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In the water-rich karst regions, high water and mud outbursts are common geological disasters in tunnel construction. To ensure the safe and smooth construction of tunnel projects, it is necessary to consider anti-water pressure, water inrush prevention and geological disasters during the design of tunnels. Based on the Yongfutun Tunnel Project, this paper studies the application and effect of radial grouting and curtain grouting, which involves those in high-water-pressure tunnels under double-layer support conditions. To obtain the effects and parameters of radial grouting and curtain grouting, the influences of different grouting ranges on the tunnel’s surrounding rocks and supporting structures were analyzed and the finite difference method was adopted. The results show that the radial grouting of the surrounding rock can notably improve the initial support of the tunnel, but the impact is less obvious when the grouting range exceeds 4 m. The design of radial grouting is recommended to be 4.0 m to 4.5 m. Curtain grouting can effectively reduce the external water pressure of the tunnel lining. The external water pressure of the grouting area is 23% greater than that without curtain grouting. Curtain grouting can slow down the infiltration of external water pressure. This is beneficial to the stress of the tunnel lining structure, but the improvement in initial support force is slight. Moreover, curtain grouting improves the safety reserve of the secondary lining by strengthening the self-stability ability of the surrounding rock. Meanwhile, the double-layer primary support can effectively share the external water pressure and surrounding rock pressure. This study provides a certain reference for the lining design of high-water-pressure tunnels.

[EN]A systematic approach is developed for the conceptual optimal design of biomethane production via carbon capture. A hybrid heuristic-mathematical procedure is proposed to determine the optimal technology and operating conditions. The heuristic step consists of a literature-based screening of the available technologies. After the prescreening stage, the technologies selected are amine absorption, pressure swing adsorption (PSA), and membrane separation. The mathematical stage is composed of two steps. First, different alternatives for each technology are modeled based on first principles and rules of thumb. These models are used to select the optimal configuration for each process considered. Second, a superstructure model for biomethane production is developed integrating the pre-selected upgrading technologies to select the optimal process, as well as to determine the optimal operating conditions. Four waste sources are analyzed: cattle manure, swine manure, municipal food waste, and sludge. The results suggest that the best amine is diethanolamine (DEA), the best membrane material is the polyimide, and the suggested zeolite is 13X among the ones studied. Finally, among the three technologies, the overall results show that carbon capture using a PSA system using zeolite 13X results in lower production and investment costs, but very close to the use of membranes. The results indicate that food waste shows the lowest production cost for biomethane 0.36 €/Nm3, due to the largest organic matter content, whereas the investment costs are 67 M€, considering a biogas production rate of 0.035 kg of biomethane per kg of waste and the processing of 311 kt/yr of food waste. Credits or incentives are still needed for biomethane to be competitive with fossil natural gas. Junta de Castilla y León y USAL

Energy is consumed at every stage of the cycle of water production, distribution, end use, and recycled water treatment. Understanding the nexus of energy and water may help to minimize energy and water consumption and reduce environmental emissions. However, the interlinkages between water and energy have not received adequate attention. To address this gap, this paper disaggregates and quantifies the energy consumption of the entire water cycle process in Beijing. The results of this study show that total energy consumption by water production, treatment and distribution, end use, and recycled water reuse amounts to 55.6 billion kWh of electricity in 2015, or about 33% of the total urban energy usage. While water supply amount increased by only 10% from 2005 to 2015, the related energy consumption increased by 215% due to water supply structural change. The Beijing municipal government plans to implement many water saving measures in the area from 2016 to 2020, however, these policies will increase energy consumption by 74 million kWh in Beijing. This study responds to the urgent need for research on the synergies between energy and water. In order to achieve the goal of low-energy water utilization in the future, water and energy should be integrated in planning and management.

Mining and mineral processing industry adversely affects ecosystems and communities in nearby areas, including high freshwater consumption and scarcity. That is why the emerging global trend is to use sea water in flotation to recover valuable minerals from finely disseminated base metals ores. Recent studies investigate sea water flotation of copper, molybdenum, nickel sulphides and pyrite, while flotation of sphalerite, the main valuable mineral for zinc production, remains uncovered. This paper examines the feasibility of sphalerite flotation by conventional collectors in artificial sea water using a bubble-particles technique and frothless flotation tests. Potassium isopropyl xanthate (PIPX) and sodium isopropyl dithiophosphate (SIDTP) were used as collectors, and copper sulphate was introduced as the activator, while zinc sulphate and sodium sulphide were used as depressants. We examined the most common size fractions of sphalerite: medium (−74 + 44 μm) and fines (−44 μm). The findings showed the feasibility of sphalerite flotation in artificial sea water. We also established correlations between the rate of bubble-particle attachment and the sphalerite flotation recovery resulting in the growth of flotation recovery with the increase of the bubble-particle attachment rate. The results can be used as guidelines in choosing flotation reagents for sphalerite flotation in sea water. Another practical application of the results is the potential for sustainable development of the industrial sector, ecosystems and societies due to the replacement of fresh water by sea water, although further technological and environmental studies are required.

