Waste Incineration Ash Research Articles

A novel method for metals extraction from municipal solid waste using a microwave-assisted acid extraction

This paper investigated the development and evaluation of an extraction process for copper, chromium, cobalt, iron, manganese, zinc, lead, cadmium, barium, magnesium, and vanadium from municipal solid waste incineration ash (bottom and fly ashes) based on microwave-assisted acid extraction method. In this study, a novel conventional microwave-mediated technique was applied by using various acidic extracting agents, namely, hydrochloric acid, nitric acid, and phosphoric acid. Several experimental conditions and parameters were modified and optimized to determine the most effective conditions for maximizing metal extraction. The results were also compared with our preliminary research, which investigated the optimization of conventional heating for extracting the same metals. The current study concluded that the microwave-assisted acid extraction method was much more effective than conventional heating. The metals from the bottom ash were much easier to extract in contrast with the fly ash. For the bottom ash, 71 wt% of Co, 75.69 wt% of Cr, 56.19 wt% of Cd, 35.23 wt% of Ba, 30.2 wt% of Pb, and 5.41 wt% of Mn were effectively extracted using the protocol C (2 M HCl and 3 M H3PO4). 13.87 wt% of Al, 10.59 wt% of Cu, 7.2 wt% of Fe, 5.25 wt% of Mg were also extracted using the protocols D and E (3 M HNO3 and 3 M H2O2) from MSW-BA. On the other hand, for the fly ash, 2.27 wt% of Cu, 0.93 wt% of Fe, 2.32 wt% of Zn, 6.28 wt% of Cd, 1.98 wt% of Ba, 3.46 wt% of Mg and 4.7 wt% of V were extracted by using the protocol A (5 M HCl and 5 M HNO3). 1.48 wt% of Cr, 0.93 wt% of Fe, 1.19 wt% of Mn, and 1.18 wt% of Al were extracted using the protocol C (2 M HCl and 3 M H3PO4). It was also confirmed that higher microwave power levels had a positive effect on the metal extraction, and longer contact times had an adverse effect. When comparing the cost analyses for both methods, it was found that the microwave-assisted acid extraction was less expensive than the conventional heating. The present study offers a promising method, which is simple and cost-effective and presents a minimal environmental risk to extract metals from municipal solid waste incineration ash.

Activation of municipal solid waste incineration ashes for green concrete

Due to the variable characteristics of municipal solid waste incineration (MSWI) ashes and the lack of coherent standards and regulations, a majority of MSWI ashes is landfilled currently. It is an urgent issue that the significant amount of residue MSWI ashes need to be better handled and reused as a renewable source. MSWI ashes have great potential to be utilized as a cementitious replacement material in concrete mixing, which is beneficial for both promoting MSWI ash reuse and reducing cement consumption. However, there are major challenges associated with MSWI ash reuse, including the presence of lack of efficient approach to restore the reactivity of MSWI ashes as a binding agent, because such ashes are usually low in reactivity or even inert. This study aims to develop an effective and reliable activation method to enable the pozzolanic and hydraulic properties of MSWI ashes. A novel activation methodology by means of physiochemical treatments, including particle size reduction and high pH activator was proposed to increase the reactivity of such bottom ashes. A rapid test method, namely solution test, was developed to test the potential reactivity after the activation. Thermogravimetric analysis (TGA) and ion chromatography (IC) were employed to evaluate the degree of reactivity. The results showed that the physicochemical treatment can indeed increase the reactivity of MSWI ashes. Compared to the existing test protocols using normal activator the new solution test can more effectively examine the latent pozzolanic activities of MSWI ashes. The successful application of the proposed activation methodology together with the developed solution test could turn those “inert or low reactivity” to-be-landfilled ashes into an active binding agent as a cement replacement material, which would contribute greatly to recycle and reuse of waste materials and reduce CO2 emission.

