Search Results (100)

The present study investigates the suitability of the invasive herbaceous species Sosnowsky’s hogweed (Heracleum sosnowskyi) and giant knotweed (Fallopia sachalinensis), together with reed (Phragmites australis), as feedstock for pressed biofuel pellets used alone and as additives to pinewood. Biomass of the three herbaceous species and pinewood was harvested, dried, chopped, milled, and pelletized through a 6 mm die to obtain pure pellets and binary mixtures of each herbaceous biomass with pinewood (25, 50, and 75% by weight of herbaceous share). The pellets were characterized for physical and mechanical properties, elemental composition, calorific value, combustion emissions, and life cycle impacts per 1 GJ of heat. Pellet density ranged from 1145.60 to 1227.47 kg m⁻³, comparable to or higher than pinewood, while compressive resistance satisfied solid biofuel quality requirements. The lower calorific values of all herbaceous and mixed pellets varied between 16.29 and 17.78 MJ kg⁻¹, with increased ash and nitrogen contents at higher herbaceous shares. Combustion tests showed substantially higher CO and NO_x emissions for pure invasive and reed pellets than for pinewood, but all values remained within national regulatory limits. Life cycle assessment indicated the highest global warming and fossil fuel depletion potentials for reed systems, followed by Sosnowsky’s hogweed and giant knotweed, with pinewood consistently exhibiting the lowest impacts. Overall, invasive plants and reed are technically suitable as partial pinewood substitutes in pellet production, supporting simultaneous invasive biomass management and renewable heat generation. Full article

This study produces high-purity nano-silica from corn straw ash (biomass power plants) using an alkaline fusion-derived sodium silicate solution. CO₂ replaces traditional acids in the carbonation reaction, enabling high extraction yield (93.11%). The process addresses the gap in directly utilizing combustion ash for such high-purity silica. Key optimal conditions identified were 5 M aq. HCl concentration, NaOH fusion reagent, 1:1.2 mixing ratio, 3 M aq. NaOH solvent, and 12 h ripening. The resulting nano-silica achieved 92.73% purity, 10–50 nm particle size, 270 × 10⁻⁵ m³/kg dibutyl phthalate (DBP) absorption, 55.9916 m²/g specific surface area, 6.38% loss on drying (LOD), and 6.69% loss on ignition (LOI). These properties meet national standards for premium, loosely structured nano-silica. This method provides an economical and effective silicon source, reducing costs and offering economic-environmental benefits. Full article

The novelty lies in combining chemical and ecotoxicological approaches to evaluate the safety of ashes from different fuels. Its practical relevance is in demonstrating that only mixed firewood ash shows sufficiently low toxicity for safe use in home gardens, offering guidance for sustainable household ash management. The use of ash in agriculture as a fertilizer has become a topic which is gaining growing attention because of its high nutrient content and its capacity to enhance soil structure. Ash from the combustion of wood, coal or plant biomass, although at first glance it seems to be a useless residue, contains a large amount of components essential for the healthy development of plants. These include potassium, phosphorus, magnesium, calcium and many microelements that can significantly affect the yield and condition of crops. For this reason, it was deemed necessary to investigate the toxicity of ashes produced during the burning of solid materials. The study material consisted of samples collected under controlled conditions resulting from the burning of the following materials: lumps of hard coal larger than 60 mm, hard coal graded between 25 and 80 mm, fine hard coal ranging from 8 to 25 mm, wood pellets, and a mixture of firewood types. A leaching procedure was then carried out to obtain eluates from the individual ash types. The analyses made it possible to determine and evaluate the extent to which polycyclic aromatic hydrocarbons (PAHs) leach from ashes originating from different fuels. Furthermore, the effect of fuel type on the transfer of these substances into the water environment was established. Carcinogenic equivalents of ash solutions, as well as the acute ecotoxicity of the eluates, were also assessed using Microtox^® biotests with luminescent bacteria Aliivibrio fischeri. Based on the results, it was shown that the eluate derived from the combustion of mixed firewood exhibited the lowest toxicity, both with respect to PAH-related indicators and Microtox^® outcomes. In our view, only this type of ash can be regarded as suitable for agricultural application in home gardens. Full article

