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This study focuses on the essential task of monitoring the strength of structural concrete in construction and rehabilitation projects. The conventional non-destructive testing (NDT) approach offers an indirect estimation of concrete compressive strength. However, the existing models lack the ability to address the estimation of compressive strength in concrete mixtures containing bottom ash (BA) and recycled coarse aggregate (RCA). This study aims to bridge this gap by accurately estimating the compressive strength of such concrete using the ultrasonic pulse velocity (UPV) technique. To achieve this objective, various concrete specimens with different cement content, water–cement ratios (w/c), recycled coarse aggregate, and bottom ash contents through weight batching, were prepared. UPV and compressive strength measurements were taken on cylindrical concrete specimens after 28 and 90 days of curing. The analysis revealed an exponential relationship between the compressive strength and UPV, with a high correlation coefficient across the evaluated concrete mixes, independent of the curing time. Ultimately, two robust models were developed to predict the compressive strength of concrete mixes containing different percentages of RCA and BA, respectively, at 28 and 90 days of curing. These models offer valuable insights and practical tools for ensuring the structural integrity of concrete in construction and rehabilitation projects involving bottom ash and recycled coarse aggregate. [ABSTRACT FROM AUTHOR]

Peat soil is a problematic soil that has very high compressibility and water content. Peat soil also has a low soil carrying capacity so repair techniques are needed. In this research, a mixture of Fly Ash, Bottom Ash, and Fly Ash+Bottom Ash was used. The use offly ash and bottom ash as a mixture is because this material has fine grains, is grayish in color and is obtained from burning coal containing chemical elements including silica (SiO2), alumina (Al2O3), ferrous oxide (Fe2O3) and calcium oxide (CaO) and contains other elements. This research uses variations in fly ash and bottom ash levels, namely 0%, 10%, 15%, 20%, 25%. The location for taking peat soil samples was taken in Parit Village, North Indralaya District, Ogan Ilir Regency, South Sumatra Province. Laboratory testing includes soil properties testing and California Bearing Ratio (CBR) Unsoaked. Soil properties results (location 1) are: Water content (ω) 550.64%, Organic Content (OC) 49.54%, Ash Content (AC) 50 .46%, Fiber Content (FC) 42.03%, Specific Gravity (Gs) 1.754 gr/cm3, and pH Value 3. CBR Test Results for original peat soil were 4.73% (Location 1) and 4.55% (Location 2). The CBR value of Unsoaked Peat Soil + fly ash is 3.99%; 4.94%; 7.30%; 9.86%; 12.16%; 15.97%. Peat + bottom ash, namely 3.99%; 4.44%; 6.66%; 8.32%; 10.57%; 13.86%. Peat + fly ash + bottom ash, namely 3.99%; 5.43%; 7.84%; 10.03%; 12.95%; 18.72%. [ABSTRACT FROM AUTHOR]

The building sector is responsible for about 37% of the global carbon dioxide emissions, 6% of which result from concrete (and particularly cement) production. Using recycled and supplementary cementitious materials and adopting a whole building life cycle approach can be seen as multi‐beneficial strategies for materials' design. In this framework, this study aims to formulate a green concrete, by replacing 10, 15 and 20% of cement with a secondary raw material constituted of vitrified bottom ash derived from municipal solid waste incineration. The basic physical and mechanical properties were measured up to 365 days, so to evaluate the effects of the cement replacement both on short and long‐term behavior. Life Cycle Assessment was used as a tool to evaluate the environmental performance of the developed green concrete. An Eco‐Mechanical Analysis was also performed to match the environmental impacts with the mechanical behavior, allowing to assess that the concrete produced by replacing 20% of cement with vitrified municipal solid waste incineration bottom ash (if classified as hazardous waste) is the one that leads to optimize the overall sustainability. The approach proposed in this work, which can be easily generalized, contributes to the definition of a route for the implementation of innovative green construction building materials by using waste. [ABSTRACT FROM AUTHOR]

The more economically viable and environmentally sustainable approach for treating the by-products of coal combustion from thermal power plants entails their collective disposal as opposed to individual disposal methods. This aligns with pertinent EU directives and domestic regulations, ensuring compliance with established standards while optimizing resource utilization and minimizing environmental impact. This study evaluated the resistance to wind erosion of the binding properties of a mixture (fly ash (FA), bottom ash (BA), and additives) using an indoor wind tunnel under simulated ambient conditions. Investigations of the mutual impact of ash, bottom ash, and additives (CaO and Ca(OH)2) with a certain percentage of water were carried out with eighteen samples. The samples consisted of the water at six addition rates 5, 8, 10, 15, 20, and 25% (w/w), and additive at three addition rates (1, 2, and 3% (w/w). Based on the obtained results, the optimal ratios of additives (3% (w/w)) and water (15% (w/w)) were determined. Prior to the wind tunnel experiments, and according to the different addition rates of additives and water, eight samples were prepared with different addition rates of ash. The mass concentrations of suspended particles (PM10) and total suspended particles (TSPs) in these samples were measured at three distinct wind velocities: 1 m/s, 3 m/s, and 5 m/s, respectively. The results indicate that the samples containing the optimal content of additives and water demonstrate a maximum increase in PM10 emission zero values of no more than 1.9 times. This finding can be considered satisfactory from the standpoint of environmental protection. [ABSTRACT FROM AUTHOR]