Utilization of waste for building materials – a review

Since ancient times naturally available materials are being used for the purpose of construction. Due to overutilization of these resources leads to its unavailability or depletion of these materials. On the other hand, lots of industrial wastes, municipal solid wastes are generated which are sent to landfill. The produced industrial and municipal wastes are not disposed properly. If they are not disposed safely or properly it will pose threats to the human community and also to the environment. These wastes need to be managed properly for safe disposal or alternate ways need to be identified for its utilization. This paper reviews the various types of waste that are used in construction and their usage as building material, its various application and the extent they can be used in building materials are discussed. Sugarcane bagasse ash, municipal solid waste incinerator ash, paper pulp, ground granulated blast furnace slag, copper slag are the wastes reviewed in this study. Many past researches have been identified for utilizing these industrial wastes sustainably in construction sector for manufacturing of bricks, concrete, special concrete etc. The general conclusion from the studies were that GGBS is a good alternative pozzolanic material for cement while the copper slag can be used in many forms as a replacement material in concrete. The MSWI ash is most suitable for use in cement and clay bricks whereas the sugarcane bagasse ash can be ideally used both in cement and clay bricks.

A Study on Manufacturing Characteristics for Ash Bricks with Different Weight Mixing Ratio of Waste Incineration Ashes and Steel Slag

A Study on Manufacturing Characteristics for Ash Bricks with Different Weight Mixing Ratio of Waste Incineration Ashes and Steel Slag

Preparation and characterization of glass ceramic foams based on municipal solid waste incineration ashes using secondary aluminum ash as foaming agent

Glass ceramic foam with high strength was developed using municipal waste incineration bottom ash, fly ash, pickling sludge and secondary aluminum ash as raw materials without foaming agent. The effect of the secondary aluminum ash content and alkalinity on the pore morphology, porosity, water absorption, compression strength and bulk density of glass ceramic foams has been evaluated. The results showed that the increase of secondary aluminum ash content is beneficial to gas generation, but it will reduce the formation of liquid phase, resulting in the variation of pore morphology. In the process of alkalinity adjustment, the degree of polymerization of glass decreased first and then increased, which is similar to the change of max pore size, providing guidance for quantitative analysis of pore formation. The optimized sample reached porosities up to 63.02%, bulk density of ~1.42 g/cm3, and excellent compressive strength ~41.93 MPa. The analysis of self-foaming mechanism proved that secondary aluminum ash can be used as a self-foaming waste results from the oxidation reaction of AlN. In this work, a clean and sustainable utilization method has been proposed for recycling multiple solid wastes by preparing glass ceramic foams with a potential application for construction insulation materials with load-bearing. Moreover, an innovative exploration of secondary aluminum ash as the self-foaming waste in high temperature environmental was proposed.

Effect of specimen preparation on the swell index of bentonite-polymer GCLs

Experiments were conducted to investigate how specimen preparation (crushing and sieving) affects the swell index (SI) of bentonite-polymer (B–P) composites and the relationship between SI and hydraulic conductivity of B–P GCLs. Seven B–P and one Na–B GCLs were used in this study. Tests were conducted using DI water and synthetic municipal solid waste incineration ash leachates. Specimens were prepared using the ASTM D5890 and two alternative methods prior to SI testing. For both Na–B and B–P composites, <100% of the specimen passed through the #100 sieve regardless of the amount of crushing performed using a mortar and pestle. SIs and loss on ignitions (LOI) of the portion of the B–P composites passing #100 sieve were comparable to the Na–B, whereas the B–P specimen retained on #100 sieve had very high SIs and LOIs. These observations indicate that crushing and sieving of the B–P composites lead to segregation of polymer. A stronger correlation (R2 = 0.90) was observed between SI and hydraulic conductivity, only when SI tests were conducted with B–P without any crushing and sieving, suggesting that SI tests should conduct with B–P composites retrieved from the GCLs without sieving to provide a better prediction of hydraulic compatibility.

Municipal Solid Waste Incineration (MSWI) Ashes as Construction Materials-A Review.