Energy production from burning biomass in bioheat plants involves the production of biomass fly ash (BFA). Due to its rich chemical composition, in the era of a circular economy, it should be reused, for example, for environmental purposes as a secondary raw material containing valuable macro- and micronutrients. Due to its alkaline nature, it can also be an alternative to commercial agricultural lime (CAL) for neutralizing the acidic reaction of agricultural soils. The basis for the presented research was a pot experiment with corn (Zea mays L.) as a test plant and increasing doses of BFA (16.20, 32.40, and 48.60 g pot⁻¹), which is equal to 6.99, 13.98, and 20.97 g of CAL pot⁻¹. The above doses were determined based on the neutralization value (NV) of BFA and CAL, calculated to neutralize the hydrolytic acidity of the soil (Hh) to 0.5, 1.0, and 1.5 Hh. The study analyzed the effect of BFA on the leaf greenness index (SPAD), plant height, yield, and chemical composition of corn, as well as macronutrient content. The observations indicate that BFA application positively modified the yield of both fresh mass and dry mass of corn and height of plants, and reduced the dry matter content compared to the effect obtained after CAL use. BFA caused a decrease in the total N and Ca content and a significant increase in P, K, and Na compared to the CAL-fertilized treatments. BFA significantly contributed to a narrowing of the Ca:P, Ca:Mg ratios, and a widening of the K:(Ca + Mg), and K:Ca ratios compared to the ionic balance observed in the CAL-fertilized corn. The obtained results allow us to conclude that fly ash from biomass combustion can be a valuable alternative to conventional soil deacidification agents used till now in agriculture. Full article

Biomass plays an important role in the energy transformation aimed at carbon neutrality, with its potential estimated at 1/3rd of the entire energy mix. One of the main ways of using biomass is combustion or co-combustion, which enables the production of heat and electricity while maintaining low emissions. A promising path to utilize the combustion by-product—ash—is the possibility of using it as a natural and cheap catalyst that can effectively support the process of solid fuel gasification. This paper reviews scientific studies on the properties of biomass ash and its use to support the gasification process. The issues related to the genesis of mineral matter in plants are presented, emphasizing the importance of its transformations during biomass combustion. Particular emphasis is placed on the characterization of biomass ash, which was carried out on the basis of a comprehensive overview of the results regarding its chemical composition. An analysis of the physicochemical and surface properties relevant to the use of biomass ashes as catalysts in the gasification process was performed. In addition, a review of studies on catalytic gasification of solid fuels using biomass ash was conducted, taking into account the impact of biomass ash on the most important parameters characterizing the course of the gasification reaction, i.e., reactivity, quality of the gaseous products, and the kinetics reaction. The summary compares the most important advantages and disadvantages of using biomass ashes in the gasification process along with recommendations for future research. Full article

Mine effluents represent a serious environmental problem on a global scale. Therefore, the effective treatment of this water is a serious issue in the scientific field. The adsorption process seems to be one of the attractive methods, especially due to the simplicity of design, affordability or high efficiency. The latest scientific knowledge has shown that the use of waste and natural adsorbents is economical and effective. This study aimed to evaluate the efficiency of the adsorption process of natural and waste materials—zeolite, bentonite and fly ash—under the influence of temperature and modification of these adsorbents. The novelty of this study resides in an adjustment of the modification method of adsorbents compared to previous research: thermal–alkaline treatment versus hydrothermal one. Another novelty is the use of modified fly ash from biomass combustion as an adsorbent in comparison with the previously used fly ash from coal combustion. The modification of the adsorbents made the adsorption process more effective at all experimental concentrations. The characterisation of adsorbent samples was performed using X-ray diffraction (XRD). The parameters of the adsorption isotherms, Langmuir, Freundlich and Temkin, were estimated by nonlinear regression analysis. The adsorption capacity of Cu(II) of fly ash was comparable to natural adsorbents. Adsorption processes were better described by pseudo-second-order kinetics. At the end of this study, the suitability of using the adsorbents to reduce the concentration of Cu(II) in neutral mine effluents was observed in the following order at 30 °C: unmodified fly ash > modified bentonite > unmodified zeolite. At the temperatures of 20 °C and 10 °C, the same trend of the suitability of adsorbents use was confirmed: modified bentonite > modified zeolite > modified fly ash. The practical applicability of this study lies in the expansion of knowledge in the field of adsorption processes and in the improvement of waste management efficiency of heating plants not only in Slovakia, but also globally. Full article