Biodiesel, an eco-friendly alternative to conventional fossil fuels, offers reduced emissions like carbon dioxide, sulfur oxides, and soot. This study explores biodiesel production from a blend of waste oils using a novel biomass-based catalyst derived from the bottom ash of a biomass boiler. Catalyst synthesis involved wet impregnation, a unique approach using previously unreported bottom ash. Characterization via SEM-EDS, BET, FTIR, and XRD revealed its composition and structure. Optimization of biodiesel production involved assessing alcohol molar ratio, catalyst concentration, and reaction time, achieving a maximum FAME concentration of 95% under specific conditions. Blending residual palm oil with waste frying oil enhanced biodiesel properties, demonstrating a maximum FAME concentration at specific catalyst concentration (8%), molar ratio (1:10), and reaction time (2 h). Catalyst reusability, up to three cycles without significant yield variation, showcased its sustainability. The catalyst, primarily composed of calcium, a characteristic biomass bottom ash component, exhibited mesoporous features. Impregnation with eggshells not only altered composition but also ensured a uniform particle size distribution. FTIR and XRD analyses indicated calcium in hydroxide and crystallized forms. Effective catalyst separation methods included decanting or water washing, with optimal biodiesel purity achieved through 3% phosphoric acid washing at 60 °C. Various recovery methods were assessed, highlighting hexane washing as the most efficient, enabling up to three catalyst reuse cycles without substantial efficiency loss. [ABSTRACT FROM AUTHOR]

In this study, the bagasse ash (BA) from biorefinery process was recovered and used as a catalyst in the co-pyrolysis of solid residue from second-generation bioethanol plant with high-density polyethylene (HDPE). The co-pyrolytic behaviors were studied using thermogravimetric analyzer at three heating rates of 10, 20, and 40 K min−1. The synergistic effects between BA and HDPE and their co-pyrolysis kinetics were investigated using two model-free methods: Kissinger–Akahira–Sunose (KAS) and Flynn–Wall–Ozawa (FWO). The pyrolysis products were determined by pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) as well. The results indicated that the addition of BA could increase the production yield. The average apparent active energy (Ea) of co-pyrolysis was 171.3 kJ mol−1 from KAS and 174 kJ mol−1 from FWO, which were lower than that for catalyst-free pyrolysis (174.8 kJ mol−1 from KAS and 177.3 kJ mol−1 from FWO). The novel co-pyrolysis process showed great potential in improving both the economic and environment sides of the second-generation biorefineries. [ABSTRACT FROM AUTHOR]

This study examines the influence of the mass percentage and maturation stage of bottom ash on bio-composite mechanical strength. Two kinds of bottom ash were used: matured and non-matured. To elaborate the composites, several different percentages of bottom ash were mixed with an organic matrix. Casein, starch, alginate, polyethylene glycol, pre-vulcanized natural latex, and water are the components of matrix. The idea was to use as much bottom ash as possible, since it can be used as 80% or more as the main charge, which was in prismatic form for mechanical testing after drying. The results show that whatever the state of maturation of the bottom ash, the resistances present a maximum for a percentage of bottom ash equal to 85%. It could also be noticed that non-matured bottom ash composites have better mechanical strengths than composites with matured bottom ash. This is due to the decrease in porosity of the composites and to the improvement in their structural integrity. These new composites could solve some of the solid waste problems created by bottom ash production. As the matrix is made from organic resources, it saves energy and reduces the carbon footprint. This bio-composite contributes to the circular economy by giving waste a second life. [ABSTRACT FROM AUTHOR]

In the last two decades, bottom ash has been widely used as an alternative to conventional granular fill in various construction activities, either by replacing the whole or a portion of the fill material. This study investigates the dynamic behaviour of bottom ash and compares its response with sand through strain-controlled constant volume cyclic simple shear tests. The effects of relative density, shear strain, vertical stress, and number of loading cycles on the dynamic behaviour of bottom ash and sand are discussed. The results of the study indicate that bottom ash is highly compressible than sand under one-dimensional anisotropic compression, attributed to the angular and vesicular texture of bottom ash particles. This texture results in associated particle breakage in dense bottom ash specimens. Further, the damping of bottom ash is lower than that of sand in most cases, and the shear modulus is found to be smaller or larger than that of sand depending on shear strain magnitude and the number of loading cycles. At medium shear strain magnitudes, bottom ash and sand exhibit almost the same initial shear modulus. However, the degradation of the shear modulus with the number of loading cycles is significant in sand compared to bottom ash, thereby indicating that bottom ash exhibits a better dynamic resistance than sand. The study highlights that specimen dimensions critically influence the results obtained from cyclic simple shear tests and that careful interpretation of results is necessary, especially when comparing materials with different particle sizes or admixtures. Furthermore, the influence of cyclic loading frequency on the overall dynamic response of tested materials is also discussed. The findings of the study contribute to the understanding of bottom ash behaviour and its potential use as a granular fill material in construction applications. [ABSTRACT FROM AUTHOR]

In tropical regions, heavy rainfall induces erosion and shallow landslides on road embankments. Cement-based stabilization methods, common in these regions, contribute to climate change due to their high carbon footprint. This study explored the potential application of coir fiber-reinforced laterite soil-bottom ash mixtures as embankment materials in the tropics. The objective is to enhance engineered embankment slopes' erosion resistance and stability while offering reuse options for industrial byproducts. This study examined various mix designs for unconfined compressive strength (UCS) and permeability, utilizing 30% bottom ash (BA) and 1% coir fiber (CF) with varying sizes ranging from 10 to 40 mm, 6% lime, and laterite soil (LS), followed by microstructural analyses. The results demonstrate that the compressive strength increases as the CF length increases to 25 mm. In contrast, permeability increases continuously with increasing CF length. Lime-treated mixtures exhibit superior short- and long-term strength and reduce permeability owing to the formation of cementitious materials, as confirmed by microstructural analyses. A lab-scale slope box was constructed to evaluate the surface erosion of the stabilized laterite soil embankment. Based on the rainfall simulation results, the LS-BA-CF mixtures show better resistance to erosion and deformation compared to untreated LS, especially when lime is added to the top layer. This study provides insights into a sustainable and cost-effective approach for slope stabilization using BA and CF, offering a promising solution for tropical regions susceptible to surface erosion and landslides. [ABSTRACT FROM AUTHOR]