Over the past decades, extensive studies on municipal solid waste incineration (MSWI) ashes have been performed to develop more effective recycling and waste management programs. Despite the large amount of research activities and the resulting improvements to MSWI ashes, the recycling programs for MSWI ashes are limited. For instance, although the U.S. generates more MSWI ashes than any other country in the world, its reuse/recycle programs are limited; bottom ash and fly ash are combined and disposed of in landfills. Reuse of MSWI ashes in the construction sectors (i.e., geomaterials, asphalt paving, and concrete products) as replacements for raw materials is one of most promising options because of the large consumption and relatively lenient environmental criteria. The main objective of this study was to comprehensively review MSWI ashes with regard to specific engineering properties and their performance as construction materials. The focus was on (1) the current practices of MSWI ash management (in particular, a comparison between European countries and the U.S.), (2) the engineering properties and performance of ashes when they are used as substitutes of construction materials and for field applications, and (3) the environmental properties and criteria for the use of MSWI ashes. Overall, the asphalt and concrete applications are the most promising, from both the mechanical and leachate viewpoints. However, cons were also observed: high absorption of MSWI ash requires a high asphalt binder content in hot-mix asphalt, and metallic elements in the ash may generate H2 gas in the high-pH environment of the concrete. These side effects can be predicted via material characterization (i.e., chemical and physical), and accordingly, proper treatment and/or modified mix proportioning can be performed prior to use.

Blending as a Strategy for Reusing Municipal Solid Waste Incinerator Ash in Road-Base Construction

AbstractBottom and combined ash samples from municipal solid waste incinerator (MSWI) facilities in Florida were compared with industry aggregate standards to determine suitability for use as a roa...

Use of municipal solid waste incineration ash in 3D printable concrete

Concrete 3D printing is an application of 3D printing technology for the construction of concrete structural and non-structural elements. It is a rapid method of construction without the use of formwork, with minimum labor involvement and reduced material wastage. Curved walls and complex structures can be constructed by modifying the print path and controlling the rheological properties of concrete. The fusion of this technology with waste materials is necessary to reduce the problems associated with the recycling of wastes and to minimize CO2 emissions associated with the production of cement. In this study, two different municipal solid waste (MSW) incineration ashes (fly ash and bottom ash) were used to develop a concrete having rheological and hardened requirements of concrete used in 3D printing. Waste incinerator ashes were added as a substitute of ordinary Portland cement in concrete mix proportions. Flow table test and Gilmore needle test were used to measure the flow and setting time of concrete, respectively. Yield stress was measured by shear vane test. The buildability of ash containing printable concrete was simulated by comparing the vertical stresses due to the printing of concrete layers with the increase in the strength of the first stacked layer. Workability, open time, and buildability of the mix proportions were related to yield stress. The effect of adding waste incinerator ash upon the compressive strength was measured. The bond strength between layers at different printing time gaps was evaluated using bi-surface direct shear test. Experimental results showed that setting time promoting effect and initial yield stress enhancement by incinerated fly ash allows for a rapid construction speed with concrete 3D printing. This study concludes that incinerated fly ash can be successfully recycled in 3D printable concrete due to its favorable effects on rheology which are favorable for printing concrete.

Effect of partially replacing ordinary Portland cement with municipal solid waste incinerator ashes and rice husk ashes on pervious concrete quality.

Pervious concrete (PC) provides multiple benefits, including reducing stormwater runoff, purifying water, recharging groundwater, and reducing the heat island effect. This study aims to determine an effective way to reuse municipal solid waste incinerator (MSWI) fly ash (FA), MSWI bottom ash (BA), and rice husk ash (RHA) as single or binary partial replacements for ordinary Portland cement (OPC) in PC. The ashes and PC specimens were characterized via X-ray fluorescence spectroscopy, X-ray powder diffraction, field emission-scanning electron microscopy, and Fourier transform infrared spectroscopy. The compressive strength, water permeability, and toxicity characteristic leaching procedure (TCLP)-released metals were investigated to evaluate the PC quality. The main components of the ashes were similar to those of OPC, suggesting that the ashes could be reused as cement materials; however, the cementitious activity of the ashes, especially MSWI FA, was relatively low. All ashes except 1100°C MSWI FA met the standard requirements and can be applied as pozzolanic materials. The three PC specimens with binary replacements containing RHA (550, 700, and 900°C) and MSWI BA (1100°C) showed a synergistic effect and exhibited a higher 90-day compressive strength than the other specimens with single and binary ash replacements containing RHA (550 and 900°C). The water permeability ranged between 0.106 and 0.391cm/s, and the TCLP-released metal concentrations from all specimens met the regulatory standards of Taiwan. The results indicated that replacement with MSWI BA and RHA in cement materials provides an acceptable compressive strength and water permeability.

