Pine Sawdust Research Articles

Enhanced pyrolysis of woody biomass under interaction of microwave and needle-shape metal and its production properties

Pyrolysis is one of the routes to value-added utilization of biomass, and the pyrolysis process can be enhanced with microwave heating, especially in the presence of catalyst. However, the catalysts used for biomass pyrolysis are usually in form of powder or grain, which leads to a problem that the catalysts are hard to separate from bio-char after the pyrolysis process. Based on this issue, the development of an enhanced microwave-assisted pyrolysis method without catalyst is of great significance. Therefore, this study proposes the method of microwave-enhanced pyrolysis of woody biomass via the interaction of microwave and needle-shape metal (iron-wire). In the paper, the pyrolysis characteristics and kinetic behaviors in the presence and in the absence of iron-wire were investigated, using pine sawdust and the mixture of biomass components as the material. Moreover, the properties of pyrolysis products with and without microwave-metal interaction were characterized, and the mechanism of microwave-metal interaction on the enhancement of pyrolysis was also analyzed. The results showed that the value of Ea reduced by 50% with microwave-metal interaction and the process under microwave-metal interaction was more conducive to the generation of bio-gas, with the yield of 62.43 wt%. Microwave-metal interaction increased ID/IG value of bio-char from 0.69 to 0.92, indicating an improvement of graphite degree, and decreased the content of aromatic compounds in bio-oil by 11.8%. The enhanced pyrolysis process is due to the increased electromagnetic distribution density after the insertion of iron wire into microwave and even microwave discharge occurred at the initial stage.

Short ozonation for effective removal and detoxification of fermentation inhibitors resulting from thermal pretreatment

Common pretreatment methods for bioethanol production from lignocellulosic biomass are carried out under acidic conditions at high temperatures and result in formation of by-products, such as formic acid, levulinic acid, furfural and HMF (5-hydroxymethylfurfural). These by-products have an inhibitory effect on yeasts, reducing yeast growth and fermentation, and thus ethanol production. In this study, the inhibitory dose of these by-products was investigated along with the use of short ozonation as a means of their detoxification. When the effect of ozone was tested directly on yeasts (without inhibitors), they exhibited tolerance to ozone, suggesting the utilization of ozonation in simultaneous saccharification and fermentation. Fifteen minutes of ozonation removed over 90% of the inhibitory effect originating from 50 mM furfural, 50 mM formic acid, 25 mM HMF, and 100 mM levulinic acid. Thermal pretreatment and enzymatic hydrolysis of pine sawdust resulted in inhibition of microaerobic yeast growth. This inhibition was relieved after short ozonation; however, continuous ozonation has motivated further inhibition, suggesting the formation of additional inhibitory compounds. The results demonstrate the applicability of short ozonation as a practical approach for removing by-products’ inhibitory effects originating from thermal pretreatment of lignocellulosic waste.

The Edible Gray Oyster Fungi Pleurotus ostreatus (Jacq. ex Fr.) P. Kumm a Potent Waste Consumer, a Biofriendly Species with Antioxidant Activity Depending on the Growth Substrate

Nowadays, climate change is not the only threat facing our planet. There are also other types of pollution such as waste that poisons soils and water and kills plants, harming humans and animals. Sustainability represents a key issue for the actual Global Citizen. For this reason, our article is dedicated to offering biofriendly solutions to decrease wastes, give them a positive meaning, such as a substrate for an edible oyster fungus with nutritive and biological properties usefully for humans. Three types of wastes such as coconut coir, pine sawdust, and paper waste—representative symbols of pollution in Ecuador—have been tested as suitable growing substrate for the edible fungi Pleurotus ostreatus (Jacq. ex Fr.) P. Kumm by analyzing parameters such as Biological Efficiency, Mushroom Yield, and Productive Rate. The influence of these “waste” substrates on the nutritive (protein content), biological characteristic (antioxidant activity), and the content of human-health-sustaining compounds (phenols, flavonoids) were also evaluated using the Kjeldahal, DPPH, ABTS, FRAP, and Folin–Ciocalteu methods. The results indicate that all the waste products represent desirable substrates for growing the edible fungi, with more focus on coconut coir waste (one of the principal pollution problems in Ecuador), but that also achieved the increase in the fungi’s desirable characteristics. Coconut coir waste could be an environmentally friendly solution that also offers for humans additional nutritive and healthy benefits.