Red mud and bottom ash are two industrial wastes generated in huge quantities by the aluminum industry and coal-based power plants, worldwide. The high alkaline nature and high specific gravity of red mud are the major hindrances in utilizing as constructional geomaterial. The manuscript aims to utilize these two wastes as subgrade material in pavement by mixing different proportions of red mud with bottom ash. The physical behavior i.e., specific gravity, grain size pattern, and chemical characterization i.e., pH of all the mixes were assessed. Geotechnical properties such as compaction, compression, strength, and permeability tests were conducted to investigate the efficiency of different mixes as suitable geomaterial. The California bearing ratio, cyclic triaxial test under different confining pressure, resilient modulus, and nonactivity of clays by methylene blue test results provide the proficiency of different mixes in utilizing as subgrade material. The highest strength, high CBR, and resilient modulus values suggest that the mixture of 70% HRM with 30% HBA is suitable and strength gain upon drying suggests that it can be used as a structural subgrade material. Further, a leachate analysis of all the mixes concluded that the chemicals are within permissible limits and hence not hazardous to the ecosystem. [ABSTRACT FROM AUTHOR]

In this scientific investigation, we explore the potential of bottom ash from municipal solid waste incineration (MSWI), hereafter referred to as BA-MSWI, as an alternative to natural aggregates in epoxy mortar production. BA-MSWI bottom ash represents a prevalent environmental issue due to its excessive production, and its use in sustainable applications could help reduce the demand for natural aggregates. We conducted experiments by replacing natural sand with varying proportions of BA-MSWI (30–100%) and using epoxy resin (15–20%) as a binder. A packing density model was employed to optimize mixture compactness, calculate total porosity, and determine the required amount of resin. The results indicate a decrease in compressive strength and flexural strength when BA-MSWI is incorporated, but they enhance the thermal properties of the mortar. Importantly, the increased proportion of epoxy resin compensates for the loss of strength induced by the addition of BA-MSWI. From an environmental perspective, this research opens up possibilities for the utilization of BA-MSWI in various construction applications. [ABSTRACT FROM AUTHOR]

Data from the DPUPR of Sragen district, the price of Merapi sand in 2020 is IDR 1,590,000 then in 2021 the price of Merapi sand is IDR 1,680,000. The increase in the material price of Merapi sand in Sragen Regency has forced the brick maker UD. Cerah, whose address is in Dayu village, Jurang Jero sub-district, Karangmalang subdistrict, Sragen district, is again racking her brains to set a selling price for the bricks to avoid losses. The making of the brick itself cannot be separated from the costs incurred for purchasing raw materials, purchasing equipment for making bricks, and labor costs. So with the high price of Merapi sand material, it requires that the brick maker, UD. Sunny innovates by replacing the cheaper sand material. In this study using experimental methods for making bricks, using the full costing method for calculating production costs and using the depreciation method to obtain the annual depreciation load for brick machines. Based on research on the characteristics of fine aggregate river sand from Ngipang village, Gawan subdistrict, Tanon sub-district, Sragen district, the results of testing for silt content, testing for organic matter content, testing for specific gravity and water absorption, gradation testing met the requirements while testing for saturated surface dry (SSD) did not meet the requirements. Then research on the characteristics of fine aggregate from coal waste (bottom ash) obtained the results of testing for mud content, testing for organic matter content, testing for gradation that met the requirements while testing for specific gravity and water absorption, testing for saturated surface dry (SSD) did not meet the requirements. Based on the research on the compressive strength test of the bricks, it was found that the compressive strength of the bricks from river sand, Ngipang village, Gawan sub-district, Tanon sub-district, Sragen district was greater than the compressive strength of the bricks from coal waste (bottom ash), the maximum average compressive strength value of bricks from river sand in the village Ngiang, Gawan sub-district, Tanon sub-district, Sragen district obtained a value of 6.51 MPa on the 1PC: 5PS FAS mixture variation of 0.5, while the maximum compressive strength value of bricks made from coal waste (bottom ash) obtained a value of 5.10 MPa on the variation mix 1PC: 5BA FAS 0.6. Based on research on the production costs of making bricks, it was found that the production costs of making 1 m3 of river sand bricks in Ngipang village, Gawan sub-district, Tanon sub-district, Sragen district were greater than the production costs of making 1 m3 of coal waste (bottom ash) bricks, the production costs of 1 m3 river sand bricks in Ngipang village, village Gawan, Tanon sub-district, Sragen district, the highest is in the mix variation of 1PC: 5PS FAS 0.6 with the production cost of IDR 962,237.49, while the largest 1 m3 coal waste (bottom ash) brick production cost is in the 1PC mix variation: 5BA FAS 0.6 with a production cost of IDR 659,285.51. [ABSTRACT FROM AUTHOR]

Bottom ash (BTA), a byproduct of burning coal in electric power plants, is often considered waste. Managing significant quantities of bottom ash remains a challenge. Laterite, commonly used in road construction, may not meet the required standards in some regions, necessitating the transport of higher-quality laterite from distant locations. This practice increases construction costs. This research explores the use of bottom ash and cement as replacements for laterite in pavement materials. The proportion of bottom ash used varied from 10 to 50% by dry weight of the laterite, while the cement contents were 1, 3, 5, and 7% by dry weight of the laterite-bottom ash mixture. The experiments included unconfined compressive strength, splitting tensile strength, California bearing ratio, and durability against wetting-drying cycles. The results indicate that the stabilised laterite significantly increases strength values—2 to 14 times greater than those of unstabilised laterite, with 20% bottom ash replacement yielding the best results. Microstructural analyses confirmed the strength test outcomes. Replacing laterite with bottom ash and cement proves to be a sustainable method for road construction, offering cost-effectiveness, conservation of natural resources, pollution reduction, and enhanced energy efficiency in accordance with the standards of the Department of Highways of Thailand.