Fire Suppression and Thermal Behavior of Biobased Rigid Polyurethane Foam Filled with Biomass Incineration Waste Ash.

Currently, there is great demand to implement circular economy principles and motivate producers of building materials to integrate into a closed loop supply chain system and improve sustainability of their end-product. Therefore, it is of great interest to replace conventional raw materials with inorganic or organic waste-based and filler-type additives to promote sustainability and the close loop chain. This article investigates the possibility of bottom waste incineration ash (WA) particles to be used as a flame retardant replacement to increase fire safety and thermal stability under higher temperatures. From 10 wt.% to 50 wt.% WA particles do not significantly deteriorate performance characteristics, such as compressive strength, thermal conductivity, and water absorption after 28 days of immersion, and at 32 °C WA particles improve the thermal stability of resultant PU foams. Furthermore, 50 wt.% WA particles reduce average heat release by 69% and CO2 and CO yields during fire by 76% and 77%, respectively. Unfortunately, WA particles do not act as a smoke suppressant and do not reduce smoke release rate.

Selective Recovery of Copper(II) from Incineration Ash Produced from a Municipal Waste Incineration Facility Using a Flow-through Type Electrolysis Method.

Recovery of copper was attempted from municipal waste incineration ashes using acid extraction and electrodeposition by a flow-through type electrolysis cell (FE). Efficient extraction of copper from the incineration ash was obtained using 0.5 mol L-1 sulfuric acid, i.e., copper extraction rate: 78% from bottom ash and 88% from fly ash. The copper in the 10-fold diluted extractant injected into the FE was quantitatively adsorbed by applying -0.4 V and was quantitatively desorbed by eluting with nitric acid.

Emerging trends in municipal solid waste incineration ashes research: a bibliometric analysis from 1994 to 2018.

The rapidly increasing generation of municipal solid waste (MSW) threatens the environmental integrity and well-being of humans at a global level. Incineration is regarded as a technically sound technology for the management of MSW. However, the effective management of the municipal solid waste incineration (MSWI) ashes remains a challenge. This article presents the global dynamics of MSWI ashes research from 1994 to 2018 based on a bibliometric analysis of 1810 publications (research articles and conference proceedings) extracted from the Web of Science database, followed by a comprehensive summary on the research developments in the field. The results indicate the rapid growth of annual publications on MSWI ashes research, with China observed as the most productive country within the study period. Waste Management, Journal of Hazardous Materials, Chemosphere and Waste Management & Research, which accounted for 35.42% of documents on MSWI research, are the most prominent journals in the field. The most critical thematic areas on this topic are MSWI ashes characterisation, dioxin emissions from fly ash, valorisation of bottom ash and heavy metal removal. The evolution of MSWI ashes treatment technologies is also discussed, together with the challenges and future research directions. This is the first bibliometric analysis on global MSWI ashes research based on a sufficiently large dataset, which could provide new insights for researchers to initiate further research with leading institutions/authors and ultimately advance this research field.

Effect of soda-lime glass powder on alkali-activated binders: Rheology, strength and microstructure characterization

Alkali-activated binders (AABs) have the potential to consume various types of cementitious waste materials, including coal ashes, municipal solid waste incinerator ash, palm-oil fuel ash, steel slags, mine tailings, cement kiln dust, ceramic tile residue, rice husk ash, and waste glass. This paper presents a study of alkali-activated cement paste produced with the substitution of the cementitious waste material soda-lime glass, which makes up the major proportion of the general glass waste stream. In the alkali-activated cement paste, crushed soda-lime glass powder (CG) was used as a replacement for class F fly ash (FA) from 0 to 30% by total solid weight, keeping the ground granulated blast furnace slag (GGBFS) content constant at 50%. The influence of activator molarity (4–8 M), alkaline liquid/solid binder (L/S) ratio (0.4–0.5) and different curing conditions (ambient air curing, wet curing, and short-term heat curing) on the rheology, strength, and microstructure of CG-substituted AABs was investigated and optimum conditions are suggested. According to the experimental results, both the workability and strength (compressive and tensile) of the AAB gradually increased with increasing level of substitution of FA by CG. Significant improvement in flow and setting time was seen with the addition of CG, even in mixtures with a low L/S ratio of 0.4. Both ambient and wet curing had more influence on the strength gain of AABs, especially after 28 days. Short-term heat curing resulted in high early strength gain. The dissolution of CG increased with increasing molarity (from 4 to 8 M) of the alkaline solution, which improved both strength and microstructure with curing time. Morphological and elemental analysis indicated an improvement of the microstructure of AABs due to the increased formation of calcium-dominant hydration products and hence reduced porosity with the substitution of CG. However, undissolved large-sized CG particles agglomerated in the binder without participating in the alkaline reactions. These agglomerated particles may induce micro-cracks due to weak bonding between the cement matrix and the smooth CG interface, which reduces the durability of AABs. Therefore, the inclusion of waste soda-lime glass powder with a mean diameter of 10–15 µm as a precursor in FA/GGBFS-based AAB as a replacement for FA is feasible and provides a good solution for waste material recycling.