Sorption-enhanced steam gasification of woody biomass assisted by Ca/Na/FS (fine slag) composite sorbents

In this research, composite sorbents with high activity in promoting H2 production during sorption-enhanced steam gasification of pine sawdust (PS) were developed by doping coal gasification fine slag (FS) and NaOH into calcined conch shell (CS). The tests performed in a laboratory-scale fixed bed reactor demonstrated that the composite sorbents greatly improved H2 concentration and yield over that achieved with CHCS (CS after hydration and calcination), reaching 73.5% and 600.7 mL/g-PS, respectively. This promotion effect on H2 production was not influenced by the unburned carbon in FS. To obtain high H2 concentration and yield with as little NaOH and as much FS as possible, the optimum sorbent was found to be 3CS-2FS-0.32Na (in mass ratio of CS:FS:NaOH = 3:2:0.32). Under this condition, the H2 concentration and yield reached 74.3% and 572.3 mL/g-PS, respectively. In five cycles of experiment, although the H2 yield of 3CS-2FS-0.32Na decreased from 572.3 mL/g-PS to 416.6 mL/g-PS, it was always higher than with CHCS alone by at least 28%. The results in this study indicate that FS has potential to be an effective inert support material that endows CaO with high activity in H2 production during sorption-enhanced steam gasification. This might help to provide a new approach to minimizing the negative environmental impact of FS.

Insights into CO2 adsorption on KOH-activated biochars derived from the mixed sewage sludge and pine sawdust

The environment issues associated with global warming and climate change caused by continuous increase in greenhouse gas emissions have attracted worldwide concerns. As renewable resources with good adsorption property, biochar is an efficient and environmental friendly adsorbsent for CO2 capture. In this study, the CO2 adsorption behavior of biochars derived from feedstock mixtures of 70% pine sawdust and 30% sewage sludge by KOH modification was investigated. The textual properties and functional groups of the pristine biochars have been significantly enhanced after KOH activation. With highly developed microporosity, the specific surface area (SSA) of the KOH-modified biochars increased by 3.9–14.5 times. Furthermore, higher CO2 adsorption capacities of 136.7–182.0 mg/g were observed for the modified biochars, compared to pristine ones (35.5–42.9 mg/g). The development of micropores by KOH activation significantly increased the CO2 adsorption capacity. Meanwhile, the presence of hetero atoms (O and K) also positively influenced CO2 adsorption capacity of biochar. Noticeably, both physical and chemical adsorption played a crucial role in CO2 capture, which was verified by different characterization methods including high resolution scanning electron microscope, X-ray photoelectron spectroscopy and in situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The Findings of this study demonstrate the -significance of chemical sorption by identifying the transformation of CO2 by biochar composites and in situ characterization of weakly adsorbed and newly formed mineral species during the CO2 sorption process. Moreover, BC700K showed 97% recyclability during 10 consecutive adsorption-desorption cycles at 25 °C, 1 bar. The results obtained in the present study may inspire new research interest and provide a comprehensive insight into the research subject to biochars derived from feedstock mixtures for CO2 capture.

Soil Enzyme Activity Response under the Amendment of Different Types of Biochar

Biochar (BC) is a material that finds many applications in agriculture and environmental activities. The aim of the study was to define the influence of biochar produced from various organic materials: mellow compost (MC), stabilized municipal sewage sludge (MSS), pine sawdust (PS), sycamore sawdust (SS) and oak leaves (OL) on soil enzyme activity, as well as its relations with carbon and nitrogen content. After a 60-day incubation of soil and BC, the activity of dehydrogenases (DEH), catalase (CAT), alkaline (AlP) and acid (AcP) phosphatases was investigated. The basic parameters of soil were also determined: TOC, TN, DOM, pH in H2O, available phosphorus (AP). The highest AP content was obtained in the S + MSS, S + OL and S + MC variants. Enzyme activity was highest in soil with MSS BC, regardless of incubation time. After 60 days, the activity of soil enzymes was inhibited. The obtained results indicate that the response of enzymatic activity to biochar depends on the feedstock material and the incubation time. When using BC as an exogenous matter, it is necessary to determine the TOC/TN ratio. For the very wide range of this parameter, supplemental nitrogen fertilization or mixtures of different biochars should be applied.