Biogas is a cost-effective, efficient, environmentally friendly, and renewable alternative energy source. While biogas contains CH4, it also contains impurities in the form of 27–45% CO2 gas. Therefore, it is necessary to purify biogas by removing CO2 gas as it can reduce the calorific value of CH4, the main component of biogas. The process of methane purification can be achieved through adsorption. Bottom ash, derived from palm oil mill waste, shows great potential for methane purification by effectively adsorbing CO2. This research simulated the methane purification process using the computational fluid dynamics (CFD) method with the student version of the ANSYS R20 software. The study utilized an adsorbent made from bottom ash obtained from palm oil mill waste. The main objective was to investigate the performance of bottom ash as an adsorbent for removing CO2 gas in a continuous gas flow within an adsorption column. The study involved varying the column bed height (4 cm, 8 cm, 12 cm) and gas flow rate (10 L/min, 15 L/min, 20 L/min). The results showed that the highest efficiency in removing CO2 gas was 84.53% with a bed height of 12 cm and a flow rate of 10 L/min, while the lowest efficiency was 47.87% with a bed height of 4 cm and a flow rate of 20 L/min. Furthermore, the highest adsorption capacity for CO2 gas was 1.64 mg/g with a bed height of 12 cm and a flow rate of 10 L/min, while the lowest capacity was 0.93 mg/g with a bed height of 4 cm and a flow rate of 20 L/min. The linearization of adsorption isotherm data indicated that the CO2 gas adsorption process using bottom ash adsorbent followed the Langmuir model.

Incineration plants for electricity generation have offered a solution to the challenges of domestic solid waste treatment in many countries. However, their emissions, fly ash (FA) and bottom ash (BA), have had a detrimental impact on environmental quality. This study investigated the morphology, element composition, and concentration of metals in FA and BA from municipal solid waste incineration plants using scanning electronic microscopy/energy-dispersive X-ray and inductively coupled plasma mass spectrometry techniques. It also evaluated the distribution ratios of metal species across five fractions: exchangeable, carbonate-bound, oxide-bound, organic-bound, and sulfide-bound, and residual. The total metal content in both FA and BA was comparable, with calcium having the highest concentration (28,170–135,130 mg·kg−1 dry weight) and silver having the lowest (5.26–19.3 mg·kg−1 dry weight). However, the percentage proportion of metals differed between the extracted fractions. Except for cadmium in FA, ecological risk assessment indicated low direct bioavailability and potential risk of metals in both FA and BA. These findings contribute to the hazard assessment of FA and BA generated from waste incinerators and provide a scientific basis for developing treatment techniques for this type of waste.

Abstract Recycling of abandoned waste bottom ash has been a key issue in Republic of Korea in terms of environmental protection as well as economic concern. In this work, a method for recycling of abandoned bottom ash has been discussed based on the results from laboratory and industrial-scale experiments. Abandoned bottom ash was magnetically separated and properties of magnetically separated bottom ash samples as well as properties of mortar and masonry cement brick made of bottom ash were investigated. According to the experimental results, bulk and skeletal densities were ranked in the order of strongly magnetic > weakly magnetic > as-received > non-magnetic (from heavier to lighter) bottom ash. From laboratory-scale experiments, compressive strengths of mortars made of bottom ash samples (measured by ASTM C 109) were lower than that of mortar made of standard sand. Among bottom ash samples, mortar made of non-magnetic bottom ash (after removal of unburnt carbon) showed higher compressive strength with lower thermal conductivity (measured by ASTM C 1113) and weight than others. Masonry cement brick made of magnetic bottom ash showed lower weight and thermal conductivity than those made of standard sand, while meeting the KS strength guideline as a masonry cement brick. The results suggest the applicability of bottom ash as lightweight aggregate for production of masonry cement brick. However, considering the lower strength obtained from masonry cement brick made of as-received bottom ash (without removal of unburnt carbon), unburnt carbon content should be removed prior to its utilization as lightweight aggregate.

Permeable pavement is a technology that allows rainwater to infiltrate into the pavement. Permeable pavements not only help reduce surface runoff by allowing rainwater to infiltrate into the pavement, but also improve water quality with the filter layer that removes particulate matter pollutants. This study evaluated the particulate matter removal efficiency of bottom ash–sand mixtures as filter layers for removing fine (≤10 μm) or ultrafine (≤2.5 μm) particulate matter in the laboratory. Five filter media were tested: silica sand, bottom ash, and bottom ash–sand mixtures with 30:70, 50:50, and 70:30 ratios. The mixed filters exhibited more consistent and stable particulate matter removal efficiency over time than either the uniform sand or bottom ash filter. The 50:50 bottom ash–sand mixture demonstrated removal rates of 58.05% for 1.8 μm particles, 93.92% for 10 μm particles, and 92.45% for 60 μm particles. These findings highlight the potential of bottom ash–sand mixtures as effective filter media for removing PM10 road dust, although field validation with actual pavement systems is necessary. [ABSTRACT FROM AUTHOR]

