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

No abstract

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.

No abstract

No abstract