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411.
热处理和pH调节协同作用下污泥调质过程研究 总被引:1,自引:0,他引:1
采用单因素实验和正交实验相结合的方式,考察了不同实验条件参数(温度、pH和反应时间)下,热处理和pH调节对污泥细胞溶出过程的影响。结果表明,污泥溶解性化学需氧量(SCOD)与反应温度、溶液pH、反应时间成正相关,其中pH对SCOD的影响最为显著,反应时间对其影响最小。污泥溶胞的最优条件:反应温度120℃,pH=11,反应时间为15 min,经过处理,SCOD可达14 810 mg/L,与总化学需氧量(TCOD)之比为49.29%,总有机碳(TOC)达4 560 mg/L,总氮(TN)则增加27%,总悬浮固体(TSS)和挥发性悬浮固体(VSS)去除率分别达22.85%和40.93%。热碱处理后污泥上清液分子量分布(MWD)状况结果显示:〉1 000 KDa MW物质含量随pH和温度的增加而增加,当pH=11时,该部分物质可从原污泥的20.94%增加到31.70%;当温度为120℃时,该部分物质可达49.83%。 相似文献
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413.
Xing-Yuan Wei Ling-Zi Sang Jia-Ning Chen Ya-Xian Zhu Yong Zhang 《Environmental pollution (Barking, Essex : 1987)》2009,157(11):3150-3157
Biodegradation of dissolved fluorene (Flu), phenanthrene (Ph) and pyrene (Py), three polycyclic aromatic hydrocarbons (PAHs), singly or as a mixture of the three, by two bacterial strains, MEBIC 5140 (Mycobacterium flavescens) and MEBIC 5141 (Mycobacterium scrofulaceum), as well as the effects of low molecular weight organic acids (LMWOAs), e.g. malic acid, citric acid and butyric acid on biodegradation of the three PAHs in mineral salts medium aqueous solution were investigated using a newly established dual-wavelength fluorimetric method. The results showed that biodegradation processes can be monitored simultaneously, quickly and simply by dual-wavelength fluorimetry. Both co-metabolism and inhibitory effects were found during the biodegradation of the three PAHs by MEBIC 5140 and MEBIC 5141. Positive effects of butyric acid and negative effects of citric acid on biodegradation of the three PAHs in a mixture were observed. 相似文献
414.
CuO(-CeO_2)/SBA-15对萘氧化的催化活性及CO_2选择性研究 总被引:1,自引:0,他引:1
通过浸渍法制备CuO/SBA-15和CuO-CeO2/SBA-15两种介孔材料催化剂,采用BET、XRD、TPR和XPS等对催化剂进行表征,重点考察催化剂对萘氧化反应的催化活性及对产物CO2的选择性。BET、XRD和XPS等实验结果表明CuO高度分散于介孔分子筛SBA-15中,CeO2可促进CuO在载体上的分散,同时能降低催化剂的TPR还原温度。活性测试结果表明CuO/SBA-15对萘氧化反应的催化活性较高,但是催化氧化的CO2选择性较低,温度在380℃时CO2的生成率仅为60%左右;CeO2的添加不仅提高了CO2的生成率,15%CuO-15%CeO2/SBA-15在325℃使CO2生成率达到99%,而且CeO2增强了催化剂的稳定性。 相似文献
415.
416.
Study on the mechanism of action between dimethyl phthalate and herring sperm DNA at molecular level
Zhenxing Chi Donglin Wang Hong You 《Journal of environmental science and health. Part. B》2016,51(8):553-557
Dimethyl phthalate (DMP), a typical phthalic acid ester, is widespread in the environment and causes extensive concern due to its adverse effects on human health. To understand the genotoxicity of DMP at molecular level, the toxic interaction of DMP with herring sperm (hs) deoxyribonucleic acid (DNA; hs-DNA) was investigated in vitro under simulated physiological conditions using multi-spectroscopic techniques and a molecular modeling method. The results of Ultraviolet-Visible absorption spectroscopy, fluorescence emission spectroscopy, and circular dichroism spectra indicated that DMP interacts with hs-DNA in a groove-binding mode that changes the double helical structure of DNA. The binding constant and the number of binding sites calculated from the fluorescence quenching data were 565.718 L mol?1 and 0.7872, respectively. A molecular modeling study revealed that DMP tends to bind with DNA in the A-T-rich regions of minor groove and that hydrogen bonding and van der Waals forces play main roles in the interaction. This research can help to elucidate the mechanism of DMP toxicity in vivo. 相似文献
417.
