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911.
针对丝绸厂汰头废水高有机物浓度高氮磷的特点,对该废水的化学除磷工艺及生物化学组合除磷工艺的除磷效能进行了对比研究,考察了有机负荷、运行工况、工艺组合、药剂种类和投加量等对除磷效能的影响.试验结果表明:对汰头废水采用厌氧-生物除磷-生物脱氮-化学除磷组合工艺除磷经济高效,当生物除磷SBBR工艺单元有机负荷为3 kgBOD5/m3·d,运行工况为进水0.5 h-厌氧2 h-曝气4 h-沉淀1 h-排水0.5 h,化学除磷工艺单元投加60 mg/L聚合氯化铝(PAC)时,可使COD及PO3-4分别为10 000 mg/L和114 mg/L的进水,出水COD及PO3-4分别为93 mg/L和0.23 mg/L;总ηCOD91.5%,ηPO3-4为99.8%.其中生物除磷工艺单元承担的ηPO3-4为75%;化学除磷工艺单元承担的ηPO3-4为24.8%. 相似文献
912.
913.
安全流变理论及其在煤矿事故中的应用 总被引:7,自引:5,他引:7
提出了“安全流变理论”,分析了事物“安全流变”的基本特征和理论基础 ,描述了煤矿事故的安全流变特性 ,同时指出煤矿事故的发生和发展可以用“安全流变理论”进行解释 ,进而说明“安全流变理论”是符合事物发展变化规律的。 相似文献
915.
Distribution and contamination assessment of heavy metals in sediment of the Second Songhua River, China 总被引:2,自引:0,他引:2
The Second Songhua River was subjected to a large amount of raw or primary effluent from chemical industries in Jilin city
in 1960s to 1970s, resulting in serious mercury pollution. However, an understanding of other trace metal pollution has remained
unclear. The objective of this study was to investigate trace metal contamination in the sediment of the river. Bottom sediment
samples were taken in the river between Jilin city and Haerbin city in 2005. An uncontaminated sediment profile was taken
in the Nen River at the same time. Total concentrations of Al, Fe, Mg, Ca, K, Na, Ti, Mn, V, Sc, Co, Cu, Cr, Ni, Pb and Zn
in the sediment samples were measured by ICP-MS or ICP-OES, following digestion with various acids. Concentrations of Co,
Cu, Cr, Ni, Pb and Zn in the surface sediments were 5.1–14.7, 18.5–78.9, 2.4–75.4, 7.2–29.0, 13.5–124.4, and 21.8–403.1 mg/kg,
respectively, generally decreasing along the course of the river from Jilin city to Haerbin city. Background concentrations
of trace metals were reconstructed by geochemical normalization to a conservative element scandium. Results showed that concentrations
of Co, Cr, and Ni in the sediment were generally only slightly higher than or equal to their background values, while concentrations
of Cu, Pb, and Zn in the some sediment samples were significantly higher than their background values. In detail, the sediment
at Jilin city was moderately contaminated by Cu, and the sediment of the Second Songhua River was moderately contaminated
by Pb and Zn. The top layer (0–10 cm depth) and bottom layers (30–46 cm depth) of one sediment profile at Wukeshu town were
generally moderately polluted by Pb and Zn. Synthetically, the surface sediment in the studied river section was classified
as natural sediment without ecological risk by the sediment pollution index (SPI) of Cu, Cr, Ni, Pb and Zn. Only the 30–45 cm
depth of the sediment profile at Wukeshu town was classified as low polluted sediment by the SPI of these metals, recording
a historical contamination of the river in the 1960s to 1970s. This buried contamination of trace metals might pose a potential
risk to water column under disturbance of sediment.
Foundation item: The National Basic Research Priorities Program of China (2004CB418502) 相似文献
916.
917.
近年来,随着全国各地排水设施的建设和发展,在污水收集,转输,处理过程中,恶臭气体大量产生,影响环境,引起越来越多的水务工作者关注.结合工程实例,文章就污水行业恶臭气体的产生,成份,抑制、控制及治理措施进行论述. 相似文献
918.
919.
为了了解广州市“亮光工程”带来的光污染问题,针对人工白昼这一类光污染,在越秀区内的商业区、城市道路、公共空间、居住区4种类型环境各选取部分有代表性的区域进行照度测量,文章对照国内外标准并结合现场环境,对越秀区的光污染情况进行分析和研究,并就光污染防治提出几点建议。 相似文献
920.
Vehicular volatile organic compounds losses due to refueling and diurnal process in China: 2010–2050 总被引:2,自引:0,他引:2
Xiaofan Yang Huan Liu Hongyang Cui Hanyang Man Mingliang Fu Jiming Hao Kebin He 《环境科学学报(英文版)》2015,27(7):88-96
Volatile organic compounds (VOCs) are crucial to control air pollution in major Chinese cities since VOCs are the dominant factor influencing ambient ozone level, and also an important precursor of secondary organic aerosols. Vehicular evaporative emissions have become a major and growing source of VOC emissions in China. This study consists of lab tests, technology evaluation, emissions modeling, policy projections and cost-benefit analysis to draw a roadmap for China for controlling vehicular evaporative emissions. The analysis suggests that evaporative VOC emissions from China's light-duty gasoline vehicles were approximately 185,000 ton in 2010 and would peak at 1,200,000 ton in 2040 without control. The current control strategy implemented in China, as shown in business as usual (BAU) scenario, will barely reduce the long-term growth in emissions. Even if Stage II gasoline station vapor control policies were extended national wide (BAU + extended Stage II), there would still be over 400,000 ton fuel loss in 2050. In contrast, the implementation of on-board refueling vapor recovery (ORVR) on new cars could reduce 97.5% of evaporative VOCs by 2050 (BAU + ORVR/BAU + delayed ORVR). According to the results, a combined Stage II and ORVR program is a comprehensive solution that provides both short-term and long-term benefits. The net cost to achieve the optimal total evaporative VOC control is approximately 62 billion CNY in 2025 and 149 billion CNY in 2050. 相似文献