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991.
悬挂链曝气工艺应用于中小城镇污水治理 总被引:3,自引:0,他引:3
王涛 《城市环境与城市生态》2004,17(1):28-30
通过对悬挂链曝气工艺特点和应用情况的分析,总结了针对中小城镇污水处理厂的设计与建设经验。结合我国国情,提出悬挂链曝气工艺为中小城镇污水处理厂的建设提供了一个良好的选择。 相似文献
992.
金属离子对好氧活性污泥活性的影响 总被引:16,自引:0,他引:16
通过小试装置研究Mg2 、Mn2 、Ni2 、Zn2 、Co2 和Mo6 单独存在时对活性污泥活性的影响.结果发现,Co2 浓度在2 mg/L以下时,对活性污泥活性稍有抑制,其他离子则均有促进作用.Mn2 、Mo6 、Zn2 、Mg2 和Ni2 的促进浓度范围分别是:0.5~3 mg/L,0.5~5 mg/L,0.5~1 mg/L,5~20 mg/L,0.25~1 mg/L.在各自最佳浓度条件下对活性污泥活性促进的主次顺序为:Mg2 >Mn2 >Zn2 >Ni2 >Mo6 . 相似文献
993.
Mn2+、Mo6+和Zn2+对活性污泥内胞外聚合物组分的影响 总被引:10,自引:2,他引:8
通过测定不同浓度的金属离子对活性污泥比耗氧率的影响, 确定了Mn2+、Mo6+和Zn2+的最佳促进浓度, 并研究了在各自促进浓度范围内3种金属离子对活性污泥内胞外聚合物(EPS)组分(蛋白质、糖类和核酸)含量变化的影响.结果发现, Mn2+、Mo6+和Zn2+的最佳促进浓度均为1mg·L-1. Mn2+和Zn2+对EPS各组分的影响较大, 而Mo6+基本没有产生影响. 试验同时发现, 经低温贮存的污泥, 其EPS含量下降, 其中多糖含量下降最为明显. 相似文献
994.
无机微滤膜分离草浆黑液中木素的机理 总被引:4,自引:0,他引:4
选用50nm,0.2μm和0.8μm的无机微滤膜,研究了它们对黑液中木素的截留效果.结果表明,微滤膜能够有效地分离黑液中的木素,0.2μm α-Al2O3和ZrO2膜的通量高于50nm和0.8μm膜的通量,当黑液SS较低时,随着SS浓度的增加各个微滤膜的通量急剧下降,当SS较高时,微滤膜的通量和SS浓度成线性关系.2g/L聚乙二醇4000(PEG4000)溶液不会显著影响0.2μm和50nm膜的通量,但却能使0.8μm膜的通量下降60%.2g/L聚乙二醇20000(PEG20000)溶液能使各个微滤膜的通量急剧下降.按照微滤膜污染模型的计算结果和实测被稀释黑液的粒径分布,膜面形成滤饼层和木素分子形成的絮体是引起膜通量下降并改变了膜的截留性能的原因. 相似文献
995.
Emmet F. Spencer Richard J. Ringwood Richard M. Brennan 《Journal of the American Water Resources Association》1975,11(4):836-847
ABSTRACT: The State of Louisiana created in 1972 the Deep Draft Harbor and Terminal Authority (commonly called Superport Authority) to plan, promote, and develop a deepwater (crude oil) terminal off the coast of Louisiana, and empowered it to establish an Authority development program to promote the economic and social welfare of its citizens. Simultaneously, the Authority was also charged with developing an environmental protection plan to preserve the environmental values of Louisiana's unique coastal marshland while permitting beneficial industrial and economic development. Consequently, in January 1974, an Environmental Protection Plan was promulgated, consisting of a series of regulations, design standards, and operating procedures aimed specifically at protecting the fragile estuarine environment of coastal Louisiana during the construction and ultimate operation of the superport. The paper describes the development of the Superport Authority's Environmental Protection Plan and the current status of the superport project. 相似文献
996.
