ABSTRACT
ABSTRACT Huge amounts of fly ash - a substance that does not conform to the ASTM C618 classification due to its chemical properties - have been abandoned in landfills around the world, despite their self-cementing property. It has not been used in concrete making applications due to its large amounts of free lime and sulfate contents. The fly ash in these plants is dumped in landfills, causing serious environmental hazards. Fly ash is disposed to the landfills by belt conveyors after being humidified with water. Therefore, the fly ashes humidified in the landfill areas are hydrated in nature. This hydration is further intensified in landfills by rain and snow. Thus, the free lime content of fly ash decreases due to its long hydration process. In this work, the lightweight masonry blocks were produced by mixing normal and hydrated fly ashes or normal, hydrated fly ash and lime without Portland cement. The compressive strength, water absorption, sorptivity, density, porosity, and thermal conductivity values of the samples produced were determined. The results obtained from these tests showed that lightweight masonry blocks could be produced by using these waste materials in building applications.
RESUMO Enormes quantidades de cinzas volantes - uma substância que não está de acordo com a classificação ASTM C618 devido às suas propriedades químicas - foram abandonadas em aterros sanitários ao redor do mundo, apesar de sua propriedade de autocimentação. Essas substâncias não têm sido usadas em aplicações de fabricação de concreto devido às suas grandes quantidades de cal livre e teores de sulfato. A cinza volante dessas usinas é despejada em aterros sanitários, causando sérios riscos ambientais. Essas cinzas são descartadas em aterros por correias transportadoras após serem umedecidas com água. Portanto, as cinzas volantes umedecidas nas áreas do aterro são hidratadas na natureza. Essa hidratação é ainda mais intensificada em aterros, pela chuva e pela neve. Assim, o teor de cal livre nas cinzas volantes diminui devido ao longo processo de hidratação. Neste trabalho, blocos de alvenaria leves foram produzidos pela mistura de cinzas volantes normais e hidratadas, ou cinza volante normal hidratada e cal sem cimento Portland. Foram determinados os valores de resistência à compressão, absorção de água, sensibilidade, densidade, porosidade e condutividade térmica das amostras produzidas. Os resultados obtidos nesses testes mostraram que blocos de alvenaria leves podem ser produzidos usando esses materiais residuais em aplicações de construção.
ABSTRACT
Globally, air pollution is the leading environmental cause of human disease and death, and it is a major contributor to cardiovascular disease. Air pollution damages the cardiovascular system by oxidative stress, inflammation, endothelial dysfunction, and pro-thrombotic changes. Ultrafine particulate matter from the combustion of fossil fuels delivers the most potent and harmful elements of air pollution. Coal fly ash is a rich source of nano-sized metal, iron oxide, and carbonaceous particles. Previous findings revealed that coal fly ash is widely utilized in undisclosed tropospheric aerosol geoengineering. Proper iron balance is central to human health and disease, and the harmful effects of iron are normallyprevented by tightly controlled processes of systemic and cellular iron homeostasis. Altered iron balance is linked to the traditional risk factors for cardiovascular disease. The iron-heart hypothesis is supported by epidemiological, clinical, and experimental studies. Biogenic magnetite (Fe3O4) serves essential life functions, but iron oxide nanoparticles from anthropogenic sources cause disease. The recent finding of countless combustion-type magnetic nanoparticles in damaged hearts of persons from highly polluted areas is definitive evidence of the connection between the iron oxide fraction of air pollution and cardiovascular disease. Spherical magnetic iron oxide particles found in coal fly ash and certain vehicle emissions match the exogenous iron pollution particles found in the human heart. Iron oxide nanoparticles cross the placenta and may act as seed material for future cardiovascular disease. The pandemic of non-communicable diseases like cardiovascular disease and also rapid global warming can be alleviated by drastically reducing nanoparticulate air pollution. It is crucial to halt tropospheric aerosol geoengineering, and to curb fine particulate emissions from industrial and traffic sources to avoid further gross contamination of the human race by iron oxide-type nanoparticles
ABSTRACT
RESUMO A cinza volante é o principal resíduo industrial do uso de carvão mineral na geração de vapor e energia. No Brasil, são produzidas 1,4 milhão toneladas ao ano. Essas cinzas podem ser convertidas em produtos zeolíticos por tratamento hidrotérmico alcalino. Este trabalho teve como objetivo principal realizar essa conversão hidrotérmica, a fim de obter unicamente fases cristalinas zeolíticas para a adsorção de íon amônio. Realizaram-se diversas sínteses alterando o método utilizado (clássico ou de duas fases), o tempo de reação (24 ou 30 h) e a massa de NaOH. A caracterização dos produtos e da cinza (in natura e calcinada) foi realizada por difratometria de raios X, microscopia eletrônica de varredura e, em alguns casos, análises térmica diferencial e gravimétrica (ATD-TG). Os resultados demonstraram que é possível sintetizar as zeólitas hidroxissodalita e cancrinita a partir da cinza estudada. O produto obtido pelo método de duas etapas foi utilizado na adsorção de íon amônio em solução, sendo, neste processo, o modelo isotérmico de Sips o mais adequado; alcançando um valor de capacidade máxima de adsorção de 2,71 mg.g-1.
ABSTRACT Fly ash is the main industrial waste generated by coal in steam and power plans. In Brazil, 1,4 million tons are produced every year. These ashes can be converted into zeolite products by alkaline hydrothermal treatment. The main objective of this paper was to induce this reaction which produces only zeolitic crystalline phases for ammonium ion absorption. So, some syntheses were done by different hydrothermal method (classical or two stages), work time (24 or 30 h) and many NaOH bulks. The characterization of ash (in natura and calcined) and products was performed by X-ray diffraction method, scanning electron microscopy and, in some cases, differential thermal and thermogravimetric analysis The product by two stages method was used in ammonium ion absorption in solution at Sips Mathematic Model: the highest capacity of 2,71 mg.g-1.
