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The present study focuses on the fate of polycyclic aromatic hydrocarbons (PAHs) in soils amended with oil shale ash (OSA). Leachability studies to assess the release of PAHs to the environment are essential before the application of OSA in agriculture. A quantitative estimation of the leaching of PAHs from two types of soil and two types of OSA was undertaken in this study. Two leaching approaches were chosen: (1) a traditional one step leaching scheme and (2) a leaching scheme with pretreatment, i.e.., incubation of the material in wet conditions imitating the field conditions, followed by a traditional leaching procedure keeping the total amount of water constant. The total amount of PAHs leached from soil/OSA mixtures was in the range of 15 to 48 μg/kg. The amount of total PAHs leached was higher for the incubation method, compared to the traditional leaching method, particularly for Podzolic Gleysols soil. This suggests that for the incubation method, the content of organic matter and clay minerals of the soil influence the fate of PAHs more strongly compared to the traditional leaching scheme. The amount of PAHs leached from OSA samples is higher than from soil/OSA mixtures, which suggests soils to inhibit the release of PAHs. Calculated amount of PAHs from experimental soil and OSA leaching experiments differed considerably from real values. Thus, it is not possible to estimate the amount of PAHs leached from soil/OSA mixtures based on the knowledge of the amount of PAHs leached from soil and OSA samples separately.

The focus of the current study is to characterise the leaching behaviour of polycyclic aromatic hydrocarbons (PAHs) from oil shale ashes (OSAs) of pulverised firing (PF) and circulating fluidised-bed (CFB) boilers from Estonian Thermal Power Plant (Estonia) as well as from mortars and concrete based on OSAs. The target substances were 16 PAHs from the EPA priority pollutant list. OSA samples and OSA-based mortars were tested for leaching, according to European standard EN 12457-2 (2002). European standard CEN/TC 15862(2012) for monolithic matter was used for OSA-based concrete. Water extracts were analysed by GC-MS for the concentration of PAHs. Naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene were detected. Still, the release of PAHs was below the threshold limit value for inert waste. The amount of the finest fraction (particle size <0.045 mm), the content of the Al-Si glass phase and the surface characteristics were the main factors, which could affect the accessibility of PAHs for leaching. The mobility of PAHs from OSA of CFB and PF boilers was 20.2 and 9.9%, respectively. Hardening of OSA-based materials did not lead to the immobilisation of soluble PAHs. Release of PAHs from the monolith samples did not exceed 0.5 μg/m(2). In terms of leaching of PAHs, OSA is safe to be used for construction purposes.

The leaching behavior of selected polycyclic aromatic hydrocarbons (PAHs) from an oil shale processing waste deposit was monitored during 2005-2009. Samples were collected from the deposit using a special device for leachate sampling at field conditions without disturbance of the upper layers. Contents of 16 priority PAHs in leachate samples collected from aged and fresh parts of the deposit were determined by GC-MS. The sum of the detected PAHs in leachates varied significantly throughout the study period: 19-315 μg/l from aged spent shale, and 36-151 μg/l from fresh spent shale. Among the studied PAHs the low-molecular weight compounds phenanthrene, naphthalene, acenaphthylene, and anthracene predominated. Among the high-molecular weight PAHs benzo[a]anthracene and pyrene leached in the highest concentrations. A spent shale deposit is a source of PAHs that could infiltrate into the surrounding environment for a long period of time., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Carbon capture, utilization, and storage (CCUS) have emerged as pivotal technologies for curtailing emissions while maintaining fossil fuel. Estonia faces a challenge due to its dependence on carbon-intensive oil shale, but the need for energy security, highlighted by the war in Ukraine, makes reducing CO2 emissions a priority while maintaining energy independence. In this context, the presented study determines the environmental impact of combustion of the Estonian oil shale from the release of SO2 emission and compares sulfur retention in the ash between different oxyfuel combustion campaigns in a 60 kWth CFB test facility. The pilot was operated under air, O2/CO2, and with recycled flue gas (RFG), and we tested the application of extremely high inlet O2 up to 87%vol. The key objective of this study is to examine how different combustion atmospheres, operating temperatures, and excess oxygen ratios influence SO2 formation. Additionally, the research focuses on analyzing anhydrite (CaSO4), calcite (CaCO3), and lime (CaO) in ash samples collected from the dense bed region (bottom ash) and the external heat exchanger (circulating ash). The results indicate that increased inlet O2% does not significantly affect SO2 emissions. Compared to air-firing, SO2 emissions were higher than 40 mg/MJ under a 21/79%vol O2/CO2 environment but were significantly reduced, approaching zero, as the inlet O2% increased to 50%. Under O2/RFG conditions, higher SO2 concentrations led to increased sulfur retention in both the bottom and circulating ash. The optimal temperature for sulfur retention in air and oxyfuel combustions is below 850 °C. This study for the first time provides a technical model and discusses the effects of operating parameters on sulfur emissions of the Estonian oil shale CFB oxyfuel combustion. [ABSTRACT FROM AUTHOR]

