Amelia Zielińska

This study addresses degraded post-mining soil reclamation by developing a novel, microbially-inoculated waste-derived feather–straw–lignite organic-mineral compost material. Formulated from chicken feathers (20%), wheat straw (60%), and lignite (20%) to optimize the initial C:N ratio, the substrate was inoculated with a multi-strain complex (MIX) of Bacillus altitudinis 33, Bacillus methylotrophicus Alk, and Streptomyces fulvissimus K59. Testing progressed from laboratory scale to a 200 dm³ dynamic reactor and a 2025 field evaluation with maize (Zea mays L.) on sandy mining soils in Konin (Poland). Inoculation accelerated maturation, yielding a favorable C:N ratio of 12.09 and stabilized NH4-N of 0.03%. Peak dehydrogenase activity reached 16 DU by day 3. Field application enhanced sandy soil properties, increasing urease activity to 3.91 UU and providing 3.4 g/kg P₂O₅. Consequently, maize showed a highly significant 15% increase in average shoot height (30.23 cm vs. 25.88 cm in control; t(645) = 6.63, p < 0.001) and intense green coloration. However, absolute soil enzymatic activity remained low due to early spring moisture limitations and temperature constraints typical of temperate climates. These initial findings suggest that the microbially-enriched compost shows strong potential as a safe functional soil-reclamation material and compliant alternative to synthetic fertilizers.

The growth of waste electrical and electronic equipment has intensified the search for effective recovery technologies of valuable metals from printed circuit boards (PCBs). In this study, the hydrometallurgical behavior and recovery potential of nickel from thermally treated PCB were investigated. The PCB waste was subjected to steam gasification as a pretreatment step, followed by mechanical separation and subsequent leaching using different acidic media, including 2 M sulfuric acid, aqua regia, and dilute acids assisted by ultrasonic treatment. The results indicate that thermal pretreatment improves the accessibility of nickel-bearing phases and promotes their dissolution during hydrometallurgical processing. Leaching efficiency depended on the leaching agent and particle size. Ultrasound-assisted leaching with dilute acids further enhanced nickel extraction.

This study evaluates the potential of fine-grained waste gneiss as a soil improver, with particular emphasis on its chemical and grain composition and its effects on plant growth. The experimental material consisted of mixtures of fine-grained waste gneiss with varying proportions (from 0.38% to 7.5% in the pot) supplemented with varying proportions of dolomite (from 0.14% to 0.22% in the pot). Pot experiments were conducted for 57 days under controlled conditions using selected crops. Plant response was assessed based on growth rate, green mass production, and dry mass. For most tested variants, the results demonstrated a dose-dependent enhancement in plant productivity associated with gneiss supplementation. Compared to the control, experiments containing higher proportions of fine-grained gneiss resulted in an increase in green and dry mass from 8.14% to 78.73% and by 12.5% to 96.88%, respectively. Additionally, strong positive correlations between gneiss content and yield parameters (Pearson’s r > 0.8) were observed. In contrast, the dolomite fraction mainly conceptually affected soil chemical properties, including calcium and magnesium availability and pH stabilization. Overall, the findings suggest that fine-grained waste gneiss acts as a growth-promoting soil conditioner, as evidenced by the marked improvement in plant biomass. The findings confirm the high potential of waste gneiss as a functional soil improver, supporting sustainable resource management and aligning with the principles of the circular economy.

The growing demand for lithium, driven by its crucial role in energy storage technologies such as lithium-ion batteries for electric vehicles, renewable energy storage, and portable electronics, is intensifying the need for sustainable extraction methods. While lithium is sourced from both primary and secondary resources, particularly from recycled materials, the recovery from spent lithium-ion batteries remains challenging. This article presents acidic reductive leaching as a promising alternative for lithium extraction from secondary sources and unconventional ores, emphasizing its potential benefits, such as higher recovery rates, faster processing, and adaptability to various waste materials. Notably, this method facilitates the selective recovery of lithium before cobalt and nickel, providing a strategic advantage. This study highlights the lack of optimization studies on leaching conditions (e.g., acid concentration, reducing agents, temperature, and time) that could maximize lithium recovery while minimizing environmental and economic costs. The article aims to investigate and optimize the parameters of acidic reductive leaching for more efficient lithium recovery. Additionally, the results contribute to the principles of the circular economy and sustainable supply chains in the energy sector, providing a method to reduce dependency on geopolitically constrained lithium resources and supporting the global energy transition toward cleaner energy solutions.