ABSTRACT
The leaf erectness is known to be one of the important factors that affect light conditions in plant population. Thereby triggers photosynthetic activity. A field experiment was carried out in low Si soil and observations made on leaf erectness at tillering stage and correlated with Si uptake and dry matter production. The leaf openness varied greatly due to application of graded levels of fly ash with and without SSB and FYM. Application of fly ash @ 100 t ha-1 with SSB and FYM registered the lowest value (16.7) which was on par with application of 50 t ha-1 fly ash +SSB and FYM. This parameter was negatively and significantly correlated with Si content (r = -0.83) and uptake (r = -0.92) in rice plant at tillering. Similarly, significant and negative correlation (r= -0.70) was observed with grain yield in loamy sand soil with low Si status. In sandy loam soil with low to medium Si status the parameter was best correlated with grain yield (r=-0.94) and negatively, significantly correlated with Si content (r =-0.55) and uptake (r=-0.82) in plant at tillering. Among the different treatments, application of SSB + FYM recorded the lowest leaf openness of 14.9 which was on par with SSB (16.4) followed by FYM (17.4) whereas control recorded the highest leaf openness of 20.0. The interaction between different main treatments and graded levels of fly ash has not rendered significant change in leaf openness under high soil Si status.
ABSTRACT
A study was carried out to observe the impact of a consortium of bacteria isolated from the fly ash on the metal accumulation by T. latifolia. When a consortium of bacteria Bacillus endophyticus NBRFT4 (MTCC 9021), Paenibacillus macerans NBRFT5 (MTCC 8912) and Bacillus pumilus NBRFT9 (MTCC 8913) was bioaugmented into the rhizosphere of T. latifolia, it enhanced the metal concentration in root, stem and leaves of the plants through increased bioavailability of metals Fe, Cd, Pb, Cr, Ni, Cu and Zn in the fly ash. Besides, these bacteria also promoted the plant growth perhaps due to utilization of ACC, synthesis of phytoharmones and solubilisation of essential metals found in fly ash. As compared to fly ash alone, the accumulation of Fe was maximally enhanced by 164%, 196%, and 251%, followed by Ni by 92%, 44% and 56%, Zn by 82%, 57% and 91%, Cu by 71%, 53% and 60%, Cr by 96%, 80% and 105 %, Pb by 119%, 87% and 140%, Cd by 80%, 109% and 115% in root, stem and leaves, respectively in fly ash with bacteria. Thus, an increased solubilisation of metals coupled with enhanced plant growth stimulated the phytoextraction of metals by T. latifolia from fly ash.
ABSTRACT
Fly ash from Chandrapura Thermal Power Station, Bokaro, Jharkhand (India) was used for amending soil at levels 0, 60, 120, 180 and 240 tons ha-1 in which, brinjal (Solanum melongena) was grown and elemental residues of amended soil and plant parts were enumerated. Fly ash amendments caused significant improvement in soil quality, water holding capacity (52.64-65.76), pH (6.45-7.05), composition of photosynthetic pigment (chlorophyll a, chlorophyll b, total chlorophyll and carotenoid) and few growth parameters (fresh weight, root length, shoot length) of brinjal with the increase in fly ash amendments. Fruit (edible part) of plants grown in fly ash amended soils had metal residues (mg kg-1) like Cr (0.80-1.16), Co (0.34-1.46), Ni (0.85-1.00), Zn (24.41-32.33), Cu (10.61-15.49), and Mo (0.49-1.46) within the permissible limits. Results indicate that soil amended with fly ash at 180 tons ha -1, not only improved the physical properties of the soil but also contributed to the better growth and yield of brinjal.
ABSTRACT
The present investigation deals with the accumulation of heavy metals in fields contaminated with fly ash from a thermal power plant and subsequent uptake in different parts of naturally grown plants. Results revealed that in the contaminated site, the mean level of all the metals (Cd, Zn, Cr, Pb, Cu, Ni, Mn and Fe) in soil and different parts (root and shoots) of plant species were found to be significantly (p<0.01) higher than the uncontaminated site. The enrichment factor (EF) of these metals in contaminated soil was found to be in the sequence of Cd (2.33) > Fe (1.88) > Ni (1.58) > Pb (1.42) > Zn (1.31) > Mn (1.27) > Cr (1.11) > Cu (1.10). Whereas, enrichment factor of metals in root and shoot parts, were found to be in the order of Cd (7.56) > Fe (4.75) > Zn (2.79) > Ni (2.22) > Cu (1.69) > Mn (1.53) > Pb (1.31) > Cr (1.02) and Cd (6.06) ~ Fe (6.06) > Zn (2.65) > Ni (2.57) > Mn (2.19) > Cu (1.58) > Pb (1.37) > Cr (1.01) respectively. In contaminated site, translocation factor (TF) of metals from root to shoot was found to be in the order of Mn (1.38) > Fe (1.27) > Pb (1.03) > Ni (0.94) > Zn (0.85) > Cd (0.82) > Cr (0.73) and that of the metals Cd with Cr, Cu, Mn, Fe; Cr with Pb, Mn, Fe and Pb with Fe were found to be significantly correlated. The present findings provide us a clue for the selection of plant species, which show natural resistance against toxic metals and are efficient metal accumulators.