Lakes play a crucial role in the global biogeochemical cycles through the transport, storage, and transformation of different biogeochemical compounds. Their regulatory service appears to be disproportionately important relative to their small areal extent, necessitating continuous monitoring. This study leverages the potential of optical remote sensing sensors, specifically Sentinel-2 Multispectral Imagery (MSI), to monitor and predict water quality parameters in lakes. Optically active parameters, such as chlorophyll a (CHL), total suspended matter (TSM), and colored dissolved matter (CDOM), can be directly detected using optical remote sensing sensors. However, the challenge lies in detecting non-optically active substances, which lack direct spectral characteristics. The capabilities of artificial intelligence applications can be used in the identification of optically non-active compounds from remote sensing data. This study aims to employ a machine learning approach (combining the Genetic Algorithm (GA) and Extreme Gradient Boost (XGBoost)) and in situ and Sentinel-2 Multispectral Imagery data to construct inversion models for 16 physical and biogeochemical water quality parameters including CHL, CDOM, TSM, total nitrogen (TN), total phosphorus (TP), phosphate (PO4), sulphate, ammonium nitrogen, 5-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), and the biomasses of phytoplankton and cyanobacteria, pH, dissolved oxygen (O2), water temperature (WT) and transparency (SD). GA_XGBoost exhibited strong predictive capabilities and it was able to accurately predict 10 biogeochemical and 2 physical water quality parameters. Additionally, this study provides a practical demonstration of the developed inversion models, illustrating their applicability in estimating various water quality parameters simultaneously across multiple lakes on five different dates. The study highlights the need for ongoing research and refinement of machine learning methodologies in environmental monitoring, particularly in remote sensing applications for water quality assessment. Results emphasize the need for broader temporal scopes, longer-term datasets, and enhanced model selection strategies to improve the robustness and generalizability of these models. In general, the outcomes of this study provide the basis for a better understanding of the role of lakes in the biogeochemical cycle and will allow the formulation of reliable recommendations for various applications used in the studies of ecology, water quality, the climate, and the carbon cycle. [ABSTRACT FROM AUTHOR]

The document titled "Remote Sensing of Coastal Waters, Land Use/Cover, Lakes, Rivers, and Watersheds II" explores the significance of remote sensing in monitoring and analyzing coastal regions, land masses, lakes, rivers, and watersheds. It emphasizes the advancements in remote sensing technologies that have improved data collection and understanding of environmental changes. The document includes 22 research papers covering topics such as land cover change, ecological environments, wetlands and habitats, water quality, and marine disasters and environmental impacts. These papers offer valuable insights into the interactions between human and natural factors and aim to inform sustainable resource management efforts. The integration of artificial intelligence with remote sensing data further enhances accuracy and understanding. The authors express their gratitude to the contributors and reviewers for their valuable contributions to this Special Issue. [Extracted from the article]

The European Union's (EU) regulation for the waste classification based on their ecotoxicological hazard (hazardous property HP14) came into force on 5 July 2018. The regulation advocates the utilisation of computational formulae for the hazard classification of waste associated with hazardous property HP14. Concurrently, ecotoxicological testing remains an alternative. To date, the absence of a consensus regarding test organisms and methodologies has vested EU member states with autonomy in determining the approach for conducting ecotoxicity assessments. The discussions on waste classification are also ongoing globally, namely the discussions under the Basel Convention. This paper endeavours to elucidate whether the widely employed test organisms, Daphnia magna and Aliivibrio fischeri, may serve as suitable indicators for the evaluation of the ecotoxicity of waste. The research is grounded in the examination of ashes derived from a combustion process of calcium-rich fuel. Ecotoxicity testing was conducted on 14 ash samples with a liquid-to-solid ratio of 10:1. The results of the Aliivibrio fischeri testing indicated that all 14 ash samples were non-hazardous in terms of their ecotoxicity. However, the results of the Daphnia magna testing showed the opposite, suggesting that the ash samples may have the potential to be ecotoxic. This study offers valuable insights into ecotoxicity assessment and waste classification, emphasising the need for scientific rigour and comprehensive understanding before making regulatory decisions. It also situates its findings within the broader global context of waste management discussions, particularly those related to international agreements like the Basel Convention., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Concrete is a widely used material in various industries, including hazardous waste management. At the same time, its production creates a significant carbon footprint. Therefore, intensive research is being conducted to create more eco-friendly concrete, for example, partially replacing cement with by-products such as oil shale ash (OSA) or improving properties by adding dispersed fibers such as basalt fibers (BFs). The article consists of experimental testing of nine types of concrete and the modeling of crack propagation in bending. The basic trends of crack propagation in samples of concrete with OSA and BFs are simulated using a two-dimensional Finite Element (FE) model considering only material degradation on the opening crack surface and experimental data of three- and four-point bending tests. Crack propagation is modeled using the bridging law approach. A surrogate model for predicting the peak loading as a function of tensile strength and fracture work was created. An examination of the results of the FE model shows that the bilinear and nonlinear bridging law functions best describe the crack growth in the analyzed material. A comparison of experimental and modeled results showed that the length of the composite BF strongly affects the accuracy of the numerical model. [ABSTRACT FROM AUTHOR]

