Search Results (487)

In recent years, there has been growing interest in using wood biomass for energy production, which has led to an increase in post-processing waste in the form of wood biomass ash (WBA). Due to the rich composition of WBA, its fertilising potential should be considered. In the conducted studies, WBA was used both alone and in combination with digestate (DG). The WBA was obtained from the Municipal Heat Energy Company and the DG from the Agricultural Biogas Plant in the form of unseparated liquid digestate (ULD), separated solid digestate (SSD) and separated liquid digestate (SLD). The studies included four series: (1) WBA, (2) WBA + ULD, (3) WBA + SSD and (4) WBA + SLD. In each series, WBA was introduced in three increasing doses (0.5, 1.0 and 1.5, expressed in hydrolytic acidity units (HACs) and determined based on the general alkalinity of the material). The digestates (DGs) were applied in fixed doses, which were balanced with respect to the nitrogen introduced into the soil. The test plant was the maize (Zea mays L.) variety Garantio, which was grown in a vegetation hall. The obtained results indicate that the combined use of WBA and DGs (especially ULD and SLD) had a positive effect on the plant height, leaf greenness index (SPAD), and thus, maize yield and dry matter content. In the series with DG addition, the maize yield ranged from 615.5 g (WBA + SSD) to 729.6 g pot⁻¹ (WBA + SLD), which was 28–52% higher than in the series with WBA alone. In turn, the application of increasing doses of WBA alone did not significantly affect the biomass yield but significantly increased the content of N (34%), K (60%), Mg (56%), Ca (60%) and Na (4%). In the series with WBA and DGs, the increase in the content of the above-mentioned macronutrients depended on the type of DG and the dose of WBA. The exception among the macronutrients was P, whose content generally decreased (by 4–23%) with an increasing WBA dose, regardless of the test series. The most favourable results in terms of the chemical composition, excluding the P content, were observed following the combined application of WBA and liquid forms of DG (ULD and SLD). Full article

The utilisation of agrifood waste ashes has the potential to enhance the nutrient content of cereal crops, thereby optimising both yield and grain quality. This study investigated rye grain composition, the fermentation efficiency, and volatile compounds in mashes made from crops fertilised with agrifood waste ashes derived from the combustion of corn cob, wood chips, and biomass with defecation lime. The ashes were applied at 2, 4, and 8 t/ha, separately and as mixtures of corn cob (25%) with wood chips (75%) and corn cob (50%) with biomass and defecation lime (50%). Rye mashes were prepared using the pressureless starch liberation method. The starch content in the majority of the rye grains was comparable to the control sample (57.12 g/100 g). The range of ethanol concentrations observed in the fermented mashes was from 55.55 to 68.12 g/L, which corresponded to fermentation yields of 67.25–76.59% of theoretical. The lowest fermentation yield was exhibited by the mash derived from rye cultivated on soil fertilised with a 50:50 mixture of ashes from corn cob and biomass with defecation lime at 8 t/ha. This mash contained more than double the acetaldehyde concentration and total aldehyde content compared to the other samples. These findings demonstrate the potential of using waste biomass ash as a source of macro- and microelements for rye cultivation, enabling the production of agricultural distillates. To ensure high fermentation efficiency and low aldehyde levels, ash dosage and composition need to be established based on experimental optimisation. Full article

The feasibility of utilizing biochar as a static floating material for agricultural applications was researched to prevent evaporation from open water static storage systems or as a floating barrier in slurry pits, for instance. Five types of biochar were created from chips, bark, and pellets of pine and residues from two acacia species using a pyrolysis time between 60 and 120 min and mean temperatures between 380 and 690 °C in a simple double-chamber reactor. Biomass and biochar were characterized for their main properties: bulk density, moisture content, volatile matter, ash content, fixed carbon, and pH. Biochar was also evaluated through a basic floatability test over 27 days (648 h) in distilled water. The highest fixed carbon content was observed in pine bark biochar (69.5%), followed by the pine pellets (67.4%) and pine chips (63.4%). Despite their high carbon content, the pellets exhibited a low floatability level, whereas pine bark biochar showed superior static floatage times, together with chip and ground chip biochar. These results suggest that biochar produced from bark and wood chips may be suitable for application as floatability material in water or slurry management systems. These results warrant further research into the static floating of biochar. Full article

