Ash Emissions Research Articles

Geodetic monitoring of the recent activity and the dome forming eruption at Nevado del Ruiz (Colombia), 2010–2023

Nevado del Ruiz (Colombia) is infamous for the catastrophic eruption of 1985 that destroyed the villages of Armero and Chinchiná. However, this was not the volcano’s first destructive event; similar eruptions also occurred in 1595 and 1845. In 1985, the limited geodetic data available failed to provide a clear warning of the impending eruption. Since then, advancement in geodetic monitoring, now incorporating tilt and satellite geodesy, along with improvements in seismic, geochemical, geological and remote sensing monitoring, have enhanced hazards assessment and mitigated the risk during subsequent eruptions in 1989, 2012, and 2015–2019, as well as during periods of unrest over the last 13 years. Modeling of deformation data over the past 13 years reveals complex interactions between the local, shallow magmatic system beneath Nevado del Ruiz and a deep, regional magmatic system beneath Nevado de Santa Isabel, 9 km southwest of Nevado del Ruiz. Before February 2012, the volcano deflated because of the depressurization of the local shallow reservoir. This same reservoir later fueled ash emissions and gas release (2012–2023), and a dome-forming eruption (2015–2019). In contrast, the inflation observed from 2012 to 2023 is linked to the pressurization of the deep reservoir beneath the Nevado de Santa Isabel.

Ashfall characteristics and development of the ash monitoring network during three decades of the long-lived eruption of Popocatépetl Volcano, México

A long-lived eruption of Popocatépetl volcano in central México has produced almost continuous ash fall on the populated areas for 30 years. The eruptive phase that began in 1994, has been characterized since 1996 by the growth of about 90 subsequent crater domes and their destruction that has produced most of the ongoing ash emissions. Since the beginning of the ash emission in 1994, we designed, established, and maintained an ash-sampling network of more than 200 sites around the volcano. This sampling network has been improved over the years and there are currently also 19 automated samplers, that we describe in this manuscript. This ash sampling network is part of the Popocatépetl monitoring system run by Universidad Nacional Autónoma de México (UNAM). The sampling sites that are distributed over an area of ∼8000 km2 where ash fall occurs, involve collection of ash over 0.4 cm2 and 1 m2 areas during ash emission events associated with plumes over 1 km high. Community participation has greatly enhanced both, ash sample collection efficiency and public awareness.Growth and destruction of lava domes are variable over time, with growth times that could last up to weeks and residence times ranging from days to months, producing frequent ash emissions. There have been about 1225 ash emissions >1 km high, of these, 110 have been identified with ash columns from 3 to 13 km high above the crater (8.5–18.5 km asl), some of which has produced abundant ash fall in nearby populations. Ashfall has been distributed in all directions around the volcano up to 2 50 km from the crater but dominantly in the east and northeast direction. The total minimum volume of non-compacted ash emitted over these three decades is >149 × 106 m3 while the estimated total volume of lava emitted in the form of domes is >70 × 106 m3.The average ash mass load is 32 g/m2 and the ash is commonly deposited <30 km from the crater and up to 250 g/m2 have been deposited in periods of intense activity. Ash grainsizes range from coarse to extremely fine (MdPhi 1–6) with up to 37% of particles smaller than 10 μm and up to 10% smaller than 2.5 μm. Medium lapilli (MdPhi −3) was ejected during a sub Plinian event in 2001.Ash emission is common in both dome growth and destruction phases, as well as in the clearing of the conduits during explosive phases in the absence of domes. Vitreous lithic fragments are produced by fragmentation of the degassed lava domes in the vent. Higher amounts of vesicular clasts, individual glass particles and crystals, on the other hand, are associated with magma ascent into a more open vent. The higher percentage of accidental lithic particles is linked to clearing of the vent.