The production process of nitroaromatic hazardous compounds, with the generation of acidic wastewater, represents a significant danger for the health and safety of the workers and the environment. The present study is focused on the development of an efficient installation to treat acidic wastewater resulting from the synthesis process of nitroaromatic compound, considering workers safety and environmental criteria. In this research, a detailed study of the different alternatives that can be used for effective and safe treatment of acidic wastewater was performed. The analysis of several technological schemes for the acidic wastewaters neutralization and the selection of the most feasible alternative from a technical-economic point of view were carried out. The simulation and mathematical modeling developed in this research represent a significant advance in the knowledge of this process for working in a much more secure form. The technological scheme of the process was defined, and the design of the main and auxiliary equipment as well as the piping system was carried out using different computational programs. Finally, this paper proposes a technological design for the treatment of acidic wastewater generated by the production process of nitroaromatic compound, which represents the basic criteria for the further design, construction, and equipment installation of the plant.

This study aims to identify potential hydropower sites and calculate the theoretical potential hydropower capacity based on watershed modelling of the Mindanao River Basin (MRB) in the Philippines for the sustainable development of a previously unstudied region. The Soil and Water Assessment Tool (SWAT) was applied to delineate the watershed of the MRB and simulate the river discharges with inputs from observed precipitation and global gridded precipitation datasets. Observed weather data, such as temperature, humidity, and solar radiation, from four meteorological stations in the Philippines were also used as inputs for SWAT modelling. Simulated discharges were calibrated at three river gauges on the Nituan, Libungan and Pulangi Rivers. However, due to limited river discharge records, model validations were conducted in proxy basins: the calibrated model parameters in river A were used in the watershed modelling of proxy river B. Of the delineated 107 sub-basins in the MRB watershed, only 33 were identified as having potential sites for hydropower development. These potential sub-basins hosted a total of 154 potential sites with an estimated monthly average power capacity of 5,551.35 MW for all 33 sub-basins. The estimated theoretical power capacity of 15,266.22 MW for all sites in the MRB is approximately equivalent to the Philippines’ total available power capacity in 2017 of 15,393 MW. These sites were classified into 16 mini-scale hydropower sites, 114 small-scale hydropower sites and 24 medium-scale hydropower sites based on the simulated river discharges and potential power capacities. Based on these results, hydropower development could be an alternative to strengthen the exploration of renewable energy resources and improve the energy situation in Mindanao; hydropower development could also have mitigation effects on frequent floods in flat, low-lying downstream areas.

AbstractA simple experiment for capillary sealed trap shows that leakage would occur only from the weakest point in the trap. As an extens ion of this concept, the sequestrated and accumulated CO2 in the structural high may happen to leak from the unexpected weak point near the top of sealing layer. On the other hand, if CO2 were sequestrated into the flank of tilted aquifer, CO2 in separate phas e would migrate upward within aquifer with no CO2 leakage into the sealing layer above and leaving some residual amount behind. According to this concept, the best location for sequestration of CO2 could be the flank of the structure rather than the top.

The fresh green and yellow banana peel of, (Musa, cv. Cavendish) fruits were treated with 70% acetone, which were partitioned with chloroform (CHCl3) and ethyl acetate (EtOAc), sequentially. The antioxidant activities of the extracts were evaluated by using the thiocyanate method, β-carotene bleaching method and 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical elimination. While, antimicrobial activities of the extracts and isolated components were evaluated using paper disc methods and Minimum Inhibition Concentration (MIC). The EtOAc and water soluble fractions of green peel displayed high antimicrobial and antioxidant activity, respectively. Antioxidant activity of water extracts was comparable to those of synthetic antioxidants such as butylated hydroxyanisole and butylated hydroxytoluene. Among all isolated components β-sitosterol, malic acid, succinic acid, palmatic acid, 12-hydroxystrearic acid, glycoside, the d-malic and 12-hydroxystrearic acid were the most active against all the Gram-negative and positive bacterial species tested. The MIC of d-malic and succinic acid was varying between 140-750 ppm, respectively.