Solid waste generation and its sustainable disposal are big concerns in the present decade. Mine tailings and incinerated bottom ash are among the greatest solid waste contributors to the environment. To promote sustainable development, material reuse and recycling are important. In the present study, a feasibility study was conducted by utilizing such tailings and bottom ash for the production of controlled low-strength material (CLSM). The amount of cement was utilized less, and by controlling the design mix with a targeted flow, low-strength material was produced. Three different cement contents (60, 80, and 100 kg/m3) and 100% mine tailings or incinerated bottom ash were used as fine aggregate material. Fresh properties of different CLSM mixes, mechanical performance, and leaching behavior were conducted to confirm the final product. It was observed that both the mine tailings and bottom ashes are suitable as an aggregate material for CLSM mixes. The compressive strength values of different CLSM mixes at 28 days were observed between 0.13 and 1.88 MPa for various aggregate materials (mine tailings and bottom ash) and cement content. Moreover, there is an influence in the reactivity of cement hydration by the aggregate (tailings and ash), which was confirmed by the calorimetry study. The selected mine tailings and bottom ashes are not inert (like natural aggregate) within the CLSM mixes, and the chemical composition of the raw materials affects their fresh and hardened properties. The leaching test further shows that the final product could leach different heavy metals beyond the limit for inert materials, but within the nonhazardous limits by international standards. The present work deals with CLSM mixes with locally available industrial side streams; some important properties such as hardening time, penetration resistance, shrinkage, excavatability, and other durability properties (i.e., acid attack, freezing and thawing resistance) were not considered in the study and can be studied further. [ABSTRACT FROM AUTHOR]

Biogas is a cost-effective, efficient, environmentally friendly, and renewable alternative energy source. While biogas contains CH4, it also contains impurities in the form of 27–45% CO2 gas. Therefore, it is necessary to purify biogas by removing CO2 gas as it can reduce the calorific value of CH4, the main component of biogas. The process of methane purification can be achieved through adsorption. Bottom ash, derived from palm oil mill waste, shows great potential for methane purification by effectively adsorbing CO2. This research simulated the methane purification process using the computational fluid dynamics (CFD) method with the student version of the ANSYS R20 software. The study utilized an adsorbent made from bottom ash obtained from palm oil mill waste. The main objective was to investigate the performance of bottom ash as an adsorbent for removing CO2 gas in a continuous gas flow within an adsorption column. The study involved varying the column bed height (4 cm, 8 cm, 12 cm) and gas flow rate (10 L/min, 15 L/min, 20 L/min). The results showed that the highest efficiency in removing CO2 gas was 84.53% with a bed height of 12 cm and a flow rate of 10 L/min, while the lowest efficiency was 47.87% with a bed height of 4 cm and a flow rate of 20 L/min. Furthermore, the highest adsorption capacity for CO2 gas was 1.64 mg/g with a bed height of 12 cm and a flow rate of 10 L/min, while the lowest capacity was 0.93 mg/g with a bed height of 4 cm and a flow rate of 20 L/min. The linearization of adsorption isotherm data indicated that the CO2 gas adsorption process using bottom ash adsorbent followed the Langmuir model. [ABSTRACT FROM AUTHOR]

In this study, the effect of particle size of pozzolinic additives (bottom ash and zeolite) on alkali-silica reaction (ASR) and compressive strength as mechanical properties of cement based mortar was investigated. In order to obtain pozzolanic additive in different particle sizes, the bottom ash/zeolite was subjected to grinding process in 5 different times (0, 30, 60, 180 and 240 minutes) in a ball mill. Concrete mortars were prepared by using different proportions (10, 20 and 30%) of pozzolinic additive in each particle size to replace cement. Natural fine aggregate and CEM-I 42.5 type Protland cement were used in cement based mortars. The amount of expansion of each mortar bar resulting from ASR according to TS 13517 and compressive strength according to TS EN 12390-3 were determined. As a result, it was determined that zeolite was more effective than bottom ash in suppressing ASR occurring in concrete mortar and the lowest ASR expansion value was obtained by 240 minutes grounded and 10% replacement of zeolite by cement. However, when the effect of both pozzolanic additives on the compressive strength of the concrete mortar was compared, it was observed that the bottom ash additive did not have a significant effect on the compressive strength, whereas the zeolite additive reduced the compressive strength a little (10 - 29 %). [ABSTRACT FROM AUTHOR]

The construction industry is a leading sector for coal ashes utilization, including in cement manufacturing and soil stabilization applications. In soil stabilization, coal ashes, alongside Ordinary Portland Cement (OPC), are the most commonly used materials. However, the environmental impact of coal ashes, particularly the leaching of heavy metals from stabilized soil when exposed to rainfall, remains underexplored. There is a notable gap in assessing the environmental impacts of this utilization, particularly when the stabilized soil interacts with rainfall in real-world scenarios. Therefore, this study aimed to contribute to filling this gap. Accordingly, in this study, peat soil was stabilized by using fly ash, bottom ash, and OPC. The characterization of soil mixture materials, including physicochemical and engineering properties, was established and studied first. Following the environmental impact, simulations were conducted using a column to study soil leachate under different conditions and seasons (dry and wet) in response to its interaction with rainfall. The leachate was analyzed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to measure the concentrations of heavy metals, including copper (Cu), aluminum (Al), manganese (Mn), iron (Fe), and zinc (Zn). Additionally, Ion Chromatography (IC) was employed to determine the concentrations of major anions, including fluoride (F⁻), chloride (Cl⁻), nitrate (NO₃⁻), phosphate (PO₄³⁻), and sulfate (SO₄²⁻). The findings revealed the complex interaction of the chemical stabilization processes and environmental factors with the leaching behavior of heavy metals and anions, highlighting the significant impact of stabilization on leaching patterns. To conclude, this study provides a valuable contribution to understanding the environmental and engineering implications of utilizing coal ashes in soil stabilization.