The hydration of oil shale ash at different water-to-ash weight (W/A) ratios ranging from 0.4 to 0.8 was experimentally investigated. The ash hydrate’s physical characteristics, its particles’ elemental composition, and the existing crystalline phases were identified using N2 BrunauerEmmerich-Teller (N2 -BET), Energy Dispersive X-ray (EDX) and X-ray Powder Diffraction (XRD) measurement techniques. The formed hydration cementitious products were found to be stratlingite (2CaO·Al2 O3 ·SiO2 ·8H2 O), ettringite (6CaO·Al2 O3 ·3SiO3 ·32H2 O), and melilite (2CaO·Al2 O3 ·SiO2 ) in the oil shale ash hydrated at W/A = 0.6. These same phases with different relative amounts were found in the oil shale ash hydrated at W/A = 0.8 in addition to calcium silicate hydrates (CSH). The drop in the physico-thermal properties (bulk density and thermal conductivity) of the hydrated ash was attributed to the formation of cementitious products, mainly to stratlingite, melilite, and ettringite. The hydrated ash’s mechanical properties (bending and compressive strengths) were found to increase at higher W/A due to the formation of cementing materials, particularly CSH. [ABSTRACT FROM AUTHOR]

In Brazil, with the ban on the production, sale, and use of chrysotile asbestos, the sector's industry opted to replace asbestos with CRFS Technology—Cement Reinforced with Synthetic Wire (fiber cement); that is, another product to be disposed of in landfills. This work aimed to determine a composite based on clay, fiber cement powder, and cement that meets the technical specifications of Brazilian soil–cement application standards to contribute to a more sustainable treatment of the future disposal of fiber cement products. With the characterization analysis of the materials, we identified that the clay granulometry is heterogeneous and distributed from 0.1 µm to 25 µm. In comparison, 75% of the fiber cement powder has grains greater than 10 µm. For clay, the liquidity limit is 39.67%, the plasticity limit is 25.01%, and the plasticity index is 14.66%. In the semiquantitative chemical analysis, silicon oxide (SiO2) and calcium oxide (CaO) stood out as the main oxides found, reflected in the mineralogy as quartz and calcium silicate. Therefore, we identified the percentage of organic matter in clay at 2%, using the result of the thermogravimetric analysis. The results described met the normative parameters foreseen for soil–cement applications. That said, the technological characterization was carried out by tests of linear retraction, water absorption, and simple mechanical compression on the specimens made under an axial pressure of 31.2 Mpa in the formulations defined in this work. The formulations with 10% cement and 20% and 30% fiber cement powder are suitable for use in soil–cement bricks, as they have volumetric shrinkage percentages from 2% to 2.5%, water absorption ranging from 18.66% to 19.39%, and simple compressions from 4.25 Mpa to 6.88 Mpa, meeting the requirements of Brazilian standards for soil–cement applications. It is concluded that the results showed that it is possible to produce soil–cement bricks with passive fiber cement products converted into powder, avoiding improper disposal and unwanted environmental impacts. [ABSTRACT FROM AUTHOR]

The preparation of oil-based cutting thermal desorption residues into subgrade materials is one of the methods of their resource utilization. While the environmental safety for subgrade materials is lack of discussions. In this study, through the semi-dynamic leaching tests, the leaching characteristics of pollutants from residues subgrade materials under extremely acidic conditions were simulated. According to Fick's second law, combined with the effective diffusion coefficient (De), the risk of pollutant leaching and release in residue subgrade materials were evaluated. The concentrations of naphthalene, anthracene, benzo(a)anthracene, dibenzo(a,h)anthracene, Cd, and Zn met the requirements of class III water quality in the Chinese standard GB/T14848-2017. The release of naphthalene, anthracene, benzo(a)anthracene, dibenzo(a,h)anthracene, and Cd of leaching was dominated by diffusion. The release of benzo(a)pyrene and Zn of leaching was mainly dissolution. Hence, based on the investigation, the release law and characteristics of pollutants were explored when thermal desorption residues were applied as subgrade materials, which provided an important reference basis for the resource and utilization of oil-based cutting thermal desorption residues. [ABSTRACT FROM AUTHOR]