In the context of the growing need to reduce greenhouse gas emissions and to develop sustainable solutions for the construction industry, foamed geopolymers represent a promising alternative to traditional binders and insulation materials. This study investigates the thermal properties of novel low-emission, insulating geopolymer binders made from fly ash with diatomite, chalcedonite, and wood wool aiming to assess their potential for use in thermal insulation systems in energy-efficient buildings. The stability of the foamed geopolymer structure is also assessed. Measurements of thermal conductivity, specific heat, microstructure, density, and compressive strength are presented. The findings indicate that the selected geopolymer formulations exhibit low thermal conductivity, high heat capacity and low density, making them competitive with conventional insulation materials—mainly load-bearing ones such as aerated concrete and wood wool insulation boards. Additionally, incorporating waste-derived materials reduces the production carbon footprint. The best results are represented by the composite incorporating all three additives (diatomite, chalcedonite, and wood wool), which achieved the lowest thermal conductivity (0.10154 W/m·K), relatively low density (415 kg/m³), and high specific heat (1.529 kJ/kg·K). Full article

This study presents a cost-effective, carbon-negative construction material for affordable housing, developed entirely from locally available agricultural wastes: rice husk ash, wood ash, and rice straw—materials often problematic to dispose of in many African regions. Rice husk ash provides high amorphous silica, acting as a strong pozzolanic agent. Wood ash contributes calcium oxide and alkalis to serve as a reactive binder, while rice straw functions as a lightweight organic filler, enhancing thermal insulation and indoor climate comfort. These materials undergo natural pozzolanic reactions with water, eliminating the need for Portland cement—a major global source of anthropogenic CO₂ emissions (~900 kg CO₂/ton cement). This process is inherently carbon-negative, not only avoiding emissions from cement production but also capturing atmospheric CO₂ during lime carbonation in the hardening phase. Field trials in Kenya confirmed the composite’s sufficient structural strength for low-cost housing, with added benefits including termite resistance and suitability for unskilled laborers. In a collaboration between the University of Tartu and Kenyatta University, a semi-automatic mixing and casting system was developed, enabling fast, low-labor construction of full-scale houses. This innovation aligns with Kenya’s Big Four development agenda and supports sustainable rural development, post-disaster reconstruction, and climate mitigation through scalable, eco-friendly building solutions. Full article

This study evaluated birch and oak ash extracts as alternative extractants for isolating humic substances (HSs) from peat and lignite. The effects of ultrasound intensity, extraction time, and temperature were optimized using a Box–Behnken design and validated statistically. The highest HSs yields were obtained from peat with oak ash extract (pH 13.18), compared to birch ash extract (pH 12.09). Optimal process parameters varied by variant, falling within 309–391 mW∙cm⁻², 116–142 min, and 67–79 °C. HSs extracted under optimal conditions were fractionated into humic acids (HAs) and fulvic acids (FAs), and then analyzed by elemental analysis, Fourier Transform Infrared Spectroscopy (FTIR), and Cross-Polarization Magic Angle Spinning Carbon-13 Nuclear Magnetic Resonance Spectroscopy (CP/MAS ¹³C NMR). The main differences in HSs quality were influenced by raw material and fraction type. However, the use of birch ash extract consistently resulted in a higher proportion of carboxylic structures across all fractions. Overall, wood ash extract, especially from oak, offers a sustainable and effective alternative to conventional extractants, particularly for HSs isolation from lignite. Notably, HSs yield from lignite with oak ash extract (29.13%) was only slightly lower than that achieved with 0.5 M NaOH (31.02%), highlighting its practical potential in environmentally friendly extraction technologies. Full article