Hydrogen-Rich Gas Production from Two-Stage Catalytic Pyrolysis of Pine Sawdust with Nano-NiO/Al2O3 Catalyst

Hydrogen production from biomass pyrolysis is economically and technologically attractive from the perspectives of energy and the environment. The two-stage catalytic pyrolysis of pine sawdust for hydrogen-rich gas production is investigated using nano-NiO/Al2O3 as the catalyst at high temperatures. The influences of residence time (0–30 s) and catalytic temperature (500–800 °C) on pyrolysis performance are examined in the distribution of pyrolysis products, gas composition, and gas properties. The results show that increasing the residence time decreased the solid and liquid products but increased gas products. Longer residence times could promote tar cracking and gas-phase conversion reactions and improve the syngas yield, H2/CO ratio, and carbon conversion. The nano-NiO/A12O3 exhibits excellent catalytic activity for tar removal, with a tar conversion rate of 93% at 800 °C. The high catalytic temperature could significantly improve H2 and CO yields by enhancing the decomposition of tar and gas-phase reactions between CO2 and CH4. The increasing catalytic temperature increases the dry gas yield and carbon conversion but decreases the H2/CO ratio and low heating value.

Mikrovolnovaya obrabotka prirodnykh sorbentov v tekhnologii ochistki stochnykh vod [Microwave treatment of natural sorbents in wastewater purification

Purpose: Modification of natural sorbents to improve their sorption properties. Design: Microwave treatment effect on the properties of peat, reindeer moss, moss and pine sawdust. Research findings: Short-term microwave treatment has no effect on the moisture and oil absorption by peat and moss. On the contrary, the properties of reindeer moss and sawdust are improved, especially of wood waste, i. e., oil capacity increases by 41 %. The microwave treatment of reindeer moss and pine sawdust provides 11.4 and 17 % increase in the sorption capacity in relation to oil products dissolved in water, respectively. The best effect is observed for pine sawdust irradiation with 600 W microwaves for one minute. Practical implication: Activated sorbents can be used in purification of wastewater containing petroleum products. Originality/value: The sorption properties of Arctic natural materials modified with microwaves are studied for the first time.

Preparation of coke from biomass char modified by vapour deposition of tar generated during pyrolysis of woody biomass

ABSTRACT In this study, in order to use woody biomass for coke production, carbon/carbon composites are first prepared using the vapour deposition (VD) method, whereby gaseous-tars generated by the pyrolysis of pine sawdust is deposited onto the pyrolysed pine sawdust char by a vertical flow-type fixed-bed reactor with pyrolysis and VD zones. Then, coke properties and gasification reactivity of composite and composite/coal blends are investigated to clarify the binder effect of biomass tar on the properties of prepared coke. The carbon/carbon composites could be prepared with a high yield at a low VD temperature. High-strength and high-reactivity coke was produced from the composite. The properties of the coke produced from composite/caking coal blending showed that the optimum blending amount depends on the type of caking coal, but high-strength and high-gasification reactivity coke can be produced. Additionally, it was found that 3–15wt-%-biomass could be added as char for coke production.

Kinetic and thermodynamic studies of biomass pseudo-components under thermo-oxidative degradation conditions using asymmetric function of Bi-Gaussian as deconvolution technique

This work aimed at investigating the kinetic and thermodynamic characteristics of components of pine sawdust (PS), edible fungi spent substrate (FVSS) and their blend during thermo-oxidative degradation. The novelty focused on applying deconvolution technique to distinguish an overlapped peak into three individual peaks corresponding to pseudo-hemicellulose, pseudo-cellulose and pseudo-lignin, respectively. Particularly, the function of Bi-Gaussian was employed to capture the asymmetric reaction shapes. Mass loss was recorded using a thermal analyzer at heating rates of 10, 20 and 30 K min−1 in air atmosphere. Methods of Starink and master-plots were used for estimating kinetic triplet. The average activation energies of FVSS are lower than PS, with an order of pseudo-lignin > pseudo-hemicellulose > pseudo-cellulose corresponding to the ranges of 211.70–342.78, 139.00–172.53 and 128.08–146.99 kJ mol−1, respectively. The pre-exponential factor are all higher than E+10 s−1 demonstrating some simple complex chemical reactions occurred. Models of D2 and A1 dominate the degradation of pseudo-hemicellulose and pseudo-cellulose, respectively, in PS and the blend. The average values of ΔS, ΔH and ΔG are −51.62-146.31 J mol−1, 122.99–335 kJ mol−1 and 78 144.87–216.59 kJ mol−1, showing the non-spontaneous process and need energy to maintain.