Metal(loid) bioaccessibility and risk assessment of ashfall deposit from Popocatépetl volcano, Mexico

Ash emission from volcanic eruptions affects the environment, society, and human health. This study shows the total concentration and lung bioaccessible fraction of eight potential toxic metal(loid)s in five Popocatépetl ashfall samples. Mineralogical phases and particle size distribution of the ashfall were analyzed by X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) techniques, respectively. The bioaccessibility test of Gamble solution (GS) and Artificial Lysosomal Fluid (ALF) were conducted to simulate extracellular (pH 7) and intracellular (pH 4.5) conditions, respectively. The studied metal(loid)s showed the following total concentration (mg kg−1): 1.98 (As), 0.17 (Cd), 134.09 (Cr), 8.66 (Cu), 697.33 (Mn), 55.35 (Ni), 8.77 (Pb), and 104.10 (Zn). Geochemical indices suggested that some metal(loid)s are slightly enriched compared to the local soil background concentrations. Several mineralogical phases were identified in the collected ashfall deposits, such as plagioclase, pyroxene, and Fe–Ti oxide, among others. According to the risk assessment results, the non-carcinogenic risk related to ashfall exposure returns an HQ > 1 for children. In contrast, the estimation of carcinogenic risk was found to be within the tolerable limit. Metal(loid)s showed low bioaccessibility (< 30%) in GS and ALF, with the highest values found in ALF solution for As (12.18%) and Cu (7.57%). Despite their metal-bioaccessibility, our findings also showed that dominant ash particle size ranged between fine (< 2.5 μm) and extremely fine (< 1 μm), considered highly inhalable fractions. The results obtained in this work indicate that volcanic ashes are bioinsoluble and biodurable, and exhibit low bioaccessibility when in contact with lung human fluids.

THE PERCEPTION OF THE LOCAL COMMUNITY OF THE DEGREE OF POLLUTION GENERATED BY THE TURCENI THERMAL POWER PLANT, ROMANIA

Coal-fired power plants emit large amounts of pollutants. Our study focused on the Turceni thermal power plant, which, while providing significant regional economic benefits through energy supply, also serves as a local source of pollution. Emissions of oxides and ash from the plant negatively impact the environment, public health, and the comfort of local communities. Our research was conducted along several key lines of investigation: residents' perception of pollution levels, the frequency of pollution-related complaints submitted to authorities, the number of individuals receiving financial compensation, the authorities' efforts to reduce pollution, and the intention of some residents to relocate due to pollution. Our findings confirmed the presence of significant pollution and highlighted the need for greater community involvement and awareness in environmental decision-making. Additionally, our study revealed the necessity for improved relations between local authorities and communities, particularly in the context of developing and implementing effective environmental policies.

Coupled physicochemical dual-crosslinking Ti3C2Tx composite aerogels for the selective adsorption of gallium ions in acid fly ash leaching

Herein, in order to extract Ga3+ from acid fly ash leaching, we propose a functionalized Ti3C2Tx-based MXene composite aerogel adsorbent for Ga3+ adsorption. The prepared physicochemical dual-crosslinking network aerogel MPHG-40 possesses good Ga3+ adsorption performance (132.52 mg g−1) at the pH of 3 and Ga3+ initial concentration of 50 mg L−1 within 6 h. After five adsorption-desorption cycles, the material shows good mass retention and a 95.65 % retention of its initial adsorption capacity, compared to most reported adsorbents. The optimized adsorbent realized good selective adsorption of Ga3+ against Cu2+, Zn2+, Fe3+, and Al3+ in a simulated acid fly ash leaching with the selective coefficient of 8.63, 96.10, 4.49, and 28.30, respectively. The adsorption may comply with a combined mechanism of physical adsorption, electrostatic interactions, ion-exchange mechanism, and ligand chelation, dominated by chemical adsorption, as identified by theoretical calculations based on density functional theory and experimental data. The three-dimensional solid adsorbent constructed in this study provides a new strategy for selective adsorption of Ga3+, making it possible to be applied to solid waste utilization of fly ash.

The integrated approach of carbon capture, utilization, and storage via CO2 mineralization for the removal of fly ash, bottom ash, and exhaust gas―A case study of circulating fluidized bed combustion

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.

