Today it is obvious that the existing linear model of the economy does not correlate with the principles of sustainable development. The circular economy model can replace the current linear economy whilst addressing the issues of environmental deterioration, social equity and long-term economic growth. In the context of effectively implementing circular economy objectives, particular importance should be attributed to wastewater treatment sludge management, due to the possibility of recovering valuable raw materials and using its energy potential. Anaerobic digestion is one of the methods of recovering energy from sewage sludge. The main goal of this study is to make a preliminary evaluation of possible sewage sludge biogas and biomethane solutions using a computation model called MCBioCH₄ and compare its results with laboratory tests of sewage sludge fermentation from the northern wastewater treatment plant (WWTP) of Ekaterinburg (Russian Federation). Laboratory experiments were conducted to determine the volume and qualitative composition of biogas produced throughout anaerobic fermentation of raw materials coming from the WWTP. The specific productivity of samples ranged between 308.46 Nm³/t_vs and 583.08 Nm³/t_vs depending if mesophilic or thermophilic conditions were analyzed, or if the experiment was conducted with or without sludge pre-treatment. Output values from the laboratory were used as input for MCBioCH₄ to calculate the flow of biogas or biomethane produced. For the case study of Ekaterinburg two possible energy conversion options were selected: B-H (biogas combustion with cogeneration of electrical and thermal energy) and M-T (biomethane to be used in transports). The results of the energy module showed a net energy content of the biogas between 6575 MWh/year and 7200 MWh/year. Both options yielded a favorable greenhouse gas (GHG) balance, meaning that avoided emissions are higher than produced emissions. The results discussion also showed that, in this case, the B-H option is preferable to the M-T option. The implementation of the biogas/biomethane energy conversion system in Ekaterinburg WWTP necessitates further investigations to clarify the remaining technical and economic aspects

The article presents the conceptual features of energy security management under a radically changed context, increasing crisis phenomena, and threats of various natures. The authors substantiate the claim that energy security is a complex category, which expresses the ability of the fuel and energy complex of the region to supply the required amount and range of energy resources to the domestic market at stable and reasonable prices; to promptly mitigate unexpected fluctuations in demand for fuel and energy resources; and to ensure uninterrupted energy supply and energy carrier parameters in real time. Based on an analysis of scientific publications and practical energy security models, the authors developed theoretical provisions, methodological principles, and management tools for energy security that meet modern requirements. In particular, the authors developed the terminological apparatus and identified the types and forms of modern energy threats and risks. The authors analyzed the impact of structural shifts in the electric power industry on the cost of electricity. The authors proposed a set of measures to neutralize negative scenarios in the field of energy security, which had appeared because of geopolitical factors, structural changes in the economy, and high volatility in energy prices. In addition, the authors considered the impact of the transition to low-carbon energy production on energy security, and developed the organizational and technical concept of the energy transition, which aimed to provide energy systems and individual energy facilities with properties of self-protection from emerging threats. The results of the study are of practical interest in the development of regional energy policy, plans, and specific actions that aim to ensure energy security in a turbulent global environment.

Soils contaminated with organic substances is an important issue across Europe: In some areas, these are the main causes of pollution, or the second after contamination from waste disposal. This paper included an experimental application that compared three methods of remediation of contaminated sites, based on electric fields: A single treatment (electroremediation); and two combined treatments, phyto-electrochemical and electrooxidation (a combination of chemical treatment and a DCT—direct current technology). The contaminated soil was taken from a former industrial area devoted to oil refining, located between two roads: The one national and the other one for industrial use. Nine soil samples were collected at two depths (0.2 and 0.4 m). The initial characterization of the soil showed a density of 1.5 g/cm³ and a moisture of about 20%; regarding grain size, 50% of the soil had particles with a diameter less than 0.08 mm. The electrochemical treatment and electrooxidation had an efficiency of 20% while the two combined methods had efficiencies of 42.5% for electrooxidation (with H₂O₂) and 20% for phyto-electroremediation (phyto-ER) with poinsettias.

In order to ensure their market sustainability, it is essential for energy-intensive industrial companies to address the issues of efficient energy use. Companies that are prepared to embrace tariff hikes, structural changes in fuel and energy markets, and a shortage of energy resources have a wider range of options to respond to the new challenges posed by the external environment and to reduce their risks. This task becomes particularly relevant in the context of the development of the circular economy that is aimed at resource optimization, energy conservation, zero-waste manufacturing, and business models that are based on maximum operational efficiency. This study aims to develop a methodology for rational behavior of the energy consumer in the context of the circular economy. The concept of “rational behavior” is defined by the authors as the intention to make the maximum use of the advantages and potential of energy markets in order to reduce the cost of energy supply, increase the level of electrification in industrial production, and use the capabilities of their own energy business. The article describes the main principles of rational behavior that serve as the foundation for effective implementation of various strategies (that of the seller, buyer, or both) in a company. A link is shown between rational behavior and energy market potential management in a company as a mix of technological, economic, and organizational activities performed by the energy consumer in a competitive market and effective market risk management. Forms of off-grid power supply and conditions for their application in manufacturing, for example, mini-combined heat and power (CHP) plants and quadgeneration plants at large metallurgical facilities were analyzed.

The paper suggests a methodological approach for assessing the sustainability of the urban transport system. Parameters were selected for assessing the sustainability of the transport system and significant factors affecting sustainability were determined. Parameters of the sustainability of the system when changes in the weather and road conditions affect vehicle operation were estimated on the basis of the simulation modeling. An integral indicator of sustainability was introduced to evaluate the sustainability of the transport flow management subsystem and the methodological approach to its calculation was substantiated. The results from changing the parameters of the traffic flow were demonstrated in the case of a significant amount of precipitation and the constraints put on the movement of vehicles on the road infrastructure unit due to snow-removal operations and road traffic accidents. Also, the parameters of road traffic under the reconstruction of the main street of regulated traffic into a street of uninterrupted traffic were presented.

High-quality managerial decision-making is crucial for improving the resource efficiency of production companies in the context of digitalization. Currently, the use of modern methods and tools to manage the consumption and supply of resources of companies should consider the principles of a circular economy. This study focused on the development of a mechanism to manage resource efficiency in the fuel and energy sector. It used the methodological tools developed by the authors, including a comprehensive integral assessment of resource efficiency and a practice-oriented research methodology adapted for fuel and energy enterprises. Having analyzed the existing state of resource consumption, the authors discovered a disparity of indicators, methods and means in the applied assessment of the accounting, control and expenditure of energy resources. Using the analytic hierarchy process as a foundation, the authors applied a technique for identifying inefficient production processes at the fuel and energy enterprises level as a case study. With the proposed technique, the main areas of the inefficient use of resources were identified. They include the organization of accounting, control and rationing of resource consumption, supplying the resources to production, and measures to improve resource conservation. These areas were ranked by importance and priority. The calculations determined the most resource-intensive process—“Operation of equipment and technologies”. On this basis, the authors developed a methodology for resource efficiency management, including a number of digital technologies and tools. As a result of testing the developed mechanism in an oil and gas company based on the principles of a circular economy, the authors found reserves of the inefficient use of energy resources and searched for the best option for the development of an oil and gas company. Moreover, the proposed approach enabled the authors to determine the balanced growth of the company’s resource efficiency, develop managerial decisions for the its long-term development, and conduct its environmental and economic assessment.