Search Results (20)

Agricultural residues serve as a vast yet underutilized biomass resource with significant potential for bioenergy and biomaterial applications. Converting these residues into densified biomass pellets enhances energy density, handling efficiency, and transportability, offering a sustainable alternative to conventional feedstocks. While extensive research has focused on woody biomass, studies on the pelletization of vegetable crop foliage remain limited. This study examines the pelletability of foliage from corn, soybean, tomato, eggplant, cucumber, and summer squash, assessing their physical properties, bulk durability, bulk density, and energy consumption during pelletization. Results demonstrated that variation in biomass composition significantly influences pellet quality, with lignin content improving durability and ash content affecting moisture uptake and combustion properties. Cucumber had the highest pellet density (691.2 kg/m³) and durability (97.9%), making it suitable for long-term storage and transport. Sawdust exhibited the lowest moisture absorption (16–18% db), which is attributed to its highest lignin content. Pelletization energy requirements varied significantly, with cucumber (21.8 kWh/t) and summer squash (18.7 kWh/t) requiring the lowest energy input, whereas soybean (49.6 kWh/t) and sawdust (47.3 kWh/t) exhibited the highest energy demands due to greater resistance to densification. A predictive model was developed to correlate single pellet density and durability with bulk pellet properties—yielding high predictive accuracy, with R² = 0.936 for bulk density (BD_e) and R² = 0.861 for bulk durability (BD_u)—thereby facilitating process optimization for large-scale pellet production. This study demonstrated that foliage residues from greenhouse crops, such as cucumber and summer squash, can be effectively pelletized with low energy input and high physical integrity. These outcomes suggest that such underutilized agricultural residues hold promise as a densified intermediate feedstock, supporting future applications in bioenergy systems and advancing circular resource use in controlled-environment agriculture. Full article

Coffee is one of the most widely consumed beverages in the world; the European Union alone consumes about 2.5 million tons of coffee per year. Yearly, millions of tons of coffee residues are generated, becoming an attractive material for circular economy flows. This study explores the potential of utilizing pelletized coffee residues as sustainable bioenergy sources within the framework of a circular economy. The coffee residues, obtained from damaged capsules and pods from factories, were utilized in pure form or blended with sawdust at different percentages, then analyzed with respect to their physical and thermochemical parameters. The results indicate that unblended coffee residues exhibit favorable combustion properties with respect to heating value (18.84 MJ kg⁻¹), but also high concentrations of N (4.14%) compared to the conventional pellets obtained from other agricultural residues. The blending with woody material negatively affects both durability and bulk density, but simultaneously promotes a reduction in ash content (3.09%) and N content (1.94%). In general, this study confirmed the findings of previous scientific reports, highlighting that at least 50% blending with low-nitrogen biomasses is necessary to reach the marketability of the product. In addition, this study highlighted the criticality in terms of durability that these mixtures confer to the final product, emphasizing that future research should focus on optimizing the combination of these factors to improve the properties of the pellet. Full article

Auricularia heimuer is a wood-rotting edible mushroom, and with the continuous development of the industry, the research on its grass-rotting cultivation is becoming more and more important. In this study, A. heimuer was cultivated using herbaceous substrate (reed) completely replacing the traditional woody substrate (oak), and the correlation between the relative expression of cellulase gene, cellulase activity, cellulose degradation and yield of different strains of A. heimuer were studied by combining qRT-PCR technology at different growth stages. The results showed that the cellulose degradation were positively correlated with the yield of reed and sawdust substrate at two growth stages, and were positively correlated with three cellulase activities. The relative expression of four cellulase genes were positively correlated with enzyme activity. There were inter-strain differences in the expression of the enzyme genes, which were basically consistent with the trend of the enzyme activity of the strains; g5372 and g7270 were more actively expressed in the mycelium period, while g9664 and g10234 were more actively expressed in the fruiting period. The results of SEM showed that the mycelium of A15 and A125 were different in their ability to degrade and utilize lignocellulose in reed substrate. The parental hybridization test further verified that qRT-PCR could be used as a rapid method to evaluate the cellulose degradation ability of A. heimuer strains. Seven strains (A12, A15, A184, A224, Z6, Z12, and Z18) with high cellulose degradation ability were screened. This study provides a reference for further understanding the role of A. heimuer cellulase genes in the degradation and metabolism of cellulose and for breeding new varieties more suitable for herbaceous substrate cultivation. Full article