The 23–24 March 2021 lava fountain at Mt Etna, Italy

In 2021, more than 50 paroxysmal episodes occurred at the South-East Crater (SEC) of Mt Etna, Italy. The 23–24 March lava fountain was one of the longest episodes and began with weak Strombolian explosions, gradually transitioning to lava fountaining. The eruption intensity then dropped more slowly than in previous episodes, resulting in pulsating Strombolian explosions dominated by ash emission. Thirty-four tephra samples were used to reconstruct the fallout dispersal and estimate the total erupted mass. Grain size, textural, petrological and geochemical analyses indicate different features and were compared with the gas phase (SO2 and HCl) in the volcanic plume. By applying stochastic global optimization to simulations of the temporal evolution of the eruption column height and tephra dispersal and deposition, the total erupted mass retrieved (6.76 × 108 kg) matches well the total erupted mass estimation by the ground-based deposit (8.03 ± 2.38 × 108 kg), reducing the column height throughout the episode from 6.44 to 4.5 km above sea level and resulting in a mass eruption rate ranging from 1.96 × 105 to 8.18 × 103 kg/s. The unusual duration of the March episode and the characteristics of the erupted products point to the change in explosive style and magma fragmentation from fountaining to ash emission phases, associated with a slower magma supply inducing a change in magma rheology and a final, prolonged ash generation. Furthermore, this study showed that using observational data and the variation in eruption source parameters for numerical simulations can improve the accuracy of predicting the dispersal plume, thus mitigating the potential impact of longer paroxysmal episodes.

Reconstructing episodic and multi-vent, rhyolitic eruptions: The ∼ 1314 CE Kaharoa eruption of the Tarawera Dome Complex, Okataina Caldera (New Zealand)

Detailed stratigraphic reconstructions and quantitative deposit characterisations of moderate to large-scale rhyolitic eruptions are limited. This hinders our ability to model the multiple eruptive phenomena and hazards associated with rhyolitic volcanism. To gain new perspectives on the patterns and behaviours of rhyolitic eruptions, we present a study on the explosive phases of the 1314 ± 12 CE Kaharoa eruption of Tarawera, New Zealand. The eruption occurred from multiple aligned vents within the Okataina Caldera and is the youngest rhyolitic eruption of the frequently active Taupō Volcanic Zone. We systematically quantify the deposit characteristics of the Kaharoa pyroclastic succession to provide new insights into the type of eruption sequence and eruptive style changes. Based on field evidence, stratigraphic correlations, grain size and componentry analyses, we subdivide the Kaharoa deposit into 24 units and identify 7 main deposit types, which are linked to different eruptive and depositional processes. The explosive activity was discontinuous, characterised by repeated discrete episodes of sustained magma discharge separated by short time breaks. The activity consisted mainly of repeated subplinian-type columns that gave way to fallout deposition and emplacement of numerous lapilli beds. This activity transitioned to a pyroclastic density current (PDC) dominated phase in response to lateral vent migration. Ash emission activity occurred within and towards the end of the explosive sequence, indicating declines in the eruptive intensity. Six main intra-eruption phases (A to F) of dominant eruptive styles are established to describe the temporal evolution of the eruption. Phases A, B and D are associated with the repeated subplinian-type activity. Phase C comprises the major PDC activity, while the final two Phases E and F are associated with ash emission during initiation of lava dome extrusion and to the final dome-building sequence. This study highlights the complex nature of episodic, multi-phase, and multi-vent, explosive to dome-forming rhyolitic eruptions, depicting a scenario of great relevance for future volcanic hazard studies at active rhyolitic volcanoes worldwide.

Estimating volcanic ash emissions using retrieved satellite ash columns and inverse ash transport modeling using VolcanicAshInversion v1.2.1, within the operational eEMEP (emergency European Monitoring and Evaluation Programme) volcanic plume forecasting system (version rv4_17)

Abstract. Accurate modeling of ash clouds from volcanic eruptions requires knowledge about the eruption source parameters including eruption onset, duration, mass eruption rates, particle size distribution, and vertical-emission profiles. However, most of these parameters are unknown and must be estimated somehow. Some are estimated based on observed correlations and known volcano parameters. However, a more accurate estimate is often needed to bring the model into closer agreement with observations. This paper describes the inversion procedure implemented at the Norwegian Meteorological Institute for estimating ash emission rates from retrieved satellite ash column amounts and a priori knowledge. The overall procedure consists of five stages: (1) generate a priori emission estimates, (2) run forward simulations with a set of unit emission profiles, (3) collocate/match observations with emission simulations, (4) build system of linear equations, and (5) solve overdetermined systems. We go through the mathematical foundations for the inversion procedure, performance for synthetic cases, and performance for real-world cases. The novelties of this paper include a memory efficient formulation of the inversion problem, a detailed description and illustrations of the mathematical formulations, evaluation of the inversion method using synthetic known-truth data as well as real data, and inclusion of observations of ash cloud-top height. The source code used in this work is freely available under an open-source license and is able to be used for other similar applications.

