It is well understood that the partial replacement of portland cement with pozzolans in sufficient proportions results in improved long-term performance of concrete. However, dwindling availability ...of the most widely used pozzolan in the construction industry, fly ash, is forecast due to the termination of coal-fired electricity power stations around the world, necessitating the exploration of alternative pozzolans. Experimental investigations are conducted to study the performance of traditional pozzolans such as fly ash, silica fume and natural pozzolans (metakaolin, pumice, perlite and lassenite) together with novel pozzolans, including ground glasses (high-alkali and low-alkali), and ground bottom ash. Twenty-one concrete mixtures are examined for compressive strength, electrical conductivity, electrical resistivity, chloride permeability, and chloride migration coefficient. The reactivity of pozzolans studied is also determined in terms of compressive strength in lime-pozzolan mortar using a modified lime-reactivity test method. Many of the materials tested demonstrate the potential to be used in place of fly ash. However, a wide variation in the performance of these materials is evident which highlights the need for a reliable test to determine the level of reactivity of a pozzolan. The results indicate that the 7-day strength in the modified lime-reactivity test provides a good indication of the pozzolanic reactivity of the material and of how the material can be expected to contribute to the strength and permeability of concrete. The use of electrical resistivity as an indicator of the performance of pozzolans in terms of strength development and chloride penetration resistance when used to partially replace portland cement in concrete is also discussed.
This laboratory study explores the effects of mechanical activation on the properties of municipal solid waste incineration (MSWI) bottom ash (BA) in a cement hydration system. The experimental ...results showed that the mechanical activation effectively reduced the particle size of municipal solid waste incineration bottom ash (MSWIBA), increased its specific surface area by about 770%, 1674%, and 1990%, and improved the 28d compressive strength of bottom ash-cement paste samples by about 5%, 14%, and 8% after milling of 15min, 30min, and 45min, respectively. The scanning electron microscopy revealed that the microstructure of the 30min-milled bottom ash-cement sample was more homogenous than other samples, which likely accounted for the difference in compressive strength. X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis were employed to shed light on the process, products, and degree of hydration of bottom ash-cement pastes. In addition, the leachate toxicity of heavy metals was evaluated and the 30min-milled bottom ash-cement paste showed the best binding effect in reducing the leaching of heavy metals. This work demonstrates the great potential of using mechanical-activated MSWI bottom ash as a supplementary cementitious material with acceptable environmental footprint.
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•Municipal solid waste incineration bottom ash can serve as a type of SCM.•Developing a MSWIBA-cement system can decrease the environmental risk of MSWIBA.•Mechanical activation effectively improves the reactivity of MSWIBA.•Optimal mechanical activation slows down the leaching of toxicants of MSWIBA.•A longer milling time slightly decreases the engineering performance of MSWIBA.
Despite efforts to reduce dependence on coal-fired power generation due to climate concerns, continued usage for energy stability is anticipated. This study was conducted to address environmental ...issues associated with coal-fired power generation and promote its persistent utilization. we aimed to establish both eco-friendly and economically sustainable practices by mitigating waste such as fly ash (FA) and bottom ash (BA) emissions while recycling them in circulating fluidized bed combustion (CFBC). Initially, we conducted a literature review to analyze the global and domestic trends in coal-fired power generation. Subsequently, we performed experimental research on CO2 crystallization as a multifaceted approach for treating exhaust gases and waste materials such as FA and BA simultaneously. Throughout this research, we implemented a simple process to ensure scalability. In the context of carbon capture, utilization, and storage (CCUS) technology, we conducted experimental research on mineralizing CO2 targeting FA and BA by applying ambient temperature, atmospheric pressure, and simulated exhaust gas. The empirical findings demonstrated that 12.28 kg CO2/ton and 58.14 kg CO2/ton of CO2 were immobilized for BA and FA, respectively. The economic evaluation was measured based on the experimental results obtained from the techno-economic analysis (TEA). The B/C ratio stands at 1.07, with the cost of composite carbonate estimated at USD 159.6 per ton. With an internal rate of return (IRR) of 7.78 % and a net present value (NPV) of USD 7294.59, the economic viability demonstrates considerable promise. Ultimately, this study aims to mitigate the impact of coal-fired power plants on climate change and enhance environmental sustainability through CO2 removal and waste recycling.