Four biomass residues–rosemary pomace, rosemary cake, grape seed and apple pomace–were torrefied at 250, 350 and 450 °C, and the physical, chemical and structural changes were characterized. The mass and energy yield decreased with increasing torrefaction temperature; the lowest mass (~10.4%) and energy yield (~10.6%) were observed for rosemary cake torrefied at 450 °C. The HHV increased the most for all feedstocks at 350 °C, with rosemary cake reaching a peak value of 36.4 MJ/kg at 350 °C. Ash content increased with temperature due to organic mass loss, while volatiles decreased and fixed carbon increased in most samples. The FTIR spectra showed the progressive loss of hydroxyl, carbonyl and C–O functionalities and the appearance of aromatic C=C bonds, indicating the formation of the biochar. TGA and DTG analyses revealed that the torrefied samples exhibited higher initial and maximum temperatures for decomposition, confirming improved thermal stability. The TGA-FTIR analyses of gas emissions during pyrolysis and combustion showed that the emissions of CO₂, CH₄, NO_x and SO₂ decreased with increasing degree of torrefaction. Overall, 350 °C was optimal to maximize energy density. The results show that agro-industrial residues can be effectively converted into sustainable biofuels, which offer the dual benefit of reducing waste disposal problems and providing a renewable alternative. In practice, such residues could be used for decentralized power generation in rural areas, co-combustion in existing power plants, or as feedstock for advanced bioenergy systems. Full article

Sustainable waste management is one of the most serious global challenges today. Reusing waste materials can be an effective alternative to landfill, while recovering valuable nutrients. The purpose of this six-year field study was to investigate the potential of bottom ash from combustion of bituminous coal or biomass and municipal sewage sludge, and different doses of the waste mixtures, as a micronutrient source for plants. Yield, concentration, concentration index, uptake and simplified balance of the micronutrients (manganese, iron, molybdenum, cobalt, aluminium) in plant biomass were measured. Results showed that the wastes differently affected the parameters studied, which generally increased via treatment as follows: coal ash, biomass ash < coal or biomass ash mixtures with sewage sludge < sewage sludge. Irrespective of treatment, micronutrient recovery rate followed the following trend: Mn > Mo > Fe > Co > Al, from 0.32–25.82% for Mn to 0.04–0.28% for Al. For individual elements, recovery depended on waste. For Mn, Fe and Al, the application of ash separately or in mixtures with sludge at higher doses reduced recovery (0.04–0.78%). For Mn, Fe, Al and Mo, the application of ash–sludge mixtures at lower doses increased recovery (0.11–5.82%), with the highest recoveries when sludge was used separately (0.28–25.82%). For Co, the separate application of sewage sludge and ash–sludge mixture at the lower dose increased recovery (2.41–2.52%), with the highest Co recovery following the separate application of coal ash (2.78%). Ash, sludge and their mixtures were a valuable source of micronutrients for plants. Ash–sludge mixtures improved micronutrient uptake compared to ash used separately. Application of these wastes as fertilisers aligns with the EU Action Plan on the Circular Economy and can contribute to achieving SDGs 2 and 12. Full article

Cement production is a carbon-intensive process that contributes significantly to global greenhouse gas emissions. Approximately 50–60% of these emissions result from limestone calcination, while 30–40% result from fossil fuel combustion in kilns. This study presents a multi-objective optimization (MOO) framework that integrates raw mix design and alternative fuel blending to simultaneously reduce production costs and carbon dioxide (CO₂) emissions while maintaining clinker quality. A hybrid Genetic Algorithm–Linear Programming (GA-LP) model was developed to navigate the balance between economic and environmental objectives under stringent chemical and operational constraints. The approach models the impact of raw materials and fuel ash on critical clinker quality indices: the Lime Saturation Factor (LSF), Silica Modulus (SM), and Alumina Modulus (AM). It incorporates practical constraints such as maximum substitution rates and specific fuel compositions. A case study inspired by a medium-sized African cement plant demonstrates the utility of the model. The results reveal a Pareto front of optimal solutions, highlighting that a 20% reduction in CO₂ emissions from 928 to 740 kg/ton clinker is achievable with only a 24% cost increase. Optimal strategies include 10% fly ash and 30–50% alternative fuels, such as biomass, tire-derived fuel (TDF), and dynamic raw mix adjustments based on fuel ash contributions. Sensitivity analysis further illustrates how biomass cost and LSF targets affect clinker performance, emissions, and fuel shares. The GA-LP hybrid model is validated through process simulation and benchmarked against African case studies. Overall, the findings provide cement producers and policymakers with a robust decision-support tool to evaluate and adopt sustainable production strategies aligned with net-zero targets and emerging carbon regulations. Full article

