Essential oils are complex mixtures of volatile compounds obtained from plants where they play aromatic, communicative and defensive roles. They have been used for centuries in medicine, agriculture and industry due to their broad spectrum of biological activity. They exhibit antimicrobial,...

The composting of sewage sludge and maize straw mixtures was investigated in this study. The aim was to analyze the influence of different proportions of sewage sludge and maize straw in the mixtures on composting process dynamics (expressed by heat production) and gas emissions. The results showed that all examined mixtures reached a strong thermophilic phase of composting; however, the lowest dynamic of temperature growth was observed in the case of the biggest sewage sludge content (60% of sewage sludge in the composting mixture). The ammonia concentration inside bioreactor chambers was directly related to the content of sewage sludge in the composted mixture. Excessive contents of sewage sludge had a considerable effect on very low C/N ratios and high losses through ammonia emissions. Tests were carried out in reactors with a capacity of 160 dm³ under controlled conditions. All mixtures were aerated by the average air-flow of about 2.5 dm³∙min⁻¹, i.e., the minimum air-flow that allows a temperature of about 70 °C to be reached and a sufficiently long thermophilic phase, which ensures proper composting.

Mining leads to serious degradation of the ecological values of the landscape. After mining is completed, degraded areas should be reclamated in order to mitigate the destructive effects of mining activities. Effective reclamation aims to initiate soil-forming processes. The paper evaluates the effects of land reclamation in post-mining areas 12 to 14 years after the reclamation process. The assessment was based on a determination of the activity of selected enzymes. Municipal sewage sludge compost (SSC) and compost with a composition of 70% municipal sewage sludge + 30% fly ash (SSFAC) were used as an external source of organic matter in the reclamation. The activity of dehydrogenases, phosphatases, and urease was determined. The fertilization of reclaimed soil with compost caused a significant increase in the activity of the assessed enzymes. Significantly higher dehydrogenase activity was found in the soil treated with SSC. The soil treated with SSFAC was characterized by higher activity of phosphatase and urease. The one-time application of composts from sewage sludge and sludge with fly ash, and the introduction of a mixture of grasses, allow for a permanent reclamation effect. An additional ecological advantage of this reclamation model is waste management, which is part of the circular economy strategy.

Post-mining areas require reclamation. The main aim of reclamation is to restore the soil as a basic element of the terrestrial ecosystem. This paper presents the results of an evaluation of the enzymatic activity of soils formed on an afforested heap from an opencast sulphur mine. Six research sites were selected on the overburden heap of the Piaseczno sulphur mine, afforested 50 years ago. They differed in the type of soil in the subsoil and in the species composition of the stand. The activity of dehydrogenases, phosphatases, urease, total organic carbon, and total nitrogen was determined and statistical analysis of the obtained results showed that the activity of the evaluated enzymes in the soils formed in the reclaimed areas was significantly dependent on the type of substrate and the species composition of the plants. The activity of the evaluated enzymes was significantly positively correlated with the content of total nitrogen and the C/N ratio, and the activity of phosphatases and urease with the total organic carbon content. Within soils developed on the same texture, the influence of stand species was revealed. In soils formed on clay, the soils under the beech stand and under the birch stand were characterized by higher activity of enzymes. The soil developing under the stands of European larch and red oak was characterized by higher enzymatic activity on weakly clayey sands. On loose sands, the activity of dehydrogenases and urease was significantly higher under acacia robinia than under hornbeam.

Emerging demand for food coupled with increasing agricultural use of hazardous chemicals is propelling development of environmentally sustainable nanotechnologies. Nanoscale materials derived from green sources like plants and microbes could transform agriculture via nanosensors detecting toxins,...

The research was carried out to assess soil condition many years after waste introduction for reclamation purposes. The parameters of the activity of soil microorganisms responsible for the revitalization processes in degraded soils were used in the research. Soil material was derived from the area of the former sulfur mine. The results showed that even a single waste introduction to degraded soil caused long-lasting effects in the activity of soil microorganisms. The most favorable changes were caused by the addition of sewage sludge and the use of mineral wool in the form of a pad. The application of lime alone turned out to be the least beneficial for the revitalization processes, i.e., restoring the homeostasis of biological life in degraded soil. This research is a continuation of study that concerned the initial recultivation period. The obtained research results show the need for monitoring soils reclaimed with waste, not only in the initial period but also in the following years. These results allow evaluation of the usefulness of the parameters of soil microbial activity in monitoring soil environments subjected to strong human pressure. The results can be used to assess the risks associated with the introduction of waste into the environment.