Tracing sulphur dioxide in volcanic deposits and ash emission during the 2019 Sinabung eruptions

Sulphur dioxide (SO2) emissions from Mt. Sinabung eruption were quantified in time series for 2019. Both pyroclastic materials and gas or aerosol ejected during volcanic eruption contain sulphur as sulphate salt deposits coating volcanic ash grains or gasses. Sulphur dioxide from the eruption will directly impact the surrounding area. Spectral from satellite optical sensors can be used to monitor and measure SO2 gas near real-time after an eruption. The distribution of SO2 column density in the atmosphere was tracked using the Sentinel-5P satellite. Regression kriging (RK) is applied to predict the spatial distribution of sulphur. The area under study is located in a radius of 3 to 7 km from the eruptive center, covering an area of about 4,517 ha. A total of 51 soil samples and volcanic ash were collected from 0- 20 cm soil depth based on a 1x1 km grid interval. All samples were air- dried, sieved, and analyzed for pH, sulphate, and total SO3 using XRF. The Google Earth Engine (GEE) platform was also used to process Sentinel-5P satellite imagery to determine the number and distribution of SO2 column density in the atmosphere during 2019. The pH of the ash is very acidic to neutral (3.56 - 6.55), while soils are considered acidic to neutral (4.67 - 6.52). The available sulphate content in soil ranges from 0 to 303.39 ppm and 0 to 142.47 ppm in volcanic ash samples. SO2 content in ash ranges from 0 to 16.53% and 0 to 3.71% in soils. Sentinel-5P satellite image spectral data shows that SO2 is concentrated mainly in the southern region, with the highest level occurring in August 2019. This study can serve as one of the volcanic mitigation programs and forecast the distribution of SO2 in an active volcanic region of Indonesia.

Insights into the composition and properties of fly ash emissions from a municipal solid waste power plant

This study examines the fly ash from Soc Son municipal waste power plant (SMPP) and suggests ways to repurpose it to reduce its environmental impact. Fly ash from the Soc Son waste power plant has a gray color, spherical particles with a 5–103 μm diameter, and a high carbon and heavy metal content. Bermorite crystals can absorb and release heavy metals, making monitoring secondary pollutants during incineration crucial. The EDX analysis of fly ash from the Soc Son waste power plant revealed that it was predominantly contaminated with metal elements, with the highest percentage of calcium. The EDX was able to detect heavy metals in incinerator fly ash. The concentration of Zn in the fly ash exceeded QCVN 07:2009/BTNMT standards, indicating the high amounts of some elements that may be hazardous to the environment and human health. Using the SEM/EDX and XRF, the fly ash from the Soc Son landfill power plant was analyzed and discovered that it exceeds permissible limits for dangerous heavy elements. The most common inorganic elements are Ca, followed by Zn, Pb, Cd, and Ag. Fly ash is classed as hazardous waste due to its high concentration of heavy metals, which results from the combustion of municipal solid waste that has not been separated. Vietnam fights municipal solid waste incinerator fly ash production. Some nations stabilize fly ash to remove harmful components and use it in buildings. Stabilized fly ash makes unfired construction bricks and cement manufacturing components and combining fly ash with inorganic trash protects the environment.

A satellite chronology of plumes from the April 2021 eruption of La Soufrière, St Vincent