Negative effects of free-living nematodes on the populations of Bursaphelenchus xylophilus in dead pine trees

The pine wood nematode (PWN), Bursaphelenchus xylophilus Nickle, is a devastating pathogen of pine forests that has caused significant economic losses and ecological damage in East Asia and Europe. Efficient and environmentally friendly methods for controlling the PWN are limited, and it is therefore necessary to explore alternative management methods. Competition between nematode populations inhibits the growth and development of one competing population. Free-living nematodes (FLNs), which are scavengers, are reported to have biological control potential and may have important value in controlling the PWN. We created a new medium that allows the rapid production of FLNs isolated from dead pine trees and studied interspecies competition. Single-factor and orthogonal tests were utilized to screen the main components of the medium and optimize ratios, respectively. Five species of FLNs were cultured in large numbers in the optimized medium. Quantified FLN/PWN competition was quantified in the laboratory, and its impact was assessed in the field with two inoculation methods. The main components of the medium are pine sawdust, glucose and agar, and the optimal ratio is 30 g/L pine sawdust, 10–20 g/L glucose and 30 g/L agar. Of the five nematode species, JR-3 (Parasitorhabditis sp.) significantly reduced PWN population densities in both the laboratory and field. The PWN population density in the wood samples around the pupal chamber was 2.91 in the experimental group compared to 13.64 in the control group during the same period in the field. This is the first study on interspecies competition between FLNs and the PWN in dead trees. JR-3 increased the rate of PWN population eradication and has the potential to help control pine wilt disease.

BRIQUETTES PRODUCTION FROM LIGNOCELLULOSIC WASTE FOR ENERGY PURPOSES AS AN ALTERNATIVE FUEL

The briquetting process was developed seeking to reuse the waste generated both in forestry production and in industrial processes. The compression of lignocellulosic waste concentrates the available energy in terms of volume and facilitates the handling and storage of these materials. The present work aims to verify the influence on the quality of briquettes of different compositions between the residues of coffee grounds, pine sawdust and cambará sawdust by evaluating the physical, chemical and mechanical characteristics of the briquettes generated from the compaction of these waste. For this, several tests were carried out with the briquettes, analyzing the properties of particle size, resistance to diametrical compression, moisture and ash for each composition of the briquette. The briquettes were produced on a 12-tonne hydraulic press. The waste used showed a high concentration of fine particles, with pine sawdust being 50.5% of particles with a diameter of 0.425mm. Coffee beans have moisture content above 50%, positively impacting the ash content and negatively impacting briquetting and tensile strength by diametral compression. In the production of briquettes, material with up to 60% addition of coffee grounds was obtained. The compression tests showed good results for the treatments, highlighting the treatments with a high concentration of pine. It is also concluded that the coffee grounds can be used in the production of briquettes with sawdust, however, it is suggested for future articles, the correction of moisture in the briquettes for better compaction.

The composition, energy, and carbon stability characteristics of biochars derived from thermo-conversion of biomass in air-limitation, CO2, and N2 at different temperatures

This study systemically investigated the characteristics of biochars derived from thermo-conversion of pine sawdust and wheat straw in air-limitation, CO2, and N2 atmospheres at the temperatures of 300–750 °C. Meanwhile, their energy and C stability parameters were also evaluated here. The results showed that biochar produced in air-limitation had less yield, fixed C and bulk C, as well as more volatile matter and inorganic elements than that produced in CO2 and N2. Biochars derived from thermo-conversion of pine sawdust in CO2 and N2 at 450–750 °C had the greatest energy densification ratios (EDR) (range: 1.40–1.61), because pine sawdust contained more lignin than wheat straw, and the thermo-conversion of lignin in N2 and CO2 at 450–750 °C benefited for the formation of fixed C. Recalcitrance potential (R50) results showed that the biochars produced in CO2 and N2 at 600–750 °C had the highest carbon stability (R50: 0.54–0.64) for given biomass, owing to the thermo-conversion of biomass in CO2 and N2 at 600–750 °C preferring to form the organic C with high aromaticity and low polarity. Nonetheless, thermo-conversion of biomass in CO2 and N2 at 300 °C presented the greatest C sequestration potential, owing to high biochar yields under these conditions. Generally, the temperature-variability for the composition, EDR, and C sequestration potential followed the order: air-limitation > CO2 > N2, whereas carbon stability presented an opposite order. Our results contributed to selecting the appropriate atmosphere to optimize the properties and performances of biochars.