Levels of PCDDs/PCDFs in waste incineration ash of some Jordanian hospitals using GC/MS

An investigative study on the occurrence of the unintentionally produced toxic and carcinogenic polychlorodibenzo-p-dioxins (PCDDs) and polychlorodibenzo furans (PCDFs) compounds was conducted in 11 bottom ash samples of hospital waste incinerators from three public hospitals in three distanced cities: Amman, Irbid, and Ma’an/Jordan. Total ash was sampled in the after burning chamber. The analysis was performed using a developed and validated GC/MS method in the selective ion monitoring (SIM) mode. ΣPCDD/Fs concentrations as international toxicity equivalence (TEQ) in individual samples in this study varied in the range of 206–476 pg I-TEQ/g with average value of 306 ± 88 pg I-TEQ/g and were found to be lower than the limit value (10,000 pg I-TEQ/g), where furans constituted a larger portion of the contamination compared to PCDDs to signature the de novo synthesis as major route in the incineration process. Limits of quantitation were between 0.015 and 0.10 ng/g with instrumental precision expressed as coefficients of variation of <15% and recoveries between 75.5 and 95.5%. Taking into consideration the incinerator bottom ash generation rate/batch/day and expressing the whole measured concentrations per year, the estimated amounts produced per year were in the range of 1.5 mg TEQ/year (Jameel Tutunji hospital) to 15.5 mg TEQ/year (King Abdullah hospital). These are sent daily or weekly to landfill- and dumping sites in each province which would pose serious future concentration accumulation of PCDD/Fs in these areas, transportation and adverse health effects.

Accelerated carbonation technology granulation of industrial waste: Effects of mixture composition on product properties.

The use of accelerated carbonation technology in combination with a granulation process was employed to produce aggregates from a variety of industrial wastes, which included municipal solid waste incineration fly ash and air pollution control residue, oil shale ash, cement kiln dust, and quarry fines that have been produced in Estonia. Focusing mainly on the effects produced by the content of municipal solid waste incineration ash in the admixtures, the granule compositions were varied in order to tailor granule properties on the basis of CO2 uptake, strength development, leaching behaviour, microstructure, and morphology. All the steps involved in the accelerated carbonation technology granulation process, from mixing with additives to granulation and carbonation treatment, were carried out in the same apparatus - an Eirich EL1 intensive mixer/granulator. The amount of CO2 that was bound ranged from 23 to 108 kg per tonne of waste. The granules that included the optimised mixture of municipal solid waste incineration air pollution control residue, oil shale ash, cement kiln dust, and ordinary Portland cement were characterised by the highest compressive strength (4.03 MPa) and water durability for the size range of 4-10 mm. In addition, the process was found to be effective in reducing alkalinity (pH < 11.5) and immobilising heavy metals (especially zinc) and chloride. The composition and properties of the respective waste materials and mechanisms associated with the characteristics of the resulting granules were also addressed.