Abstract. Satellite instruments play a valuable role in detecting, monitoring and characterising emissions of ash and gas into the atmosphere during volcanic eruptions. This study uses two satellite instruments, the Infrared Atmospheric Sounding Interferometer (IASI) and the Advanced Baseline Imager (ABI), to examine the plumes of ash and sulfur dioxide (SO2) from the April 2021 eruption of La Soufrière, St Vincent. The frequent ABI data have been used to construct a 14 d chronology of a series of explosive events at La Soufrière, which is then complemented by measurements of SO2 from IASI, which is able to track the plume as it is transported around the globe. A minimum of 35 eruptive events were identified using true, false and brightness temperature difference maps produced with the ABI data. The high temporal resolution images were used to identify the approximate start and end times, as well as the duration and characteristics of each event. From this analysis, four distinct phases within the 14 d eruption have been defined, each consisting of multiple explosive events with similar characteristics: (1) an initial explosive event, (2) a sustained event lasting over 9 h, (3) a pulsatory phase with 25 explosive events in a 65.3 h period and (4) a waning sequence of explosive events. It is likely that the multiple explosive events during the April 2021 eruption contributed to the highly complex plume structure that can be seen in the IASI measurements of the SO2 column amounts and heights. The bulk of the SO2 from the first three phases of the eruption was transported eastwards, which based on the wind direction at the volcano implies that the SO2 was largely in the upper troposphere. Some of the SO2 was carried to the south and west of the volcano, suggesting a smaller emission of the gas into the stratosphere, there being a shift in wind direction around the height of the tropopause. The retrieved SO2 heights show that the plume had multiple layers but was largely concentrated between 13 and 19 km, with the majority of the SO2 being located in the upper troposphere and around the height of the tropopause, with some emission into the stratosphere. An average e-folding time of 6.07±4.74 d was computed based on the IASI SO2 results: similar to other tropical eruptions of this magnitude and height. The SO2 was trackable for several weeks after the eruption and is shown to have circulated the globe, with parts of it reaching as far as 45∘ S and 45∘ N. Using the IASI SO2 measurements, a time series of the total SO2 mass loading was produced, with this peaking on 13 April (descending orbits) at 0.31±0.09 Tg. Converting these mass values to a temporally varying SO2 flux demonstrated that the greatest emission occurred on 10 April with that measurement incorporating SO2 from the second phase of the eruption (sustained emission) and the beginning of the pulsatory phase. The SO2 flux is then shown to fall during the later stages of the eruption: suggesting a reduction in eruptive energy, something also reflected in ash height estimates obtained with the ABI instrument. A total SO2 emission of 0.63±0.5 Tg of SO2 has been derived, although due to limitations associated with the retrieval, particularly in the first few days after the eruption began, this, the retrieved column amounts and the total SO2 mass on each day should be considered minimum estimates. There are a number of similarities between the 1979 and 2021 eruptions at La Soufrière, with both eruptions consisting of a series of explosive events with varied heights and including some emission into the stratosphere. These similarities highlight the importance of in-depth investigations into eruptions and the valuable contribution of satellite data for this purpose; as these studies aid in learning about a volcano's behaviour, which may allow for better preparation for future eruptive activity.

Novel framework for assessing economic viability and environmental impacts: Use of waste products in soil stabilization

This study developed a framework that evaluated the carbon emission and cost-effectiveness of fly ash, rice husk ash, and face masks as additives for soil stabilization. The research scope of this study included modification of soil using varying dosages of additives, quantification of improvement in soil properties, pavement design under different traffic conditions, and estimation of cost and emission. In this process, a total of 30 pavement sections were considered, and Euclidean distance method was employed to develop a combined ranking of the pavement alternatives based on their resource consumption and environmental impacts. The study findings showed that Rice Husk Ash and Fly Ash offered lower costs of construction and carbon footprint than the control pavement sections under all traffic conditions. Additionally, face mask was found to be suitable under low traffic conditions at minimum content. It is envisaged that the framework developed in this study would provide important insights to the policymakers, engineers, practitioners, road agencies, and other stakeholders in assessing various pavement alternatives that ensure the economic and sustainable development of transportation infrastructure.

