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991.
在对天然有机物分类的基础上进行了水体中有机物的特性研究,并采用氯胺对不同特性有机物的氯化消毒副产物进行了控制研究。结果表明,疏水酸占有机物总量的24%,疏水中性物质占41%,疏水性有机物占67%;对于三卤甲烷类消毒副产物生成势,疏水酸所产生的最多,疏水碱次之,亲水酸最少;对于卤乙酸类消毒副产物生成势,疏水碱产生的三卤乙酸最多,其次为疏水酸,亲水酸最少。氯胺对不同类有机物氯化消毒副产物控制程度不同,氯胺对疏水中性物质控制三卤甲烷类消毒副产物最好,其次是疏水碱和亲水碱;对疏水酸的三卤甲烷生成量控制较弱,对亲水酸的控制效果最差;氯胺对亲水碱氯化产生卤乙酸的控制效果最好,其次是疏水碱,控制效果最差的为疏水中性物质。  相似文献   
992.
BACKGROUND, AIM AND SCOPE: Problems of long-term existence of the environmental contaminant 2,4,6-trinitrotoluene (TNT) and necessities for the use of trees ('dendroremediation') in sustainable phytoremediation strategies for TNT are described in the first part of this paper. Aims of the second part are estimation of [14C]-TNT uptake, localisation of TNT-derived radioactivity in mature tree tissues, and the determination of the degree of TNT-degradation during dendroremediation processes. METHODS: Four-year-old trees of hybrid willow (Salix spec., clone EW-20) and of Norway spruce (Picea abies) were cultivated in sand or ammunition plant soil (AP-soil) in wick supplied growth vessels. Trees were exposed to a single pulse application with water solved [U-14C]-TNT reaching a calculated initial concentration of 5.2 mg TNT per kg dry soil. Two months after application overall radioactivity and extractability of 14C were determined in sand/soil, roots, stem-wood, stem-bark, branches, leaves, needles, and Picea May sprouts. Root extracts were analysed by radio TLC. RESULTS: 60 days after [14C]-TNT application, recovered 14C is accumulated in roots (70% for sand variants, 34% for AP-soil variant). 15-28% of 14C remained in sand and 61% in AP-soil. 3.3 to 14.4% of 14C were located in aboveground tree portions. Above-ground distribution of 14C differed considerably between the angiosperm Salix and the gymnosperm Picea. In Salix, nearly half of above-ground-14C was detected in bark-free wood, whereas in Picea older needles contained most of the above-ground-14C (54-69%). TNT was readily transformed in tree tissue. Approximately 80% of 14C was non-extractably bound in roots, stems, wood, and leaves or needles. Only quantitatively less important stem-bark of Salix and Picea and May shoots of Picea showed higher extraction yields (up to 56%). DISCUSSION: Pulse application of [14C]-TNT provided evidence for the first time that after TNT-exposure, in tree root extracts, no TNT and none of the known metabolites, mono-amino-dinitrotoluenes (ADNT), diaminonitrotoluenes (DANT), trinitrobenzene (TNB) and no dinitrotoluenes (DNTs) were present. Extractable portions of 14C were small and contained at least three unknown metabolites (or groups) for Salix. In Picea, four extractable metabolites (or groups) were detected, where only one metabolite (or group) seemed to be identical for Salix and Picea. All unknown extractables were of a very polar nature. CONCLUSIONS: Results of complete TNT-transformation in trees explain some of our previous findings with 'cold analytics', where no TNT and no ADNT-metabolites could be found in tissues of TNT-exposed Salix and Populus clones. It is concluded that 'cold' tissue analysis of tree organs is not suited for quantitative success control of phytoremediation in situ. RECOMMENDATIONS AND OUTLOOK: Both short rotation Salicaceae trees and conifer forests possess a dendroremediation potential for TNT polluted soils. The degradation capacity and the large biomass of adult forest trees with their woody compartments of roots and stems may be utilized for detoxification of soil xenobiotics.  相似文献   
993.
对ABR反应器的水力流态进行了示踪剂试验,分析了特征截面面积对ABR水力特性的影响,采用停留时间分布(RTD)法研究了不同进水COD浓度和HRT条件下ABR反应器的水力特性,结果表明:不同进水COD浓度时ABR反应器的RTD曲线相似,表明进水COD浓度不是影响ABR水力特性的主要因素;不同HRT条件下RTD曲线差异很大,表明HRT对ABR的水力特性影响较大,随着水力停留时间的延长,Ⅳ值增大,1/Pe减小,ABR的流态趋于推流流态,随着HRT的缩短,Ⅳ值减小,1/Pe数增大,ABR反应器趋于完全混合流态。  相似文献   
994.