Development of water-resisting mortar by incorporation of functionalized waste incineration ashes

In this study, a method to prepare water-resisting mortars by incorporating hydrophobic incineration ashes is reported. Bottom ash is the by-products of municipal solid waste incineration with limited recycling options due to harmful contaminants. To decrease the environmental risk of bottom ash and provide an economical and green route to reuse it, a wet chemistry method is applied to prepare hydrophobic bottom ash and investigate its potential to improve transport properties of concrete. The functionalization of fine bottom ash (<0.125 μm) using stearic acid provides hydrophobic nature to the particles along with improved leaching properties. At an optimum addition of 4% stearic acid, the bottom ash present a water contact angle of 141° and can be classified as hydrophobic. The influence of functionalized bottom ash on the cement hydration, mechanical properties, water absorption and wetting property of the water resisting mortar is investigated. Results show that the up to 30% of the binder can be replaced by hydrophobic bottom ash as it decreases the capillary water absorption rate and chloride penetration depth by 57% and 65%, respectively. The samples containing hydrophobic bottom ash show better mechanical properties as compared to the samples made with untreated bottom ash. The environmental assessment shows that the mortars containing functionalized BA are environmentally friendly because of the dilution effect and immobilization potential of the hazardous material into the cementitious matrix. Results show that the proposed method is a facile and efficient way to change bottom ash into hydrophobic powders, which leads to more environmentally friendly water-resisting mortar.

Comparative leaching characteristics of fly/bottom ashes from municipal solid waste incineration under various environmental stresses

With proper leaching tests, health hazards associated with municipal solid waste incineration (MSWI) ashes, i.e., incineration bottom ashes (IBA) and incineration fly ashes (IFA), can be quantitatively defined. However, it must be coupled with specific environmental scenarios to draw the proper conclusions. Several environmental stresses based on current management of MSWI ashes were herein simulated with laboratory leaching studies to understand their impacts. The impact of bulk metal recovery on the IBA leaching potential was firstly investigated, suggesting the promoted release for certain metals including those with a relative high content (> 1000 mg/kg) such as Ba, Cu, Pb and Zn. The impact of seawater was also simulated. Most metal release was altered with the new chemistry established. Batch leaching tests were further performed under both salty and acidic environment to understand their aggregated effects, indicating an overwhelming influence from seawater buffering. Lastly, batch leaching tests of the IBA/IFA mixture were performed under various mass ratios, while data were compared with those by their individuals and the theoretical leaching value, unveiling different leaching characteristics during landfill disposal. Hereby, a comprehensive characteristic metal leaching potential was achieved under various ash managements. It provides insights into environmental risks relevant to their current practices.

Hazardous waste characterization implications of updating the toxicity characteristic list

In the US, the toxicity characteristic leaching procedure (TCLP) determines if a waste is toxicity characteristic (TC) hazardous based on leached concentrations of specific chemicals. The TC limits were originally derived from drinking water standards (DWS) adjusted by a dilution attenuation factor of 100. The TC limits have not been updated along with DWS revisions. This research examines potential implications of updating the TC limits to account for new DWS thresholds and elements, as well as tap-water risk thresholds; this allows a further expanded evaluation of elements that might be regulated as drinking water standards in the future. Fossil fuel combustion residues, batteries, electronic wastes, municipal solid waste incineration (MSWI) ashes, and treated wood were examined with TCLP and the leached metal concentrations were compared to revised TC thresholds. The two wastes most affected by updated TC limits would be batteries and MSWI ashes. Thallium and antimony, which were not included on the original TC list, exceeded the TC thresholds for batteries and MSWI ash, respectively. Copper, a chemical used in current preserved wood formulations, did not cause currently marketed treated wood to be hazardous waste, but arsenic did for older wood products.

Fluent simulation of centrifugal atomization of multi-solid wastes molten slag melted by blast furnace slag, fly ash and waste incineration ash

Based on finite element numerical simulation method, Fluent software was used to simulate the centrifugal atomization process of multi-solid wastes molten slag melted by blast furnace slag, fly ash and waste incineration ash. The feasibility of the finite element model in simulating centrifugal atomization was verified by comparing the experimental results with the calculated results. The influence of rotating speed, nozzle angle and the inlet velocity of compressed air injected on the slag particle distribution were studied. Results showed that the rotating speed of the turntable should not exceed 1000 rpm, the inlet velocity of compressed air should be about 5 m/s, and the nozzle angle of compressed air should be set between 40 and 60 degrees, which have positive effect on the centrifugal atomization of multi-solid wastes molten slag. The heat recovery efficiency can reach 73.7% under the condition of 800 rpm rotary speed, 5 m/s compressed air inlet velocity, 0.1 m/s flow rate of 1800 K molten slag beam and in 300 K ambient temperature.