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141.
研究构建了2个容积为1.1 L的好氧活性污泥反应器(即1号和2号反应器)1,号反应器每天直接通加低剂量臭氧(投加量为0.01 g O3/g TSS),不加臭氧的2号反应器作为对照平行运行,均采用每天换一次人工污水的充/排式操作。运行71 d的结果表明2,个反应器对人工污水COD的处理效果基本相同。反应器运行40 d后1,号反应器的污泥浓度比2号反应器的污泥浓度低1 400~1 700 mg/L并可稳定在8 200 mg/L,污泥减量化效果明显。低剂量臭氧的直接通加明显降低了胞内ATP浓度,并影响了微生物的抗氧化活性,2号反应器的平均超氧化物歧化酶和过氧化氢酶酶活比1号反应器分别高了24.3%和9.5%。PCR-DGGE对两反应器微生物种群的分析结果表明:Uncultured gammaproteobacteria bacteri-um、Nannocystis exedens和Uncultured actinobacterium为1号反应器的主要种群;而2号反应器的主要种群为Uncultured bacte-rium和Uncultured gammaproteobacteria bacterium。 相似文献
142.
Shigekazu Hirao Hiromi Yamazawa Jun Moriizumi 《Journal of environmental radioactivity》2010,101(11):974-984
When used with an atmospheric transport model, the 222Rn flux distribution estimated in our previous study using soil transport theory caused underestimation of atmospheric 222Rn concentrations as compared with measurements in East Asia. In this study, we applied a Bayesian synthesis inverse method to produce revised estimates of the annual 222Rn flux density in Asia by using atmospheric 222Rn concentrations measured at seven sites in East Asia. The Bayesian synthesis inverse method requires a prior estimate of the flux distribution and its uncertainties. The atmospheric transport model MM5/HIRAT and our previous estimate of the 222Rn flux distribution as the prior value were used to generate new flux estimates for the eastern half of the Eurasian continent dividing into 10 regions.The 222Rn flux densities estimated using the Bayesian inversion technique were generally higher than the prior flux densities. The area-weighted average 222Rn flux density for Asia was estimated to be 33.0 mBq m−2 s−1, which is substantially higher than the prior value (16.7 mBq m−2 s−1). The estimated 222Rn flux densities decrease with increasing latitude as follows: Southeast Asia (36.7 mBq m−2 s−1); East Asia (28.6 mBq m−2 s−1) including China, Korean Peninsula and Japan; and Siberia (14.1 mBq m−2 s−1). Increase of the newly estimated fluxes in Southeast Asia, China, Japan, and the southern part of Eastern Siberia from the prior ones contributed most significantly to improved agreement of the model-calculated concentrations with the atmospheric measurements. The sensitivity analysis of prior flux errors and effects of locally exhaled 222Rn showed that the estimated fluxes in Northern and Central China, Korea, Japan, and the southern part of Eastern Siberia were robust, but that in Central Asia had a large uncertainty. 相似文献
143.
采用牡蛎壳为曝气生物滤池填料,以含NaCl的生活污水为处理对象,在SBR操作条件下,系统考察进水NaCl浓度、曝气时间及进水pH值等对硝化性能的影响。结果表明,进水NaCl浓度为10~15 g/L时,平均氨氮去除率可稳定在97%以上;较高浓度NaCl对亚硝酸化菌活性影响较弱,对硝酸化菌活性影响较强,特别是在日曝气时间少于12 h时,其出水中亚硝氮的含率大于50%;当进水pH值在6~9变化时,反应器内pH值可稳定在6.5~7.5,硝化性能良好,表明牡蛎壳填料可为硝化反应提供碱度。 相似文献
144.
研究了UV/Fenton技术对高浓度金属清洗乳化油废水的处理效果,考察了亚铁与双氧水浓度、pH、反应时间和搅拌对COD去除效果的影响。实验结果表明,UV/Fenton技术对高浓度乳化油废水(COD平均浓度为35 000 mg/L)具有较高的去除效果,最佳工艺条件为:亚铁与双氧水浓度分别为2 400 mg/L和6 000 mg/L,pH为3,经过2 h反应,COD可降低至1 050 mg/L,去除率为97%。搅拌会降低COD的去除率。研究表明,UV/Fenton技术对高浓度乳化油废水具有很好的降解效果,且药品消耗较低,为目前此类高浓度有机废水的处理提供了技术参考。 相似文献
145.
146.
解磷微生物肥料的研究与进展 总被引:1,自引:0,他引:1
磷是植物生长必需的矿物质元素之一,在土壤中易被固定降低其有效性,目前,研究和生产含有解磷功能的微生物有机肥料是转化土壤中无效磷、提高磷肥利用率的有效途径之一。叙述了解磷微生物犯料中微生物的种类、生态分布规律和影响高效解磷微生物选育的外部因素,概述了解磷微生物菌肥的应用和研究进展,探讨了解磷微生物肥料的应用价值。为解磷微生物未来的研究重点提出理论依据。. 相似文献
147.