STUDIES OF THE AREA AROUND SINGRAULI COAL FIELD &amp; ENERGY BELT, DISTRICT SIGRAULI, MADHYA PRADESH INDIA

STUDIES OF THE AREA AROUND SINGRAULI COAL FIELD &amp; ENERGY BELT, DISTRICT SIGRAULI, MADHYA PRADESH INDIA

Phases in fine volcanic ash

Volcanic ash emissions impact atmospheric processes, depositional ecosystems, human health, and global climate. These effects are sensitive to the size and composition of the ash; however, datasets describing the constituent phases over size ranges relevant for atmospheric transport and widely distributed impacts are practically nonexistent. Here, we present results of X-ray diffraction measurements on size-separated fractions of 40 ash samples from VEI 2–6 eruptions. We characterize changes in phase fractions with grainsize, tectonic setting, and whole-rock SiO2. For grainsizes < 45 μm, average fractions of crystalline silica and surface salts increased while glass and iron oxides decreased with respect to the bulk sample. Samples from arc and intraplate settings are distinguished by feldspar and clinopyroxene fractions (determined by different crystallization sequences) which, together with glass, comprise 80–100% of most samples. We provide a dataset to approximate glass-free proportions of major crystalline phases; however, glass fractions are highly variable. To tackle this, we describe regressions between glass and major crystal phase fractions that help constrain the major phase proportions in volcanic ash with limited a priori information. Using our dataset, we find that pore-free ash density is well-estimated as a function of the clinopyroxene + Fe-oxide fraction, with median values of 2.67 ± 0.01 and 2.85 ± 0.03 g/cm3 for intraplate and arc samples, respectively. Finally, we discuss effects including atmospheric transport and alteration on modal composition and contextualize our proximal airfall ash samples with volcanic ash cloud properties. Our study helps constrain the atmospheric and environmental budget of the phases in fine volcanic ash and their effect on ash density, integral to refine our understanding of the impact of explosive volcanism on the Earth system from single eruptions to global modeling.

Volcanic ash from La Palma (Canary Islands, Spain) as Portland cement constituent

The last volcanic eruption on the island of La Palma (Spain) took place in 2021. Significant activity started in September of that year with the vigorous emission of volcanic gases and ash and lasted for three months. It is estimated that the Cumbre Vieja volcano emitted more than ten million cubic meters of ash comprising pyroclastic materials like those found in many parts of the world. Some of these volcanic ash deposits are untapped, despite their potential construction industry applications. Since the chemical composition and mineralogy of the ash depends on the type of magma from it originates, this paper characterizes this material and evaluates its suitability as a major constituent of Portland cement. This volcanic ash is rich in silica (45%) and alumina (15%), meaning it reacts with portlandite. The blended cements with up to 40% replacement content meet the standardized chemical, physical, and mechanical requirements and present good intrinsic durability values (resistivity and capillary absorption), making them viable for the manufacture of low-carbon-footprint eco-cements. This paper seeks to provide society with lasting technical, environmental, and social benefits through recovery of this ash.

Assessment of the Costs of Implementing the Best Available Ash Collection Technologies at Coal-fired Thermal Power Plants

According to existing plans, the environmental situation in Russia is going to be improved by modernizing or replacing outdated equipment at industrial enterprises and making a shift to the best available technologies. The thermal power industry is commonly referred to industrial sectors featuring the greatest negative impact on the environment. Emissions of fly ash with flue gases from coal-fired thermal power plants are of much significance from the viewpoint of atmospheric air pollution. Various ash removal technologies are used to reduce them, but a number of them are no longer able to provide the required quality of atmospheric air in areas experiencing a negative impact of thermal power plants. The aim of this work was to assess the possibility of using different types of ash collectors to fulfill the technological indicators of solid fuel ash emissions. For this purpose, the technical and environmental characteristics of various technologies for removing solid fuel ash from the flue gases of thermal power plants were compared, and their main indicators, advantages, and disadvantages were considered. The choice of the most effective ash collection technologies -- electrostatic precipitators and bag filters — to fulfill the technological indicators of ash emissions according to GOST R 50831-95 as the best available technologies is justified. A comparative technical and economic assessment of using electrostatic precipitators (EP) and bag filters (BF) downstream of the boilers of combined heat and power plants (CHPPs) and condensing thermal power plants (CTPPs) combusting the main Russian coals: grade SS Ekibastuz coal, grade SS Kuznetsk coal, grade 2B Irsha-Borodino coal, and Donetsk anthracite culm was carried out. The total capital and operating costs for the implementation, the specific costs for the removal of one ton of ash from different coals in EF and BF for pessimistic and optimistic inflation forecasts are determined. It is shown that an increase in inflation will have a very negative impact on the introduction pace of BATs at Russian thermal power plants and may slow down the introduction of bag filters, which are the most efficient BAT for ash collection. Recommendations on the use of electrostatic precipitators and bag filters at CHPPs and CTPPs for different types of coals have been formed. It is proposed to use bag filters in combusting high-ash coals, the ash of which is characterized by high electrical resistivity. Electrostatic precipitators should be used in combusting low- and medium-ash coals, because the difference in the mass of captured ash in the EF and BF for the same coal is small, whereas the cost of implementing EF is significantly lower. The specific cost of the ash removed differs little for the boilers of CHPPs and CTPPs operating on the same coal; however, it depends strongly on the level of inflation, the growth of which increases significantly the operating costs.

