Agricultural residues are produced in large quantities and their management is an issue all over the world. Many of these residues consist of plant materials in different degrees of transformation, so returning them back to soil is a management option that closes loops in a circular economy context. The objective of this paper is to summarize current knowledge on the options and effects of reusing agricultural residues as organic soil amendments. The reuse of these residues in soil is a good solution for minimizing the problems associated with their management, while improving soil health and ecosystem functions. While some agricultural residues can be applied directly to soil, others will need previous transformations such as composting to improve their properties. This allows the recovery of plant nutrients and increase in soil organic matter contents, with many positive effects on the soil’s physical, chemical and biological properties, and ultimately, crop production, although potential risks derived from some materials must also be considered. The concept of regenerative agriculture and soil management using organic soil amendments contribute to the significant enhancement of soil biodiversity, the protection of the environment and climate goal achievement.

The increasing focus on sustainability and the circular economy has brought waste-to-energy technologies to the forefront of renewable energy research. However, the environmental impacts and management of contaminants associated with these technologies remain critical issues. This article comprehensively reviews the environmental impacts of converting sewage sludge into energy and fertilizers, focusing on managing potential contaminants and assessing the implications and ecological risks. It also highlights the latest trends in waste-to-energy technologies, waste-to-soil amendment, and their integration into circular economy frameworks. The discussion encompasses challenges and opportunities in optimizing these processes in wastewater treatment plants to minimize pollutants and enhance sustainability. Addressing these challenges is essential for ensuring the long-term viability and acceptance of waste-to-energy solutions, making this topic highly relevant and timely.

High anthropogenic activities are constantly causing increased soil degradation and thus soil health and safety are becoming an important issue. The soil quality is deteriorating at an alarming rate in the neighborhood of smelters as a result of heavy metal deposition. Organic biowastes, also produced through anthropogenic activities, provide some solutions for remediation and management of degraded soils through their use as a substrate. Biowastes, due to their high content of organic compounds, have the potential to improve soil quality, plant productivity, and microbial activity contributing to higher humus production. Biowaste use also leads to the immobilization and stabilization of heavy metals, carbon sequestration, and release of macro and micronutrients. Increased carbon sequestration through biowaste use helps us in mitigating climate change and global warming. Soil amendment by biowaste increases soil activity and plant productivity caused by stimulation in shoot and root length, biomass production, grain yield, chlorophyll content, and decrease in oxidative stress. However, biowaste application to soils is a debatable issue due to their possible negative effect of high heavy metal concentration and risks of their accumulation in soils. Therefore, regulations for the use of biowastes as fertilizer or soil amendment must be improved and strictly employed to avoid environmental risks and the entry of potentially toxic elements into the food chain. In this review, we summarize the current knowledge on the effects of biowastes on soil remediation, plant productivity, and soil organic carbon sequestration.

Progressing soil degradation worldwide is a complex socio-environmental threat. Implementing environmental policies and actions such as the Sustainable Development Goals, the European Green Deal, and the Renewable Energy Directive III regarding environmental protection aims to protect, conserve, and enhance the EU’s natural capital, focusing on soil protection. As assumed in the Green Deal, the European economy has to be turned into a resource-efficient and green economy with zero net emission of greenhouse gases. Since soil quality strongly influences all ecosystem elements, soil remediation is increasingly promoted as a sustainable option to enhance soil quality and, at the same time, help achieve overarching goals set out in European climate law. Biomass in phytoremediation is particularly important in regenerative agriculture, as it emphasizes improving soil quality, increasing biodiversity, and sequestering carbon. Selected plants and microbes can clean degraded agricultural areas, removing heavy metals and pesticides, thus lowering soil toxicity and improving food and feed security. Moreover, the post-phytoremediation biomass can be processed into biofuels or bioproducts, supporting the circular economy. This article summarizes the role of plants and microbial biomass in the struggle to achieve EU environmental goals, enabling the regeneration of degraded ecosystems while supporting sustainable development in agriculture.

The commonly used and developing engineering environmental technologies do not remain neutral for an ecosystem. The deepening climate changes are generally considered as the effects of human activities. There is thus no doubt that any human interference in the environment should be comprehensively checked at the beginning for all its positive and negative aspects for the environment as well as society health. There are two different analytical tools useful in environmental management: life cycle assessment (LCA) and risk assessment (RA). The first follows the product from “from birth to the grave” summing the environmental impact at all stages of its “life” including such elements like producing, used electricity, transport and many others. LCA refers to quantification and classification of all effects at all life stages and provides direct and indirect possible environmental interactions. On the other hand, risk assessment focuses on linking stressors and its possibilities and severity. RA tools reveal environmental and human health impacts of strictly separated elements, providing insight as to which emission consists of an important threat. This paper is focused on summarizing two the most used methods and tools for supporting the decision making process in use of environmental engineering technologies. In this paper, the fundamental differences between LCA and RA and benefits from their use has been contained.

The remediation of open-cast post-mining soil remains a big challenge. Here, the post-mining soils are considered from the viewpoints of CO₂ emission and carbon sequestration. We investigated the dynamic of C stock in two different post-mining areas, i.e., the limestone post-mining soil remediated with embankment (S1), and the lignite post-mining soil remediated with sewage sludge (S2). Post-mining soils under four different remediation stages were used. The study was conducted in the spring of 2021 and 2022. The aim of the study was to assess the C sequestration in sewage sludge amended and non-amended post-mining soils at differently advanced remediation techniques. We noticed an increase in or stabilization of SOC in the S1. The stabilization of SOC was observed for the soil with a higher remediation age (S1C, S1D). The remediation of the S2 resulted in the increase in SOC among the soil remediation age. For both soils, we noticed a negative CO₂ emission from the soil under remediation, and the net CO₂ emission rate (NCER) further decreased after one year. A positive C feedback of both remediation techniques was shown to reflect lower active carbon (POXC). We also noticed an increase in nutrient content (K, Mg), and a decrease in heavy metals content after 1 year. Such a positive relationship between the remediation of post-mining soils and C sequestration indicates a step towards climate change mitigation.