The aim of the conducted research was to obtain information on the main components of ashes from 35 biomass species used in combustion processes to obtain reference data for the development of utility possibilities for these ashes, with particular emphasis on agricultural use. The examined biomass samples were divided into groups depending on origin: woody biomass and energetic woody plants I-WWB, herbaceous and grassy energy plants II-EC, agricultural waste III-AR, forest waste IV-FR and waste from the agri-food industry V-AFIW. The analysis of the studied elements contents was carried out in the designated groups. The chemical composition of ash was dominated by the macroelements Ca, K, P and S, which suggests the possibility of their agricultural use. At the same time, the low content of toxic elements such as As and Pb should not be a limiting feature in their use, with the exception of wood biomass. In addition, ashes obtained from the biomass combustion were enriched with microelements such as Zn, Cu and Mn, which further increases their possibilities of fertilizer use. The potential use of ash from each type of biomass in the aspect of its chemical composition should be considered individually, regardless of the division into groups depending on the origin of biomass.

Aquaculture wastewater contains a huge amount of substances that can cause environmental pollution. However, microalgae can absorb these compounds and convert them into useful biomass. In this study, Chlorella minutissima was grown in the wastewater resulting from saline aquaculture. The microalgae were found to effectively utilize nitrogen and phosphorus in the wastewater for its growth. During wastewater treatment, the cell density increased almost fivefold compared to the initial value (OD₆₈₀ 0.502). Moreover, batch culture resulted in the maximum biomass concentration and productivity of 4.77 g/L and 0.55 g/L/day, respectively. The contents of total nitrogen and total phosphorus in wastewater decreased by 88% and over 99%, respectively. In addition, the content of N-NO₃ was reduced by 88.6%, N-NO₂ by 74.3%, and dissolved orthophosphates (V) by 99%. At the beginning and throughout the experiment, the content of N-NH₄ in wastewater remained below 0.05 mg/L. Furthermore, a high lipid content of 46.4% (w/w) was also obtained from the studied microalgae.

During testing, the possibility of using hemp biomass for energy purposes was assessed. The criteria assessed were the physical and chemical properties of hemp biomass, as well as the combustion process of straw and briquettes made of it in a low-power boiler. The results were made and compared with currently applicable standards. Technical and chemical properties of hemp biomass are comparable with the best plants used for energy purposes. Studies have also shown the susceptibility of hemp biomass compaction. However, large emissions recorded during the combustion of the tested forms of biofuels from hemp straw in light of applicable standards disqualify this fuel for use in grate-type heating devices with air fed under the grate. It would be advisable to carry out research on the total costs of pellet production and their use in heating devices with a retort burner, while taking into account this biofuel’s ashes’ susceptibility of sintering.

Fuels and their components accumulate in soil, and many soil organisms are exposed to this pollution. Compared to intensive research on the effect of conventional fuel on soil, very few studies have been conducted on soil ecotoxicity of biofuels. Considering the limited information available, the present study evaluated the changes caused by the presence of biodiesel and diesel fuel in soil. The reaction of higher plants and soil organisms (microbial communities and invertebrates) was analysed. Conventional diesel oil and two types of biodiesel (commercial and laboratory-made) were introduced into the soil. Two levels of contamination were applied—5 and 15% (w/w per dry matter of soil). The plate method was used to enumerate microorganisms from soil contaminated with biodiesel and diesel fuel. Phytotoxicity tests were conducted by a 3-day bioassay based on the seed germination and root growth of higher plant species (Sorghum saccharatum and Sinapis alba). Fourteen-day ecotoxicity tests on earthworm were performed using Eisenia fetida. Based on the results of the conducted tests it was found out that the organisms reacted to the presence of fuels in a diverse manner. As to the microorganisms, both the growth and reduction of their number were noted. The reaction depended on the group of microorganisms, type of fuel and dose of contamination. The lipolytic and amylolytic microorganisms as well as Pseudomonas fluorescens bacteria were particularly sensitive to the presence of fuels, especially biodiesel. Fuels, even at a high dose, stimulated the growth of fungi. Monocotyledonous sugar sorghum plants were more sensitive to the presence of fuels than dicotyledonous white mustard. There was also a significant negative impact of contamination level on plant growth and development. Biodiesel, to a greater extent than conventional fuel, adversely affected the survival and volume of earthworms.

The processes of degradation of engine oils operated in passenger cars of a uniform fleet of 25 vehicles were analyzed for oxidation content using infrared (IR) spectroscopy. As part of the experiment, the changes in engine oils occurring during actual operation (under conditions which can be described as “harsh”, i.e., short distance driving, frequent starting of the engine, and extended engine idling) have been observed. An evaluation of the Fourier transform infrared spectroscopy (FTIR) spectrum of an engine oil sample was presented. The infrared spectra of both fresh and used oils were recorded with the Thermo Nicolett IS5. The tests were conducted according to the Appendix A2 of ASTM 2412. For the used engine oil differentiation process, FTIR spectra were analyzed in the regions of 1,700–2,000 cm⁻¹ and 3,600-3,700 cm⁻¹. The FTIR spectrometry is demonstrated to be effective for the analysis and monitoring of processes of oxidation and shown to provide rapid and accurate information relating to the aging process of engine oils. The results may facilitate decision-making regarding the service life of engine oils. The achieved dependencies can make it possible to upgrade the sensor assembly consisting of an FTIR source.

This article focuses on the results of investigations of selected heavy metals (Mg, Fe, Ni, Cu, Zn, Pb, Ca, Cr and Al) in engine oils of various manufacturers. The measurements were made using atomic absorption spectrometry (AAS) THERMO-iCE 3000 Series. The aim of the study was to determine the concentrations and the direction of changes of those heavy metals and to determine the statistical relationship between the car mileage and the concentration levels of individual trace elements. Statistical analysis of the test results showed significant changes in iron and copper concentrations in engine oil, depending on the engine's operating history.