Wood chips and logging residues currently comprise the largest share of biomass fuels used for heat generation in district heating plants and are provided by a variety of suppliers. Ash and moisture contents, as well as the calorific value, may vary considerably depending on the composition of the fuel, seasonality, location, and other factors. This paper provides the summarized results of the main characteristics of wood chip moisture and ash content and calorific value, experimentally tested for a significant range of samples. Chip samples were collected from two district heating companies and tested for a significant range of samples. Chip samples were collected from two district heating companies and tested for a 3-year period. The data on fuel chip prices were taken from the electronic wood chip trading platform. The tests were performed using standard express methods, where two sub-samples were taken and analyzed from every chip sample. It was determined that the moisture content of the wood chips varied from 35% to 45%, the calorific value from 18.4 to 19.6 MJ/kg, and the ash content from 0.5% to 4.5%. The calculated relative expanded uncertainty of the moisture content measurement was ±2.1%, of calorific value—±1.5%, and of ash—±1.0%. The repeatability of the results was estimated as the pooled standard deviation.

The aim of this study was to further increase the amount of straw that can be used to produce solid biofuels, as currently only about 130–140 thousand of the 3 million tonnes of straw collected annually in Lithuania are used for solid biofuel production. Therefore, the use of buckwheat hulls as an additive in solid biofuel production was investigated. Mixtures of wheat straw and buckwheat hulls were used for this research, with an increase in buckwheat hulls from 25% to 75% of the total weight of the mixture. Results of the analysis of the chemical composition, moisture, ash, and volatile matter content of the mixtures, as well as their ash properties, were compared with the corresponding results obtained with pure buckwheat hulls, wheat straw, and wood chips. It is observed an increase in all ash melting temperatures by increasing the portion of buckwheat hulls in the mixture. Additionally, the ash shrinkage starting temperature was shown to increase as the total content of buckwheat hulls also increased in the mixture. This increase ranged from 90 °C to 210 °C. Furthermore, the Cl concentration in fuel mixtures and the corrosion risk of equipment are accordingly reduced by using buckwheat hulls, as an addition that does not contain Cl.

Multi-crop plants (fibrous hemp, maize, and faba bean) can potentially be an alternative to wood biomass pellets, but there is no detailed knowledge to support the suitability of this biomass for solid biofuel production. The aim of this study is to analyze and justify the suitability of multi-crop plant biomass for the production of biofuel pellets and to assess the environmental impact of burning them. This paper presents studies of physical-mechanical, thermal, and chemical characteristics of biofuel pellets from multi-crop plants and emissions during their combustion under laboratory conditions. The main parameters of the produced pellets were determined according to international standards, which are detailed in the methodology part. The length of the produced pellets ranged from 17.6 to 26.6 mm, and the diameter was about 6 mm. The density of wet pellets varied from 1077.67 to 1249.78 kg m⁻³. The amount of ash in the pellets varied from 5.75% to 8.02%. Determined lower calorific value of all pellets was close to 17.1 MJ kg⁻¹. The lowest CO and C_xH_y emissions were determined when burning MIX2-1 pellets (biomass of the binary crop); their values were 572 and 29 ppm, respectively. The lowest content of CO₂ was determined when burning S-Mz pellets (mono crop biomass), and it was 3.5%. The lowest NO_x emissions were also determined when burning the pellets of this sample, with a value of 124 ppm. Research results show that multi-crop plants are a suitable raw material for the production of solid biofuel, the burning of which does not cause negative consequences for the environment.

Asymmetric polyphenylsulfone (PPSU) membranes were fabricated by a non-solvent induced phase inversion method. Glycerin and silica nanoparticles were added into the polymer solution to investigate their effects on the material properties and gas separation performance of prepared membranes. The morphology and structure of PPSU membranes were analyzed by scanning electron microscopy (SEM), the surface roughness of the selective layer was analyzed by atomic force microscopy (AFM), and the surface free energy was calculated based on the contact angle measurements by using various solvents. The gas separation performance of PPSU membranes was estimated by measuring the permeability of CO₂ and CH₄. The addition of glycerin as a nonsolvent into the polymer solution changed the cross-section structure from finger-like structure into sponge-like structure due to the delayed liquid-liquid demixing process, which was confirmed by SEM analysis. The incorporation of silica nanoparticles into PPSU membranes slightly increased the hydrophilicity, which was confirmed by water contact angle results. PPSU membrane fabricated from the polymer solution containing 10 wt.% glycerin showed the best CO₂/CH₄ selectivity of 3.86 and the CO₂ permeability of 1044.01 Barrer. Mixed matrix PPSU membrane containing 0.1 wt.% silica nanoparticles showed the CO₂/CH₄ selectivity of 3.16 and the CO₂ permeability of 1202.77 Barrer.

The soil contamination of petroleum hydrocarbons is a widespread problem requiring an environmentally friendly and cost-effective solution. This study aimed to test the leguminous plant resistance to heavy fuel oil (HF) soil contamination and to evaluate their phytoremediation efficiency and potential to maintain the soil nutrient content. Eight legume species were selected for the study. The selected legumes were grown in a growth chamber in HF-contaminated soil (2.5 and 4 g kg⁻¹) for 90 days. After the soil treatment, the changes in the soil HF contamination, nutrient concentrations, and plants morphology were monitored. The HF pollution significantly affected the dry weight of the shoots and roots of seven of the eight tested plant species. M. sativa, M. albus, and L. corniculatus had the highest phytoremediation potential with the efficiency of the HF removal up to 95 %. The leguminous plant-assisted HF remediation resulted in an increase in the ammonium and inorganic phosphorous soil content, with the highest increase in the case of L. corniculatus and O. viciifolia. The cultivation of Phaseolus vulgaris, L. corniculatus, and M. albus helped to maintain the soil nitrates close to the constant level. The study demonstrated that M. sativa, L. corniculatus, and M. albus were the most efficient in HF removal.