Trace Elements In Ash Research Articles

Characteristics of trace elements and potential environmental risks of the ash from agricultural straw direct combustion biomass power plant

The rapid expansion of biomass power generation has resulted in a large amount of ash, which need to be treated urgently. The trace elements in ash also have environmental risks during treatment. Therefore, the essential characteristics and potential environmental risks of biomass ash generated by direct combustion of agricultural straw were studied. The leaching characteristics of elements, including major elements (Mg, K, Ca) and trace elements (V, Cr, Mn, Co, Ni, Cu, Zn, Cd, As, Pb and Ba), in fly ash and slag produced by biomass power plant were analyzed through the static leaching experiments of simulating the possible pH value of natural water in the laboratory. The results show that the trace elements are enriched in fly ash and slag, which may be related to the volatility of elements during combustion. And during the leaching test, the leaching concentration of major and trace elements in fly ash is higher than that in slag. Sequential chemical extraction is used to reveal the occurrence forms of trace elements in biomass ash. Except for residue, Mn, Co, Zn, Cd, and Pb in fly ash mainly exist in carbonate bound, V and As are Fe–Mn oxides bound, and Cr, Ni, Cu, and Ba are mainly organic matter bound. In the slag, Cd is mainly carbonate bound, Cu is mainly organic matter bound, while other elements are mainly Fe–Mn oxides bound. The Risk Assessment Code values calculated based on the existing forms of elements show that As and Cd in slag and Mn, Co, Pb and Cd in fly ash need special attention during utilization. The research results can provide reference for the management and utilization of biomass ash.

Morphochemical investigation on the enrichment and transformation of hazardous elements in ash from waste incineration plants

The transformation of heavy metals in ash from waste incineration plants is significant for ash management. The migration behavior of trace elements in ash after combustion, semidry deacidification, fabric filtration, and chelating agent stabilization was investigated from one waste incineration plant. The hazardous elements Zn, Pb, and As were enriched in raw fly ash (ash produced at a combustion temperature of 850–1100 °C) due to their relatively high volatility. Mercury, Cd, and Pb were captured in fly ash2 and processed by activated carbon and fabric filters. The removal rate of As (71%) was the highest among all studied elements due to a large amount of quinquevalent As removed. However, the average removal rate of elements in fly ash was only 13%. In the finally obtained fly ash3 (after chelating agent stabilization), a larger particle size (~100 μm) was found than that of raw ash. Furthermore, fly ash3 contains HgSO4 and trivalent As, which are toxic and likely to be precipitated when the fly ash3 is next utilized or deposited in a landfill, causing environmental risks.

Mobility of biomass ash constituents as influenced by pretreatment and soil – An artificial weathering study

Biomass ashes are potential soil amendments that reduce soil acidity and provide plant nutrients, but trace elements in ash may be leached from the solid phase, thereby posing environmental concerns. We determined the leachability of selected major elements, trace elements and anions from wood derived bottom ash generated from an updraft gasifier as influenced by ash pretreatments and the presence of soil via serial aqueous batch extraction. We found that self-hardening reduced initial solubility and reactivity of ash (i.e. lowered electrical conductivity), and reduced initial aqueous concentrations of Ba, Ca, Cu, Fe, Hg, Pb, Sr and Zn. But, hardening of ash increased initial aqueous concentrations of B, Cr, P, Se and SO42−. Although mixing ash into soil (5% ash by mass) generally decreased the mobility of most constituents, aqueous concentrations of P and As were increased relative to that of either ash-alone or soil-alone treatments. Overall, extract concentrations of constituents in various treatments were relatively low. Results of this serial batch extraction support the use of clean wood-derived bottom ash as a safe and environmentally suitable soil amendment.

Characteristics of inorganic matter from Australian municipal solid waste processed under combustion and gasification conditions.

The presence and composition of ash in solid waste streams produced by the thermochemical processes can affect the further disposal or use of the waste. This study characterised the chemical species, mineralogy and trace element mobilisation in laboratory-produced ashes arising from different municipal solid waste (MSW) streams processed under reducing and oxidising atmospheres.The composition of cumulative ash samples produced under oxidising conditions was very similar to the composition of the industrial bottom ash samples produced during MSW incineration. We identified differences in mineral phase compositions and in some trace element concentrations of ashes produced under combustion and gasification conditions. Differences in concentrations of boron, barium, cadmium, chromium, copper, chlorine, molybdenum, antimony, lead, thorium and zinc in ashes associated with different MSW streams were also observed. On the basis of the concentrations of trace elements in ashes, we evaluated each MSW stream in terms of potential management strategies and use of the mineral matter remaining after combustion and gasification. Most of ashes produced from MSW can be at least classified as Class IV (secure) waste according to an Australian standard regulation guideline.