Oil shale can produce oil and shale gas by heating the oil shale at 300–500 °C. The high temperature and the release of organic matter can change the physical and mechanical properties of rocks and make the originally tight impervious layer become a permeable layer under in situ exploitation conditions. To realize the potential impact of the in situ exploitation of oil shale on groundwater environments, a series of water–rock interaction experiments under different temperatures was conducted. The results show that, with the increase of the reaction temperature, the anions and cations in the aqueous solution of oil shale, oil shale–ash, and the surrounding rock show different trends, and the release of anions and cations in the oil shale–ash solution is most affected by the ambient temperature. The hydrochemical type of oil shale–ash solution is HCO3-SO4-Na-K at 80 °C and 100 °C, which changes the water quality. The main reasons are that (1) the high temperature (≥80 °C) can promote the dissolution of FeS in oil shale and (2) the porosity of oil shale increases after pyrolysis, making it easier to react with water. This paper is an important supplement to the research on the impact of the in situ exploitation of oil shale on the groundwater environment. Therefore, the impacts of in situ mining on groundwater inorganic minerals should be taken into consideration when evaluating in situ exploitation projects of oil shale. [ABSTRACT FROM AUTHOR]

Fly oil shale ash (FOSA) is a waste material known for its pozzolanic activity. This study intends to investigate the optimum thermal treatment conditions to use FOSA efficiently as a cement replacement material. FOSA samples were burned in an electric oven for 2, 4, and 6 h at temperatures ranging from 550 °C to 1000 °C with 150 °C intervals. A total of 333 specimens out of 37 different mixes were prepared and tested with cement replacement ratios between 10% and 30%. The investigated properties included the mineralogical characteristics, chemical elemental analysis, compressive strength, and strength activity index for mortar samples. The findings show that the content of SiO2 + Al2O3 + Fe2O3 was less than 70% in all samples. The strength activity index of the raw FOSA at 56 days exceeded 75%. Among all specimens, the calcined samples for 2 h demonstrated the highest pozzolanic activity and compressive strength with a 75% strength activity index. The model developed by RSM is suitable for the interpretation of FOSA in the cementitious matrix with high degrees of correlation above 85%. The optimal compressive strength was achieved at a 30% replacement level, a temperature of 700 °C for 2 h, and after 56 days of curing. [ABSTRACT FROM AUTHOR]

High-energy substances like effect propellant and propellant are used in fireworks. In the process of manufacture, transportation, and use, heat can easily get out of control. The emulsifier polyisobutene succinimide (T152) is frequently used to emulsify explosives. Given the thermal safety of the propellant in fireworks, this paper used the emulsifier T152 to emulsify the propellant. Thermogravimetric Fourier-transform infrared spectrometry and differential scanning calorimetry were used to analyze and test the propellant. In addition, several methods of thermokinetic calculation were used to calculate thermal stability. The thermal stability of the propellant before and after adding T152 was compared and analyzed. The test results indicate that the apparent activation energy of the propellant increases with the addition of T152. The emulsifier improved the thermal stability of the propellant. The research results can provide relevant data and suggestions for the thermal reaction of pyrotechnic propellants, thereby reducing the potential risks of the fireworks industry. [ABSTRACT FROM AUTHOR]

The European Union (EU) presented a uniform List of Waste (LoW) in 2000 and last updated the technical guidance in 2018. The respective local regulations for the classification of waste in Estonia were set in 2015. Due to the changes in the regulations, it was necessary to review the properties of solid wastes generated in Estonian oil shale industry in light of hazardous properties. Therefore, the properties of the produced ash streams were analysed and the obtained results were compared to those for coal for being in accordance with common practices. The main objective of the paper was to answer the question whether the properties of oil shale (OS) are comparable to those of coal as coal and its combustion residues were not considered hazardous waste in Europe, but the respective counterparts of oil shale were. The EU guidelines suggest the use of calculations based on trace element concentrations for the classification of hazardous property (HP) 14 - ecotoxic. Therefore, an extensive study was conducted to investigate the hazardous properties of all the solid residues from power plants operating on oil shale and shale oil production facilities. This paper describes one part of it - the trace element compositions of the major ash streams produced in the Estonian oil shale industry and focuses on their comparison with data available for coal ash samples. The findings of the study showed that, similarly to coal, oil shale ash (OSA) should not be considered as ecotoxic due to the low concentrations of trace elements. It was found that the investigated oil shale ash samples exhibited a very similar composition and properties to those of coal, and as a result of a larger study, from the beginning of 2020, oil shale ash and other oil shale thermal treatment residues are not classified as hazardous waste in Estonia, thereby initiating policy changes that affect most areas of the economy. [ABSTRACT FROM AUTHOR]

