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901.
902.
以"怀柔应急水源地21号对井供水管线跨怀河工程"为背景,探讨了按水力坡降或比阻以及依据谢才公式计算铸铁管水头损失的方法,并对这两种计算方法的异同优劣进行了阐述,指出在长管工程中采用查表法计算管道水头损失更简单快捷。 相似文献
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Throughout recent decades, the wastewater treatment industry has identified the discharge of nutrients, including phosphates and nitrates, into waterways as a risk to natural environments due to the serious effects of eutrophication. For this reason, new tertiary treatment processes have abounded; these processes generally utilize physico-chemical and biological methods to remove nutrients from secondary wastewaters. The disadvantages of such methods involve larger reactor volumes, operating costs, and waste sludge production; furthermore, complete nutrient removal is unattainable due to thermodynamic and kinetic limitations. The subject study presents the development and performance of a new phosphate-selective sorbent, referred to as hybrid anion exchanger or HAIX. HAIX combines durability and mechanical strength of polymeric anion exchange resins with high sorption affinity of hydrated ferric oxide (HFO) toward phosphate. HAIX is essentially a polymeric anion exchanger within which HFO nanoparticles have been dispersed irreversibly. Laboratory studies show that HAIX selectively removes phosphate from the background of much higher concentrations of competing sulfate, chloride and bicarbonate anions due to the combined presence of Coulombic and Lewis acid-base interactions. Experimental results demonstrate that HAIX's phosphate-sulfate separation factor is over two orders of magnitude greater than that of currently available commercial ion exchange resins. Additionally, optimal HAIX performance occurs at typical secondary wastewater pH conditions i.e., around 7.5. HAIX is amenable to efficient regeneration and reuse with no noticeable loss in capacity. 相似文献
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Zero valent iron (ZVI) nanoparticles have been studied extensively for degradation of chlorinated solvents in the aqueous phase, and have been tested for in-situ remediation of contaminated soil and groundwater. However, little is known about its effectiveness for degrading soil-sorbed contaminants. This work studied reductive dechlorination of trichloroethylene (TCE) sorbed in two model soils (a potting soil and Smith Farm soil) using carboxymethyl cellulose (CMC) stabilized Fe-Pd bimetallic nanoparticles. Effects of sorption, surfactants and dissolved organic matter (DOC) were determined through batch kinetic experiments. While the nanoparticles can effectively degrade soil-sorbed TCE, the TCE degradation rate was strongly limited by desorption kinetics, especially for the potting soil which has a higher organic matter content of 8.2%. Under otherwise identical conditions, ∼44% of TCE sorbed in the potting soil was degraded in 30 h, compared to ∼82% for Smith Farm soil (organic matter content = 0.7%). DOC from the potting soil was found to inhibit TCE degradation. The presence of the extracted SOM at 40 ppm and 350 ppm as TOC reduced the degradation rate by 34% and 67%, respectively. Four prototype surfactants were tested for their effects on TCE desorption and degradation rates, including two anionic surfactants known as SDS (sodium dodecyl sulfate) and SDBS (sodium dodecyl benzene sulfonate), a cationic surfactant hexadecyltrimethylammonium (HDTMA) bromide, and a non-ionic surfactant Tween 80. All four surfactants were observed to enhance TCE desorption at concentrations below or above the critical micelle concentration (cmc), with the anionic surfactant SDS being most effective. Based on the pseudo-first-order reaction rate law, the presence of 1×cmc SDS increased the reaction rate by a factor of 2.5 when the nanoparticles were used for degrading TCE in a water solution. SDS was effective for enhancing degradation of TCE sorbed in Smith Farm soil, the presence of SDS at sub-cmc increased TCE degraded by ∼10%. However, effect of SDS on degradation of TCE in the potting soil was more complex. The presence of SDS at sub-cmc decreased TCE degradation by 5%, but increased degradation by 5% when SDS dosage was raised to 5×cmc. The opposing effects were attributed to combined effects of SDS on TCE desorption and degradation, release of soil organic matter and nanoparticle aggregation. The findings strongly suggest that effect of soil sorption on the effectiveness of Fe-Pd nanoparticles must be taken into account in process design, and soil organic content plays an important role in the overall degradation rate and in the effectiveness of surfactant uses. 相似文献
908.
在湖南常宁水口山矿田中部,新近发现了一个隐伏的夕卡岩型铁多金属矿床。该矿床产于3号隐伏花岗岩体接触变质交代蚀变破碎带中,受控于倒转背斜、花岗闪长岩体超覆体、栖霞组灰岩与当冲组砂页岩构成的接触带"三角地带",共伴生有铁、铜、铅、锌、银、金和铀。围岩蚀变组合复杂,其中石榴子石—透辉石—透闪石夕卡岩化、角岩化、硅化、大理岩化与成矿关系密切。矿床类型为接触交代成因的夕卡岩型。这一新类型矿体的发现,为水口山矿田隐伏矿体的找矿突破提供了新的方向与空间(隐伏岩体超覆体下接触变质交代带)。 相似文献
909.
Electrochemical recovery of hydrogen from coal acid mine drainage for the enhancement of sulphate reduction using grass cellulose as carbon source
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Jean Mulopo 《Water and Environment Journal》2017,31(3):302-309
This paper investigates the generation of hydrogen at the cathode in an electrolytic cell treating acid mine drainage (AMD) and the effect of the generated hydrogen on the biological removal of sulphate using grass cellulose. The performance of the bioreactors was assessed by means of sulphate reduction, chemical oxygen demand (COD), and volatile fatty acid (VFA) utilization. To this end, two batch reactors, A, B were operated similarly with the exception of the addition of hydrogen. Reactor A received no hydrogen to act as a control, while reactor B received hydrogen for the experimental duration. Further experiments were conducted to investigate the feasibility of sulphide oxidation to elemental sulphur using air. The results show that during sulphide oxidation, the sulphate concentration decreased from 364 to 183 mg/L, a decrease of 50% and the concentration of sulphide decreased from 163 to 70 mg/L, a decrease of 57%. 相似文献
910.