A novel approach to the dry desulfurization process by means of sodium bicarbonate: A full-scale study on SO2 emission and geochemistry of fly ash

The application of Dry Sorbent Injection (DSI) desulfurization with sodium bicarbonate was investigated to reduce SO2 emission from power sector. The sorbent was injected directly into the combustion chamber of the 29 MWth grate boiler, into a non-standard area of high temperature (approximately 700 °C), while generally the DSI method is carried out in the flue gas duct with a temperature below 250 °C. Unique nozzle design for injecting powdery sorbents was implemented and two stoichiometric ratios were tested: NSR = 1.1 and NSR = 3.0. The reduction of SO2 from a base level of 1580 mg SO2/Nm3 to 301 mg SO2/Nm3 at 6% O2 was achieved, resulting in a process efficiency of 81%. The chemical properties of fly ash were determined in terms of its safe storage and potential use according to the principles of the circular economy. Ash formed during the desulfurization process shows a different chemical composition than the reference sample. A significant increase in the concentrations of the following components and parameters was indicated: S, Na, Zn, Cu, As, Mo, Pb, loss of ignition (LOI) and total organic carbon (TOC). The change in chemical composition led to an increase of total dissolved matter (TDS) in water leachate as well as sulphates, chlorides, fluorides, As, PB, Cu and Zn concentrations.

Experimental study on the contribution of included/excluded minerals to particulate formation during coal char combustion

The contributions of included and excluded minerals to particulate matter formation are quantified in this work. By devolatilization of three typical Chinese coals, three coal chars with low (LA), moderate (MA), and high ash (HA) content (with both included and excluded minerals) were prepared, from which three float coal chars with low (LA−), moderate (MA−), and high ash (HA−) content (without excluded minerals) were separated by density differentiation method. The coal chars before and after separation were burned in a drop-tube furnace at 1600 K, the results of three float coal chars can directly reveal the contribution of included minerals, and the comparison of two kinds of chars with and without excluded minerals would reveal the excluded mineral contribution to ash distribution. The size distributions of the combustion-generated ash particle were obtained from the combination of ELPI+ and laser particle-size analyzer. The fractions of included/excluded minerals were obtained from SEM images. The results from the combustion of the float chars indicate the physical transformation of included minerals, while the results from original coal chars involve the transformation of both included and excluded minerals. Results indicate that the distribution of ash particles from included minerals for HA− char possesses a single peak, while the ash distributions of MA− and LA− char show a bi-modal shape. The excluded minerals in LA and MA chars mainly contribute to the ash emissions with sizes larger than 80 μm. The contribution from excluded minerals reach 86% to the ash particles of 205 μm for HA char, 54% for MA char and 51% for LA char. The number fractions of included minerals continuously decrease with a transformation into excluded minerals during char dynamic combustion.

Environmental Stress and Health Vulnerability Assessment around Kolaghat Thermal Power Plant, West Bengal

One of the 17 types of severely polluting sectors in the nation is thermal power plants which exert pressure upon the environment and health aspects in several ways e.g. creating thermal, air, and water pollution, exacerbating physiological acute and chronic responses, and affecting the subjective wellbeing of an individual residing proximal to the source. Situated on the right bank of the Rupnarayan river, Kolaghat thermal power plant is one of the major power generating plants of West Bengal, which is also producing 7500-8000 metric tons of fly ash every day but having only 325 acres of land for its disposal. Hence the plant has been exerting pressure upon the surrounding environment since its establishment and growth between 1980-1985. This study is to evaluate the overall impact of thermal power plants on the local environment and public health using a composite index that incorporates environmental and health dimensions i.e. Air quality index, drinking water quality index, land surface temperature, social parameters, Non–communicable disease rate, etc. The study reveals the local-level impact of air pollution and the impact of fly ash emissions. Nandakumar, Tamluk, and Kolaghat have been identified as blocks under stress. The workers of the plant have reported undesirable thermal and ambient air quality conditions within the battery limit, with the prevalence of skin problems, allergies, and fatigue among them. Site-specific plantation and phytoremediation techniques with the use of riparian buffers have been recommended.