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Filled with effective methods for recovering gas energy using expanders, this practical resource offers in-depth details on different types of expanders, addressing the background, mechanical design features, design and operating requirements, operational processes, and potential problems for each class expander.

A technology that directly injects CO2-rich industrial waste gas (CO2-rich IWG) into underground spaces for unconventional natural gas extraction and waste gas storage has received increasing attention. The pore characteristics of coal and shale in a coal-bearing rock series before and after CO2-rich IWG treatment are closely related to gas recovery and storage. In this study, three coals ranging from low to high rank and one shale sample were collected. The samples were treated with CO2-rich IWG using a high-precision geochemical reactor. The changes in the pore volume (PV), specific surface area (SSA), and pore size distribution of micropores, mesopores, and macropores were analyzed. The correlations between the Langmuir volume and the PV and SSA of the micropores and mesopores were analyzed. It was confirmed that for micropores, SSA was the dominant factor influencing adsorption capacity. The effectively interconnected pore volume was calculated using macropores to characterize changes in the sample’s connectivity. It was found that the PV and SSA of the micropores in the coal samples increased with increasing coal rank. The CO2-rich IWG treatment increased the PV and SSA of the micropores in all of the samples. In addition, for mesopores and macropores, the treatment reduced the SSA in the coal samples but enhanced it in the shale. The results of this study improve the understanding of the mechanisms of the CO2-rich IWG treatment method and emphasize its potential in waste gas storage and natural gas extraction.

\"Carbon peaking and carbon neutrality\" is an essential national strategy, and the geological storage and utilization of CO2 is a hot issue today. However, due to the scarcity of pure CO2 gas sources in China and the high cost of CO2 capture, CO2-rich industrial waste gas (CO2-rich IWG) is gradually emerging into the public's gaze. CO2 has good adsorption properties on shale surfaces, but acidic gases can react with shale, so the mechanism of the CO2-rich IWG–water–shale reaction and the change in reservoir properties will determine the stability of geological storage. Therefore, based on the mineral composition of the Longmaxi Formation shale, this study constructs a thermodynamic equilibrium model of water–rock reactions and simulates the regularity of reactions between CO2-rich IWG and shale minerals. The results indicate that CO2 consumed 12% after reaction, and impurity gases in the CO2-rich IWG can be dissolved entirely, thus demonstrating the feasibility of treating IWG through water–rock reactions. Since IWG inhibits the dissolution of CO2, the optimal composition of CO2-rich IWG is 95% CO2 and 5% IWG when CO2 geological storage is the main goal. In contrast, when the main goal is the geological storage of total CO2-rich IWG or impurity gas, the optimal CO2-rich IWG composition is 50% CO2 and 50% IWG. In the CO2-rich IWG–water–shale reaction, temperature has less influence on the water–rock reaction, while pressure is the most important parameter. SO2 has the greatest impact on water–rock reaction in gas. For minerals, clay minerals such as illite and montmorillonite had a significant effect on water–rock reaction. The overall reaction is dominated by precipitation and the volume of the rock skeleton has increased by 0.74 cm3, resulting in a decrease in shale porosity, which enhances the stability of CO2 geological storage to some extent. During the reaction between CO2-rich IWG–water–shale at simulated temperatures and pressures, precipitation is the main reaction, and shale porosity decreases. However, as the reservoir water content increases, the reaction will first dissolve and then precipitate before dissolving again. When the water content is less than 0.0005 kg or greater than 0.4 kg, it will lead to an increase in reservoir porosity, which ultimately reduces the long-term geological storage stability of CO2-rich IWG.

The cultivation of microalgae and microalgae–bacteria consortia provide a potential efficient strategy to fix CO 2 from waste gas, treat wastewater and produce value-added products subsequently. This paper reviews recent developments in CO 2 fixation and wastewater treatment by single microalgae, mixed microalgae and microalgae–bacteria consortia, as well as compares and summarizes the differences in utilizing different microorganisms from different aspects. Compared to monoculture of microalgae, a mixed microalgae and microalgae–bacteria consortium may mitigate environmental risk, obtain high biomass, and improve the efficiency of nutrient removal. The applied microalgae include Chlorella sp., Scenedesmus sp., Pediastrum sp., and Phormidium sp. among others, and most strains belong to Chlorophyta and Cyanophyta. The bacteria in microalgae–bacteria consortia are mainly from activated sludge and specific sewage sources. Bioengineer in CBB cycle in microalgae cells provide effective strategy to achieve improvement of CO 2 fixation or a high yield of high-value products. The mechanisms of CO 2 fixation and nutrient removal by different microbial systems are also explored and concluded, the importance of microalgae in the technology is proven. After cultivation, microalgae biomass can be harvested through physical, chemical, biological and magnetic separation methods and used to produce high-value by-products, such as biofuel, feed, food, biochar, fertilizer, and pharmaceutical bio-compounds. Although this technology has brought many benefits, some challenging obstacles and limitation remain for industrialization and commercializing. Graphical Abstract