Chlorinated benzenes (CBzs) are a group of organic pollutants, which have been industrially or unintentionally produced through various chemical and thermal processes. Studies on full congener profiles of CBzs in waste and environmental samples are relatively limited and not updated. In the present study, concentrations of 12 CBzs were determined in fly ash (FA) and bottom ash (BA) samples collected from one municipal waste incinerator (MWI) and one industrial waste incinerator (IWI) in northern Vietnam. Levels of Σ12CBzs were higher in bottom ash (median 25.3; range 1.59–45.7 ng/g) than in fly ash (median 7.30; range 1.04–30.0 ng/g). The CBz profiles were dominated by di- and tri-chlorinated congeners with the major congeners as 1,2,4-TCB, 1,2,3-TCB, 1,2-DCB, and 1,3-DCB. However, CBz profiles varied greatly between sample types and incinerators, implying differences in input materials, formation pathways, and pollutant behaviors. Incomplete combustion is possibly responsible for high levels of CBzs in industrial bottom ash. The emission factors of Σ12CBzs ranged from 21 to 600 µg/ton for fly ash and from 190 to 4570 µg/ton for bottom ash, resulting in annual emissions of about 6 and 3 g/year for the IWI and MWI, respectively. Our results suggest additional investigations on industrial emission and environmental occurrence of all 12 CBzs rather than solely focusing on regulated congeners like hexachlorobenzene and pentachlorobenzene. [ABSTRACT FROM AUTHOR]

The road network is the most important infrastructure for the country's economic development. Asphalt concrete (AC) pavement is a common type of pavement surface used in both developing and developed countries. In this study, bottom ash (BA), a by-product from coal-fired power plants, was used to improve the performance of AC in combination with various aggregates in Thailand. The aggregates used with the BA were comprised of limestone (L), granite (G), and basalt (B) aggregates. The asphalt cement penetration grade 60/70 (AC 60/70) was used for this research. The influence of BA replacement ratio (0%, 10%, 15%, 20%, and 25% by total weight of fine aggregate) on the Marshall properties and indirect tensile strength (ITS), as well as mechanistic performance (indirect tensile resilient modulus (IT Mr), indirect tensile fatigue life (ITFL), rut depth, and skid resistance), was evaluated. The B-AC exhibited the best Marshall properties, ITS and performance due to its highest optimum asphalt cement. The BA replacement ratio could improve the Marshall properties, ITS and performance of BA-AC for all studied aggregates due to the reaction between BA molecular and asphalt cement up to the best value at the optimum BA replacement ratio (OPT-BA), which was 15, 20, and 5% BA for BA-AC containing B, G, and L aggregates, respectively. The IT Mr was found to be directly related to ITS in a linear function. The IT Mr controls not only the ITFL (tensile failure) but also the rut depth resistance (compression failure). Based on the critical analysis of this research output, a stepwise procedure to determine the optimum BA replacement ratio and the mechanistic parameters of BA-AC is suggested to determine the thickness of pavement surface at a reasonable cost. [ABSTRACT FROM AUTHOR]

To enhance the recovery and grade of the final product, reducing the entrainment of the hydrophilic particles during flotation is critical. We conducted the improvement of entrainment to reduce the amount of ash in the concentrate with the purpose of recovering high-quality unburned carbon from the bottom ash and reusing it as fuel in power plant. In this study, we investigated the effects of airflow rate and agitation speed on the entrainment of hydrophilic particles. In the selfaerating flotation machine, it was difficult to independently control the agitation speed and airflow rate, resulting in the degree of entrainment of 0.74. By independently controlling the airflow in which hydrophobic particles can float under conditions of the degree of entrainment with 0.7 (low agitation speed: 900 rpm), the combustible recovery and unburned carbon content of concentrate were 93.71% and 93.60%, respectively. The degree of entrainment was found to be 0.57, and entrainment could be minimized through independent control of airflow rate and agitation speed. To minimize entrainment, it is effective to inject air that can suspend hydrophobic particles in a low agitation speed condition. [ABSTRACT FROM AUTHOR]

India generates 759.02 million metric tons of coal ash annually. Part of that quantity is successfully utilized, and the remaining portion of the ash is discarded into a landfill. There also is a need to address pollution. Cement industries are responsible for 7% of global warming. Cement has been replaced entirely by thermal power plant waste, and bottom ash is used as a binder to overcome those issues. A few researchers have carried out strength characterization, but an extensive study needs to be carried out under different environmental exposures. Therefore, the present study investigated macro and micro properties of bottom ash geopolymer concrete (BAGPC) subjected to aggressive ecological exposure conditions such as acid, salt, and sulfate attack. Sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) of eight molarities were used as activators for the bottom ash geopolymer concrete (BAGPC) binder. Further bonding between steel and conventional concrete BAGPC mixes was investigated. The durability of conventional concrete (CC) was taken as the control mix to compare the durability of the optimized mix (B4) of bottom ash geopolymer. The test samples were cured for 28 days under ambient temperature and tested for the effect of MgSO4, NaCl, and HCl. The strength loss and weight loss of the BAGPC B4 mix after 7, 28, 56, 90, and 180 days under aggressive conditions showed better performance than CC. It has been observed that geopolymer concrete has good bonding in nature, and the bond strength results indicate excellent bonding between steel and concrete. Microstructure studies revealed that the BAGPC B4 mix had a strong microstructure and not as much of a porous structure. It is concluded that BAGPC has potential value in the construction industry based on all aspects of the experiment. [ABSTRACT FROM AUTHOR]