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•We present a comprehensive review of eco-friendly practices in coal-fired power generation.•We explored CO2 crystallization to treat emissions and recycle FA and BA.•We demonstrated CO2 immobilization with significant reductions for BA and FA.
This work aims to evaluate the use of bottom biomass ash as an alternative raw material in porcelain stoneware bodies. For this purpose, ash coming from a biomass thermoelectric power plant in ...Emilia-Romagna (Italy) was selected and its chemical, mineralogical and thermal properties determined. Data indicated its technological role as a flux, so it was introduced in a porcelain stoneware batch in partial replacement of feldspars and experimented at laboratory scale. A bottleneck, relative to the rheological behavior of the slips, was overcome by a slight deflocculant increase. The powder compacts were fired from 1000° to 1220 °C in order to follow the evolution of the technological properties, phase composition (XRPD-Rietveld) and microstructure (SEM). The introduction of ash allowed to lower the firing temperature by 20 °C, while keeping the technological properties comparable with those of the benchmark. Moreover, the mineralogical and microstructural data revealed different sintering kinetics.
Phosphate in freshwater possesses significant effects on both quality of water and human health. Hence, many treatment methods have been used to remove phosphate from water/wastewaters, such as ...biological and electrochemical methods. Recent researches demonstrated that adsorption approaches are convenient solutions for water/wastewater remediation from phosphate. Thus, the present study employs industrial by-products (bottom ash (BA)), as a cost-effective and eco-friendly alternative, to remediate water from phosphate in the presence of competitor ions (humic acid). This study was initiated by characterising the chemical and physical properties of the BA, sample, then Central Composite Design (CCD) was utilised to design the required batch experiments and to model the influence of solution temperature (ST), humic acid concentration (HAC), pH of the solution (PoS) and doses of adsorbent (DoA) on the performance of the BA. The Langmuir model was utilised to assess the adsorption process. The outcomes of this study evidenced that the BA removed 83.8% of 5.0 mg/l of phosphates at ST, HAC, PoS and DoA 35 °C, 20 mg/L, 5 and 55 g/L, respectively. The isotherm study indicated a good affinity between BA and phosphate. Additionally, the developed model, using the CCD, reliably simulated the removal of phosphates using BA (R
= 0.99).
•Comparison between commercial catalyst and industrial waste catalyst were studied.•High quality syngas was attained in catalytic pyrolysis of rice husk using coal bottom ash catalyst.•Coal bottom ...ash catalyst has the potential to replace the commercial catalysts in industrial pyrolysis of biomass.
Comparison between industrial waste coal bottom ash catalyst and commercial catalysts (nickel and natural zeolite) in catalytic pyrolysis of rice husk were investigated in this study. Characterization through X-ray fluorescence (XRF), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and energy disperse X-ray analysis (EDX), and Brunauer–Emmett–Teller analysis (BET) were carried out to understand the physiochemical activity of the catalysts in pyrolysis of rice husk. The catalyst to rice husk ratio of 0.1 was pyrolyzed in the temperature range of 323–1173 K using thermogravimetric analyzer coupled with mass spectrometer (TGA-MS) equipment to investigate the effect of catalysts in thermal degradation behavior of biomass and syngas production. The study revealed that lowest coke formation (3.65 wt%) associated with high syngas (68.3 vol%) were attained in catalytic pyrolysis using coal bottom ash catalyst compared to nickel and natural zeolite catalysts. Moreover, the hydrogen concentration had increased 8.4 vol% in catalytic pyrolysis of rice husk using coal bottom ash catalyst compared to non-catalytic pyrolysis.