Siedlecka EM Stepnowski P 《Environmental science and pollution research international》2009,16(4):453-458
Background, aim, and scope Ionic liquids are regarded as essentially “green” chemicals because of their insignificant vapor pressure and, hence, are
a good alternative to the emissions of toxic conventional volatile solvents. Not only because of their attractive industrial
applications, but also due to their very high stability, ionic liquids could soon become persistent contaminants of technological
wastewaters and, moreover, break through into natural waters following classical treatment systems. The removal of harmful
organic pollutants has forced the development of new methodologies known as advanced oxidation processes (AOPs). Among them,
the Fenton and Fenton-like reactions are usually modified by the use of a higher hydrogen peroxide concentration and through
different catalysts. The aim of this study was to assess the effect of hydrogen peroxide concentration on degradation rates
in a Fenton-like system of alkylimidazolium ionic liquids with alkyl chains of varying length and 3-methyl-N-butylpyridinium chloride.
Materials and methods The ionic liquids were oxidized in dilute aqueous solution in the presence of two different concentrations of hydrogen peroxide.
All reactions were performed in the dark to prevent photoreduction of Fe(III). The concentrations of ionic liquids during
the process were monitored with high-performance liquid chromatography. Preliminary degradation pathways were studied with
the aid of 1H NMR.
Results Degradation of ionic liquids in this system was quite effective. Increasing the H2O2 concentration from 100 to 400 mM improved ionic liquid degradation from 57–84% to 87–100% after 60 min reaction time. Resistance
to degradation was weaker, the shorter the alkyl chain.
Discussion The compound omimCl was more resistant to oxidation then other compounds, which suggests that the oxidation rates of imidazolium
ionic liquids by OH· are structure-dependent and are correlated with the n-alkyl chain length substituted at the N-1-position. The level of degradation was dependent on the type of head group. Replacing
the imidazolium head group with pyridinium increased resistance to degradation. Nonetheless, lengthening the alkyl chain from
four to eight carbons lowered the rate of ionic liquid degradation to a greater extent than changing the head group from imidazolium
to pyridinium. 1H-NMR spectra show, in the first stage of degradation, that it is likely that radical attack is nonspecific,
with any one of the carbon atoms in the ring and the n-alkyl chain being susceptible to attack.
Conclusions The proposed method has proven to be an efficient and reliable method for the degradation of imidazolium ionic liquids by
a Fenton-like reagent deteriorated with lengthening n-alkyl substituents and by replacing the imidazolium head group with pyridinium. The enhanced resistance of 1-butyl-3-methylpyridinium
chloride when the resistance of imidazolium ionic liquids decreases with increasing H2O2 concentration is probably indicative of a change in the degradation mechanism in a vigorous Fenton-like system. H-NMR spectra
showed, in the first stage of degradation, that radical attack is nonspecific, with any one of the carbon atoms in the ring
and the n-alkyl chain being susceptible to attack.
Recommendations and perspectives Since ionic liquids are now one of the most promising alternative chemicals of the future, the degradation and waste management
studies should be integrated into a general development research of these chemicals. In the case of imidazolium and pyridinium
ionic liquids that are known to be resistant to bio- or thermal degradation, studies in the field of AOPs should assist the
future structural design as well as tailor the technological process of these chemicals 相似文献
148.
149.
Abstract: As zebra mussels (Dreissena polymorpha) continue to spread among inland lakes of the United States and Canada, there is growing interest from professionals, citizens, and other stakeholders to know which lakes are likely to be colonized by zebra mussels. Thus, we developed a classification of lake suitability for zebra mussels on the basis of measured or estimated concentrations of dissolved calcium in lake water and applied the classification to >11,500 lakes in Wisconsin and the Upper Peninsula of Michigan. The majority of lakes (58%) were classified as unsuitable (<10 mg/L Ca) for survival and reproduction of zebra mussels, 27% were identified as suitable (≥21 mg/L Ca), and 15% were classified as borderline suitable (≥10 and <21 mg/L Ca). Of the 77 inland lakes with confirmed zebra mussel records for which data on dissolved calcium were available, our method classified 74 as suitable and 3 as borderline suitable. To communicate this lake‐specific suitability information and to help prioritize regional efforts to monitor and prevent the expansion of zebra mussels and other invasive species, we developed a web‐based interface (available from http://www.aissmartprevention.wisc.edu/ ). Although we are still uncertain of how access to suitability information ultimately affects decision making, we believe this is a useful case study of building communication channels among researchers, practitioners, and the public. 相似文献
150.
石油污染土壤的生物修复技术及微生物生态效应 总被引:10,自引:5,他引:5
利用投菌法和生物刺激法对陕北子长石油污染土壤进行微生物修复研究.通过利用红外分光光度法测定不同处理方法对石油烃的去除效果确定了修复陕北石油污染土壤的最佳方案.修复过程中利用最大可能计数法(MPN)、PCR-琼脂糖电泳法、PCR-DGGE法分别测定了石油烃降解菌数目、催化基因、土壤微生物多样性对土壤微生物生态效应进行研究.结果发现石油污染土壤不同生物处理修复效果为:生物刺激(加入N、P营养物质)生物强化(投加降解菌)其他.土壤中石油烃降解率与可降解石油烃的催化基因含量之间存在正相关关系,修复过程中土壤中的石油烃和烷烃降解菌数量显著多于多环芳烃降解菌数量,投加外源降解菌SZ-1可以显著提高土壤细菌群落的多样性.研究结果有助于深入理解生物修复石油土壤过程中的微生物生态效应变化. 相似文献