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851.
贫营养好氧反硝化细菌在水环境能量流动和物质循环过程中扮演着重要的角色。从山东某水源水库沉积物中共驯化分离出216株好氧反硝化细菌,复筛得到3株高效菌株ZN1、ZN2和ZN3。经形态学指标和16S rRNA序列分析,ZN1和ZN3属于铁还原细菌(iron-reducing bacterium),ZN2属于粘液菌属(Zoogloea sp.)。关键酶基因检测表明3株菌均含有周质硝酸盐还原酶基因(nap A)。在30℃、120 r/min条件下,培养47 h后3株菌对培养液中NO3-N的去除率均在80%以上,TN去除率均在40%以上,且无明显的亚硝氮积累。对3株菌分别进行原水适应,以20%的梯度增加原水的比例直至100%原水。原水培养72 h后,3株菌NO3-N去除率为30%~40%,TN去除率为20%~25%。 相似文献
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853.
基于GIS的我国农村老年人口时空发展研究 总被引:1,自引:0,他引:1
以2000年、2003年、2006年和2009年4个时间点的农村老年人口数据为基础,从农村老年人口系数、老少比和养老负担3个指标对我国大陆31个地区的农村老年人口状况做了时间和空间上的对比分析。结果表明,农村老龄化发展迅速且从东部向中西部快速递进,农村老龄化的集中程度趋于降低。 相似文献
854.
抗生素制药废水有机污染物分布特性研究 总被引:1,自引:0,他引:1
采用气相色谱/质谱法对β-内酰胺类抗生素制药废水中有机污染物进行了定性与定量分析,得到了废水中有机污染物的种类、相对含量及分子量分布特性.通过理论COD计算公式,计算分析了废水中有机污染物对COD指标的贡献程度.结果表明,该类废水中含有84种有机物,其中以胺类、烷烃类和烯烃类有机物的相对含量最高.有机污染物的分子量集中在100~400,分子量小于100或大于500的有机物含量相对较低,其中分子量在100~200的有机物含量最大.通过对比有机污染物的理论COD贡献度可知,胺类、烷烃类和烯烃类有机物含量对废水污染负荷影响最大.根据有机物污染源分析,提出了此类抗生素制药废水合理化处理的生产工艺建议和处理工艺方案. 相似文献
855.
Jingjing Fang Na Yang Liming Shao 《Journal of the Air & Waste Management Association (1995)》2013,63(11):1287-1297
The concentrations and chromatographic profiles of gaseous pollutants emitted from a municipal solid waste (MSW) biological treatment plant were investigated to identify the major odor substances and atmospheric photochemical reactive species (PRS). Four methods were used to measure different gaseous pollutants in this study, including colorimetric tubes, gas chromatography with mass spectrometry/flame ionization detection/pulsed flame photometric detection (GC-MS/FID/PFPD) preceded by cold trap concentration, GC-FID preceded by solid-phase microextraction (SPME), and high-performance liquid chromatography (HPLC) after derivation by 2,4-dinitrophenylhydrazine (DNPH). Seventy-five gaseous compounds belonging to nine groups (nitrogen compounds, sulfur compounds, alkanes, alkenes, aromatics, terpenes, alcohols, carbonyls, and volatile fatty acids [VFAs]) were identified. In the pre-biotreatment facility, the total concentration of the gaseous pollutants reached the maximum value on day 7 (317 ppm). During the post-biotreatment process, the total concentration of gaseous pollutants decreased from 331 ppm at the beginning to 162 ppm in the end. The group with the greatest decrease was carbonyls, from 64 to 7.4 ppm, followed by alcohols, from 40 to 4.5 ppm, which were both oxygenated compounds. The proportion of aromatics was notably high in the pre-mechanical treatment facility, accounting for 50.6% of the total, revealing the xenobiotic compounds disseminated by stirring and agitating the waste in the initial stage. The proportions of nitrogen compounds were lower in the pre- and post-mechanical treatment facilities (1.5% and 6.9%) than in the pre- and post-biotreatment facilities (11.9% and 13.8%), suggesting that their generation was closely associated with waste degradation. The major odor compounds in the facilities were acetic acid, butyric acid, valeric acid, isovaleric acid, and dimethyl sulfide. The major PRS in the facilities were aromatics, acetaldehyde, butyraldehyde, hexanal, isopentyl aldehyde, alcohol, α-pinene, limonene, and terpinene. Outside the facilities, VFAs and aromatics were the most important compounds causing an environmental impact.
Implications: The aim of this work is to assess the gaseous environmental impacts of mechanical biological treatment technology. The emission of gaseous pollutants greatly affects the living quality of nearby residents and odor complaints are becoming a major problem now. In this study, the authors utilized various pretreatment and analytical methods to obtain integrated emission information of gaseous pollutants. The results showed the transformation and fate of the gas pollutants during the treatment processes, which would help to improve the processes and to mitigate gaseous pollution. Supplemental Materials: Supplemental materials are available for this paper. Go to the publisher's online edition of the Journal of the Air & Waste Management Association for information on the concentrations of the nine compound families at different sampling locations in the plant. 相似文献
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857.
感应热固定床(IHFB)作为新型热传递方式下非均相反应器,利用感应加热铁磁材料将热量传递至液相,形成固液界面高温微反应区,实现有机废水低能高效降解。实验以海绵铁为感应内核,淀粉为碳源,0.2 mol/L硝酸镍为浸渍溶液,按照一定固液比采用浸渍焙烧法制备了C包覆表层负载NiO的感应热催化剂(mNiO/C),对mNiO/C材料的形态结构进行了SEM、ES和XRD表征。结果表明,铁碳比(Fe/C)3∶1、浸渍固液比1∶1、500℃下焙烧2 h,重复包覆3次所得的mNiO/C材料结构最稳定、催化活性最大。并以直接紫D-BL模拟废水为进水,考察了流动状态下感应热固定床催化湿式过氧化氢氧化法(CWPO)降解染料废水的性能,在最优条件下,染料降解率高达80%以上。 相似文献
858.
Escherichia coli is known to respond to certain toxic chemicals through an increased expression of various stress genes. In this study, therefore, the expression of recA, katG, fabA and grpE genes was used as a representative for DNA, oxidative, membrane and protein damage, respectively, after E. coli was exposed to different polycyclic aromatic hydrocarbons (PAHs), i.e., phenanthrene, naphthalene and benzo[a]pyrene. To accomplish this, the expression levels of these four genes were quantified using a real-time RT-PCR analysis when E. coli cultures were under stressful conditions, such as those caused by an exposure to mitomycin C, hydrogen peroxide and phenol. It was found that the primary toxic effect of each chemical is clearly seen when the expression levels of the different genes are compared. Tests with the PAHs showed naphthalene and benzo[a]pyrene to be genotoxic, while phenanthrene had no clear effect on the expression of any of these genes. Based on these results, the effects due to these toxic chemicals and the extent of each stress can be evaluated with ease using the expression levels of different stress responsive genes. 相似文献
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860.