Oil production (1942-1966) and uranium extraction (1953-1961) from the Alum Shale Formation in Kvarntorp, Sweden has had a great environmental impact on the area. Other industrial activities have also contributed to pollution. This study combines archive research with monitoring data and new sampling in order to assess the extent of the impact. During the production period, process water containing oil, phenols, sulfur compounds and high concentrations of iron reached the stream resulting in low water quality downstream. Also the landscape was reshaped, resulting in water filled pit lakes and a 100-meter-high shale waste deposit. Today, past alum shale activities still have an impact on the environment. Sulfate concentrations in the pit lakes are significantly higher than background values and downstream water also shows higher concentrations of elements such as nickel and uranium. The waste deposit still has a hot interior and an important question is the cooling rate and possible future leaching scenarios. Remaining hydrocarbons show today only a local impact while trace elements are transported downstream and affect a larger area. [ABSTRACT FROM AUTHOR]

Oil shale has received attention as an alternative energy source to petroleum because of its abundant reserves. Exploitation of oil shale can be divided into two types: ex situ and in situ exploitation. In situ transformation has been favoured because of its various advantages. Heating of oil shale leads to the production of oil and gas. To explore the influence of solid residue after pyrolysis of oil shale on the groundwater environment, we performed ultrapure water–rock interaction experiments. The results showed that Pb tended to accumulate in solid residues during pyrolysis. Additionally, the Pb concentration goes up in the immersion solution over time and as the pyrolysis temperature increased. In contrast, when we measured the soaking data of benzene series, the concentrations of benzene and toluene produced at temperatures over 350 ℃ were highest in the four oil shale pyrolysis samples after pyrolysis. The water–rock interaction experiment for 30 days led to benzene and toluene concentrations that were 104 and 1070-fold over the limit of China's standards for groundwater quality. Over time, the content of benzene series was attenuated via biological actions. The results show that in situ oil shale mining can lead to continuous pollution in the groundwater environment. [ABSTRACT FROM AUTHOR]

In this study, traditional strongly endothermic anaerobic retorting (AR) and relatively novel self‐heating retorting (SHR) processes for oil shale (OS) were investigated and compared in detail. These studies mainly involve the structural and quantitative evolution of organic matters in OS during retorting, including varieties of crystallite parameters, carbon framework structure, amounts of various structural carbons and toxic polycyclic aromatic hydrocarbons, and so on. The obtained results well elucidate some reaction pathways in AR and SHR as well as certain differences between the two retorting processes. Moreover, based on our former work that verifies SHR greatly simplifies retorting operation by in situ generating heat to replace external heat carrier/provision, this study further demonstrates that SHR also alleviates the environmental effect of organic toxic residues as compared to AR. The present study provides some critical results not only for penetrating the reaction mechanism but also for assessing or controlling the environmental impact of both retorting processes. [ABSTRACT FROM AUTHOR]

The combustion of low-grade solid fuels such as oil shale generates huge amounts of solid wastes such as fly ash. Use of oil shale combustion ash in granulated form for liming and amending peat soil has been suggested as a feasible recycling opportunity. However, the effect of granulated oil shale ash application on the characteristics of soil moisture and mobility of potentially toxic elements has not been thoroughly studied. The aim of the work was to study the environmental safety of the granulated oil shale fly ash when applied at peat soil in post-harvested peatlands. The oil shale ash was granulated using Na-alginate gel. The pH, EC and mobility of selected elements such as Al, As, Ba, Ca, Cd, Cr, Cu, Hg, K, Mo, Ni, Pb and Zn in amended peat soil was followed by analyzing soil water samples from the field. During vegetation period from April 2016 to September 2016 the pH value of the soil water samples in areas amended with granulated oil shale ash increased from 3 up to 6. The concentration of essential nutrients as well as other beneficial trace elements increased in soil water samples. The concentrations of potentially toxic microelements Cd, Hg and Pb were below detection limits in all collected soil water leachates. Granulated oil shale ash did not increased the mobility of other potentially hazard elements in amended peat soil during the study. [ABSTRACT FROM AUTHOR]