Nitrate Dynamics in Two Streams Impacted by Wastewater Treatment Plant Discharge: Point Sources or Sinks?
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Brian G. Rahm Nicole B. Hill Stephen B. Shaw Susan J. Riha 《Journal of the American Water Resources Association》2016,52(3):592-604
We examined nitrate processing in headwater stream reaches downstream of two wastewater treatment plant outfalls during low streamflow. Our objectives were to quantify nitrate mass flux before and after effluent discharge and to use field and laboratory techniques to assess the mechanism of nitrate uptake. Microcosm experiments were utilized to determine the location of nitrate processing, and molecular biomarkers were used to detect and quantify microbial denitrification. At one site, downstream nitrate mass flux was significantly (p = 0.01) lower than sum of upstream and wastewater effluent fluxes, indicating rapid stream assimilation of incoming nitrate in the vicinity of the point source. Microcosm experiments supported the theory that nitrate processing occurs in sediments. Molecular assays for denitrifcation‐associated functional genes nosZ, nirS, and nirK, provided evidence that effluent contained enriched denitrifying communities relative to ambient stream water. Nitrate loss at the site with greater uptake was correlated with sulfate loss (p < 0.01; r2 = 0.86), suggesting a possible link between sulfate reducing bacteria and denitrifying bacterial communities. Results suggest there is an opportunity to better understand nitrate dynamics in cases where point sources may act as point sinks under specific sets of conditions. 相似文献
418.
采用膨胀颗粒污泥床(EGSB)反应器对城市生活垃圾焚烧厂产生的垃圾沥滤液进行处理。实验结果表明:中温条件下,当COD浓度为55 000 mg/L左右,有机容积负荷(OLR)为22.8 kg COD/(m3.d)时,EGSB对垃圾沥滤液具有较好的的处理效果,COD去除率可达94.2%。当进水COD为72 000 mg/L左右时,为保证反应器的稳定运行,OLR应降低至18.2 kg COD/(m3.d),此时COD去除率可以达到88%左右,出水COD平均为9 103 mg/L。垃圾沥滤液和EGSB处理出水均以小分子量有机物为主,其中<4 kDa的有机物分别占76.5%和74.4%。EGSB对整个分子量区间的溶解性有机物都有较好的处理效果,其中对大分子有机物的处理效率相对更高。 相似文献
419.
Zhi F. Xu Ge Wen Dai Z. Kuang Fu X. Zhang Si P. Tang 《Journal of environmental science and health. Part. B》2013,48(5):336-343
A deltamethrin-imprinted polymer (MIP1) was prepared using bis(-6-O-butanediacid monoester)-β-cyclodextrin (BBA-β-CD) as the functional monomer and toluene 2,4-diisocyanate (TDI) as the cross-linker. In comparison to the molecularly imprinted polymer where β-CD was applied as the functional monomer (MIP2), MIP1 showed a higher specific binding capacity (ΔCP) and an improved imprinting factor (IF) for deltamethrin. The selective recognition experiments demonstrated that compared to MIP2, MIP1 could better recognize its template over other substrates that had similar chemical structures. The solid phase extraction (SPE) of deltamethrin using MIP1 as the adsorbent was further investigated. The recoveries of the molecularly imprinted solid phase extraction (MISPE) column for deltamethrin were 83.2–93.4% with relative standard deviations (RSD) of 2.03–6.19%. The method has been successfully applied to the enrichment of trace deltamethrin from real water samples. 相似文献
420.
针对人类粪便污染,选择来源于拟杆菌和双歧杆菌16S rRNA的基因片段作为标记物,分别建立了相应的实时荧光定量PCR检测方法.选取不同来源的粪便样品进行检测,证实了引物的特异性.回收纯化从污水中扩增所得的目标PCR片段,经过连接转化,筛选阳性克隆提取其重组质粒作为实时荧光定量PCR的标准品.通过检测一系列梯度稀释的标准品,确定了拟杆菌基因标记物和双歧杆菌基因标记物定量PCR检测方法分别在1.98×102~1.98×107 copy/μL和2.12×101~2.12×107 copy/μL范围内具有良好的线性关系. 相似文献