In recent years, a sudden upsurge in the quantity of municipal solid waste (MSW) has been observed, and the status quo demands a constructive and economically viable solution. The use of stabilized municipal solid waste (SMSW) in road construction can help in reducing the burden on landfills and waste management authorities. In the existing study, SMSW was accumulated from the Okhla landfill which is situated in New Delhi that is rich in an organic content. This SMSW was then blended with soil (5%, 10%, and 15%) and bottom ash with varying percentages (10%, 20%, 30%) individually and a mix of soil and bottom ash in the ratio of 1:1 to reduce the content of organic matter. The blended sample was then tested to check its compaction value, California bearing ratio (CBR), unconfined compressive strength (UCS), durability, and scanning electron microstructure (SEM). The results indicated that the addition of bottom ash to SMSW decreases the maximum dry unit weight that varies between 1.65 and 1.51 KN/m3 while this value reduces to 1.72 to 1.67 KN/m3 in the case of the bottom ash–soil blend. Also, CBR value reduces to 25.50 to 18.00% in case of bottom ash and 25.89 to 21.92% for bottom ash–soil samples and inverse in the case of SMSW samples blended with soil ranges between 19.95 and 22.59%. The California bearing ratio value of all samples under soaked condition meets the minimum criteria (> 10%) as specified in IRC SP-72 for low-volume roads, but at the same time failed to meet the durability specifications. Thus, it is recommended to use this soil subgrade material in arid regions. [ABSTRACT FROM AUTHOR]

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Incineration, or waste-to-energy, is a widespread means of greenwashing municipal solid waste collection worldwide. This paper looks at incineration and the trade of bottom ash to discuss how urbanization in one country pressures urban expansion elsewhere in the modern world-system. Incineration is a coping mechanism for excess waste produced by cities under capitalism. It generates energy, reduces the volume of waste, and creates ash that can be used in cement production. However, it is far from sustainable, as it facilitates expansion-oriented growth. Using UN Comtrade data, we find that incineration is a material and metabolic process that promotes global urbanization in the following ways: 1.) Corporations producing and selling incineration are part of a transnational growth machine that fuels the treadmill of production. 2.) North-North, North-South, and South-South relationships encourage incineration as a means of ecological modernization. 3.) These relationships have both hierarchical and polycentric dimensions--allowing us to create a typology for understanding such processes within the modern world-system. [ABSTRACT FROM AUTHOR]

This study explores for the first time the potential use of carbonation as a method for managing cork ash, a byproduct of biomass waste incineration. Additionally, the cork ash was combined with fly ash from municipal solid waste incineration to leverage the carbonation reaction's ability to stabilize heavy metals. The findings suggest that subjecting biomass ash to carbonation can lead to the formation of mineral carbonates, effectively capturing CO2 and reducing its release into the atmosphere. The combination of various alkaline wastes and the stabilization of leachable heavy metals through carbonation reactions also opens opportunities for synergies between different industrial sectors. Finally, the study proposes a route for the obtained materials valorisation via ‘end of waste’: the reuse of the resulting materials as substitutes for natural resources, particularly in applications like building materials and polymer composites, can further enhance carbon dioxide savings.

This study investigated ordinary Portland cement substituted with ground bottom ash (BAOPC) under various conditions of BA contents and CO2 curing. In samples without CO2 curing, the strength development along with degree of hydration were limited as expected. A higher BA content led to decreased compressive strength, indicating an inferior pozzolanic reaction of BA. Meanwhile, in the CO2-cured samples, a positive correlation between calcium carbonate (CC) content and compressive strength was confirmed, suggesting that CC is a key factor influencing strength development as a result of external CO2 supply. In particular, a higher amount of CC was present in the BAOPC composite with 20% BA substitution compared to the sample with 100% OPC, and substantial mechanical bonding between CC crystals was also confirmed. This study revealed that the combination of BA with limited Ca content and CO2 curing holds promise for developing eco-friendly formulations with enhanced mechanical properties and CO2 utilization.

Incineration, or waste-to-energy, is a widespread means of greenwashing municipal solid waste collection worldwide. This paper looks at incineration and the trade of bottom ash to discuss how urbanization in one country pressures urban expansion elsewhere in the modern world-system. Incineration is a coping mechanism for excess waste produced by cities under capitalism. It generates energy, reduces the volume of waste, and creates ash that can be used in cement production. However, it is far from sustainable, as it facilitates expansion-oriented growth. Using UN Comtrade data, we find that incineration is a material and metabolic process that promotes global urbanization in the following ways: 1.) Corporations producing and selling incineration are part of a transnational growth machine that fuels the treadmill of production. 2.) North-North, North-South, and South-South relationships encourage incineration as a means of ecological modernization. 3.) These relationships have both hierarchical and polycentric dimensions—allowing us to create a typology for understanding such processes within the modern world-system.

