Due to its nitrogen, phosphorus, and magnesium content, sewage sludge is used, among other things, to grow plants for energy purposes or to intensify biogas production. These processes are always accompanied by odor emissions, which are treated as pollution according to European legislation and are subject to legal regulations in many countries. Therefore, this publication presents the results of a study on the removal of odor from sewage sludge by adsorption on biochars produced from selected biowaste. Beekeeping waste (grain) and coffee brewing residues (spent coffee grounds) were selected for the study. Both materials were pyrolyzed to produce biochar which was applied for adsorption of odors from sewage sludge. Commercial Organosorb 200-1 Wi activated carbon was used as a comparison material. The odors were taken from dried sewage sludge from a municipal wastewater treatment plant. The obtained biochars are suitable for odor adsorption and can be an alternative to commercial adsorbents. The biochar from beekeeping waste showed the highest efficiency, allowing 100% odor removal. Slightly worse results were obtained for biochar from spent coffee grounds.

This study evaluated the effectiveness of regenerating WG-12 granular activated carbon used in drinking water treatment, based on a case study of the “Miedwie” Water Production Plant supplying the city of Szczecin, Poland. The investigation was conducted using samples collected from eight adsorption beds after five years of operation. Thermal regeneration was performed in a steam atmosphere at 600–850 °C for 20 min, and the regenerated samples were subsequently demineralized using a 1.75% HCl solution. The effectiveness of the process was evaluated using changes in the iodine number, BET specific surface area, bulk density, mechanical strength, regeneration mass yield, and an adsorption–mechanical trade-off index. Thermal regeneration substantially improved the adsorption properties of the spent carbon. The mean iodine number increased from 528.2 mg/g to 858.1 mg/g after regeneration at 800 °C, while the specific surface area increased from 480.4 to 806.9 m²/g. The application of demineralization further enhanced process efficiency. In the 800 °C + 1.75% HCl variant, an iodine number of 903.9 mg/g and a specific surface area of 883.6 m²/g were obtained, corresponding to recoveries of 95.1% and 98.2% of the reference values for virgin carbon, respectively. The improvement in adsorption properties was accompanied by a decrease in bulk density and a moderate reduction in mechanical strength. The most favorable process variant was regeneration at 800 °C combined with HCl demineralization, for which the adsorption–mechanical trade-off index reached 93.7%. The results indicate that regeneration of WG-12 effectively restores the adsorption potential of the material and may reduce the need for complete bed replacement while maintaining acceptable mechanical durability. The analysis also indicates that increasing the temperature to 850 °C is not technologically justified because it does not improve adsorption performance and simultaneously increases material loss, which is important from both economic and sustainability perspectives. The proposed I_SM index should be regarded as a supplementary screening tool for comparing regeneration variants within the same experimental system, whereas mass yield and cost-related aspects should be evaluated separately to avoid overstating the universality of the index.

This study covers the investigation and preliminary testing of fuel formulations for hybrid rocket motors utilizing nitrous oxide as the oxidizer, with the primary objective of enhancing volumetric specific impulse (Isp∗ρ). Conventional HTPB based fuels, while reliable and widely used, often...

This study presents experimental characterization of the HyPEx-B high-density hybrid rocket fuel comprising aluminium, bismuth trioxide and HTPB binder with nitrous oxide across a range of oxidizer to fuel ratios near the theoretical performance optimum. The oxidizer to fuel ratio was varied by...