The modernisation of the oil shale (OS) industry in Estonia over the last decade has also led to significant changes in the composition and binding properties of the ash generated as a by-product. These changes also influence the environmental impact that the ash can have. In the current investigation, oil shale ash (OSA) samples were collected from different points along the ash separation systems of a large pulverized fuel combustion plant (LCP), various points in a circulating fluidized bed (CFB) combustion plant, and from an oil shale pyrolysis plant that utilises oil shale to produce liquid fuels. The results obtained can be used for optimising the deposition conditions, as well as guiding utilisation-recycling processes for ash generated from changing oil shale composition and characteristics. When it comes to developing the circular economy aspects of oil shale utilisation, mapping out the properties of OSA is crucial. [ABSTRACT FROM AUTHOR]

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In this paper, step-by-step groundwater-rock interaction experiments were performed to investigate the migration of heavy metals (Pb, Cr, Zn) into the water and the pH change of oil shale and oil shale ash aqueous solutions (hereinafter OS solution and OSA solution, respectively) during the in-situ production of oil shale. For geochemical calculations the PHREEQC software was used to simulate pH variation in the aqueous solutions at different temperatures and CO2 partial pressures (PCO2). The pH of most solutions was between 6.95 and 7.49 and changed significantly with increasing reaction time. The simulated data were closest to the experimental results at PCO2 = 10-2. A clear effect of reaction temperature and pH on the Pb content in the aqueous solutions was observed. The Pb content in the OSA solution was 0.36-0.47 µg/L, being higher than that in the OS solution (0.13-0.26 µg/L). The Cr content in OS and OSA solutions was from 0.55 to 0.70 µg/L. The Zn content in the OS solution was 1.17-3.61 µg/L, being significantly influenced by reaction temperature. [ABSTRACT FROM AUTHOR]

The separation and enrichment can be targeted to enrich in fly ash and reduce the cost of leaching and recovering of fly ash. Regarding their different properties, the single-component separation was used to obtain uncompleted burned carbon, glass microbeads, minerals, and other characteristic components from the ash. Also, the mineral composition of each component was analyzed by electron microscopy. The metal minerals were mainly concentrated in the mineral components. Besides, the electron probe microanalysis shows that the Pt content in the minerals of fly ash was significantly correlated with the metal contents of Ni and Cu. After the obtainment of the characteristics of fly ash metal enrichment, the heavy minerals with Cu, Ni, Pt, Pd, and other target metal elements were enriched by gravity separation and flotation. The enrichment coefficients of Cu, Ni, Pt, and Pd were 1.45, 1.33, 1.90, and 1.60, respectively, and the recovery rates were 77%, 81%, 97%, and 88%, respectively. Since the yield of heavy minerals obtained by separation was 62.24%, it indicated the physical separation method could significantly reduce the cost of leaching and recovering of fly ash metal resources. [ABSTRACT FROM AUTHOR]

Oil shale ash (OSA) from the circulating fluidized bed (CFB) boiler was granulated and used as a sorbent for the removal of phenols from shale oil wastewater. The method for preparation of the sorbent involved washing of the ash, mixing with clay, gelling the mixture with sodium alginate solution, solidifying the granules in barium chloride solution, drying and calcination of the granules and modifying with a surfactant -- hexadecyltrimethylammonium bromide (CTAB). The sorbent was characterized by specific surface area (BETN2), X-ray diffraction (XRD) and 29Si Magic Angle Spinning- Nuclear Magnetic Resonance (MAS-NMR) analysis. Batch adsorption experiments were conducted to determine the phenol adsorption isotherm at 20 °C and removal of water-soluble phenols from phenolic shale oil processing wastewater. Removal of phenols from wastewater was found to be 50--65% under given conditions. [ABSTRACT FROM AUTHOR]

Pollution by sewage irrigation of groundwater environment is slow and imperceptible. The pollution risk accumulated gradually, and the reasons for it are very complicated. Pollutants enter the underground aquifer through the leakage, leaching and other ways, and cause groundwater environment pollution. This paper presents the theory and quantification method for the degree of groundwater environment pollution caused by sewage irrigation, based on the study of the way and approach of groundwater environment pollution caused by sewage irrigation, critical content evaluation and current situation evaluation. By establishing the index model of the pollution degree of the groundwater environment, the study makes a quantitative description of the pollution risk of the groundwater environment. Finally, it analyses the study area, and the results show that: its pollution degree is 0.365, which means that the long-term sewage irrigation in the area has less risk to the groundwater environment. [ABSTRACT FROM AUTHOR]