This paper describes the process of drying sewage sludge mixtures with the addition of various components: straw chaff, wood sawdust, ash, bark, wood chips, and walnut shells. The tests were conducted in two series: summer and autumn (with maximum insolation of 24.1 and 29.8 MJ∙m⁻², respectively). Using a set of sensors with which the experimental station was equipped, the parameters of the environment (temperature, humidity, and insolation) and the parameters of the dried mixtures (temperature and humidity) were measured. Based on the results obtained, the influence of external factors on the parameters, time, and drying effect of the respective mixtures was analyzed. With the initial moisture content of the mixtures ranging from 41 to 79%, a final moisture content of 6 to 49% was obtained, depending on the components and drying conditions. It was found that the drying rate was most influenced by the amount of solar energy and the associated outdoor (maximum 29 °C and 19 °C) and indoor (maximum 33 °C and 24 °C) air temperatures, and in the second series, there was an additional effect of the temperature of the mixtures (maximum 30 °C), upon which the intensity of water evaporation depended. Straw chaff and walnut shells proved to be the best additives, for which the highest drying rates were obtained (max. 50 to 60% humidity drop). The possibility of using dried materials for agricultural and energy purposes was indicated. This approach is in line with the principles of sustainable development. Full article

The amount of waste generated by society is constantly increasing. Consequently, there is a need to develop new and better methods of treating it. A significant part of municipal waste is biowaste, which can be treated as a source of valuable resources such as nutrients, organic matter, and energy. The present work aims to determine the properties of the tested household biowaste and the possibility of using it as feedstock in slow pyrolysis to obtain biochar. The slow pyrolysis process of the biowaste was carried out in an electrically heated Horizontal Tube Furnace (HTF) at temperatures of 400 °C, 500 °C, and 600 °C in a nitrogen atmosphere. The analysis showed that depending on the type and composition of the biowaste, its properties are different. All the biowaste tested has a high moisture content (between 63.51% and 81.53%), which means that the biowaste needs to be dried before the slow pyrolysis process. The characteristics of kitchen biowaste are similar to those of food waste studied by other researchers in different regions of the world. In addition, the properties of kitchen biowaste are similar to those of the typical biomasses used to produce biochar via slow pyrolysis, such as wood, almond shells, and rice husks. Both kinds of garden biowaste tested may have been contaminated (soil, rocks) during collection, which affected the high ash content of spring (17.75%) and autumn (43.83%) biowaste. This, in turn, affected all the properties of the garden biowaste, which differed significantly from both the literature data of other garden wastes and from the properties of typical biomass feedstocks used to produce biochar in slow pyrolysis. For all biowaste tested, it was shown that as the pyrolysis temperature increases, the yield of biochar decreases. The maximum mass yield of biochar for kitchen, spring garden, and autumn garden biowaste was 36.64%, 66.53%, and 66.99%, respectively. Comparing the characteristics of biowaste before slow pyrolysis, biochar obtained from kitchen biowaste had a high carbon content, fixed carbon, and a higher HHV. In contrast, biochar obtained from garden biowaste had a lower carbon content and a lower HHV. Full article

The accurate estimation of the higher heating value (HHV) of wood biomass is essential to evaluating the latter’s energy potential as a renewable energy material. This study proposes an Artificial Neural Network (ANN) model to predict the HHV by using proximate analysis parameters—moisture, volatile matter, ash, and fixed carbon. A dataset of 252 samples (177 for training and 75 for testing), sourced from the Phyllis database, which compiles the physicochemical properties of lignocellulosic biomass and related feedstocks, was used for model development. Various ANN architectures were explored, including one to three hidden layers with 1 to 20 neurons per layer. The best performance was achieved with the 4–11–11–11–1 architecture trained using the backpropagation algorithm, yielding an adjusted R² of 0.967 with low mean absolute error (MAE) and root mean squared error (RMSE) values. A graphical user interface (GUI) was developed for real-time HHV prediction across diverse wood types. Furthermore, the model’s performance was benchmarked against 26 existing empirical and statistical models, and it outperformed them in terms of accuracy and generalization. This ANN-based tool offers a robust and accessible solution for carbon utilization strategies and the development of new energy storage material. Full article

