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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/tvs and 583.08 Nm3/tvs 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

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.

Vehicle modernization has been developed towards the growing necessities of speed, power, efficiency, ergonomics, and design etc. The requirements, nowadays of environmental safety and operational efficiency of vehicles are being brought to the forefront. The aim of this work is to increase efficiency and reduce the harmful environmental impact of automobile transport by improving the quality of fuels during its operation. The improvement of the quality of fuels by means of highly-effective additives is the most rapidly implemented and lowcost method. According to the settled requirements of the properties of additives and the analysis of the catalytic and physicochemical properties of the substances, the universal content of the additive to gasoline and diesel fuel was found and the technology of its production was proposed. In addition, the additive was thoroughly tested in the laboratory, test bench, traffic operation and experimental-industrial checkout. It was found that the application of the additive in minor quantities significantly improves operational and environmental properties of fuels and engine characteristics.

Climate change and anthropogenic pollution have put limited water resources under pressure. Lack of basic sanitation services as well as the discharge of improperly treated effluent from wastewater treatment plants (WWTP) result in the deposition of large amounts of organic matter and nutrients, which have major detrimental effects on health. Wastewater treatment (WWT) can reduce water pollution but at the cost of increasing energy consumption and the corresponding atmosphere and climate problems. Sustainable WWT management is a global challenge to preserve fresh water and decrease energy consumption. Nowadays it becomes obvious that existing WWTP operation model, based on the linear "take-make-dispose" pattern, is no longer sustainable. Furthermore, disposal of a product in landfill means that all residual energy is lost. The adoption of circular economy (CE) practices with its 3R principles of reducing, reusing and recycling material appears as a timely, relevant and practical option to meet the goals of sustainable development. WWTP is a critical element in CE implementation policy and to measure the degree of "circularity" there is a need for indicators. This study considers the holistic overview of measuring the progress of CE implementation at WWTP under 3R principles using life cycle analysis (LCA) and material flow analysis (MFA) frameworks. The paper presents the principles of CE indicators set construction using managerial approach. The proposed set of indicators and integral circularity index are studied under three scenarios, based on real performance of northern and southern WWTP in Ekaterinburg, Russia. This study provides an efficient assessment tool of CE progress, which is rather simple for calculation and interpretation and suitable for the use of wide range of stakeholders.

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The oil refining industry in Russia produces poor quality motor fuels that meet neither the standards of developed countries nor the needs of a rapidly growing domestic vehicle fleet. The aim of this work is to substantiate the optimal direction for reforms to modernize the Russian oil industry, which will then enable it to achieve in a timely manner the necessary changes to the quality of motor fuel that will improve both the energy efficiency and environmental safety of motor vehicles. The prospective requirements for fuel quality in Russia were formulated based on analytical investigation. The necessity to change the ratio between reforming and isomerization capacities to improve fuel properties is herein demonstrated. The proposed scheme for highly efficient residueless oil refining will give a motor fuel yield of approximately 85% with inherent high environmental and operational characteristics. The optimal direction for the rapid improvement of the quality of motor fuels through the use of the developed multifunctional fuel additive in trace amounts is proposed.

Abstract.The current obstacles to the sustainable development of the vehicle fleet present one of the most serious and complex challenges for technogenic civilization in view of the consumption of rapidly depleting oil and gas resources and the increasing emissions of the products of fuel combustion. The aim of this paper is to study and discuss the impact patterns of the quality of fuel on the environmental and performance characteristics of vehicles and to develop an approach towards improving the quality of fuel as a means of increasing the sustainability of vehicles. The patterns of influence of the chemical composition of the fuel on the temperature conditions in the engine, the emissions of toxic substances and carbon dioxide from the fuel's combustion, the toxicity of the gasoline vapor, carbonization, fuel consumption, engine power and the requirements for a gasoline octane rating have been identified. The use of a fuel additive has been proposed which improves fuel injection in the engines and excludes tarry deposits in the fuel system through the effective detergency and catalyzes the gasification reactions in the engine. The developed fuel additive was shown to have a positive effect by significantly reducing fuel consumption and toxic emissions and improving the performance of vehicles.