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181.
城市污水条件下ASBR厌氧氨氧化的启动与脱氮性能 总被引:2,自引:0,他引:2
采用ASBR在城市污水条件下进行厌氧氨氧化的启动与脱氮性能研究。实验接种好氧硝化污泥,在温度为(35±1)℃、HRT为24 h、pH为7.3~8.5的条件下经过130 d的培养,成功启动了厌氧氨氧化反应。实验结果表明,厌氧氨氧化反应稳定运行时,TN容积负荷平均为0.179 kg/(m3.d),NH4+-N、NO2--N和TN去除率分别达到了95.30%、91.30%和76.28%。启动期和稳定运行期NH4+-N、NO2--N去除量和NO3--N生成量的比值分别达到1∶1.54∶0.25和1∶1.27∶0.27;稳定运行期进出水pH差值由启动时的0.85下降到0.24。启动期反硝化和厌氧氨氧化反应同时存在而在稳定运行期厌氧氨氧化发展成为主导反应。MLSS和MLVSS/MLSS先减少后增加,反映了启动过程中硝化细菌、反硝化细菌的衰亡和厌氧氨氧化菌逐渐富集的过程,这与反应器的宏观运行效果相一致。 相似文献
182.
To examine and quantify the effects of glass beads and chemoattractant on bacterial motility in granular media, we examined the motile behavior of P. aeruginosa in a saturated granular medium and quantified the effects of glass beads and the presence of a chemoattractant. By recording individual cell trajectories in microfluidic channels under a high-speed confocal microscope, we directly measured the cell's run direction and corresponding run-length, speed and turn angle. Bacterial run speed increased in the presence of chemoattractant in both aqueous and granular media. But it decreased in glass-beads compared to in aqueous media due to the restricted pore geometry and interactions between bacteria and grain surfaces. Notably, the relatively higher frequency distribution at turn angles of 170° decreased dramatically, while the smaller peak at 70° increased and became dominant on a bimodal distribution, showing more bacteria changed directions at smaller turn angles rather than reverse their swimming directions. Additionally, the presence of glass beads also decreased the chemotactic velocity and random motility by similar proportions due to the restrictive geometry and the interactions between bacteria and glass beads surface. Our study indicates that the swimming parameters measured from aqueous media cannot be directly adopted in models for predicting bacteria travel in granular media. 相似文献
183.
Tracing the sources of refractory dissolved organic matter in a large artificial lake using multiple analytical tools 总被引:2,自引:0,他引:2
Structural and chemical characteristics of refractory dissolved organic matter (RDOM) from seven different sources (algae, leaf litter, reed, compost, field soil, paddy water, treated sewage) were examined using multiple analytical tools, and they were compared with those of RDOM in a large artificial lake (Lake Paldang, Korea). Treated sewage, paddy water, and field soil were distinguished from the other sources investigated by their relatively low specific UV absorbance (SUVA) values and more pronounced fulvic-like versus humic-like fluorescence of the RDOM samples. Microbial derived RDOM from algae and treated sewage showed relatively low apparent molecular weight and a higher fraction of hydrophilic bases relative to the total hydrophilic fraction. For the biopolymer types, the presence of polyhydroxy aromatics with the high abundance of proteins was observed only for vascular plant-based RDOM (i.e., leaf litter and reed). Molecular weight values exhibited positive correlations with the SUVA and the hydrophobic content among the different RDOM, suggesting that hydrophobic and condensed aromatic structures may be the main components of high molecular weight RDOM. Principal component analysis revealed that approximately 77% of the variance in the RDOM characteristics might be explained by the source difference (i.e., terrestrial and microbial derived) and a tendency of further microbial transformation. Combined results demonstrated that the properties of the lake RDOM were largely affected by the upstream sources of field soil, paddy water, and treated sewage, which are characterized by low molecular weight UV-absorbing and non-aromatic structures with relatively high resistance to further degradation. 相似文献
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186.
脱硝催化剂孔结构及其脱硝特性的研究 总被引:2,自引:0,他引:2
选择性催化还原脱硝技术(SCR)所采用的催化剂多数为多孔介质,其内部孔隙有助于提高催化剂的反应活性。文中采用浸渍负载法,通过改变制备温度制备出不同孔结构的催化剂样品,采用N2吸附法对其孔结构进行测定和分析,并对不同孔结构的催化剂样品进行了脱硝实验。研究表明:煅烧及干燥温度对催化剂孔结构有很大的影响,比表面积越大,其催化剂内的孔分布宽度越窄,平均孔径越小;在活性温度范围(360~390℃)内,脱硝过程中主要是属于化学反应过程控制,脱硝效果随着比表面积的增大而增强;在非活性温度范围内,脱硝过程同时受到气体扩散过程及化学反应过程控制。 相似文献
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188.
In industrialized countries, the idea of degrowth has emerged as a response to environmental, social, and economic crises.
Realizing environmental limits to and failures of more than half a century of continual economic growth in terms of social
progress and environmental sustainability, the degrowth paradigm calls for a downscaling of consumption and production for
social equity and ecological sustainability. The call for economic degrowth is generally considered to be delimited to rich
countries, where reduced consumption can save “ecological space” enabling people in poor countries to enjoy the benefits of
economic growth. China, as one of the economically most expanding countries in the world, has dramatically improved its living
standards, particularly along the Eastern coast, over the latest 30 years. However, China is absent from the international
debates on growth. This article discusses the implications of the Western degrowth debates for China. Given the distinctive
features of China’s development, the paper aims to enrich the degrowth debates, which have hitherto been dominated by Western
perspectives. Based upon reflections on social, environmental, and moral dimensions of economic growth, the paper argues that
limited natural resources may not continuously support universal affluence at the current level of the rich countries, a level
that China is likely to reach within a few decades. Priority for growth in China should therefore be given to the poor regions
of the country, and future growth should be beneficial to social and environmental development. 相似文献
189.
在借鉴已有理论的基础上,界定了人口长期均衡发展的内涵,提出人口长期均衡包含人口内部均衡和人口外部均衡两个方面,人口内部均衡包括人口数量、人口质量和人口结构三个维度,人口外部均衡包括人口与经济、人口与社会、人口与资源、人口与环境四个维度;在此基础上构建了人口长期均衡发展的指标体系和评价模型,指标体系设定为三级,第一级包括人口内部均衡和人口外部均衡两个方面,第二级由人口数量、人口质量、人口结构等七个部分构成;第三级指标包括反映内部均衡的7个指标以及反映外部均衡的13个指标.并使用层次分析法确定了指标的权重;采用2000-2007年31个省级单位的数据对人口长期均衡发展评价模型进行了验证,并对人口总体均衡水平以及影响人口均衡发展的关键要素进行了实证分析.结果表明.北京、上海和浙江分列前三,人口均衡发展程度最高.从影响均衡程度的关键因素看.人口质量和人口结构是制约人口自身均衡的主要因素,人口与社会的均衡状况对人口与外部系统均衡制约最大,其次是人口与经济的均衡状况. 相似文献
190.