在铁路车站噪声影响中,车站影响区域产生的次生噪声相对于站中心的原生噪声,是城区噪声污染的主要因素。根据不同规模车站区对周边社会及人文景观的影响程度,划分出站区噪声监测范围。通过监测对比分析,发现站中心噪声与车站规模具有显著的正相关关系,而车站影响区噪声值在中小规模车站中,二者有一定的正相关关系,但当车站发展到一定大规模后,影响区内的噪声反而略有下降并趋于平稳。通过分析认为,大规模车站的建立有利于促进周边城市更合理地规划布局。根据车站布局与兴建对城市环境噪声影响的关系,以及站区噪声源变化特点,建立了不同车站规模站区的噪声值预测模型,其预测结果为新建铁路路站在城市中的规划布局,提供了实用的参考依据及有价值的建议。 相似文献
997.
Jean E. Weber Chester C. Kisiel Lucien Ducksteiri 《Journal of the American Water Resources Association》1973,9(6):1075-1088
ABSTRACT: Many difficulties exist in the matching of models with data. This paper identifies elements of this problem and discusses considerations involved in model evaluation. The well known multivariate linear regression model is used to illustrate the distinctions between accuracy and precision and between estimation and prediction (because the model is commonly misused.) No amount of additional data will improve the accuracy of a poor model. A high R2, while indicative of a good matching between the observed data and model estimates, is a poor criterion for judging adequacy of the model to make good predictions of future events. Model evaluation also includes the problem of introducing secondary data and proxy variables into a model. Secondary data frequently enter, for example, the mass, energy and water budget equations because of difficulties in measuring the primary variables. Proxy variables arise because of a desire to collapse a vector of incomparable values, say, of water quality into a single number. Review of the above issues indicates that model evaluation is a multi-criterion problem, often imbedded in a larger framework where models are intended to meet multiple objectives. The mismatch of models and data has increasing legal and social consequences. 相似文献
998.
The Precautionary Principle: Scientific Uncertainty and Omitted Research in the Context of GMO Use and Release 总被引:3,自引:0,他引:3
Commercialization of genetically modified organisms (GMOs) have sparked profound controversies concerning adequate approaches to risk regulation. Scientific uncertainty and ambiguity, omitted research areas, and lack of basic knowledge crucial to risk assessmentshave become apparent. The objective of this article is to discuss the policy and practical implementation of the Precautionary Principle. A major conclusion is that the void in scientific understanding concerning risks posed by secondary effects and the complexity ofcause-effect relations warrant further research. Initiatives to approach the acceptance or rejection of a number of risk-associated hypotheses is badly needed. Further, since scientific advice plays a key role in GMOregulations, scientists have a responsibility to address and communicate uncertainty to policy makers and the public. Hence, the acceptance of uncertainty is not only a scientific issue, but is related to public policy and involves an ethical dimension. 相似文献
999.
The atmospheric deposition of reactive nitrogen on turf grassland in Tsukuba, central Japan, was investigated from July 2003
to December 2004. The target components were ammonium, nitrate, and nitrite ions for wet deposition and gaseous ammonia, nitric
and nitrous acids, and particulate ammonium, nitrate, and nitrite for dry deposition. Organic nitrogen was also evaluated
by subtracting the amount of inorganic nitrogen from total nitrogen. A wet-only sampler and filter holders were used to collect
precipitation and the atmospheric components, respectively. An inferential method was applied to calculate the dry deposition
velocity of gases and particles, which involved the effects of surface wetness and ammonia volatilization through stomata
on the dry deposition velocity. The mean fraction of the monthly wet to total deposition was different among chemical species;
37, 77, and 1% for ammoniacal, nitrate-, and nitrite-nitrogen, respectively. The annual deposition of inorganic nitrogen in
2004 was 47 and 48 mmol m−2 yr−1 for wet and dry deposition, respectively; 51% of atmospheric deposition was contributed by dry deposition. The annual wet
deposition in 2004 was 20, 27, and 0.07 mmol m−2 yr−1, and the annual dry deposition in 2004 was 35, 7.4, and 5.4 mmol m−2 yr−1 for ammoniacal, nitrate-, and nitrite-nitrogen, respectively. Ammoniacal nitrogen was the most important reactive nitrogen
because of its remarkable contribution to both wet and dry deposition. The median ratio of the organic nitrogen concentration
to total nitrogen was 9.8, 17, and 15% for precipitation, gases, and particles, respectively. 相似文献
1000.