Quantitative Study of Trace Elements in Coal and Coal Related Ashes using PIXE

ABSTRACT Trace element analysis of feed coal, fly ash and bottom ash samples acquired from NTPC, Visakhapatnam was done by Particle Induced X-ray emission (PIXE) method. Sixteen inorganic elements K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, and Pb were quantified. The enrichment and partition ratios were determined to understand the distribution and behavior of trace elements in coal and its residues. Enrichment factor for trace elements in ashes with respect to the concentration of Fe normalized relative to the earth’s continental crustal values was calculated to understand the effect of these elements on the environment. It was expected that the results of the present study may be useful in determining the coal combustion residue recovery potential and also help in reducing their potential impact on eco systems.

Effect of Pine Bark Combustion Temperature on Content of Major, Minor, and Trace Elements in Ashes: Experimental Study and Thermodynamic Equilibrium Calculations

AbstractWood biomass is widely used as fuel in the so-called green power units producing heat and electricity. Wood biomass, like other solid fuels, contains many elements, most of which are found ...

Mineralogical, chemical and leaching characteristics of ashes from residential biomass combustion.

Four types of pellets and three agro-fuels were chemically characterised and burned in a pellet stove. To assess the influence of the material composing the firebox and the combustion efficiency of distinct biomass heating devices in the composition of the bottom ashes, three of the pellets were also burned in a conventional woodstove and in a fireplace. Ashes were analysed for their C, H and N contents by an elemental analyser, whilst major and trace elements were quantified by inductively coupled plasma atomic-emission spectrometry and inductively coupled plasma mass spectrometry, respectively. The mineralogy of ashes was determined by X-ray powder diffraction. The European standard test was applied to samples to determine the leaching potential of major, minor and trace elements. The contents of major and trace elements in the different types of biomass presented enormous variations, which are reflected in dissimilar mineralogical and chemical compositions of the respective ashes. The leachable potential of several elements of environmental concern present in oxy-anionic form at the alkaline pH of biomass ashes were generally high in all samples. Concentrations of some elements in the leachates were in the range of values with classification of "hazardous materials" by the European legislation in what respects the acceptance of these wastes at landfills. Pellets made up of wood wastes and containing preservatives (chromated copper arsenate and ammoniacal copper arsenate) are of concern. Due to lower combustion efficiencies, the leachable potential for most of the trace elements in ashes from the woodstove, and especially from the fireplace, was lower than that of the pellet stove.

Mineral matter and trace elements in ashes from a high-arsenic lignite fired power plant in Inner Mongolia, China

The distribution, enrichment, and environmental influence of trace elements and mineral matter in fly ash (FA), bottom ash (BA), and flue gas desulfurization gypsum (FGDG) from a high arsenic coal-fired power plant in Inner Mongolia, China were studied by X-ray diffraction spectrometry (XRD), X-ray fluorescence spectrometry (XRF), field scanning electron microscopy equipped with energy dispersive X-ray spectrometry (FSEM-EDX), atomic fluorescence spectroscopy (AFS), and inductively coupled plasma-mass spectrometry (ICP-MS).The results showed that mineral matter in FA included quartz, mullite, and gypsum, and that in BA included quartz, enstatite, magnetite, and hematite. The arsenic content in the lignites reached 44.4 μg/g, which was much higher than the global average content of lignite. Most of the trace elements in lignite, except for Mo, Sb, and W, had enrichment trends in the fine grade samples. Arsenic is a toxic element enriched in FA compared with the world lignite ash, while there are several elements of environmental concern are depleted elements (Mo, Cd, Ba, and U). The Cs and Hf are also enriched elements in FA, where Hf showed a significant enrichment. The contents of most trace elements in the smaller particles of FA were higher than those in the larger particles, except for Y and Re. The arsenic content in BA was evidently lower than that in FA, which was 24.4 μg/g, and the trace elements enriched in the smaller particles of BA included Li, Zn, Ga, Rb, Mo, Cd, In, Sb, Cs, Nd, Tl, Pb, Bi, and Th. With the exceptions of As, Sr, Cd, and Sb, the amount of trace elements in flue gas desulfurization gypsum was much lower than that in average Chinese soil. Because the fly ash was stacked for a long time, arsenic and several other trace elements leached into soil surrounding the fly ash dump. As a results the elemental content of old fly ash is less than those collected in this study, which indicates the soil in vicinity need to be monitored continuously for their possible environmental effect.