Thermogravimetric analysis (TGA) was performed on six samples of pine wood, poplar sawdust and olive residue, and the kinetic parameters were evaluated by using isoconversional models. The hemicellulose, cellulose and lignin contents were also estimated using the Fraser–Suzuki deconvolution method. In addition, a range of thermodynamic parameters and combustion indices was calculated. Significant correlations were found between the kinetic, thermodynamic and combustion parameters. The ignition index showed an inverse relationship with the activation energy, whereas the burnout index correlated with enthalpy values for most samples. Higher heating rates during TGA increased ignition and combustion efficiencies but decreased combustion stability. Differences in behaviour were detected between the olive residues, which had a much higher lignin content (51.2–56.9%), and the woody biomass samples (24.2–29.2%). Moreover, the sample with the highest ash content also exhibited some distinctive characteristics, including the lowest high heating value and ignition index, coupled with the highest activation energy, indicating a less favourable combustion behaviour than the other samples. The particle size of the samples was also found to be critical for both combustion efficiency and safety. Full article

The behavior of wheat straw biomass (WS), woody sawdust biomass (WB), and their blends during catalytic co-pyrolysis are analyzed in the presence of CaO catalyst, which is obtained from the calcination of mussel shells. Synergy analysis of blends and pure materials is measured by studying the difference between theoretical and experimental values of wt.%/min, (RL%), and (WL%), which correspond to maximum weight loss rate, residue left, and weight loss, respectively. The Coats–Redfern method is utilized for evaluating the thermo-kinetic properties. The chemical reaction order model F1 is the best model that describes the Ea of 60.05 kJ/mol and ∆H, ∆G, and ∆S values of 55.03 kJ/mol, 162.26 kJ/mol, and −0.18 kJ/mol.K, respectively, for the optimum blend 80WS−20WB, reducing the thermo-kinetic properties. Model D3 showed better results for the Ea, ∆H, ∆G, and ∆S for the 5% CaO blend, which certified the viability of co-pyrolysis of WS and WB, while DTG indicated that exothermic and endothermic reactions occur together. Full article

As a by-product of wastewater treatment, sewage sludge can be used for natural, agricultural, or energy purposes. One method of preparing sludge for management and use is solar drying. To intensify the drying process, natural additives can be used to alter the structure of the sludge and accelerate the evaporation of water. This research aimed to evaluate the influences of different organic additives in sewage sludge mixtures on the physicochemical and energy parameters of briquettes. This research was carried out without thermal boosting in a 4 × 2.5 × 2 m plastic tunnel. The tunnel was equipped with three drying stations and control and measuring equipment. In two test series, sludge additives in the form of straw and lignocellulosic materials, sawdust, bark, woodchips, and walnut shells, were used. Briquettes were made from the resulting mixtures and then subjected to physical and chemical analyses. This research showed high variability in the contents of trace elements, nitrogen, and sulphur in relation to an increase in the amount of sludge in the briquettes, which, for the briquettes made from sewage sludge, was nearly twice as high as for the briquettes made from the mixtures. The results of the flue gas analysis for the briquettes with sawdust and wood chip additives were very similar. The briquettes made from sewage sludge with lignocellulosic materials (bark and wood chips) had fuel properties similar to woody biomass, with a calorific value and heat of combustion of 15–16 MJ/kg. Fibrous additives (straw) significantly increased the strength parameters of the briquettes, by more than 50% of the value. The compositions and properties of the mixtures affected the following briquetting parameters: temperature and compressive force. The briquettes made from sewage sludge and additives can be classified according to ISO 21640 as SRFs (solid recovered fuels). In most of the results, the net calorific value (NCV) was 3 to 4; the chlorine content (CL) was 2 to 1; and the mercury content (Hg) was 1. The sewage sludge mixtures facilitated the agricultural and energy use of the briquettes. Full article