厌氧-气浮-UASB-SBR工艺处理酒精废水   总被引:2,自引:0,他引:2  
介绍了厌氧-气浮-UASB-SBR处理工艺在酒精废水处理工程中的实际应用,分析并总结了工程设计及运行的经验。实践表明,经厌氧-气浮-UASB-SBR的工艺处理后,废水中COD和SS总去除效率分别可达到99.6%和99.8%以上,并可以回收大量的沼气和部分废水回用于生产过程中。该工艺具有运行稳定和处理效率高等优点,为企业带来了良好的经济效益和社会效益。  相似文献   
995.
Surface waters have a great impact on ecology and life of man. Because of their current use and exploitation, chemical and biological pollution, as well as physical changes of rivers and lakes are common. Natural self-purification potential helps to compensate harms to a certain degree. Proposals are given to detect restrictions of the purification potential in time as well as to support and to enhance the natural purification potential.  相似文献   
996.
This work describes the nitration of aromatics upon near-UV photolysis of nitrate and nitrite in aqueous solution and upon photocatalytic oxidation of nitrite in TiO2 suspensions. Phenol is used in this work as a model aromatic molecule and as a probe for *NO2/N2O4. The photoinduced nitration of phenol in aqueous systems occurs upon the reaction between phenol and *NO2 or N2O4, and is enhanced by the photocatalytic oxidation of nitrite to *NO2 by TiO2. Aromatic photonitration in the liquid phase can play a relevant role in the formation of nitroaromatics in natural waters and atmospheric hydrometeors, thus being a potential pathway for the condensed-phase nitration of aromatics. Furthermore, the photoinduced oxidation of nitrite to nitrogen dioxide suggests a completely new role for nitrite in natural waters and atmospheric aerosols.  相似文献   
997.
天然沸石具有较大的孔隙率和比表面积,对氨氮有较强的选择性离子交换能力.运用天然沸石曝气生物滤池处理城市污水厂二级生化出水,结果表明,曝气生物滤池有良好的去除效果.在气水比为3∶1,水力负荷为1 m/h,温度>20℃情况下,沸石曝气生物滤池对城市污水厂二级生化出水COD去除率为12.7%,NH3-N去除率为96.6%;试验系统沿程微生物活性和微生物量呈现逐渐下降趋势,而单位生物量的生物活性沿程分布则与此相反;曝气生物滤池对水中污染物的去除主要集中在底部进水端部分,当水流达到距进水端上方105 cm时,曝气生物滤池对水中NH3-N的去除率已达86.8%(占氨氮总去除率的90%),COD的去除率为13.3%(占COD总去除率的67%).  相似文献   
998.
本文以废水生物除磷的原理及特点为基础,介绍了城市污水生物除磷的主要工艺及其改进方法。  相似文献   
999.
太阳能用作污泥厌氧消化加热的可靠性进行了小试和中试研究.小试结果表明污泥吸热效率高.是一种较好的吸热体.浅槽式集热器水温随太阳辐射强度增高而升高,随水深增加而降低,小试采用单(双)层玻璃浅槽式集热器.中型试验太阳能水箱水温温升,在气温低时12.4℃~20.5℃,气温高时16℃~24.8℃,太阳能集热器可作为污泥厌氧消化加热补充热源.  相似文献   
1000.
城市有机生活垃圾厌氧发酵处理研究   总被引:31,自引:2,他引:31  
张记市  张雷  王华 《生态环境》2005,14(3):321-324
在适当的PH值和搅拌条件下,研究了反应温度、总固体含量、pH值、碳氮比、碳磷比以及接种物量对有机牛活垃圾厌氧发酵产沼气的影响。实验结果表明:有机生活垃圾厌氧消化产沼气的适宜条件是:反应温度50~55℃,总固体含量23%~28%,pH=6.8~7.4,w(C)/w(N)=(20~30),w(C)/w(P)=50,60%~75%的生物气,可实现能量回收;发酵剩余物可制有机肥,时间为15~20d。接种物量为25%~30%。在厌氧的条件下,可以制取含甲烷实现物质再利用。有机生活垃圾在厌氧消化反应器的停留时间为15~20d。  相似文献   
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