Major and trace elements in soils and ashes of eucalypt and pine forest plantations in Portugal following a wildfire

Wildfires can play an important role in the environmental distribution of major and trace elements, including through their mobilization by fire-induced runoff and associated transport of soil and ash particles. In particular, fire-induced inputs of these elements into the environment are relevant due to their toxicity and environmental persistence. This study aimed to evaluate the role of wildfire and time-since-fire on the redistribution of major and trace elements, which is a topic poorly documented. To this end, levels of V, Mn, Co, Ni, Cu, Cd and Pb were assessed in soil and ash samples collected immediately following a wildfire in north-central Portugal as well as 4 (after the first post-fire rainfall events), 8 and 15months later. The role of forest type was determined by sampling burnt eucalypt and pine plantations. The main findings of this study were the following: (1) levels of V, Mn, Ni, Cd and Pb were consistently higher in the burnt than unburnt soils, while levels of Co and Cu revealed no differences; (2) time-since-fire affected major and trace elements in three different ways: concentrations of Mn and Cd declined abruptly after the first rainfall events while levels of V, Co and Ni increased during the first 8months and levels of Cu and Pb hardly changed during the study period; (3) all studied elements revealed peak concentrations in the ashes immediately after the fire, which then declined sharply four months later; (4) levels of Co and Ni soils and ashes were higher at the pine plantations than at the eucalypt plantations. This study highlighted the role of wildfire in enhancing levels of major and trace elements in ashes and topsoil of forest plantations and their mobilization within the first year after fire, pointing towards recently burnt forest areas as a potential source of environmental contamination.

Distribution and leaching characteristics of trace elements in ashes as a function of different waste fuels and incineration technologies

Impact of waste fuels (virgin/waste wood, mixed biofuel (peat, bark, wood chips) industrial, household, mixed waste fuel) and incineration technologies on partitioning and leaching behavior of trace elements has been investigated. Study included 4 grate fired and 9 fluidized boilers. Results showed that mixed waste incineration mostly caused increased transfer of trace elements to fly ash; particularly Pb/Zn. Waste wood incineration showed higher transfer of Cr, As and Zn to fly ash as compared to virgin wood. The possible reasons could be high input of trace element in waste fuel/change in volatilization behavior due to addition of certain waste fractions. The concentration of Cd and Zn increased in fly ash with incineration temperature. Total concentration in ashes decreased in order of Zn>Cu>Pb>Cr>Sb>As>Mo. The concentration levels of trace elements were mostly higher in fluidized boilers fly ashes as compared to grate boilers (especially for biofuel incineration). It might be attributed to high combustion efficiency due to pre-treatment of waste in fluidized boilers. Leaching results indicated that water soluble forms of elements in ashes were low with few exceptions. Concentration levels in ash and ash matrix properties (association of elements on ash particles) are crucial parameters affecting leaching. Leached amounts of Pb, Zn and Cr in >50% of fly ashes exceeded regulatory limit for disposal. 87% of chlorine in fly ashes washed out with water at the liquid to solid ratio 10 indicating excessive presence of alkali metal chlorides/alkaline earths.

Quantitative Estimation of Major and Trace Elements in Coals of the Benue Trough, Nigeria

The concentrations of major and trace elements in ash residues of coals of the Benue Trough, Nigeria have been determined by electron microprobe and laser ablation-inductively coupled plasma-mass spectrometry, respectively. Major and trace element determination in rocks by fusion on an iridium strip heater followed by electron microprobe and laser ablation-inductively coupled plasma-mass spectrometry is extended here to coal ash, and the accuracy of the method is evaluated by including an Argonne Premium Coal reference sample in each analysis program. Si and Al are the major elements detected in the coal ashes. An assessment using worldwide concentration ranges of trace elements in coal ashes indicates that the Benue Trough coal ash residues are enriched in some hazardous trace elements, including Be, V, Co, and Cr. The estimated concentrations of most of the elements in the raw coals are higher than the world averages for coal. The results obtained for the Argonne Premium Coal show very good correlations with the literature and certified values, indicating that the technique described in this study can be routinely used to determine element concentrations in coals.

Determination of Trace Elements in Ashes of Milk Samples by Using XRF Technique

Determination of Trace Elements in Ashes of Milk Samples by Using XRF Technique