The shortage of CO2 source and the challenges associated with the separation of pure CO2 have led to a growing interest in the potential utilization of CO2-contained IWG. Therefore, this study has established an acid-rock interaction kinetic model to characterize the long-term interactions between CO2-contained IWG and shale. The findings delineate the reaction process into three phases: during the initial 10 years, solubility trapping predominates, with minimal mineral dissolution. This increases shale porosity, promoting the diffusion and storage range of CO2-contained IWG. Between 10 and 300 years, mineral dissolution/precipitation assumes primacy, with mineral trapping gradually supplanting dissolution. Notably, shale porosity diminishes by a minimum of approximately 40%, effectively inhibiting gas leakage. After 300 years, equilibrium is reached, with rock porosity consistently lower than the initial porosity. Throughout the entire reaction process, as the initial CO2 concentration decreases, the initial pH drops from 4.42 to 3.61, resulting in a roughly 20% increase in porosity. Additionally, it is necessary to regulate its concentration to avoid H2S leakage during CO2-contained IWG geological sequestration. And particular attention should be directed towards the risk of gas leakage when the IWG exhibit high levels of SO2 or NO2.

Ceramic kiln in the use of the process of high energy consumption, high resource consumption, serious environmental pollution and other problems are the current ceramic industry development of serious problems.Kiln combustion exhaust gas pollution types mainly include: SO2, NOx, CO, particulate matter, lead, cadmium, nickel and its compounds, fluoride and chloride and so on, and the traditional kiln direct emissions into the atmosphere, causing serious pollution to the environment, the need to have reliable purification treatment devices to meet emissions requirements, but the original purification plant purification effect is poor, process complex aspects of problems.This paper introduces a new porous ceramic purification device to improve the electric kiln exhaust gas purification to improve the catalytic conversion of CO, NOX, SO2 desulfurization and particulate matter purification.

The prevention of over-exploitation and the efficient use of natural resources are key goals of environmental managment in Industry.Waste Gas Treatment for Resource Recovery presents the reader with technical, ecological and economical aspects of gaseous effluent treatment and resource recovery.

The cement industry generates a substantial amount of gaseous pollutants that cannot be treated efficiently and economically using standard techniques. Microalgae, a promising bioremediation and biodegradation agent used as feedstock for biofuel production, can be used for the biotreatment of cement flue gas. In specific, components of cement flue gas such as carbon dioxide, nitrogen, and sulfur oxides are shown to serve as nutrients for microalgae. Microalgae also have the capacity to sequestrate heavy metals present in cement kiln dust, adding further benefits. This work provides an extensive overview of multiple approaches taken in the inclusion of microalgae biofuel production in the cement sector. In addition, factors influencing the production of microalgal biomass are also described in such an integrated plant. In addition, process limitations such as the adverse impact of flue gas on medium pH, exhaust gas toxicity, and efficient delivery of carbon dioxide to media are also discussed. Finally, the article concludes by proposing the future potential for incorporating the microalgae biofuel plant into the cement sector.

Concern has been raised in the scientific literature about the environmental implications of extracting natural gas from deep shale formations, and published studies suggest that shale gas development may affect local groundwater quality. The potential for surface water quality degradation has been discussed in prior work, although no empirical analysis of this issue has been published. The potential for large-scale surface water quality degradation has affected regulatory approaches to shale gas development in some US states, despite the dearth of evidence. This paper conducts a large-scale examination of the extent to which shale gas development activities affect surface water quality. Focusing on the Marcellus Shale in Pennsylvania, we estimate the effect of shale gas wells and the release of treated shale gas waste by permitted treatment facilities on observed downstream concentrations of chloride (Cl ⁻) and total suspended solids (TSS), controlling for other factors. Results suggest that (i) the treatment of shale gas waste by treatment plants in a watershed raises downstream Cl ⁻ concentrations but not TSS concentrations, and (ii) the presence of shale gas wells in a watershed raises downstream TSS concentrations but not Cl ⁻ concentrations. These results can inform future voluntary measures taken by shale gas operators and policy approaches taken by regulators to protect surface water quality as the scale of this economically important activity increases.

In underground repositories for radioactive waste, significant quantities of gases may be generated as a result of several processes. The potential impact of gas generation, accumulation and migration on the performances of the various barriers and, ultimately, on the long-term safety of a repository, should therefore be assessed in the development of safety cases for underground repositories. It was in this context that the EC and the NEA organised a workshop on \"Gas Generation, Accumulation and Migration in Underground Repository Systems for Radioactive Waste: Safety-relevant Issues\" in Reims, France on 26-28 June 2000. This book includes the texts of the invited presentations, the reports of the deliberations held in the five working groups, as well as the main conclusions of the workshop.