Spent coffee ground is a massively produced coffee industry waste product whose reusage is beneficial. Proximate and ultimate and stochiometric analysis of torrefied spent coffee ground were performed and results were analyzed and compared with other research and materials. Spent coffee ground is a material with high content of carbon (above 50%) and therefore high calorific value (above 20 MJ·kg⁻¹). Torrefaction improves the properties of the material, raising its calorific value up to 32 MJ·kg⁻¹. Next, the phytotoxicity of the aqueous extract was tested using the cress test. The non-torrefied sample and the sample treated at 250 °C were the most toxic. The sample treated at 250 °C adversely affected the germination of the cress seeds due to residual caffeine, tannins and sulfur release. The sample treated at 350 °C performed best of all the tested samples. The sample treated at 350 °C can be applied to the soil as the germination index was higher than 50% and can be used as an alternative fuel with net calorific value comparable to fossil fuels.

Tea waste as a potential biofuel and bio fertilizer was analyzed. Samples were collected from various tea species and torrefied to five different temperatures. All samples were analyzed for their proximal composition and calorific value. From the results, stoichiometric properties were calculated. A phytotoxicity test was performed, and the germination index was measured. Tea waste torrefied at 350 °C may be suitable biofuel reaching the calorific value of 25–27 MJ kg⁻¹, but with quite a high share of ash, up to 10%, which makes its use technically challenging and may lead to operating issues in a combustion chamber. The same biochar may be a suitable fertilizer for increasing the germination index, therefore, applicable to the soil. The non-torrefied sample and the sample treated at 250 °C are not suitable as fertilizers for being toxic. The total phenolic content in waste black tea was reduced from 41.26 to 0.21 mg g⁻¹, depending on the torrefaction temperature. The total flavonoid content was also reduced from 60.49 to 0.5 mg g⁻¹. The total antioxidant activity in the non-torrefied sample was 144 mg g⁻¹, and after torrefaction at 550 °C, it was 0.82 mg g⁻¹. The results showed that black tea waste residues have the potential for further use, for example, in agriculture as a soil amendment or as a potential biofuel.

Walnut, pistachio, and peanut nutshells were treated by pyrolysis to biochar and analyzed for their possible usage as fuels or soil fertilizers. All the samples were pyrolyzed to five different temperatures, i.e., 250 °C, 300 °C, 350 °C, 450 °C, and 550 °C. Proximate and elemental analyses were carried out for all the samples, as well as calorific value and stoichiometric analysis. For sample usage as a soil amendment, phytotoxicity testing was performed and the content of phenolics, flavonoids, tannin, juglone, and antioxidant activity were determined. To characterize the chemical composition of walnut, pistachio, and peanut shells, lignin, cellulose, holocellulose, hemicellulose, and extractives were determined. As a result, it was found that walnut shells and pistachio shells are best pyrolyzed at the temperature of 300 °C and peanut shells at the temperature of 550 °C for their use as alternative fuels. The highest measured net calorific value was in pistachio shells, which were biochar pyrolyzed at 550 °C, of 31.35 MJ kg⁻¹. On the other hand, walnut biochar pyrolyzed at 550 °C had the highest ash share of 10.12% wt. For their use as soil fertilizers, peanut shells were the most suitable when pyrolyzed at 300 °C, walnut shells at 300 and 350 °C, and pistachio shells at 350 °C.

The grains of durum wheat (Triticum durum Desf.) and achenes of common buckwheat (Fagopyrum esculentum Moench) were tested after treatment with two sources of non-thermal atmospheric pressure plasma (DCSBD, MSDBD) with different treatment times (0, 3, 5, 10, 20, 30, and 40 s). The effect of these treatments was monitored with regard to the seed surface diagnostics (water contact angle—WCA, chemical changes by Fourier transform infrared spectroscopy—FTIR); twenty parameters associated with germination and initial seed growth were monitored. A study of the wettability confirmed a decrease in WCA values indicating an increase in surface energy and hydrophilicity depending on the type of seed, plasma source, and treatment time. Surface analysis by attenuated total reflectance FTIR (ATR-FTIR) showed no obvious changes in the chemical bonds on the surface of the plasma-treated seeds, which confirms the non-destructive effect of the plasma on the chemical composition of the seed shell. A multivariate analysis of the data showed many positive trends (not statistically significant) in germination and initial growth parameters. The repeated results for germination rate and root/shoot dry matter ratio indicate the tendency of plants to invest in underground organs. Durum wheat required longer treatment times with non-thermal plasma (10 s, 20 s) for germination and early growth, whereas buckwheat required shorter times (5 s, 10 s). The responses of durum wheat grains to the two non-thermal plasma sources used were equal. In contrast, the responses of buckwheat achenes were more favorable to MSDBD treatment than to DCSBD.

This study investigates the effects of compost and vermicompost derived from sewage sludge and moulded pulp on wheat yield, nutrient uptake, photosynthetic activity, and drought resistance. Optimal weather conditions in March facilitated timely wheat sowing, contributing to ideal yields, while subsequent higher temperatures and rainfall influenced grain formation and weight. The experiment demonstrated that vermicompost significantly enhances plant physiological and yield parameters, including photosynthetic activity, chlorophyll content, and water use efficiency. Fertilized variants exhibited improved soil properties, leading to higher grain and straw yields compared to the control. Macronutrient uptake was notably higher in vermicompost-treated variants, with variant VI showing the highest values. Enhanced photosynthetic activity and drought resistance were observed in fertilized variants, attributed to better stomatal regulation and osmotic adjustment under stress conditions. The study underscores the role of vermicompost in promoting sustainable agriculture by improving nutrient availability, soil structure, and plant resilience. These findings suggest that compost and especially vermicompost applications can effectively enhance wheat productivity and resilience, offering a sustainable approach to improving crop performance under varying environmental conditions.

Important representatives of mucilaginous seeds from different plant species, namely amaranth (Amaranthus hypochondriacus L.), garden cress (Lepidium sativum L.), common flax (Linum usitatissimum L.), psyllium (Plantago ovata Forssk.), and chia (Salvia hispanica L.) were subjected to non-thermal plasma (NTP) generated by diffuse coplanar surface barrier discharge with different exposure times (1, 3, 5, 10, 20, 30 s). Seed water uptake, kinematic viscosity, parameters of seed germination and initial seedling growth were monitored along with chemical and morphological changes on the seed surface. Water absorption increased with increasing plasma exposure time for garden cress, psyllium and chia seeds, but it was greatest for chia seeds. For all seed species, the kinematic viscosity decreased with increasing plasma exposure time. The highest values were found for chia seeds after a treatment for 30 s. Surface analyses did not reveal any chemical and morphological changes of the seed surface. According to a PCA comparison of basic characteristics of germination and initial growth, common flax seeds differ in their reaction to NTP from the other tested plants. On the contrary, chia seeds showed the best water uptake and kinematic viscosity. It was shown that NTP treatment improves the absorption of mucilaginous seeds and does not change the surface and structural properties of the seeds. These mucilaginous seeds can be used as raw seed, whereby NTP accelerates their preparation during soaking.