municipal solid waste incinerator (MSWI) fly ash poses intricate compositional challenges and potential environmental hazards. Effective management of such hazardous waste is imperative to mitigate the release of toxic compounds into the environment. Solidification/stabilization (S/S) processes have emerged as a viable strategy to transform MSWI fly ash from incineration waste into a safer and more environmentally benign material. This study aims to comprehensively investigate the potential of utilizing cow bone waste to stabilize heavy metals, focusing on Pb, within municipal solid waste incineration fly ash. Experimental investigations encompassed cow bone-to-fly ash weight ratios ranging from 0.0 (control group) to 7:3, a settling time of 2h, and a liquid-to-solid (L/S) ratio of 1.0mL/g. Cow bone waste exhibited pronounced efficacy, particularly within the short settling time, yielding a remarkable Pb removal efficiency of up to 99% at a cow bone waste dose of merely 2% and an L/S ratio of 1.0mL/g. Concurrently, other heavy metals such as Cd, Cu, and Zn were effectively stabilized with a cow bone waste dose of 1.5% during the same 2-h settling period. The results underscore the pivotal roles of ash/bone ratio and settling time in augmenting Pb stabilization in MSWI fly ash. The application of cow bone waste is anticipated to offer a cost-effective and environmentally sound approach, aligning with sustainable waste management principles.

Research on oxygen enrichment for municipal solid waste fly ash melting: A pilot-scale study on natural gas and coal as the melting fuel

High energy consumption is the main obstacle of melting/vitrification technology for the disposal of municipal solid waste incineration fly ash (MSWIFA) for industrial applications. To reduce energy consumption and lower operating costs, oxygen enrichment melting was proposed and studied in this work. This research was conducted in a pilot-scale melting furnace, and three melting conditions were compared and discussed. The results showed that 66% of natural gas was saved and the operating cost was reduced by 55% when oxygen enrichment technology was applied to MSWIFA melting. When coal was used as the fuel with the oxygen enrichment melting technology, the operating cost was even lower at 66.39 dollar/ton of fly ash. Because MSWIFA was a Ca-rich material, the relatively high content of Si and Al in the coal fly ash promoted the formation of vitrificated slag, leading to a reduction in the overall pollution toxicity index (OPTI) of MSWIFA by 99.98%. Meanwhile, SO2, HCl, and secondary fly ash were the main pollutants during MSWIFA melting, and when coal was used as the fuel, the emissions of SO2 and HCl could be reduced and the OPTI of secondary fly ash was suppressed. These results suggested that to obtain the lowest operating cost and reduce secondary pollution during MSWIFA melting, the best option consisted of oxygen enrichment technology with coal as the fuel.