The use of pozzolans to partially replace Portland cement in concrete has generally demonstrated beneficial impacts on the durability characteristics of concrete for decades. In this paper a diverse ...range of pozzolans including natural pozzolans, ground glasses and industrial by-products such as coal ash (fly ash and bottom ash) and silica fume were investigated for their synergistic potential in binary or ternary blends with Portland cement in improving resistance to chemical sulfate attack and alkali-silica reaction (ASR). It is generally considered that pozzolans improve most of the durability issues encountered in concrete, including reducing the risk of sulfate attack or ASR. But this is not always the case. For example, it was found that ground glasses were very efficient in improving sulfate resistance, but their ability to mitigate expansion due to ASR was dictated by the equivalent alkalis content (Na2Oe) of the glass and high-alkali soda glass was generally not effective in this role. On the other hand, metakaolin, a highly reactive pozzolan, was highly effective in reducing ASR expansion, but may actually increase the damage due to sulfate attack when used at moderate replacement levels. Most pozzolans, such as low-CaO coal fly ash and ground coal bottom ash, silica fume, and pumice, were effective in controlling expansion due to both ASR and sulfate attack. The results demonstrated that the extent of the positive impact of using natural pozzolans on both properties was variable. The pozzolanic reactivity of materials alone was an unreliable indicator to assess the ability of the pozzolan to suppress expansion due to sulfate attack or ASR.
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•Incineration bottom ash (IBA) was good support for Ni in catalytic toluene reforming.•An activation stage was observed for Ni/IBA because of the metal-support interaction.•Formation ...of Ni-FeOx improves the redox ability and is responsible for activation.•Resistance to coking is due to the FeOx and alkali and alkaline earth metals in IBA.
The incineration bottom ash (IBA) was impregnated with nickel to catalyze toluene (tar surrogate) steam reforming. A toluene conversion of >80 % was achieved at 800℃ without activity decay in a 100-h test for 15 %Ni/IBA. An activation stage was observed for Ni/IBA catalysts in the initial 50 ∼ 400 min under different reaction conditions. A series of experiments and characterizations were performed to explore the possible mechanisms for the activation. It was found that the iron species in IBA gradually migrated to the catalyst surface and formed a Ni-FeOx complex owing to the metal-support interaction. The synergy of Ni-FeOx played an important role in improving the activity of Ni/IBA due to the enhanced lattice oxygen activity. Additionally, Ni/IBA catalysts showed a much lower coke deposition rate than Ni/Al2O3 (1.12 vs. 3.45 mg-C/gcat∙h) because of the variable states of FeOx and the abundant basic sites caused by the alkali and alkaline earth metals contained in IBA.
In Switzerland, municipal solid waste incineration bottom ash is deposited in open landfills, which leads to its interaction with rainwater and thus the formation of a polluted leachate. This study ...attempts to provide a better understanding of the hydraulic and geochemical properties of bottom ash landfills by combining field and laboratory investigations. The results show that a bottom ash landfill can be described as a generally unsaturated body with several layers of different grain sizes. Three different water domains with variable hydraulic and geochemical properties were identified in the landfill: (1) zones of preferential flow, (2) a reservoir of mobile porewater, and (3) an immobile porewater reservoir. Preferential flow systems account for approximately 5–10 vol.%. The landfill layering is primarily responsible for the formation of various flow systems during heavy rainfall events. The domains and reservoirs provide variable volumetric contribution to the leachate, depending on precipitation rates and duration of dry periods. Sampling of leachate during heavy rainfall events revealed dilution effects for Na (− 59–61% compared to concentrations prior to the event), Ca (− 44–47%), Cl (− 57–77%), and SO
4
(− 35–47%), while
pH
(+ 7–8%) and concentrations of Al (+ 368–1416%), Cu (+ 7–58%), Cr (+ 29–48%), V (+ 100–118%), and Zn (+ 289%) increased significantly. The findings of this study serve as a basis for the development of a hydrogeochemical model of a bottom ash landfill, which allows better prediction of the future evolution of leachate quality.
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