A huge amount of organic waste is generated annually around the globe. The main sources of solid and liquid organic waste are municipalities and canning and food industries. Most of it is disposed of in an environmentally unfriendly way since none of the modern recycling technologies can cope with such immense volumes of waste. Microbiological and biotechnological approaches are extremely promising for solving this environmental problem. Moreover, organic waste can serve as the substrate to obtain alternative energy, such as biohydrogen (H₂) and biomethane (CH₄). This work aimed to design and test new technology for the degradation of food waste, coupled with biohydrogen and biomethane production, as well as liquid organic leachate purification. The effective treatment of waste was achieved due to the application of the specific granular microbial preparation. Microbiological and physicochemical methods were used to measure the fermentation parameters. As a result, a four-module direct flow installation efficiently couples spatial succession of anaerobic and aerobic bacteria with other micro- and macroorganisms to simultaneously recycle organic waste, remediate the resulting leachate, and generate biogas.

The production of biomethane from biogas energy costsfor the most widely used amine and water processes for extracting carbon dioxide from biogas were analyzed using computer simulation. Combined water-amine absorption method of biogas purification from CO₂ wasincluded in the comparative analysis. For the CO₂ content of the biogas from 32 to 42 %, the specific energy costs when using water absorption to extract carbon dioxide from biogas are, on average, in ~ 2.5 times lower than amine absorption, but the loss of CH₄ by water absorption was 7.1–7.6 % due to its watersolubility with practically zero CH₄ loss when using amine absorption and insignificant loss (0.17–2.8 %) using water-amine technology. Using preliminary water absorption of CO₂ saved CH₄ can compensate the power consumption of the biogas compressor or the heatcosts of saturated amine absorbent regenerating. This will allowto reduce energy consumption to almost equal to water absorptionone. The results of simulation of carbon dioxide extraction from biogas can be used to optimize technological absorption schemes for the production of biomethane — an analogueof natural gas. Bibl. 13, Fig. 5, Tab. 6.

The main technologies for carbon dioxide capturing are analyzed. Promising technologies include “before burning” CO2 capture and CO2 injection into depleted oil fields to enhance oil recovery, which make it possible not only to reduce residual oil saturation, but also to reduce carbon dioxide emissions into the atmosphere effectively. The energy costs of amine processes for extracting carbon dioxide from biogas are analyzed with the use of computer simulation. To extract carbon dioxide from process gases a traditional single-flow absorption scheme can be used in which MDEAmod absorbents the optimal in terms of energy performance minimizing. The MDEAmod absorbent is universal and can be used in CO2 extraction processes, including those under high pressure, from various process gases, in which the CO2 content can vary over a wide range of concentrations and reach 45 % (vol.). The use of this absorbent reduces the heat consumption for the regeneration of the saturated sorbent by 1.4–2.5 times compared to 18 % MEA and reduces the absorbent consumption by 30 %. A laboratory unit for extracting target fractions of biomethane and carbon dioxide from biogas has been created. The model calculation results of the amine CO2 extracting from biogas and those obtained on a laboratory unit are quite close and the deviation of the calculated from the experimentally obtained CH4 concentration in biomethane at a pressure in the absorber Pabs = 0.11–0.2 MPa does not exceed 3 %. The results of extracting carbon dioxide from biogas modeling can be used to optimize the technological absorption schemes for the production of biomethane - an analogue of natural gas. Experimental technology has been developed and equipment for the production and decomposition of natural gas and carbon dioxide hydrates has been created. The thermodynamic parameters of hydrate formation by bubbling have been determined, and hydrate samples have been obtained. Thermodynamic trend of pressure difference of 1.5–2 MPa to methane replace with carbon dioxide in hydrates was experimentally established and thus the possibility of replacing methane gas hydrates with carbon dioxide and using this technology for the conditions of developing gas hydrate deposits in the Black Sea was confirmed. Bibl. 30, Fig. 10, Tab. 3.

One of the problems in the implementation of natural gas liquefaction technology in a closed high-pressure cycle is the accumulation of low-boiling components, in particular, nitrogen in the circulating gas stream, as a result of which the throttle effect decreases and, accordingly, the specific energy consumption of the liquefaction plant increases. The nitrogen concentration influence on the liquefaction plant operation in the throttle cycle of high-pressure natural gas with a nitrogen content of 0 to 6 % was studied using the GazCondNafta software system for computer simulation of technological processes. To solve the problem of liquefaction of nitrogen-containing gases, a liquefaction scheme with two stages of throttling and intermediate separation with nitrogen vapor stripping is proposed. The effect of gas pressure in the nitrogen separator was determined from the point of view of minimizing losses of the main component of natural gas — methane — with stripping gas with a relatively small decrease in energy efficiency. Bibl. 14, Fig. 6, Tab. 4.

The article presents the results of the development of the modernization of the complex gas preparation installation, namely the modeling of the processes of removing heavy hydrocarbons at the stage of preparing natural gas for transportation. Heavy hydrocarbons, which are removed at this stage, become a separate commodity product in the process of processing. With the use of software systems for computer simulation of technological processes of GazCondNafta and HYSYS, a variant of the modernization of the existing installation of complex gas preparation of the gas condensate field was developed. Options for modeling technological schemes for obtaining target fractions of methane, ethane, propane, butane from natural gas, gas synthesis and pyrolysis gas are given. Bibl. 9, Fig. 5, Tab. 8.

The presence of carbon dioxyl as a non-combustible admixture in the landfill biogas of solid household waste and the absorption of ambient air into the layer of landfill waste, and therefore its entry into the landfill gas, significantly reduces the concentration of methane in it, which affects the efficient operation of the gas piston engine of the power plant and the reduction of volumes electricity generation. With the use of computer modeling for the composition of biogas with an increased content of N2 and a reduced concentration of CH4 £ 32 %, calculations were made on the enrichment of biogas to concentrations of CH4 in it of 36–44 % due to the use of CO2 amine absorption technologies, in which the costs for the regeneration of the absorbent are compensated by the produced thermal energy of the gas piston engine of the power plant. The removal of carbon dioxide from biogas makes it possible to simultaneously increase the concentration of methane in it at the input to the heat engine, which contributes to the stable and efficient operation of the gas piston engine of the power plant and the increase in the amount of electricity generation as a result of energy utilization of landfill gas. The use of complex biogas utilization technology in the cogeneration mode allows obtaining not only electricity, but also heat, which can be used in absorption amine technologies for CO2 extraction from biogas and thus reducing carbon dioxide emissions into the atmosphere. Bibl. 17, Fig. 9, Tab. 3.