Current Issue : January-March Volume : 2023 Issue Number : 1 Articles : 5 Articles
Strengthening the transmission uniformity of remedial amendments in heterogeneous porous media is important for improving in situ groundwater remediation efficiency. This study developed a characterization method to represent the improvement of transmission uniformity in heterogeneous media using the degree of difference in hydraulic conductivity of porous media between xanthan solution and pure water, which was defined as the transmission uniformity control coefficient U. Research results showed thatU of medium sand/fine sand (2.44) was the most ideal among the three medium combinations tested when the concentration of xanthan solution was 100 mg/L. Then, factors that may influence U were analyzed, and the obtained results showed that xanthan’s control ability is affected by permeability contrast (media combinations) and polymer concentration. Generally, when concentrations were in the range of 100~800 mg/L, Umf > Ucf > Ucm. Finally, the actual degree of polymer propulsion under different concentrations and media combinations was analyzed, and the obtained results showed that as different media were varied in permeability change degree, while the migration speed presented an overall decrease as the concentration increased, where the maximum migration front in the low-permeability zone (LPZ) was more obvious than that in the high permeability zone (HPZ). This was consistent with the results characterized by U....
Alternative water treatment techniques are needed to overcome the limitations of chemical disinfectants. Stemming from recent findings which point to high levels of shear stress induced by flow as the cause of microbial removal in water, we conducted systematic experiments on bacterial solutions in well-controlled hydrodynamic conditions to evaluate the effect of different levels of shear stress on the viability of Escherichia coli. We investigated a wide range of shear stresses (57-4240 Pa) using viscous substrates prepared by mixing a bacterial solution with thickeners (2- hydroxyethyl cellulose and/or guar gum). Substrate samples were tested for up to 60 min in a laminar shear flow at a constant temperature using a rotational rheometer equipped with a coneplate measuring system so that the whole sampling volume was exposed to the same shear stress. Results show that, contrary to previous studies, high shear stresses (i.e., of order 10³ Pa) do not induce inactivation or lysis of E. coli, even for prolonged exposure times. Stemming from our results and a thorough discussion of the literature on E. coli mechanical lysis and modeling cell dynamics, we infer that E. coli can resist high shear forces because of stress relaxation in a wide range of hydrodynamic conditions....
The SORGENTINA-RF project aims at developing a 14 MeV fusion neutron source featuring an emission rate in the order of 5–7 × 1013 s−1. The plant relies on a metallic water-cooled rotating target and a deuterium (50%) and tritium (50%) ion beam. Beyond the main focus of medical radioisotope production, the source may represent a multi-purpose neutron facility by implementing a series of neutron-based techniques. Among the different engineering and technological issues to be addressed, the production of incondensable gases and corrosion product into the rotating target deserves a dedicated investigation. In this study, a preliminary analysis is carried out, considering the general layout of the target and the present choice of the target material....
Plastic pollution is a major problem: it damages health, reduces ecosystem services, and affects local economies. Despite its importance, available valuation efforts have focused primarily on the damages caused by plastic in marine environments. Far less is known about the effects of plastic waste in inland settings. This paper addresses this gap by estimating in monetary terms the damages caused by the inappropriate disposal of plastic waste in an inland context. The study area is located along a canal that crosses N’Djamena, the capital of Chad. Using data from a primary survey and applying standard valuation techniques, the paper estimates the social cost of plastic pollution at over USD3000 per ton in 2020. In addition, it shows that the impacts of plastic waste vary significantly across the study area: households residing within 20 meters of the canal bear more than 75 percent of the total damages. The paper identifies the main valuation challenges and proposes recommendations to reduce plastic waste damages....
With the rapid development of the economic system and the continuous development of industry, environmental pollution is becoming more and more important, so wastewater treatment urgently needs to be strengthened. This article uses fly ash-coated iron electrode electrocoagulation method to carry out experimental tests on the treatment of comprehensive wastewater from chemical and pharmaceutical parks. Fly ash is used as a raw material to prepare a shaped adsorbent; in order to analyze whether the adsorbent has many potential applications in actual wastewater treatment and use. The experiment research of iron electrode electrocoagulation was carried out on actual groundwater, aiming to provide data and theoretical support for the utilization of fly ash and the optimization of comprehensive wastewater treatment technology. The article mainly conducts related research on title distribution, firstly the physical and chemical properties of fly ash, and secondly, discusses the related structure of electrocoagulation method, and solves the problem of comprehensive wastewater based on the combination of the two solving issues. Aware of the importance of sewage treatment and the characteristics of related treatment methods such as adsorption, membrane separation technology, and ion exchange, the advantages of these methods are also used for reference in subsequent experiments to achieve the purpose of reliable experimental results. The experimental results show that the effect of sewage treatment with fly ash with different average diameter particles is obvious. Among them, the maximum value of vibration grinding ash before and after application increased from 5.62 to 8.31, and the maximum removal rate is also 8.31; the removal effect is significant. It can be seen that the fly ash-coated iron electrode electrocoagulation method can have a great effect on the treatment of comprehensive wastewater in the chemical and pharmaceutical park....
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