This study analyzes the combustion of pellets and briquettes made of plant biomass in low-power heating devices powered periodically with fuel being placed on the grate, as well as after modification using an automatic fuel feeding system in the gutter burner. The use of herbaceous biomass in the form of pellets in low-power heating devices with automatic fuel feeding and combustion in a gutter burner is not widely promoted and popular. Therefore, this study used four types of herbaceous waste biomass (wheat straw, rye straw, oat straw and hay) and one type of woody waste biomass (birch sawdust) for testing. The basic chemical characteristics were determined for the raw materials. After appropriate preparation, the selected starting materials were subjected to briquetting and pelleting processes. Selected physical properties were also determined for the obtained biofuels. Biofuels made from birch sawdust had the lowest heat value (16.34 MJ·kg⁻¹), although biofuels made from wheat, rye and hay straw had a slightly lower calorific value, respectively: 16.29; 16.28 and 16.26 MJ·kg⁻¹. However, the calorific value of oat straw biofuels was only 15.47 MJ kg⁻¹. Moreover, the ash content for herbaceous biomass was 2–4 times higher than for woody biomass. Similar differences between herbaceous and woody biomass were also observed for the nitrogen and sulfur content. To burn the prepared biofuels, a domestic grate-fired biomass boiler was used, periodically fed with portions of fuel in the form of pellets or briquettes (type A tests), which was then modified with a gutter burner enabling the automatic feeding of fuel in the form of pellets (type B tests). During the combustion tests with simultaneous timing, the concentration of CO₂, CO, NO and SO₂ in the exhaust gases was examined and the temperature of the supplied air and exhaust gases was measured. The stack loss (qA), combustion efficiency index (CEI) and toxicity index (TI) were also calculated. The research shows that the use of automatic fuel feeding stabilizes the combustion process. The combustion process is balanced between herbaceous and woody biomass biofuels. Disparities in CO₂, CO and T_gas emissions are decreasing. However, during type B tests, an increase in NO emissions is observed. At the same time, the research conducted indicates that the combustion of herbaceous biomass pellets with their automatic feeding into the combustion chamber is characterized by an increase in combustion efficiency, indicating that when the combustion process is automated, they are a good replacement for wood biofuels—both pellets and briquettes. Full article

Wood pellets are a versatile ingredient to produce bioenergy and bioproducts. Wood pellet manufacturing in Canada started as a way of using the excess sawdust from sawmilling operations. With the recent dwindling availability of sawdust and the growth in demand for wood pellets, the industry uses more non-sawdust woody biomass as feedstock. In this study, woody biomass materials received from nine wood pellet plants in British Columbia (BC) and Alberta were analyzed for their properties, especially those used for fractionating feedstock to make pellets. Half of the feedstock received at the plants was non-sawdust. Moisture contents varied from 10 to 60% wet basis, with the hog having an average of 50%. Ash contents ranged from 0.3 to 4% dry basis and were highest in the hog fraction. Bulk density varied from 50 to 450 kg/m³, with shavings having the lowest bulk density. Particle density ranged from 359 kg/m³ for infeed mix to 513 kg/m³ for sawdust. In total, 25% of particles received were larger than 25 mm. The extraneous materials (sand, dirt) in the infeed materials ranged from 0.03% to 1.2%, except for one hog sample (8.2%). Plant operators use mechanical fractionation and blending to meet the required ash content. In conclusion, further instrumental techniques to aid in fractionation should be developed. Full article

