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.

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.

Arsenic represents a serious health threat in localities with a high arsenic-polluted environment and can easily get into the human food chain through agronomy production in areas affected by arsenic contamination. Onion plants that were grown in controlled conditions in arsenic-contaminated soil (5, 10, and 20 ppm) were harvested 21 days after contamination. Arsenic levels (from 0.43 ± 0.03 µg g−1 to 1761.11 ± 101.84 µg g-1) in the onion samples were high in the roots and low in the bulbs and leaves, which is probably caused by a reduced ability of the onions to transport arsenic from roots to bulbs and leaves. Arsenic species As(V) and As(III) in As(V)-contaminated soil samples were represented strongly in favor of the As(III) species. This indicates the presence of /*/arsenate reductase. Levels of 5-methylcytosine (5-mC) (from 5.41 ± 0.28% to 21.17 ± 1.33%) in the onion samples were also higher in the roots than in the bulbs and leaves. Microscopic sections of the roots were examined, and the most damage was found in the 10 ppm As variant. Photosynthetic parameters pointed to a significant decrease in photosynthetic apparatus activity and the deterioration of the physiological state of plants as arsenic content increased in the soil.

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.

Zea mays L. plants were exposed to acetaminophen (APAP). Experiments were conducted in an experimental greenhouse with semi-controlled conditions. Experimental plants were grown in concentrations of APAP of 0, 200, 400, 600, 800, and 1000 mg L−1 for 14 days in an NFT hydroponic system. The impact of APAP contamination was observed on photosynthetic rate, water potential, proline content, and levels of 5-methylcytosine (5 mC%). The results showed that the selected parameters were influenced by different concentrations of APAP. High concentrations of APAP caused a decrease in transpiration rate, stomatal conductance, and water use efficiency. The water potential between the control and highest APAP concentration value increased by 388%. An upward trend of 5 mC% levels was observed, growing with APAP contamination. A 51% growth of 5 mC% was found between the control variant and the highest 1000 mg L−1 APAP contaminated variant. In most of the observed parameters, between 600 mg L−1 and 800 mg L−1 of APAP treatments, a turning point was shown with a noticeable increase in the stress in experimental plants according to the changes in the monitored parameters.