This study presents the results of an analysis of combustion waste, namely fly ashes produced from the burning of solid fuels mixed with municipal waste. Heavy metal concentrations in the fly ashes examined fell within the following ranges (mg/kg): Cd 0.39–0.79, Cr 13.48–58.51, Ni 17.01–49.37 and Pb 14.95–59.74. As this type of waste does not exceed the limit values of pollutants for organic and organic-mineral fertilisers, it is often discarded on agricultural land or dumped in illegal landfills. Fine particles of fly ashes travel considerable distances and pose a risk to human health as they stick to people's hands during field works. The mean hazard quotient (HQ) values for non-carcinogenic forms of the elements analysed were 1.06E+00 for children and 1.47E-01 for adults. A HQ>1 indicates the probability of adverse health effects. The study has shown that the dominant exposure pathway was ingestion, which accounted for approx. 91% of total health risk, while the respective percentages for other pathways were less than 9% for dermal contact and 0.05% for inhalation. The highest health risk in the ingestion exposure pathway was observed for Cr (HQing= 4.50E-01 for children, HQing= 5.23E-02 for adults) and Pb (HQing= 4.31E-01 for children, HQing= 5.01E-02 for adults). Health risk associated with the presence of Ni and Cd in the material analysed was markedly lower. For carcinogenic forms, the Risk index was established at 6.13E-08 for children and 2.13E-07 for adults. As the exposure limit (10E-5) was not exceeded, the conditions in the area studied should be considered satisfactory. [ABSTRACT FROM AUTHOR]

Based on the requirement of national energy conservation and environmental protection, attention has been given to building an environment-friendly and resource-saving society. Shale gas oil-based drilling cutting pyrolysis residues (ODPRs) have been used as the main research object to developing new technology which can convert the residues into a harmless and recyclable material. Using the test data of ODPR, we analyze the development prospect in the building material industry and provide a scheme to utilize this particular solid-waste efficiently. Theoretically speaking, the ODPR resource utilization such as admixture of cement, making sintered brick, and non-fired brick, by the exploration and development of Fuling shale gas is feasible. [ABSTRACT FROM AUTHOR]

The elemental characterization of coal fly ash samples is required to estimate the coal burning emissions into the environment and to assess the potential impact into the biosphere. Fly ash samples collected from a coal fired power plant in center Java, Indonesia were characterized by instrumental neutron activation analysis at two different facilities (BATAN, ANSTO) and synchrotron based techniques at Elettra Italy. Assessment of thirty (30) elements and an investigation of the potential toxicity of As species in coal fly ash were presented. The results obtained are discussed and compared with those reported from other regions of the world. [ABSTRACT FROM AUTHOR]

The thermal behavior of green clay samples from the Arumetsa and Füzérradvány deposits (Hungary) and the influence of two new types of Estonian oil shale (OS) ashes and cement bypass dust (clinker dust) additives on it were the objectives of this study. Thermal and thermo-dilatometric analysis methods were applied using a Setaram Setsys 1750 thermoanalyzer coupled with a Pfeiffer Omnistar spectrometer and a Setaram Setsys 1750 CS Evolution dilatometer. The kinetic parameters were calculated based on the differential isoconversional method of Friedman. The results of the thermal analysis of clays and blends indicated the emission of physically bound water at 200–250 °C. At temperatures from 200–250 °C to 550–600 °C the release of water is caused by oxidation of organic matter and dehydroxylation of different clay minerals like illite, illite-smectite, mica and kaolin. From blends, in addition, also from the decomposition of portlandite. The emission of CO2 at these temperatures was a result of the oxidation of organic matter contained in the clays. In the temperature range from 550–600 °C to 800–900 °C, the mass loss was caused by ongoing dehydroxylation processes in clay minerals but was mainly due to the decomposition of the carbonates contained in the OS ashes and clinker dust. These processes were accompanied by contraction and expansion of the ceramic bodies with the corresponding changes in the SSA and porosity values of the samples. Therefore, the decomposition of the clays took place in one step which blends in two steps. At first, dehydroxylation of the clay minerals occurs, followed by decomposition of the carbonates. The value of the conversion-dependent activation energy E along the reaction progress α varied for the Arumetsa and illitic clay between 75–182 and 9–206 kJ mol−1, respectively. For the blends based on Arumetsa and illitic clay, the activation energy of the first step varied between 14–193 and 5–205 kJ mol−1, and for the second step, it was between 15–390 and 135–235 kJ mol−1, respectively, indicating the complex mechanism of the processes. [ABSTRACT FROM AUTHOR]