Wood ash is a promising supplementary cementitious material (SCM) due to its inherent pozzolanic properties. Intensive grinding has been shown to enhance this aspect and reduce the negative effects of variability in the chemical composition. This study investigated the influence of grinding through ball milling on the pozzolanic properties of wood ash. Four different types of wood ash were studied, each subjected to grinding durations of 10 and 20 min. Coal fly ash was used as a reference material. The pozzolanic activity of raw and ground wood ashes was evaluated using the strength activity index (SAI), the Frattini test, the R3 test, thermogravimetric analysis (TGA/DTG), X-ray diffraction (XRD) analysis, and scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS). The results indicated that both 10 min and 20 min grinding durations enhanced the reactivity and compressive strength. However, the 10 min grinding duration showed better overall performance than 20 min grinding, likely due to reduced agglomeration and more effective particle refinement. For calcium-rich wood ashes, the reactivity was linked to the hydraulic properties rather than the pozzolanic properties. Full article

The Mixed Ombrophyllous Forest (MOF), inserted in the Atlantic Forest biome, is of great ecological value, with deficient management strategies. In this context, sustainable management helps to promote the regeneration and growth of individual trees and control others, while maintaining the natural forest structure. This study therefore aimed to discuss opportunities and limitations of biochar, produced from two species from the MOF, which are currently only utilized to a limited extent in the study area in southern Brazil. A slow pyrolysis process at a lab scale was designed, biochar was produced, and key properties were analyzed from Hovenia dulcis Thunb. (chosen as an invasive species) and Mimosa scabrella Benth. (chosen as a native, fast-growing species), including branches and stems. The results showed that branches of Mimosa scabrella (BMS) had the highest biochar yield (30.32 ± 0.3%) and the highest electrical conductivity (415.08 ± 24.75 mS cm⁻¹). Stems of Mimosa scabrella (SMS) showed the highest higher heating value (HHV—31.76 ± 0.01 MJ kg⁻¹), lower heating value (LHV—31.03 ± 0.01 MJ kg⁻¹), and energy yield (49.1%), while the branches of Hovenia dulcis (BHD) showed the lowest values. For the elemental analysis, SMS showed the best results, with the highest amount of fixed carbon (78.62 ± 0.22%) and carbon content (85.87 ± 0.083%), and consequently the lowest amount of ash (3.52 ± 0.08%). BHD showed a better water-holding capacity (303.26 ± 15.21%) and higher pH value (7.65 ± 0.14). The investigations conducted on the biochar from both species indicate a strong suitability of these woods for producing high-quality biochar. Full article

Pellets can be produced not only from forest dendromass but also from agricultural dendromass derived from short rotation coppice (SRC) plantations, as well as surplus straw from cereal and oilseed crops. This study aimed to determine the thermophysical properties and elemental composition of 16 types of pellets produced from four types of forest biomass (Scots pine I, alder, beech, and Scots pine II), four types of agricultural biomass (SRC willow, SRC poplar, wheat straw, and rapeseed straw), and eight types of pellets from mixtures of wood biomass and straw. Another aim of the study was to demonstrate which pellet types met the parameters specified in three standards, categorizing pellets into thirteen different classes. As expected, pellets produced from pure Scots pine sawdust exhibited the best quality. The quality of the pellets obtained from mixtures of dendromass and straw deteriorated with an increase in the proportion of cereal straw or rapeseed straw in relation to pure Scots pine sawdust and SRC dendromass. The bulk density of the pellets ranged from 607.9 to 797.5 kg m⁻³, indicating that all 16 pellet types met the requirements of all six classes of the ISO standard. However, it was determined that four types of pellets (rapeseed, wheat, and two others from biomass mixtures) did not meet the necessary requirements of the Premium and Grade 1 classes. The ash content ranged from 0.44% DM in pellets from pure Scots pine sawdust to 5.00% DM in rapeseed straw pellets. Regarding ash content, only the pellets made from pure Scots pine sawdust met the stringent requirements of the highest classes, A1, Premium, and Grade 1. In contrast, all 16 types of pellets fulfilled the criteria for the lower classes, i.e., Utility and Grade 4. Concerning the nitrogen (N) content, seven types of pellets met the strict standards of classes A1 and Grade 1, while all the pellets satisfied the less rigorous requirements of classes B and Grade 4. Full article

