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801.
气水比对曝气生物活性炭处理原水的影响 总被引:1,自引:1,他引:0
针对从臭氧-活性炭工艺中开发出来的预臭氧-曝气生物活性炭,在不同气水比工况下进行实验,分析了不同气水比对曝气生物活性炭处理微污染原水的影响与作用。结果表明:在滤速为8~12 m/h,空床接触时间为11.5~15.4 min,装填密度为510 g/L条件下,不同气水比对去除氨氮的影响大于对CODMn的影响。气水比为0.3∶1时,对氨氮浓度为1.65~2.10 mg/L范围的进水平均去除率为81.9%,亚硝酸盐氮平均积累率为1.4%,CODMn去除率为70.6%。当气水比逐渐增加时,氨氮平均去除率有所提高,亚硝酸盐氮积累率则有所下降,对较低浓度的CODMn影响不大。 相似文献
802.
接种比对碱超声波耦合溶胞污泥水解酸化的影响 总被引:2,自引:1,他引:1
以城市污水生物处理过程中的剩余污泥减量化为研究背景,通过实验研究了经碱超声波耦合溶胞后的剩余污泥在不同接种比下水解酸化的效果,分析了污泥上清液中pH、SCOD、VFAs、NH4+-N和PO34--P等参数随时间的变化趋势。结果表明,溶胞污泥经过72 h的水解酸化反应,20%接种比下的水解酸化COD溶出率和VFAs增长率最高,分别为75.5%和177%。蛋白质水解程度为16.9%,也高于50%和70%两组接种比。此外,COD、NH4+-N和PO34--P等主要溶出物均在12 h后达到基本稳定状态。 相似文献
803.
The present study was developed to assess the chronic toxicity predictions and extrapolations for a set of chlorinated anilines (aniline (AN), 4-chloroaniline (CA), 3,5-dichloroaniline (DCA) and 2,3,4-trichloroaniline (TCA)). Daphnia magna 21 d chronic experimental data was compared to the chronic toxicity predictions made by the US EPA ECOSAR QSAR tools and to acute-to-chronic extrapolations. Additionally, Species Sensitivity Distributions (SSDs) were constructed to assess the chronic toxicity variability among different species and to investigate the acute versus chronic toxicity in a multi-species context.Since chlorinated anilines are structural analogues with a designated polar narcotic mode of action, similar toxicity responses were assumed. However, rather large interchemical and interspecies differences in toxicity were observed. Compared to the other three test compounds, TCA exposure had a significantly larger impact on growth and reproduction of D. magna. Furthermore, this study illustrated that QSARs or a fixed ACR are not able to account for these interchemical and interspecies differences. Consequently, ECOSAR was found to be inadequate to predict the chronic toxicity of the anilines and the use of a fixed ACR (of 10) led to under of certain species. The experimental ACRs determined in D. magna were substantially different among the four aromatic amines (ACR of 32 for AN, 16.9 for CA, 5.7 for DCA and 60.8 for TCA). Furthermore, the SSDs illustrated that Danio rerio was rather insensitive to AN in comparison to another fish species, Phimphales promelas. It was therefore suggested that available toxicity data should be used in an integrative multi-species way, rather than using individual-based toxicity extrapolations. In this way, a relevant overview of the differences in species sensitivity is given, which in turn can serve as the basis for acute to chronic extrapolations. 相似文献
804.
采用脱色菌Citrobacter sp. CK3,以活性红KN-3B染料为处理对象,在厌氧批式反应条件下,系统考察了pH值,温度和染料浓度对脱色反应速度的影响;通过动力学模拟及反应过程中染料的UV-Vis扫描图分析,探讨了脱色反应机理。结果表明:Citrobacter sp. CK3对活性红KN-3B的脱色反应的适宜pH为7~9;脱色反应速度在温度为32℃时达到最大。染料初浓度从57 mg/L逐渐增大到458 mg/L时脱色率逐渐降低。脱色过程中染料的偶氮键发生断裂,脱色反应符合二级反应动力学。 相似文献
805.
Tang X Chen J Wang WH Liu TW Zhang J Gao YH Pei ZM Zheng HL 《Environmental pollution (Barking, Essex : 1987)》2011,159(12):3784-3792
This study characterized the changes of nitric oxide (NO) production during the growth of Microcystis aerugrinosa, a cyanobacterium which usually cause cyanobacterial blooms. Results showed a drastic NO release accompanying with cell density and Chl-a content sharp rises when M. aerugrinosa grew from fifth day to sixth day. Moreover, high N:P ratio accelerated the cyanobacterial growth and NO burst. Sodium nitroprusside, an exogenous NO donor, promoted M. aerugrinosa growth with the optimal concentration of 0.1 mg/L. Experiments by supplementing with sodium nitrite and l-arginine demonstrated NO production in M. aerugrinosa cells was mainly through nitrate reductase (NR) pathway while minorly through NO synthase pathway. All these data suggested M. aerugrinosa produced increasing NO during its growth mainly by NR pathway, during which NO positively regulated the growth of M. aerugrinosa. 相似文献
806.
We examined root hydraulic conductivity (Lp) responses of one-year-old seedlings of four conifers to the combined effects of elevated CO2 and inorganic nitrogen (N) sources. We found marked interspecific differences in Lp responses to high CO2 ranging from a 37% increase in P. abies to a 27% decrease in P. menziesii, but these effects depended on N source. The results indicate that CO2 effects on root water transport may be coupled to leaf area responses under nitrate (NO3−), but not ammonium (NH4+) dominated soils. To our knowledge, this is the first study that highlights the role of inorganic N source and species identity as critical factors that determine plant hydraulic responses to rising atmospheric CO2 levels. The results have important implications for understanding root biology in a changing climate and for models designed to predict feedbacks between rising atmospheric CO2, N deposition, and ecohydrology. 相似文献
807.
Flores-Cervantes DX Bucheli TD 《Environmental pollution (Barking, Essex : 1987)》2011,159(12):3793-3796
We tested the resistance of five different fullerenes (C60, C70, C76/78 mix, and C84) to chemothermal oxidation at 375 °C (CTO-375), a method that has been used and tested for quantifying black carbon (BC) and CNTs in soils and sediments. C60 survived CTO-375 the most (50%), while C70 was the fullerene with the lowest survival rate (<1%). Standard additions of C60 to soil and sediment reference materials yielded recoveries between 18 and 36%. Although lower than recoveries previously observed for soot and CNTs, these results demonstrate the capability of CTO-375 to partially isolate C60 from solid environmental matrices. Standard additions of C70, C76/78, and C84 yielded slightly higher survival rates when added to soil and sediment than in their pure form. These results indicate that the mineral matrices of these samples probably had a catalytic effect towards C60 and a protective effect towards C70, C76/78, and C84 during CTO-375. 相似文献
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