Co-pyrolysis is one possible method to handle different biomass leftovers. The success of the implementation depends on several factors, of which the quality of the produced bio-oil is of the highest importance, together with the throughput and constraints of the feedstock. In this study, the fast co-pyrolysis of palm kernel shell (PKS) and woody biomass was conducted in a micro-pyrolyser connected to a Gas Chromatograph–Mass Spectrometer/Flame Ionisation Detector (GC–MS/FID) at 600 °C and 5 s. Different blend ratios were studied to reveal interactions on the primary products formed from the co-pyrolysis, specifically PKS and two woody biomasses. A comparison of the experimental and predicted yields showed that the co-pyrolysis of the binary blends in equal proportions, PKS with mahogany (MAH) or iroko (IRO) sawdust, resulted in a decrease in the relative yield of the phenols by 19%, while HAA was promoted by 43% for the PKS:IRO-1:1 pyrolysis blend, and the saccharides were strongly inhibited for the PKS:MAH-1:1 pyrolysis blend. However, no difference was observed in the yields for the different groups of compounds when the two woody biomasses (MAH:IRO-1:1) were co-pyrolysed. In contrast to the binary blend, the pyrolysis of the ternary blends showed that the yield of the saccharides was promoted to a large extent, while the acids were inhibited for the PKS:MAH:IRO-1:1:1 pyrolysis blend. However, the relative yield of the saccharides was inhibited to a large extent for the PKS:MAH:IRO-1:2:2 pyrolysis blend, while no major difference was observed in the yields across the different groups of compounds when PKS and the woody biomass were blended in equal amounts and pyrolysed (PKS:MAH:IRO-2:1:1). This study showed evidence of a synergistic interaction when co-pyrolysing different biomasses. It also shows that it is possible to enhance the production of a valuable group of compounds with the right biomass composition and blend ratio. Full article

Agriculture can degrade soils and reduce microbial diversity. The reduction in microbial diversity of degraded soils is due to their long-term agricultural use. In most cases, such areas are afforested but rarely succeed in converting them into first-generation pine forests without adequately revitalizing the soils and restoring the natural relationships characteristic of forest habitats. This is possible thanks to the positive changes in soil biodiversity. To facilitate and enhance this phenomenon in the present experiment, various forms of organic matter were added to the soil: pine bark compost scattered on the soil surface (BCS) or placed under the roots of the seedlings at planting (BCR), woody debris (WW) and sawdust (S), while the control plot was not treated. The studies started in 2001 on two experimental plots, a poorer one in Bielsk and a more fertile one in Czarne Człuchowskie (eastern and northern Poland, respectively). The following year, 2-year-old pine seedlings (Pinus sylvestris L.) were planted on the plots. After 20 years, the physicochemical properties of the soil and its microbial composition were determined and compared with the control. The results encourage the use of organic matter for established pine forest crops on post-agricultural land for revitalization: C, N, and P content increased both in the organic layer and in the topsoil (up to 40 cm), where most fine roots are located. The total content of exchangeable base cations (Ca, Mg, K) and the sorption capacity of the soils (a measure of the ion binding capacity of the soil) also improved. The genetic analyses carried out using the molecular method (NGS) showed positive changes in the composition of the soil microbiome. Compared to poorer soil conditions in richer habitats, the number of taxa increases when organic matter is added, leading to significant qualitative changes in the bacteriome. The addition of organic material from the forest had a positive effect on the bacterial communities, which in turn accelerated the changes in the diversity of bacteriomes characteristic of agricultural soils and brought them closer to the forest ecosystem. The organic horizon was restored, and at the same time, the biodiversity of the soil microbiome increased, which is important for the health and sustainability of pine stands on formerly agricultural land. Full article

