共查询到20条相似文献,搜索用时 78 毫秒
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一种聚羧酸系高效减水剂的试验研究 总被引:1,自引:0,他引:1
主要研究以烯丙醇聚氧乙烯醚、丙烯酸、马来酸酐和甲基丙烯磺酸钠为主要原料的聚羧酸系减水剂的合成工艺,探讨了影响减水剂性能的各种因素,得到最佳工艺条件,并对减水剂的性能进行测试。结果表明,该聚羧酸减水剂具有低掺量、高分散性、高减水率等特点。在掺量为0.25%时,初始水泥净浆流动度达310 mm,减水率高达30.5%,混凝土的抗压强度得到大幅度的提高,适宜配制高性能混凝土。 相似文献
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国家标准《混凝土外加剂》GB 8076—2008及上海市工程建设规范《预拌混凝土生产技术规程》DG/TJ 08—227—2009实施后,原先在中低标号混凝土中普遍使用的木质素磺酸盐减水剂由于其减水率小、混凝土抗压强度比低等弱点,很难满足该标准的要求。为此,利用聚羧酸减水剂及木质素减水剂为主要原料,通过复配,研制出一种新的聚羧酸-木质素复合型外加剂。该外加剂具有低成本、高减水率、工艺简单、质量易控制、成本合理以及减少环境污染的特点,可广泛应用于工业与民用建筑、水利、道路交通、核电工程等领域。 相似文献
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Per Larsson 《Water research》1983,17(10)
Tetra-, hexa- and octachlorobiphenyls were added to aquatic model systems composed of undisturbed sediment cores with an overlying water phase. Using impactor plates transport of the compounds from sediment to air was observed. About one per cent of the sediment-bound PCBs recovered in the systems left the water by jet drops from bursting bubbles. The transport of PCBs from the sediment to the air was nearly constant over time, with a transport rate of 0.62 μg · dm−2 week−1 for tetrachlorobiphenyl. Tetrachlorobiphenyl was mobile in systems with and without macroinvertebrates and in those fixed with HgCl2. Hexa- and octachlorobiphenyls were transported from sediment to water mainly by bioturbation processes. The two latter substances had a higher adsorption to particles than tetrachlorobiphenyl. Compared to tetrachlorobiphenyl, more hexa- and octachlorobiphenyls accumulated in chironomids and tubificids. 相似文献
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The overall purpose of this research was to investigate disinfection by-product (DBP) concentrations and formation potential in filter backwash water (FBWW) and evaluate at bench-scale the potential impact of untreated FBWW recycle on water quality in conventional drinking water treatment. Two chlorinated organic compound groups of DBPs currently regulated in North America were evaluated, specifically trihalomethanes (THMs) and haloacetic acids (HAAs). FBWW samples were collected from four conventional filtration water treatment plants (WTP) in Nova Scotia, Canada, in three separate sampling and plant audit campaigns. THM and HAA formation potential tests demonstrated that the particulate organic material contained within FBWW is available for reaction with chlorine to form DBPs. The results of the study found higher concentrations of TTHMs and HAA9s in FBWW samples from two of the plants that target a higher free chlorine residual in the wash water used to clean the filters (e.g., clearwell) compared to the other two plants that target a lower clear well free chlorine residual concentration. Bench-scale experiments showed that FBWW storage time and conditions can impact TTHM concentrations in these waste streams, suggesting that optimization opportunities exist to reduce TTHM concentrations in FBWW recycle streams prior to blending with raw water. However, mass balance calculations demonstrated that FBWW recycle practice by blending 10% untreated FBWW with raw water prior to coagulation did not impact DBP concentrations introduced to the rapid mix stage of a plant’s treatment train. 相似文献
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This paper discusses strategies to increase the feasibility of microorganisms for the removal of toxic xenobiotics from waste water and drinking water. Based on the principles of adaptational mutations and genetic exchange of catabolic activities, it becomes possible to select and engineer microorganisms that are suitable for the degradation of recalcitrant compounds. The detailed biochemical knowledge that is required for this is now rapidly evolving, and especially for the degradation of chlorinated organics several detoxifying dehalogenation mechanisms have been studied in detail. The feasibility of specialized bacteria for waste and water treatment will be dependent on the possibility to obtain stable performance and maintenance in treatment systems. 相似文献
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根据对某两条铁路隧道的水质监测,分析了隧道施工废水对地表水环境的影响,得出主要污染物质为悬浮物(SS),其对地表水环境的物理性质方面产生较大的影响,并提出废水处理措施,以确保隧道施工安全。 相似文献
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连通器和混水器在一二次水系统中的应用 总被引:4,自引:2,他引:2
用直接连接方式划分热源(或冷源)侧一次水和负荷侧二次水的供暖或空调水系统,需要采用连通器或混水器。介绍了连通器和混水器在工程中的应用。 相似文献
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针对石家庄南火车站三口机车用水井的水污染现状,对水的细菌总数和大肠菌群超标、嗅和味以及硬度等方面的治理措施进行了阐述,验证了机车用水井改生活饮用水井的可行性。 相似文献