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It is necessary to enhance the barrier performance of cutoff walls in order to improve the contamination control level, especially for reconstruction or expansion of existing landfill sites. This paper presents a comprehensive laboratory investigation on the synergistic effects of microorganisms and fibers on the hydraulic conductivity of silty sand to evaluate the applicability to the field condition as an alterative barrier material. Inside the soil, the added carbon fibers not only provided good biocompatibility, but also formed spatial three-dimensional network between soil particles to improve the bacterial adhesion that eventually caused 2–3 orders of magnitude decrease in soil permeability. The resistance of the biofilm to extreme conditions was tested by permeation with solutions of different salinity and pH values, and by subjecting specimens to various hydraulic gradients and soil conditions. Despite the microbial growth inhibition occurred at these conditions, however, biofilm can largely remain intact and continue to reduce k, which due to the gradual adaptation of microorganisms to the extreme environment and the gradual recovery of their activity. Results of these tests demonstrate that biofilm treatment may be a feasible technology for creating waste containment barriers in soil. 相似文献
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《International Journal of Hydrogen Energy》2019,44(11):5220-5229
At present, the proportion of tight oil in non-renewable hydrogen energy is increasing. According to an initial exploration and attemptable practice on the exploration of tight oil, it is found that the cost can be controlled effectively and positive effects are achieved. But this technique cannot make sure the proppants filled uniformly in the long fracture. Several researches on the proppants migration experiment devices and factors influencing on proppant setting are reviewed and a new set of experimental device to simulate the laws of proppants setting in long fracture is developed. This device can simulate the main factors influencing proppants setting performance. It analyzes several factors such as wall filtration, construction displacement, sand concentration, proppant size and density, viscosity of fracturing fluid is used to rank the influencing degree of every factor. Considering the effects of mutual interference between proppants, width of fracture, rough fracture surface and fracture surface filtration during the proppants setting progress, the mathematical model of proppant setting is modified by adding sand concentration correction factor, wall effect correction factor and filtration correction factor. The experimental data verify the accuracy of the settlement model is established using the data getting from experiment. 相似文献
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Wirginia Tomczak Jean-Henry Ferrasse Marie-Thérèse Giudici-Orticoni Audrey Soric 《International Journal of Hydrogen Energy》2018,43(41):18883-18895
The present paper reports on results obtained from experiments carried out in a laboratory-scale anaerobic packed bed biofilm reactor (APBR), with recirculation of the liquid phase, for continuously biohydrogen production via dark fermentation. The reactor was filled with Kaldnes® biofilm carrier and inoculated with an anaerobic mesophilic sludge from a urban wastewater treatment plant (WWTP). The APBR was operated at a temperature of 37 °C, without pH buffering. The effect of theoretical hydraulic retention time (HRT) from 1 to 5 h on hydrogen yield (HY), hydrogen production rate (HPR), substrate conversion and metabolic pathways was investigated. This study indicates the possibility of enhancing hydrogen production by using APBR with recirculation flow. Among respondents values of HRT the highest average values of HY (2.35 mol H2/mol substrate) and HPR (0.085 L h?1L?1) have been obtained at HRT equal to 2 h. 相似文献
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绒囊转向剂通过改变岩石强度控制裂缝走向,已在现场应用获得印证,但是缺乏裂缝转向理论研究。转向剂强度与转向角的关系是转向裂缝准确地延伸至预定位置的关键之一。室内进行转向剂封堵实验和岩石三轴实验,用囊层剂+1.5%绒毛剂+0.3%成核剂+0.5%成膜剂配制绒囊转向剂,测得注入量为4、8、10、12 mL时,封堵后承压达到10.15、12.37、16.52、25.14 MPa;绒囊转向剂封堵直径75 mm致密砂岩岩心人造裂缝,通过三轴试验机测得封堵前后岩心径向应力应变曲线拐点从0.004 8 mm/mm升至0.012 7 mm/mm,轴向曲线拐点从0.014 3 mm/mm升至0.018 6 mm/mm,说明岩心强度提高。测得转向角增量分别为24.9°、23.2°、37.5°和55.9°。根据4组岩心封堵后弹性模量19.55、16.65、19.61、19.77 GPa和泊松比0.36、0.30、0.46、0.38,选择影响转向角度的参数为弹性模量和泊松比,用最小二乘法方法拟合参数与裂缝转向角度之间的数学关系,得到弹性模量与泊松比商的自然对数与转向角度呈线性关系,进而得到注入量与转向角的函数关系。结果表明,绒囊流体的注入量可以控制转向角度,进而实现转向裂缝准确延伸至目的层位。 相似文献
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Argillaceous limestone formations are being proposed as sites suitable for constructing a deep geologic repository for storing low-to intermediate-level nuclear waste in southern Ontario, Canada. The Cobourg limestone is characterized by a visual appearance of heterogeneity resulting from light gray calcite nodular regions interspersed with dark gray calcite-dolomite-quartz partings containing a clay component. This paper presents the results of experiments conducted to determine the permeability of both the light gray and the dark gray species of the Cobourg limestone. The permeabilities were successfully estimated from both steady state and hydraulic pulse tests conducted using specially designed miniature water entry ports, which were epoxied to the surface of the rock sample containing cavities drilled into the rock species of interest. The results show that the dark gray species of the Cobourg limestone has a permeability that is roughly one order of magnitude greater than the light gray calcite species. 相似文献
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本文通过对两级伸缩式液压缸与四柱滑轨结合使用中所出现问题及处理过程的阐述,提出了在液压系统设计与制造中,准确的原理仅仅是基础,其上还有许许多多的细枝末节需要仔细修剪,比如污染、噪声、温度、泄漏以及与机械的协调等等。 相似文献