Afforestation of former agricultural land poses a real challenge for foresters because soil life is often severely limited by the loss of natural soil fungal diversity. In addition, former agricultural soils have low levels of fungal species typical of forest soils, which have a unique microbiome that plays a protective role (antagonists, plant growth promoters, mycorrhizal fungi, etc.). This study aimed to determine the effect of using organic material in the form of bark compost, wood waste, and sawdust to improve the soil mycobiome of soils that have been damaged by their agricultural use. This study used experimental plots established 20 years ago, and we compared the biodiversity of the treated soils with that of the control soils by analysing soil samples with powerful molecular methods. Next-generation sequencing analysis of DNA extracted from soil samples and subsequent analysis of their species composition and biodiversity showed that the mycobiome of soil fungi has been altered by the addition of various forms of organic material. The proportion of fungi belonging to the Ascomycota decreased in favour of species from the Basidiomycota and Mucoromycota. The dominant fungal groups in the soil of the control area were Sagenomella, Wilcoxina, Oidiodendron, Meliniomyces, and Penicillium. Enrichment with organic matter by adding bark compost under the roots led to an increase in Penicillium, Inocybe, and Amphinema. The application of bark compost on the surface led to an increase in the dominance of Inocybe fungi in the soil. The mycobiome of the plant to which woody debris was applied was characterised by a marked dominance of fungi of the genera Russula, Oidiodendron, and Penicillium. Similar ratios were found in the plant to which sawdust was applied, where the fungi Meliniomyces, Penicillium, Oidiodendron, and Russula dominated. A comparative analysis of fungal diversity with the Shannon diversity index showed that the most diverse fungal communities were found in the sawdust plant (6.56), while the control sample (a soil sample from an agricultural area where no organic material was applied) had an index of 5.71. After the treatments, more potential antagonists against pine pathogens and mycorrhizal fungi were found to form beneficial symbiotic relationships with them. In our opinion, the results of this study show that it is worthwhile to introduce different forms of organic matter to post-agricultural land to improve soil biodiversity and mycorrhizal associations of pine roots with fungi to ensure the sustainability of the first generation of forests created. Full article

A high load of inorganics in raw lignocellulosic biomass is known to inhibit the yield of bio-oil and alter the chemical reactions during fast pyrolysis of biomass. In this study, palm kernel shell (PKS), an agricultural residue from palm oil production, and two other woody biomass samples (mahogany (MAH) sawdust and iroko (IRO) sawdust) were pretreated with distilled water or an acidic solution (either acetic, formic, hydrochloric (HCl) or sulfuric acid (H₂SO₄)) before fast pyrolysis in order to investigate its effect on the primary products and pyrolysis reaction pathways. The raw and pretreated PKS, MAH and IRO were pyrolysed at 600 °C and 5 s with a micro-pyrolyser connected to a gas chromatograph–mass spectrometer/flame ionisation detector (GC-MS/FID). Of the leaching solutions, HCl was the most effective in removing inorganics from the biomass and enhancing the primary pyrolysis product formed compared to the organic acids (acetic and formic acid). The production of levoglucosan was greatly improved for all pretreated biomasses when compared to the original biomass but especially after HCl pretreatment. Additionally, the relative content of the saccharides was maximised after pretreatment with H₂SO_4, which was due to the increased production of levoglucosenone. The relative content of the saccharides increased by over 70%. This increase may have occurred due to a possible reaction catalysed by the remaining acid in the biomass. The production of furans, especially furfural, was increased for all pretreatments but most noticeable when H₂SO₄ was used. However, the relative content of acids and ketones was generally reduced for PKS, MAH and IRO across all leaching solutions. The relative content of the phenol-type compound decreased to a large extent during pyrolysis after acid pretreatment, which may be attributed to dehydration and demethoxylation reactions. This study shows that the production of valuable chemicals could be promoted by pretreatment with different acid solutions. Full article

A 20-year study of a pine stand on post-agricultural land showed that woody debris in the form of organic matter can be successfully used to restore symbiotic mycorrhizal communities, as is the case with forest soils. Woody substrates restored organic matter in soils altered by long agricultural use and had a positive effect on the composition of mycobiota antagonistic to pathogens, especially to Heterobasidion annosum, the causal agent of the dangerous disease root and stump rot of many forest tree species, including stands of Pinus sylvestris (L.). In a study that started in 2001 in the forest district of Czarne Człuchowskie (northern Poland), the following organic materials were used: wood residues (W), sawdust (S), bark compost (B), and compost applied to the root zone during planting (G). The organic materials were spread in the form of mulch over the entire area during planting. After twenty years, it was found that the substrates used provided suitable growth conditions for mycobiome useful for pines. The addition of organic matter did not change the alpha biodiversity of the soil, but in the long term led to significant changes in the composition of mycobiota (beta biodiversity). The changes in the soil after the addition of organic material naturally accelerated the formation of the forest habitat. A number of fungi evolved that degraded added lignin and cellulose while being antagonists of H. annosum and other pine pathogens. In particular, the well-known hyperpathogens of the genus Trichoderma played an important role by promoting resistance of the soil environment to pathogens. Soil enrichment by bark compost and wood residues increased the relative abundance of Trichoderma more than fourfold.Mycorrhizal fungi became dominant in soil enriched with organic matter. After enriching the soil with bark compost, the relative abundance of Amphinema and Inocybe increased to 5%. The relative abundance of Russula in soil enriched with wood residues and sawdust increased to 9% and 5%, respectively. Mycorrhizal fungi, e.g., of the genus Ąmanita, Rusula, which formed root mycorrhizae, not only increased the root receiving area many times over, but also protected the roots (mechanically and chemically from pathogens). Altogether, the observed positive changes increase the chances that the first generation of pines will survive on the ground. Full article