This study investigates the emission characteristics and environmental impacts of pollutants from bagasse-fired biomass boilers through the integrated field monitoring of two sugarcane processing plants in Guangxi, China. Comprehensive analyses of flue gas components, including PM_2.5, NOx, CO, heavy metals, VOCs, HCl, and HF, revealed distinct physicochemical and emission profiles. Bagasse exhibited lower C, H, and S content but higher moisture (47~53%) and O (24~30%) levels compared to coal, reducing the calorific values (8.93~11.89 MJ/kg). Particulate matter removal efficiency exceeded 98% (water film dust collector) and 95% (bag filter), while NOx removal varied (10~56%) due to water solubility differences. Heavy metals (Cu, Cr, Ni, Pb) in fuel migrated to fly ash and flue gas, with Hg and Mn showing notable volatility. VOC speciation identified oxygenated compounds (OVOCs, 87%) as dominant in small boilers, while aromatics (60%) and alkenes (34%) prevailed in larger systems. Ozone formation potential (OFP: 3.34~4.39 mg/m³) and secondary organic aerosol formation potential (SOAFP: 0.33~1.9 mg/m³) highlighted aromatic hydrocarbons (e.g., benzene, xylene) as critical contributors to secondary pollution. Despite compliance with current emission standards (e.g., PM < 20 mg/m³), elevated CO (>1000 mg/m³) in large boilers indicated incomplete combustion. This work underscores the necessity of tailored control strategies for OVOCs, aromatics, and heavy metals, advocating for stricter fuel quality and clear emission standards to align biomass energy utilization with environmental sustainability goals. Full article

Aggregates such as sand and gravel are the most mined resources on Earth and are the largest component in concrete. They are essential for construction but are becoming increasingly scarce. At the same time, large amounts of biomass ashes are produced in wood-fired power plants, offering potential as a partial substitute for decreasing sand resources. Due to the combustion technology of circulating fluidized bed boilers, their bottom ash offers high potential as a viable alternative to natural sand. This review examines previous research to assess the feasibility of replacing sand in concrete with bottom ash. Specific cementitious products are identified, where the substitution could realistically be performed in the concrete industry. Benefits and issues with partial substitution of bottom ash from wood combustion are discussed, and gaps in the research regarding sand replacements with bottom ash, notably the durability of the resulting concrete, are shown. Bottom ash has positive properties relevant for use in mortar and concrete, both regarding physical and chemical properties. Although limited research exists in the field, several researchers have demonstrated promising results when substituting sand for bottom ash in mortars. For lower substitution levels, little effect on the fresh and hardened properties is found. Full article

One of the approaches to limit the negative impact on the environment from the burning of coal in the production of heat and electricity is to limit their use by blending them with biomass. Blended fuel combustion leads to the generation of a solid ash residue differing in composition from coal ash, and opportunities for its utilization have not yet been studied. The present paper provides results on the carbon capture potential of adsorbents developed through the alkaline conversion of ash mixtures from the combustion of lignite and biomass from agricultural plants and wood. The raw materials and the obtained adsorbents were studied with respect to the following: their chemical and phase composition based on Atomic Absorption Spectroscopy with Inductively Coupled Plasma (AAS-ICP) and X-ray powder diffraction (XRD), respectively, morphology based on scanning electron spectroscopy (SEM), thermal properties based on thermal analysis (TG and DTG), surface parameters based on N₂ physisorption, and the type of metal oxides within the adsorbents based on temperature-programmed reduction (TPR) and UV-VIS spectroscopy. The adsorption capacity toward CO₂ was studied in dynamic conditions and the obtained results were compared to those of zeolite-like CO₂ adsorbents developed through the utilization of the raw coal ash. It was observed that the adsorbents based on ash of blended fuel have a comparable carbon capture potential with coal fly ash zeolites despite their lower specific surface areas due to their compositional specifics and that they could be successfully applied as adsorbents in post-combustion carbon capture systems. Full article

