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Physical Processes in Wastewater Treatment
Published in Sreedevi Upadhyayula, Amita Chaudhary, Advanced Materials and Technologies for Wastewater Treatment, 2021
Ning Zhang, Ankur Dwivedi, Amita Chaudhary
Fly ash, a by-product of coal-based thermal power plants, carries out adsorption through molecular attraction, which depends on the pore size and specific areas of fly ash. It has been discovered that fly ash contains adequate silica and alumina, making them efficient materials to remove dyes, organic compounds, heavy metals, and several other pollutants. Additionally, aluminum salt and iron salt contained in fly ash can complex with water to form Al(H2O)3+ and Fe(H2O)3+ once they mix with water and further produce flocs to enhance the adsorption. However, fly ash is also reported as a hazardous material owing to various heavy metal constituents present. Swarcewicz et al. (2013) developed adsorbent materials from a mixture of soil and fly ash for carbamazepine removal. The removal was reported as high as 92.8% as the fly ash contents present in the adsorbent are greater than 30%.
Energy and Environment
Published in T.M. Aggarwal, Environmental Control in Thermal Power Plants, 2021
Fly ash is captured and removed from the flue gas by electrostatic precipitators or fabric bag filters (or sometimes both) located at the outlet of the furnace and before the induced draft fan. The fly ash is periodically removed from the collection hoppers below the precipitators or bag filters. Generally, the fly ash is pneumatically transported to storage silos for subsequent transport by trucks or railroad cars.
Building Materials
Published in P.K. Jayasree, K Balan, V Rani, Practical Civil Engineering, 2021
P.K. Jayasree, K Balan, V Rani
Fly ash is a byproduct from burning pulverized coal in electric power generating plants. During combustion, mineral impurities in the coal (clay, feldspar, quartz, and shale) fuse in suspension and float out of the combustion chamber with the exhaust gases. As the fused material rises, it cools and solidifies into spherical glassy particles called fly ash. Fly ash is collected from the exhaust gases by electrostatic precipitators or bag filters.
Effect of fly ash on mechanical and durability properties of mortar containing microfibers with different length
Published in European Journal of Environmental and Civil Engineering, 2022
Fly ash, which is an industrial solid waste annually generated about 15 million tons in Turkey, is one of the most commonly used pozzolanic materials (Bicer, 2018; Saha, 2018; Saran, 2007). Fly ash is obtained from the chimneys of coal-fired power plants using electrostatic methods. It is generally spherical in shape and varies between 1 and 150 µm in size (Saran, 2007). Fly ash from thermal power plants causes storage and environmental problems, and therefore, its reuse is an important issue (Bicer, 2018). Fly ash is widely used as a replacement material in cement (Donatello et al., 2013). Significant progress has been made in the area of utilisation of fly ash as it reduces cement consumption (Saha, 2018). Research shows that fly ash can be potentially used in traditional building materials and is widely used in cement and concrete. Fly ash increases the processability of fresh concrete and improves the durability properties of hardened concrete (Bicer, 2018; Saran, 2007). Fly ash contains little lime, and therefore, concrete strength decreases with an increase in replacement level. However, the pozzolanic activity of fly ash at long curing times improves the strength and decreases the sorptivity of concrete (Saha, 2018).
Properties of concrete containing fly ash and bottom ash mixture as fine aggregate
Published in International Journal of Sustainable Engineering, 2021
Thermal power plants produce enormous quantities of coal ash. About one-fifth of this ash content is bottom ash, and the rest is fly ash. Bottom ash has a granular structure due to which it is sometimes used as a replacement of sand in concrete. On the other hand, during the past few years, fly ash has been widely used in concrete as a replacement for cement. It is understood that, due to low calcium content in fly ash, the replacement of cement with it decreases initial strength development. Therefore, to limit such detrimental effect generally up to 30% of cement replacement is made. Since the amount of cement used in building and general construction works is about 20% of concrete volume, the overall use of fly ash in the concrete industry is much less. In contrast, the quantity of fine aggregate, which acts as inert filler within a concrete mix, is about 50–100% more than cement content. For that reason, if the purpose is to achieve the maximum usage of waste materials like coal ash; the full replacement of fine aggregate can be a better option. Further, fly ash is a pozzolanic material and contributes to strength development that can be an additional benefit.
Growth and yield of lemongrass (Cymbopogon citratus) in fly ash with nutrient amendments and Mycorrhiza for three-ratoon period
Published in International Journal of Phytoremediation, 2020
The current practice of dumping fly ash in landfills and dumpsites creates land use issues aside from the associated pollution. Improper disposal of fly ash can cause water and soil pollution, disrupt ecological cycles, and pose environmental hazards (Kgomo 2017). Fly ash is a hazardous waste which is toxic to human and causes several diseases such as cancer, developmental delays, and behavioral problems among children; and respiratory diseases (Baba et al. 2016). Despite this, dumpsite disposal is still considered as the best solution for coal fly ash because of ease of operation and low cost especially when the disposal site is near the power plant (Ghosh and Kumar 2020). Currently, there are many initiatives for fly ash utilization, but most of these are still not available for commercial-scale; hence, priority for better management and reduction of environmental pollution should be in place (Ghosh and Kumar 2020).