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.

One of the goals of adding adjuvants to agricultural spray solutions is to enhance the droplet size characteristics of this spray. Droplet size, in turn, has an influence in the deposited spray quality, in addition to the drift and losses of spray to off-target places. The aim of this research was to evaluate the effect of adding adjuvants to two types of water from different sources on the droplet size characteristics. Two types of adjuvants were employed in the tests: the active substance content of the first adjuvant was a 50% aqueous solution of sodium salt of alkylbenzenesulfonic acid—10% (HY), whereas the second was from rapeseed oil (natural origin)—85% (OL). Both adjuvants were tested in two concentrations: the first was with the concentration recommended by the manufacturer (100%), whereas the second concentration was 50% of the recommended dose. Two types of water from different sources were used in the tests: the first was from a village in the eastern part of Poland (WS), whereas the second was tap water from the city of Lublin, Poland (WUP). D_v0.1, D_v0.5, or volume median diameter (VMD), D_v0.9, Sauter mean diameter (SMD), relative span (RS), and the droplet size distribution were measured and calculated as characteristics of the droplet size. Results showed that the source of water affected the influence of adding adjuvant to the spray solution. Water from the WS source with adjuvant resulted in a numerical decrease in the D_v0.5 values in the percentage of droplet size range below 150 µm, whereas water from the WUP source resulted in an increase in these values (except when adding the HY adjuvant at 50% concentration). Adjuvant concentration significantly (p < 0.05) influenced the features of D_v0.9, SMD, and RS. Adding the OL adjuvant type numerically decreased the percentage of droplet size below 150 µm, and the D_v0.5 values, but only when the WS water source was used.

The effectiveness and quality of agricultural spraying largely depends on the technical efficiency of the nozzles installed in agricultural sprayers. The uniform spraying of plants results in a decrease in the amount of pesticides used in agricultural production and affects environmental safety. Both newly developed sprayers and those currently in use need quality control as well as an assessment of the performance of the spraying process, especially its uniformity. However, the models applied presently do not ensure accurate estimates or predictions of the spray liquid coverage uniformity of the treated surface. Generally, the distribution of the atomized liquid quantity is symmetrical and leptokurtic, which means that it does not fit well to the commonly used standard distribution. Therefore, there is a need to develop and design new tools for the evaluation, modeling, and prediction of such a process. The research problem studied in the present work was to find a new model for the distribution of atomized liquid quantity that could provide capabilities better than have been available so far to assess and predict the spraying process results. The research problem was solved through the formulation of a new function for the probability density distribution of sprayed liquid accumulation on the surface of the preset dimension size. The development of the new model was based on the results from a series of water atomization tests with an appropriate measurement device design based on the widely applied flat fan nozzles (AZ-MM type).

The operation of an agricultural biogas plant is associated with the formation of a large amount of digestate. The basic trend in digestate management, after taking into account its physicochemical properties, should be its use as a fertilizer. The possibility of the agricultural use of digestate as a fertilizer was determined. Digestate obtained from the agricultural biogas plant was tested for the content of macronutrients and heavy metals. The content of macronutrients was also determined in soil for winter rape cultivation. The analysis showed an increase in the yield depending on the digestate dose applied. In addition, an increase in the fat and protein content was found in winter rape seeds. The best results of mean values were obtained during the application of the 50,000 L ha⁻¹ dose. The average diameter of the stem base was 1.48 cm. The average height was 36.20 cm. The seed yield was 3.44 t ha⁻¹. The thousand seed weight was—5.34 g. The fat and protein contents were 43.62% and 22.95%, respectively. By applying a digestate dose of 50,000 L ha⁻¹, the highest content of macronutrients, as well as polyunsaturated fatty acids (PUFA) (31.17%), monounsaturated fatty acids (MUFA) (61.89%) and saturated fatty acids (SFA) (6.87%), was recorded.

This study analyzes the combustion of pellets and briquettes made of plant biomass in low-power heating devices powered periodically with fuel being placed on the grate, as well as after modification using an automatic fuel feeding system in the gutter burner. The use of herbaceous biomass in the form of pellets in low-power heating devices with automatic fuel feeding and combustion in a gutter burner is not widely promoted and popular. Therefore, this study used four types of herbaceous waste biomass (wheat straw, rye straw, oat straw and hay) and one type of woody waste biomass (birch sawdust) for testing. The basic chemical characteristics were determined for the raw materials. After appropriate preparation, the selected starting materials were subjected to briquetting and pelleting processes. Selected physical properties were also determined for the obtained biofuels. Biofuels made from birch sawdust had the lowest heat value (16.34 MJ·kg⁻¹), although biofuels made from wheat, rye and hay straw had a slightly lower calorific value, respectively: 16.29; 16.28 and 16.26 MJ·kg⁻¹. However, the calorific value of oat straw biofuels was only 15.47 MJ kg⁻¹. Moreover, the ash content for herbaceous biomass was 2–4 times higher than for woody biomass. Similar differences between herbaceous and woody biomass were also observed for the nitrogen and sulfur content. To burn the prepared biofuels, a domestic grate-fired biomass boiler was used, periodically fed with portions of fuel in the form of pellets or briquettes (type A tests), which was then modified with a gutter burner enabling the automatic feeding of fuel in the form of pellets (type B tests). During the combustion tests with simultaneous timing, the concentration of CO₂, CO, NO and SO₂ in the exhaust gases was examined and the temperature of the supplied air and exhaust gases was measured. The stack loss (qA), combustion efficiency index (CEI) and toxicity index (TI) were also calculated. The research shows that the use of automatic fuel feeding stabilizes the combustion process. The combustion process is balanced between herbaceous and woody biomass biofuels. Disparities in CO₂, CO and T_gas emissions are decreasing. However, during type B tests, an increase in NO emissions is observed. At the same time, the research conducted indicates that the combustion of herbaceous biomass pellets with their automatic feeding into the combustion chamber is characterized by an increase in combustion efficiency, indicating that when the combustion process is automated, they are a good replacement for wood biofuels—both pellets and briquettes.

In this study, in terms of the mechanisms of nitric oxide (NO) emissions, research was carried out to consider the impact of physical and chemical properties of wood and herbaceous biomass processed into pellets and briquettes in the course of the combustion process (in individual phases) in a low-power heating device. Combustion tests in the grate heating device showed statistically significant differences in the combustion process and thus carbon monoxide (CO), nitric oxide (NO), and sulfur dioxide (SO₂) emissions in the fuel form and the combustion phase. In terms of assessing the ecological and energy parameters of the combustion process, the nitrogen content in biomass was not the most important factor indicating the formation of NO emissions. Usually, the strongest correlations were observed with the formation of NO emissions in the first phase of combustion, which was related to the emissions of CO and SO₂. In the second and third flame phases, a significant reduction in NO emissions was observed, which was poorly positively dependent on the nitrogen contained in the fuel. In addition, it has been shown that the fuel geometric features greatly influence NO content in the exhaust gases in the first combustion phase. It is also indicated that further research is required, considering the possibility of reducing volatile flue gas fractions, which will lead to the development of low-emission and highly efficient biofuel combustion technologies in low-power heating devices.