The growing demand for energy biomass encourages the use of waste and by-products from agriculture. The aim of this study was to assess the suitability of tobacco stalks (TSs) for energy use in the combustion and anaerobic digestion (AD) process, as well as the technical and environmental effects of energy production from this waste raw material. Laboratory tests were conducted on the energy parameters of TS biomass, the chemical composition of ash from its combustion, and the efficiency and composition of biogas generated during the AD process of TS silage with various silage additives. The tests were conducted in accordance with the standards applicable to biomass fuels. The energy yield and emission reduction obtained by the replacement of conventional energy sources were calculated. The energy parameters of TS were inferior compared to the raw materials most often burned in boilers (wood, straw). The high ash content (7.31% in dry mass) and its chemical composition may adversely affect heating devices. Methane yield from TS silage was lower (18.55–24.67 m³/Mg FM) than from silage from crops grown for biogas plants (i.e., 105 m³/Mg for maize silage). Silage additives improved TS silage quality and methane yield (from 18.55 to 21.71–24.67 m³ CH₄/Mg in case of silages with additives. Energy yield and emission reduction were higher in the case of TS combustion, but AD is a process consistent with the circular economy. Both TS energy management processes are in line with the Sustainable Development Goals as they prevent the devaluation of agricultural waste, providing a valuable resource for bioenergy. Full article

Bioenergy production generates huge amounts of ash from biomass combustion. One of the attempts to utilize them is to use them in agriculture as fertilizers. The response to this challenge is a three-year field experiment (2018–2021) where the effect of fertilization with ash from forest biomass (approx. 70%) and agricultural biomass (approx. 30%), and soil type (Gleyic Chernozem and Haplic Luvisol), on the fatty acid (FA) profile of winter rape seeds (Brassica napus L. ssp. oleifera Metzg) was studied. Environmental factors modified the accumulation of fatty acids in winter oilseed rape seeds to the greatest extent and included all labelled unsaturated and saturated fatty acids from C12:0 to C24:0, with exceptions. In warm and dry years, C18:1n9c, C18:2n9c and C18:3n6 accumulated more, while cooler and humid years promoted an increase in the content of, among others, C20:2, C24:1, C18:3n3, C20:4 and C22:2. Cultivation of plants in Gleyic Chernozem soil promoted the accumulation of unsaturated fatty acids C18:3n3 and C18:3n6 in winter rape seeds—important from the nutritional point of view. The soil type Haplic Luvisol influenced a larger number of saturated acids and promoted an increase in their content to a greater extent than the Gleyic Chernozem soil type. Among unsaturated fatty acids, fertilization had an effect only on C18:3n3 with mineral fertilization (variant D1) and a very high K dose (variant D5) and C24:1 with the highest K dose (variant D6). No negative changes in the proportions of FAs, including omega-3 and omega-6, were demonstrated under the influence of BA application. Full article

This study provides a cost-effective method for using bottom ash from biomass combustion, which would otherwise constitute waste, to remove cadmium from acidic industrial wastewater. The X-ray powder diffraction method was used to identify the crystal forms, i.e., the arrangement of atoms in the crystal lattice, and to determine the composition of bottom ash, and the X-ray fluorescence method was used to obtain information on the elemental composition of bottom ash. The Fourier Transform Infrared method was used to analyse and identify the different functional groups occurring in bottom ash. Scanning Electron Microscopy with energy-dispersive X-ray was used to obtain detailed information on the bottom ash surface. The effect of various factors on Cd removal was studied, and optimal experimental conditions were found. The kinetic and thermodynamic equations showed that the removal of Cd²⁺ using bottom ash from biomass combustion was a single-layer chemical adsorption meeting the requirements of pseudo-second-order kinetics. The limiting parameter for the effective adsorption of Cd²⁺ using bottom ash from biomass combustion is its alkaline nature. It can only be used for solutions with pH < 2, which, on the other hand, is its advantage in practical application, namely, in the final treatment of acidic industrial wastewater. Full article