As a core structure within the Qing Changling Mausoleum, a UNESCO World Cultural Heritage site, Long’en Hall preserves a relatively complete set of Qing dynasty imperial lacquered furniture. These furnishings provide critical physical evidence for studying Qing dynasty sacrificial rituals and the craftsmanship of court lacquerware. However, limited research has been conducted on the surface finishing techniques of such furnishings, posing challenges to their conservation and accurate restoration. This study focuses on representative furnishings from Long’en Hall—including an offering table, an incense pavilion, a throne, and a poke lamp—and employed a multi-method analytical approach comprising fluorescence microscopy (FM), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared (FTIR) spectroscopy. The analysis was conducted on the following two levels: the lacquer layer structure and material composition. The results show that the furnishings in the Long’en Hall adopt the typical structure of “lacquer ash layer–color lacquer layer”, and the color lacquer layer is composed of raw lacquer, tung oil, animal glue, and other natural organic ingredients as film-forming materials, supplemented with inorganic mineral pigments such as red lead (Pb₃O₄) and Au metal, which constitutes a stable organic–inorganic composite structure with the lacquer ash layer. The multi-analysis results show a good complementary and cross-corroboration relationship, providing the necessary technical support and a theoretical reference for Qing dynasty palace lacquer wood furniture as cultural relics worthy of scientific protection and imitation. Full article

This article sheds light on the historical dyeing traditions of rural inhabitants of the Eastern Baltic region. The 19th- and early 20th-century Estonian archival sources mention that rotted alder buckthorn (Frangula alnus Mill.) bark was used to dye woollen yarn red. The bark was rotted by leaving it outside for weeks or months before dyeing. Although dyeing red with alder buckthorn bark by fermenting it in wood ash lye is well known, the combination of rotting the bark and using the boiling method to dye red has not been reported. Practical experiments testing shorter and longer-term rotting of alder buckthorn bark both on and under the ground were conducted. Woollen yarns were dyed with rotted bark using the boiling method and were tested for lightfastness and alkaline pH sensitivity, and analysed using HPLC-DAD. The results show that rotting alder buckthorn bark has a strong effect on the achievable colours and that woollen yarns can be dyed different shades of red. The colours were sensitive to alkaline pH and their light fastness varied from very low to good. HPLC-DAD analysis showed that the pretreatment of the bark affected not only the colour but also the dye composition of the dyed wool. Full article

Fraxinus angustifolia, the main ash species in Croatia in terms of economic and ecological importance, is affected by a severe dieback initially attributed to the fungal pathogen Hymenoscyphus fraxineus. Recently, another pathogen, Diplodia fraxini, has been shown to play a key role in ash dieback in several European countries. Therefore, because the dieback symptoms of ash trees observed in Croatia are typical of Botryosphaeriaceae attacks, the aim of this study was to define the etiology of F. angustifolia dieback. To this end, symptomatic shoots and branches and cross-sections of the main stem were sampled from 20 symptomatic trees at eight locations and analyzed for the presence of D. fraxini and other possible fungal pathogens. Diplodia fraxini was the fungus most frequently associated with branch cankers and dieback; it was isolated from 17 trees in all sites monitored, and its pathogenicity towards F. angustifolia was confirmed. The fungus was also associated with wood necrosis at the base of the trunk in two trees. Other fungi, namely H. fraxineus, Diaporthe eres, Diplodia seriata, Botryosphaeria dothidea, Armillaria gallica, and Lentinus tigrinus, were isolated sporadically. Full article