Drilling of natural fiber-reinforced based polyurethane foam composite

The combination of natural fibers and renewable source matrices is an option to replace materials from non-renewable sources used in the manufacture of composites. One example is the use of pinus sawdust and sisal fibers together with a matrix of polyurethane (PU) foam derived from vegetable oils. For the application of composites in sectors such as building or furniture industry, one of the necessary processes is drilling, which allows assembling through different fastening systems. The aim of this work is to investigate the drilling process of the composites of PU foam derived from vegetable oils matrix with only pinus sawdust and hybrid pinus sawdust and sisal fibers taking into account surface damages of the holes and temperature generated during the process. Results showed that drilling parameters influence on the generation of damages mainly at the edges of the holes. Lower cutting speed and feed rate were most appropriate for drilling these types of composites, and temperatures generated during drilling showed relationship with the generation of damages.

Biosorption of nickel ions Ni2+ by natural and modified Pinus caribaea Morelet sawdust

The potential of Pinus caribaea Morelet sawdust for the removal of nickel ions (Ni2+) and other metallic trace ions (Co2+, Cr3+, Mn2+) from aqueous solutions was investigated under batch conditions. Several parameters such as size of particles, contact time, pH, initial metal and biomass concentrations, desorption conditions and reusability were evaluated on natural biomass. Biosorption was fast, effective (73%) and biomaterial can be reused after five cycles. To enhance the removal capacity of nickel, pine sawdust was modified by acidic and oxidative treatments. Cellulosic residues from sawdust sequential extraction showed great biosorption capacity (96%). In the presence of a metal mixture, oxidized sawdust had better selectivity for Cr3+ ions than for Ni2+. Pinus caribaea biomass could be an environmental, inexpensive and renewable material for the depollution of water laden with metallic trace elements.

Study on the Staged and Direct Fast Pyrolysis Behavior of Waste Pine Sawdust Using High Heating Rate TG-FTIR and Py-GC/MS.

To understand the fast pyrolysis kinetics and product evolution of waste pine sawdust, high heating rate thermogravimetry-Fourier transform infrared (TG-FTIR) was used to obtain the kinetic parameters and the chemical groups formed during the pyrolysis process, while pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was used to investigate the detailed compositions of products under the staged (seven stages from 300 to 600 °C) and direct fast pyrolysis process. Spectral bands were identified for acids, alcohols, aldehydes, aromatics, esters, ethers, hydrocarbons, ketones, phenols, and sugars. Research found that the apparent activation energy for fast pyrolysis is much higher than that of slow pyrolysis. The evolution of CO2 is the major deoxygenation route. Cracking mainly occurred at the 450 °C stage with phenols, ketones, aldehydes, and sugars as the main products. The product distributions for different stages are significantly different; the selectivity of aldehydes decreased, while phenols showed an upward trend with an increase in pyrolysis temperature. Ketones and sugars reached their peak values at 450 °C. The changes in the molecular composition of each stage helped to understand the pyrolysis process. Compared with the staged pyrolysis, the direct pyrolysis process had higher selectivity of acids, aldehydes, esters, and sugars and lower selectivity of phenols, ketones, and alcohols.

Hydrogen-Rich Gas Production from Two-Stage Catalytic Pyrolysis of Pine Sawdust with Calcined Dolomite

The potential of catalytic pyrolysis of biomass for hydrogen and bio-oil production has drawn great attention due to the concern of clean energy utilization and decarbonization. In this paper, the catalytic pyrolysis of pine sawdust with calcined dolomite was carried out in a novel moving bed reactor with a two-stage screw feeder. The effects of pyrolysis temperature (700–900 °C) and catalytic temperature (500–800 °C) on pyrolysis performance were investigated in product distribution, gas composition, and gas properties. The results showed that with the temperature increased, pyrolysis gas yield increased, but the yield of solid and liquid products decreased. With the increase in temperature, the CO and H2 content increased significantly, while the CO2 and CH4 decreased correspondingly. The calcined dolomite can remove the tar by 44% and increased syngas yield by 52.9%. With the increasing catalytic temperature, the catalytic effect of calcined dolomite was also enhanced.