Burning woody biomass for energy is gaining attention due to the environmental issues associated with fossil fuels and carbon emissions. The carbon released from burning wood is absorbed by plants and, hence, offsets pollution. The purpose of this study was to investigate the combustion characteristics (heat calorific values and ash contents) of three timbers: Araucaria cunninghamii, Instia bijuga, and Pometia pinnata to recommend for fuelwood. The test samples were sawdust particles (treatment) and solid woods (control) extracted from the heartwoods. The sawdust particles were oven dried, sieved, and pelletized into pellets using a hand-held pelletizing device, thus, forming a cylindrical dimension (volume 1178.57 mm³, oven-dry density 0.0008 g/mm³). Meanwhile, the solid woods were cubed and oven dried (volume 1000.00 mm³, oven-dry density 0.001 g/mm³). Prior to combustion in a semi-automatic bomb calorimeter, 90 test specimens (15 replicates per treatment and control per species) were conditioned to 14% moisture content (at a temperature of 105 °C) and weighed to a constant (unit) mass (1.0 g). The heat energy outputs and ash residues (of treatments) were analyzed statistically. The results indicated variability in heat energy outputs and ash residues between the test specimens of the three species. Comparatively, the treatment specimens of A. cunninghamii produced a higher calorific value (18.546 kJ/g) than the control (18.376 kJ/g), whilst the treatment specimens of I. bijuga and P. pinnata generated lower heat calorific values (17.124 kJ/g and 18.822 kJ/g, respectively) than the control (18.415 kJ/g and 20.659 kJ/g, respectively). According to ash content analysis, A. cunninghamii generated higher residues (6.3%), followed by P. pinnata (4.5%), and I. bijuga (2.8%). The treatment specimens of the three species could not meet the standard heat energy requirement (20.0 kJ/g) and, thus, were unsuitable for fuelwood. However, the control specimens of P. pinnata generated an equivalent heat energy (20.659 kJ/g) and could be a potential fuelwood. Full article

This study investigated the quantitative and qualitative attributes of liquid product and biochar obtained from pyrolysis of woody biomass (rubberwood sawdust (RWS)) and non-woody biomasses (oil palm trunk (OPT) and oil palm fronds (OPF)). The prepared biomass was pyrolyzed at temperatures of 500 °C, 550 °C, and 600 °C by using an agitated bed pyrolysis reactor, and then the yields and characteristics of liquid product and biochar were determined. The results showed that liquid product and biochar yields were in the respective ranges of 35.94–54.40% and 23.46–25.98% (wt.). Pyrolysis of RWS at 550 °C provided the highest liquid yield. The energy content of the water free liquid product was in the range 12.19–22.32 MJ/kg. The liquid product had a low pH and it mainly contained phenol groups as indicated by GC-MS. The biochars had high carbon contents (75.07–82.02%), while their oxygen contents were low (14.22–22%). The higher heating value (HHV) of biochar was in the range 26.42–29.33 MJ/kg. XRF analysis revealed that inorganic elements had higher contents in biochar than in the original biomass. The slagging and fouling indexes of biochar were also different from those of the biomass. High carbon content of the biochar confirms potential for its use in carbon sequestration. The specific surface of biochar was lower than that of biomass, while the average pore diameter of biochar was larger than for raw biomass as revealed by BET and SEM. These results on liquid product and biochar obtained from RWS, OPT, and OPF demonstrate that they are promising feedstocks for biofuels and other value-added products. Full article