The amount of medical waste generated has increased enormously since the COVID-19 outbreak. An incineration process is the main method that is usually used to treat this waste, causing an increase in both medical waste bottom ash (MWBA) and medical waste fly ash (MWFA). In this work, the physical and chemical characteristics of MWFA and MWBA were reviewed. This ash contains high levels of polychlorinated dibenzo-p-dioxin (PCDD), dibenzofurans (PCDFs), and heavy metals. Furthermore, medical waste ash appears to have high leachability in the toxicity characteristics leaching procedure (TCLP) test and the European standard test (EN 12457). Owing to its toxicity, medical ash can be treated using various methods prior to disposal based on the covered review. These techniques include chemical, supercritical fluid, cement-based, melting, microwave, and mechanochemical techniques. The shortcomings of some of these treatment methods have been identified, such as the emission of high levels of chlorine from the melting technique, limited applications of the flotation method on the industrial scale, long-term stability of leachate treated by cement-based methods that have not been confirmed yet, and high energy consumption in the supercritical technique. This review also covers possible applications of medical waste ash in cement production, agriculture, and road construction. HIGHLIGHTS Medical waste ash contains high concentrations of dioxins.; Heavy metals in medical waste ash have a high leachability in the soil and groundwater.; Further investigations to solve multiple problems in treatment techniques of medical waste ash are required.; Medical waste ashes have been found to be beneficial in concrete production.;

This study examines the influence of the mass percentage and maturation stage of bottom ash on bio-composite mechanical strength. Two kinds of bottom ash were used: matured and non-matured. To elaborate the composites, several different percentages of bottom ash were mixed with an organic matrix. Casein, starch, alginate, polyethylene glycol, pre-vulcanized natural latex, and water are the components of matrix. The idea was to use as much bottom ash as possible, since it can be used as 80% or more as the main charge, which was in prismatic form for mechanical testing after drying. The results show that whatever the state of maturation of the bottom ash, the resistances present a maximum for a percentage of bottom ash equal to 85%. It could also be noticed that non-matured bottom ash composites have better mechanical strengths than composites with matured bottom ash. This is due to the decrease in porosity of the composites and to the improvement in their structural integrity. These new composites could solve some of the solid waste problems created by bottom ash production. As the matrix is made from organic resources, it saves energy and reduces the carbon footprint. This bio-composite contributes to the circular economy by giving waste a second life.

Biodiesel, an eco-friendly alternative to conventional fossil fuels, offers reduced emissions like carbon dioxide, sulfur oxides, and soot. This study explores biodiesel production from a blend of waste oils using a novel biomass-based catalyst derived from the bottom ash of a biomass boiler. Catalyst synthesis involved wet impregnation, a unique approach using previously unreported bottom ash. Characterization via SEM-EDS, BET, FTIR, and XRD revealed its composition and structure. Optimization of biodiesel production involved assessing alcohol molar ratio, catalyst concentration, and reaction time, achieving a maximum FAME concentration of 95% under specific conditions. Blending residual palm oil with waste frying oil enhanced biodiesel properties, demonstrating a maximum FAME concentration at specific catalyst concentration (8%), molar ratio (1:10), and reaction time (2 h). Catalyst reusability, up to three cycles without significant yield variation, showcased its sustainability. The catalyst, primarily composed of calcium, a characteristic biomass bottom ash component, exhibited mesoporous features. Impregnation with eggshells not only altered composition but also ensured a uniform particle size distribution. FTIR and XRD analyses indicated calcium in hydroxide and crystallized forms. Effective catalyst separation methods included decanting or water washing, with optimal biodiesel purity achieved through 3% phosphoric acid washing at 60 °C. Various recovery methods were assessed, highlighting hexane washing as the most efficient, enabling up to three catalyst reuse cycles without substantial efficiency loss.

The more economically viable and environmentally sustainable approach for treating the by-products of coal combustion from thermal power plants entails their collective disposal as opposed to individual disposal methods. This aligns with pertinent EU directives and domestic regulations, ensuring compliance with established standards while optimizing resource utilization and minimizing environmental impact. This study evaluated the resistance to wind erosion of the binding properties of a mixture (fly ash (FA), bottom ash (BA), and additives) using an indoor wind tunnel under simulated ambient conditions. Investigations of the mutual impact of ash, bottom ash, and additives (CaO and Ca(OH)2) with a certain percentage of water were carried out with eighteen samples. The samples consisted of the water at six addition rates 5, 8, 10, 15, 20, and 25% (w/w), and additive at three addition rates (1, 2, and 3% (w/w). Based on the obtained results, the optimal ratios of additives (3% (w/w)) and water (15% (w/w)) were determined. Prior to the wind tunnel experiments, and according to the different addition rates of additives and water, eight samples were prepared with different addition rates of ash. The mass concentrations of suspended particles (PM10) and total suspended particles (TSPs) in these samples were measured at three distinct wind velocities: 1 m/s, 3 m/s, and 5 m/s, respectively. The results indicate that the samples containing the optimal content of additives and water demonstrate a maximum increase in PM10 emission zero values of no more than 1.9 times. This finding can be considered satisfactory from the standpoint of environmental protection.

AbstractThe bottom ash produced during incineration contains toxic heavy metals that can persist for a long time in the environment and accumulate in the food chain; when indiscriminately disposed of, it can adversely affect public health. The study aimed at assessing the level of heavy metals in the bottom ashes produced during the incineration of sharp medical waste. Bottom ash samples were collected from the ash pit of the incinerator twice a month for four months (two months in the rainy and two months in the dry season) in triplicates. Five grams of the sieved samples were analyzed for cadmium (Cd), chromium (Cr), Nickel (Ni), iron (Fe), lead (Pb), Copper (Cu), and zinc (Zn) using atomic absorption spectrophotometer. The mean concentrations of these heavy metals during the study period in decreasing order were Fe (18,504.66) > Zn (16,292.11) > Cr (374.47) > Pb (179.78) > Cu (128.91) > Cd (1.28) > Ni (0.50) mg/kg. The concentrations of the assessed heavy metals in the bottom ash samples obtained were compared with notable international guidelines, and it was deduced that the concentrations of all the heavy metals were above the acceptable limits except for Nickel, whose concentration was below the limit set for it. [ABSTRACT FROM AUTHOR]