Biodegradation Potential of SteccherinumOchraceum: Growth on Different Wood Types and Preliminary Evaluation of Enzymatic Activities

White-rot fungi isa source of a great variety of oxidative and hydrolytic enzymes suitable for biotechnological applications, e.g. in pulp and paper, textile and food industries, bioethanol production, degradation of recalcitrant environmental pollutants,and others. Steccherinumochraceum is a xylotrophicwhite-rot basidiomycetethat can be found in variousclimatic zones on different woody substrates (mostly well decayed). For this research, seventeenstrains of S. ochraceumwere collected in different regions of Russia from various wood substrates (aspen, alder, oak, hazel, birch and willow). Phylogeneticanalyseswere performedbasedon the nucleotide sequences of ITS1, ITS2, 5.8S rRNA, 28S rRNA, β-tubulin and tef1.Oxidaseandcellulaseactivitieswereassessedbyplate-tests with ABTS and CMC. Forevaluation of biodegradation potential,solid state fermentation on alder and pine sawdust wasperformed. Weightanddensitylossaswellas the C:Nratioweremeasuredafter 90 days of cultivation.All S. ochraceum strains exhibited high oxidative activity towards ABTS, indicating secretion of oxidative enzymes (i.e. laccases and class II peroxidases). Cellulase activity was medium or low for most strains and in some strains – absent. Allstrainswereabletodegradealderandpinesawdust. There was no correlation between the enzymatic activity, biodegradation potential and geographic origin of S. ochraceum strains. However, S. ochraceum strains isolated from the same wood substrates exhibited similar characteristics in most cases. Strain LE-BIN 3398 was the most effective for degrading both alder and pine sawdust and could be regarded as a promising source of oxidative enzymes for biotechnology.
 Keywords: basidiomycetes, biodegradation, solid state fermentation, oxidase activity, Steccherinumochraceum

Vacuum Pyrolysis of Pine Sawdust to Recover Spent Lithium Ion Batteries: The Synergistic Effect of Carbothermic Reduction and Pyrolysis Gas Reduction

Minimizing the energy consumption and expanding the usage of renewable material in the recovery of spent lithium ion batteries (LIBs) are significant for exploring more sustainable recycling approaches. Herein, we report a biomass carbothermic reduction approach to selectively recycle Li and Co from spent LIBs at a low temperature of 673 K. Pine sawdust (PS) was selected as the sample to provide reducing gas and carbon during the pyrolysis. During the reduction process, the PS-derived reducing gas and charcoal codrove the conversion of LiCoO2 to Co/CoO and Li2CO3, and over 94% of Li and 97% of Co were recovered. The synergistic effect of carbon and reducing gas is key to achieving the transformation process at a lower temperature than the common carbothermic reduction. Economic and environmental analysis based on the EverBatt model shows that this strategy reduces energy consumption and greenhouse gas (GHG) emissions, thereby increasing potential profit. Overall, this paper provides a green method to recycle spent LIBs via waste biomass with minimized secondary wastes.

Influence of Geometrical Features of Solid Biofuels on the Implementation of the Combustion Process

ABSTRACT The article discusses the influence, in a broad spectrum, of geometric features of various solid biofuels (pellets and briquettes in several sizes) of plant origin (wheat straw, rye straw, oat straw, birch, and pine sawdust) on the combustion process, in particular on the ignition time, flame duration and fuel afterburning in a low-power boiler. The research used a test stand, an essential element of which was the standard grate boiler with a cuboidal combustion chamber surrounded by a water jacket. This type of device allowed for the combustion of fuels with various geometrical features – pellets and briquettes – in the same combustion chamber. The particles of the combusted fuel had a surface area (S) from 281 to 13188 mm2, a volume (V) from 345 to 115 787 mm3 and a density (ρ) from 602 to 1127 kg·m−3, which resulted in a total combustion total time from 600 to 1500 s. The duration of individual combustion stages of the tested biofuels was proportional to the product of the square of the volume/area quotient and the fuel density. It was found that the coefficients C0 (start combustion time coefficient), C1 (flame combustion time coefficient), C2 (afterburning combustion time coefficient) of their duration increase with the decrease in the value of the product of the square of the ratio of the volume to the area and the fuel density, which is characteristic for pellets. The distribution of the fuel ignition, flame combustion, and afterburning constants as a function of the product of the square of the volume/area quotient and the fuel density takes the power distribution with the fit values of 0.9017; 0.9779; 0.9322 respectively. The conducted correlation tests showed quite strong dependencies between the geometrical features of the fuel and the time of its combustion. At the same time, the correlations between the ash content in fuels and the duration of individual combustion stages did not show solid, regular relationships. The analysis of the course of their combustion concerning the duration of the various stages of combustion regarding variable geometrical features given to formed biofuels allows predicting the course of their combustion. It is essential at the level of exploitation of heating devices. From the perspective of this research fuels with a higher value of the square of the quotient of the volume to the area and the fuel density would be optimal.