Waste fly ash, with both low (with the addition of vermiculite) and high contents of unburned coal, were subjected to hydrothermal syntheses aiming to obtain zeolite composite materials—zeolite + vermiculite (NaX–Ver) and zeolite + unburned carbon (NaX–C). The composites were compared with parent zeolite obtained from waste fly ash with a low content of unburned carbon (NaX–FA). In this study, the physicochemical characteristics of the obtained materials were evaluated. The potential application of the investigated zeolites for the adsorption of ammonium ions from aqueous solutions was determined. Composite NaX–Ver and parent zeolite NaX–FA were characterized by comparable adsorption capacities toward ammonium ions of 38.46 and 40.00 mg (NH₄⁺) g⁻¹, respectively. The nearly 2-fold lower adsorption capacity of composite NaX–C (21.05 mg (NH₄⁺) g⁻¹) was probably a result of the lower availability of ion exchange sites within the material. Adsorbents were also regenerated using 1 M NaCl solution at a pH of 10 and subjected to 3 cycles of adsorption–desorption experiments, which proved only a small reduction in adsorption properties. This study follows the current trend of waste utilization (fly ash) and the removal of pollutants from aqueous solutions with respect to their reuse, which remains in line with the goals of the circular economy.

New ways of managing hop sediments from brewing and fermentation of beer are constantly being sought and the existing ones improved as part of the circular economy. These wastes are not generated in large amounts, but the absence of their proper characteristics may lead to further processing errors. The study analyses the composting of hop waste under laboratory conditions and the effects of the biological activity of composts introduced into the soil. The study was carried out on two-hop sediments from two different technological stages of beer production: hot trub (HT) and spent hops (SH). Chemical, microbiological and biochemical analyses, as well as the assessment of phytotoxicity to Lepidium sativum L., were performed in the materials. The results proved that, due to their formation technology, the tested feedstocks are safe from an epidemiological point of view and are not a source of microbial contamination. Inhibitory properties for plant development were found for HT and it most likely results from the organic compound content. The mineral composition of hot trub does not exclude composting if its share in biomass is low. Spent hops (SH) were characterised by a significant total nitrogen content, which affected the composting process. Composting this sediment required the selection of substrates with a wide C:N ratio. The number of microorganisms inhabiting the analysed material was very diverse and varied depending on the type of sediments. The sample that contained the composted SH from dry hopping had a much larger number of microorganisms than the sample with HT from wet hopping.

The aim of the study was to evaluate the effect of different mineral-organic mixtures on changes in soil microbial composition and chemical properties. The design of the pot experiment included 6 treatments: soil without fertilization – C, soil fertilized with mineral NPK fertilizers – MF,...

Changes of the addition of poultry litter (PL) and poultry litter biochar (PLB) on quantitative and qualitative humus parameters in loamy sand were estimated during the 5-year study period. The following properties were determined in soil: pH, total carbon (Ctotal), total nitrogen (Ntotal), humic and fulvic acids, extracted carbon, and non-hydrolysing carbon. Additionally, light absorbance in the solutions of humic acids was computed at the wavelength of 280, 465, and 665 nm. It was demonstrated that organic matter mineralisation was most intense in soil with the addition of PL, causing significant quantitative and qualitative changes in humus compounds in soil. A slower rate of organic matter mineralisation was observed in soil amended with PLB, especially in a dose of 5.0 t ha⁻¹, which indicated the long-term effect of this material on improving soil properties. Spectrophotometric indexes for the solution of humic acids also showed that PLB had a more favourable effect on the structure durability and lower mobility of humic acid carbon compared with PL. The application of PL and PLB significantly increased the non-hydrolysing carbon content in soil, indicating greater stabilisation of humus compounds and, at the same time, lower CO₂ emissions. It was found that the addition of organic materials to soil significantly increased the soil organic carbon contents. Our study has shown that the identification of changes that may occur in the quantitative and qualitative composition of soil humus after the application of PLB may be helpful in determining the appropriate biochar dose.

The aim of this study was to evaluate the influence of innovative mineral–organic mixtures containing zeolite composites produced from fly ashes and lignite or leonardite on the fractional composition of soil organic matter in sandy loam soil under two-year pot experiments with maize. The fractional composition of soil organic matter (SOM) was analyzed and changes in the functional properties of soil groups were identified using the ATR-FTIR method. Changes in the content of phenolic compounds were assessed, and the potential impact of fertilizer mixtures on soil carbon stocks was investigated. The addition of these mixtures improved the stability of SOM. The application of mineral–organic mixtures significantly increased the total organic carbon (TOC) by 18% after the 2nd year of the experiment. The maximum TOC content in the soil was observed by 33% with the addition of MC3%Leo3% amendment. Nitrogen content in soil was increased by 62% with MV9%Leo6% additive, indicating increased soil fertility. The study highlighted an increase in fulvic acid carbon relative to humic acid carbon, signaling positive changes in organic matter quality. The new mineral–organic mixtures influence changes in specific functional groups (ATR-FTIR) present in the soil matrix, compared to mineral fertilization alone. The additive mixtures also contributed to an increase in soil carbon stocks, highlighting their potential for long-term improvement of soil fertility and carbon sequestration.