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991.
分置式膜-生物反应器处理生活污水的抗冲击负荷能力 总被引:8,自引:0,他引:8
分置式膜 -生物反应器处理生活污水的运行结果表明 ,在 3倍于正常水平的冲击负荷下 ,分置式膜 -生物反应器能够正常运行 ,膜过滤出水 COD维持在 1 0 mg/ L以下 ,生物反应器污泥上清液 COD和透膜压力 TMP比正常水平略微上升 ,但在冲击负荷消除后能够恢复正常水平 ,呈现出较强的抗冲击负荷能力 .分置式膜 -生物反应器与普通活性污泥法相比 ,在冲击负荷下 ,其有机物去除速率、污泥浓度都呈现较快增长 ,而污泥混合液 COD浓度上升幅度较小 ,并且在冲击负荷消除后迅速恢复稳态运行 .分析表明分置式膜 -生物反应器的强抗冲击负荷能力来自于膜对污泥的完全截流作用 .膜 -生物反应器的强抗冲击负荷能力意味着该技术出水水质的安全稳定性和操作简便性 . 相似文献
992.
Kyle E. Juracek 《Journal of the American Water Resources Association》2000,36(3):633-645
ABSTRACT: The stability of the Neosho River channel downstream from John Redmond Dam, in southeast Kansas, was investigated using multiple‐date aerial photographs and stream‐gage information. Bankfull channel width was used as the primary indicator variable to assess pre‐ and post‐dam channel change. Five sin‐mile river reaches and four stream gages were used in the analysis. Results indicated that, aside from some localized channel widening, the overall channel change has been minor with little post‐dam change in bankfull channel width. The lack of a pronounced post‐dam channel change may be attributed to a substantial reduction in the magnitude of the post‐dam annual peak discharges in combination with the resistance to erosion of the bed and bank materials. Also, the channel may have been overwidened by a series of large floods that predated construction of the dam, including one with an estimated 500‐year recurrence interval. 相似文献
993.
994.
Meri Suhartini H. Mitomo F. Yoshii N. Nagasawa T. Kume 《Journal of Polymers and the Environment》2001,9(4):163-171
Three kinds of poly(butylene succinate)s (PBS) with different molecular weight were irradiated with electron beams in the presence of inorganic material. Fourteen kinds of inorganic materials were used in this work. The presence of inorganic material inside cross-linked PBS samples enhances the yield of gel formation. The heat stabilities of PBS samples were checked; it was found that silicon dioxide and carbon black significantly improve these properties. Enzymatic and soil burial tests were performed; the presence of these inorganic materials in cross-linked PBS accelerates the rate of biodegradation. 相似文献
995.
The stabilities in water and dry storage of two solid-state disinfectants (3-chloro-4, 4-dimethyl-2-oxazolidinone, agent I, and calcium hypochlorite) have been compared under a variety of conditions. Variables in the study included pH, temperature, and water quality. Agent I is considerably more stable in dry storage and in water, especially at pH 4.5 and 7.0, than is calcium hypochlorite. This is true for solutions of the two compounds in sterile, distilled, deionized, demandfree water or in a synthetic water containing heavy organic load. Prior work in these laboratories concerning use of agent I as a disinfectant for lake water in a laboratory-scale treatment plant had suggested that agent I has considerable potential for use as an alternative to cholorine gas for water disinfection. The present work suggests that agent I is of sufficient stability to be of use as a solid-state disinfectant for swimming pools and for potable water for remote areas. 相似文献
996.
Burchard H. Heede 《Environmental management》1985,9(5):427-432
Fallen trees and their large debris often form log steps in small mountain streams, where they are incorporated into the hydraulic geometry. The hypothesis here was that these log steps take the place of gravel bars that otherwise would have been required for channel slope adjustment. In this experiment, the treated as well as the control stream were located in virgin mixed conifer forests and until the study began, no human activity had interfered with the natural developments. All log steps were removed from a stream and the formation of new log steps was prohibited by periodic removal of fallen trees and branches. Five years later, 74% of all removed log steps had been replaced by gravel bars, thus proving the hypothesis that increased bedload movement was required to offset the loss of log steps. Implications are that streamside forests should be managed so that they can provide a steady supply of debris for channel stability. 相似文献
997.
五大连池火山危险性分析 总被引:4,自引:0,他引:4
针对五大连池火山危险性问题进行了一系列的地球物理反演和分析,通过对现代岩交流心概念和国外活火山实例剖析,采用岩浆固结的Stefan问题的葩演了岩浆房的固结曲线和固结时间:引入SFT理论探讨了五大连池火山岩浆碎屑化机制;利用壳幔结构化R值的分析方法分析了五大连池火山区地壳稳定性;采用火山区卫星重力异常剖面的分析方法探讨了五大连池火山区地幔物质活动性,结合五大连池火山现代喷发的史料分析,模拟了五连池火 相似文献
998.
999.
Audrey Athlan Christian Braud Michel Vert 《Journal of Polymers and the Environment》1997,5(4):243-247
Oligomers of poly(3-hydroxybutyric acid) (P(3-HB)) were prepared by partial degradation of high molecular weight P(3-HB) dissolved
in 1,2-dichloroethane/water mixture in the presence of p-toluene sulfonic acid (p-TSA). The water-soluble fraction of the
resulting oligomers was extracted from the mixture with neutral sodium phosphate buffer. Capillary zone electrophoresis showed
that the aqueous extracts were composed of two series of oligomers. The first one was composed of one to seven P(3-HB) oligomers
(O(3-HB)). In contrast, the second series was composed of four oligomers characterized by the presence of a terminal C=C bond
[O’(3-HB)]. Both series of oligomers behaved differently insofar as their fate in aqueous medium was concerned. The 0(3-HB)
compounds were stable over a period of 2 months. On the other hand, the population of the O’(3-HB) oligomers varied, the proportion
of oligomers increasing with aging time. 相似文献
1000.
It is argued that standard environmental economic and 'ecological economics', have the same fundamentals of valuation in terms of money, based on a demand curve derived from utilitymaximization. But this approach leads to three different measuresof value. An invariant measure of value exists only if the consumer has 'homothetic preferences'. In order to obtain a numerical estimate of value, specific functional forms are necessary, but typically these estimates do not converge. This is due to the fact that the underlying economic model is not structurally stable.According to neoclassical economics, any environmental remediation can be justified only in terms of increases in consumer satisfaction, balancing marginal gains against marginal costs. It is not surprising that the optimal policy obtained fromthis approach suggests only small reductions in greenhouse gases.We show that a unidimensional metric of consumer's utility measured in dollar terms can only trivialize the problem of global climate change. 相似文献