Implementation of construction works on weak (e.g., compressible, collapsible, expansive) soils such as peatlands often is limited by logistics of equipment and shortage of available and applicable materials. If preloading or floating roads on geogrid reinforcement or piled embankments cannot be implemented, then soil stabilization is needed. Sustainable soil stabilization in an environmentally friendly way is recommended instead of applying known conventional methods such as pure cementing or excavation and a single replacement of soils. Substitution of conventional material (cement) and primary raw material (lime) with secondary raw material (waste and byproducts from industries) corresponds to the Sustainable Development Goals set by the United Nations, preserves resources, saves energy, and reduces greenhouse gas emissions. Besides traditional material usage, soil stabilization is achievable through various secondary raw materials (listed according to their groups and subgroups): 1. thermally treated waste products: 1.1. ashes from agriculture production; 1.2. ashes from energy production; 1.3. ashes from various manufacturing; 1.4. ashes from waste processing; 1.5. high carbon content pyrolysis products; 2. untreated waste and new products made from secondary raw materials: 2.1. waste from municipal waste biological treatment and landfills; 2.2. waste from industries; 3. new products made from secondary raw materials: 3.1. composite materials. Efficient solutions in environmental engineering may eliminate excessive amounts of waste and support innovation in the circular economy for sustainable future. [ABSTRACT FROM AUTHOR]

Phosphorus depletion represents a significant problem. Ash of incinerated biological sewage sludge (BSS) contains P, but the presence of heavy metals (e.g., Fe and Al) is the main issue. Based on chemical characterization by SEM-EDS, ED-XRF and ICP-OES techniques, the characteristics and P content of bottom ash (BA) and fly ash (FA) of incinerated BSS were very similar. On BA, P extraction carried out in counter- current with an S:L ratio of 1:10 and H2SO4 0.5 M led to better extraction yields than those of a similar test with H2SO4 1 M and an S:L ratio of 1:5 (93% vs. 86%). Comparing yields with H2SO4 0.5 M (S:L ratio of 1:10), the counter-current method gave better results than those of the crossflow method (93% vs. 83.9%), also improving the performance obtained with HCl in crossflow (93% vs. 89.3%). The results suggest that the purification of the acid extract from heavy metals with pH variation was impractical due to metal precipitation as phosphates. Extraction with H2SO4 and subsequent treatment with isoamyl alcohol represented the best option to extract and purify P, leading to 81% extraction yields of P with low amounts of metals. [ABSTRACT FROM AUTHOR]

A circular economy becomes an object of actual discussions as a real alternative to the existing linear economy system. The problem is actually in Estonia also, first of all in the sector of heat and power production which based mainly on the combustion of local solid fossil fuel—Estonian oil shale (OS) resulting in the formation of ~5–6 million tons of OS ashes annually. The thermooxidative decomposition of OS samples from different deposits and estimation of the possibilities of utilization of OS ashes formed at both—pulverized firing (PF) and circulating fluidized bed combustion (CFBC) of Estonian OS were studied. The thermal analysis combined with evolved gas analysis (EGA) methods like Fourier transform infrared (FTIR) and mass-spectroscopy (MS) was exploited. It was established that the differences in the thermal behaviour of different OS samples are caused by the differences in the chemical matrix of organic matter, chemical and mineralogical composition of the inorganic part of OS, and morphology of samples. It was also found that moderate grinding of OS ashes with simultaneous moderate water treatment notably improved the SO2 binding efficiency of cyclone ash, and that the strength and leachability characteristics of granulated OS ashes strongly depend on the post-granulation treatment conditions allowing to increase the soil neutralizing ability of the granulated products. This overview was based on our investigations carried out during the last fifteen years. [ABSTRACT FROM AUTHOR]

Oil shale ash (OSA) was used for road construction in a pristine swamp area in East-Estonia during 2013-2014. OSA was used as a binder both in mass stabilization of soft peat soil and in the upper layer. Use of OSA in civil engineering always raises questions about the environmental safety of such activities. Post-construction environmental monitoring of the pilot section was carried out in 2014 and 2015. The monitoring program involved surface water and soil sampling campaigns. Samples were analyzed for selected constituents and parameters of environmental concern. The paper gives data for assessing the environmental impact and evaluation of potential risks associated with construction of roads using OSA. Leaching of hazardous compounds from the pilot section to surrounding aqueous environment was not observed during the monitoring program. Still, the road construction affected the concentration of sulfates in surrounding surface water. Also, the water-soluble content of barium in surface water correlated significantly with the concentrations of chloride and sulfate ion and electric conductivity of the surface water. Therefore, it is recommended to monitor the electric conductivity, concentrations of sulfates, chlorides, and barium in nearby surface water when OSA is used in road construction. [ABSTRACT FROM AUTHOR]