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概述了高速微涡活性污泥法的工艺特点,并对该法提高氧的转移及利用效率进行了研究和机理分析。 相似文献
53.
SBR工艺设计经验探讨 总被引:2,自引:0,他引:2
提出了SBR工艺中,反应池容积、反应时间以及需氧量的计算方法和设计经验。同时,在研读和对比国内外相关资料的基础上,探讨了SBR工艺发生污泥膨胀的可能性和原因,介绍了控制方法与措施。 相似文献
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Runoff and dissolved organic carbon loss from a paired-watershed study of three adjacent agricultural Watersheds 总被引:2,自引:0,他引:2
Kristen S. Veum Keith W. Goyne Peter P. Motavalli Ranjith P. Udawatta 《Agriculture, ecosystems & environment》2009,130(3-4):115-122
Organic matter plays several important roles in the biogeochemistry of terrestrial and aquatic ecosystems including the mobilization and transport of nutrients and pollutants. Cropping, tillage practices and vegetative buffer strip installation affect losses of dissolved organic carbon (DOC). While many studies show reductions in pollutant export from agroecosystems where vegetative buffers have been implemented, buffer strips may be a source of DOC and contribute to surface water pollution. Using a paired-watershed approach, the objectives of this study were to determine the effect of grass and agroforestry buffers on runoff and DOC loss, compare runoff and DOC losses between the growing and fallow seasons, and investigate crop effects on runoff and DOC losses. The study design consisted of three small agricultural Watersheds in a no-till, maize-soybean rotation located in the claypan region of northeast Missouri, USA; one watershed was planted with grass buffer strips, one with agroforestry buffer strips, and one unaltered watershed served as the control. Runoff and DOC loss were measured during a six-year calibration period (1991–1997) prior to buffer installation and for a nine-year treatment period (1997–2006). The grass buffer strips significantly decreased runoff by 8.4% (p = 0.015) during the treatment period while the agroforestry buffer system exhibited no significant change in runoff (p = 0.207). Loss of DOC was not significantly affected by grass or agroforestry buffer installation (p = 0.535 and p = 0.246, respectively). Additionally, no significant difference in runoff or DOC loss was found between crops (maize and soybean) or between seasons (growing and fallow). Overall, this study indicates that grass buffer systems are effective at reducing runoff and that DOC contamination of surface waters is not exacerbated by either type of vegetative buffer strip. 相似文献
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We describe here a one-step method for the synthesis of Au/TiO2 nanosphere materials, which were formed by layered deposition of multiple anatase TiO2 nanosheets. The Au nanoparticles were stabilized by structural defects in each TiO2 nanosheet, including crystal steps and edges, thereby fixing the Au–TiO2 perimeter interface. Reactant transfer occurred along the gaps between these TiO2 nanosheet layers and in contact with catalytically active sites at the Au–TiO2 interface. The doped Au induced the formation of oxygen vacancies in the Au–TiO2 interface. Such vacancies are essential for generating active oxygen species (*O−) on the TiO2 surface and Ti3 + ions in bulk TiO2. These ions can then form Ti3 +–O−–Ti4 + species, which are known to enhance the catalytic activity of formaldehyde (HCHO) oxidation. These studies on structural and oxygen vacancy defects in Au/TiO2 samples provide a theoretical foundation for the catalytic mechanism of HCHO oxidation on oxide-supported Au materials. 相似文献
58.
Microbial bioavailability of dissolved organic nitrogen (DON) in the sediments of Lake Shankou, Northeastern China 总被引:2,自引:0,他引:2
Mingzhou Su Jingtian Zhang Shouliang Huo Beidou Xi Fei Hua Fengyu Zan Guangren Qian Jianyong Liu 《环境科学学报(英文版)》2016,28(4):79-88
Dissolved organic nitrogen(DON)extracted from Lake Shankou sediments using KCl was isolated into hydrophobic and hydrophilic fractions.The bioavailabilities of the hydrophobic and hydrophilic fractions to three types of bacterial communities collected from sediments,activated sludge and compost products were examined.The DON recoveries obtained by DAX-8 and cation exchange resins treatment were 96.17% ± 1.58% and 98.14% ±0% for the samples obtained from N4 and N14 stations,respectively.After 25 days of incubation at 25°C,most DON(59% to 96%)was degraded.Hydrophilic DON exhibited a higher reduction rate than hydrophobic DON during the growth phase.Untreated wastewater from Changshuihe town was the main degradable DON source to station N4,and 93% of hydrophilic DON and 80% of hydrophobic DON were degraded.Station N14 received a large amount of refractory DON from forest soils and exhibited DON degradation rates of 82% and 71% for the hydrophilic and hydrophobic fractions,respectively.Amino acid contents and fluorescence intensities were also analyzed.Approximately 27% to 74% of amino acids were taken up by day 5,and their concentration gradually increased in the following days due to the decomposition of dissolved proteins.Parallel factor analysis resulted in identification of tryptophan-like proteins,tyrosine-like proteins and FA-like substances.During the growth phase,40%–51% of the tryptophan-like proteins were taken up by bacteria,and the accumulation of tyrosine-like proteins was attributed to the release of biotic substances.The concentration of the FA-like substances decreased due to microbial decomposition. 相似文献
59.
水温对氧转移速率的影响研究 总被引:3,自引:0,他引:3
通过对上澳塘水体的曝气充氧实验,研究了温度对氧转移速率的影响,测定了温度系数,为上澳塘水体曝气净化的工程实践提供了可靠的技术参数。 相似文献
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《环境科学学报(英文版)》2023,35(7):1-15
Due to the combined effect of sluices and sea tide, the sluice-controlled coastal plain river would be characterized by both trophic state and salinity gradients, affecting the spatiotemporal optical properties of dissolved organic matter (DOM). In this study, we investigated the spatiotemporal variation of water quality parameters and optical properties of DOM in the Haihe River, a representative sluice-controlled coastal plain river in Tianjin, China. A significant salinity gradient and four trophic states were observed in the water body of the Haihe River. Two humic- and one protein-like substances were identified from the DOM by the three-dimensional fluorescence spectra combined with the parallel factor (PARAFAC) analysis. Pearson's correlation analysis and redundancy analysis (RDA) showed that the salinity significantly affected the abundance of chromophoric DOM (CDOM) but did not cause significant changes in the fluorescence optical characteristics. In addition, the effect of Trophic state index (TSI) on the CDOM abundance was greater than that on the fluorescence intensity of fluorescent dissolved organic matter (FDOM). In the water body with both salinity and trophic state gradients, TSI posed a greater influence than salinity on the CDOM abundance. Our results fill the research gap in spatiotemporal DOM characteristics and water quality variation in water bodies with both salinity and trophic state gradients. These results are beneficial for clarifying the joint influence of saline intrusion and sluices on the DOM characteristics and water quality in sluice-controlled coastal plain rivers. 相似文献