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91.
92.
曝气强度对膜生物反应器污泥混合液可滤性的影响 总被引:8,自引:1,他引:7
主要研究了曝气强度对膜生物反应器(MBR)膜污染的影响.2套MBR采用恒流出水模式连续运行60 d,曝气强度分别为500及100 L/h,应用死端过滤装置来检测不同阶段污泥混合液的可滤性.实验中对不同曝气强度下的溶解性微生物代谢产物(SMP)分子质量分布、颗粒粒径分布、胞外聚合物(EPS)含量进行了测定.结果表明,过高的曝气强度将恶化污泥混合液的可滤性,增加了膜污染速率.进一步研究表明,曝气强度的增加导致了污泥混合液上清液中相对分子质量>10000的SMP浓度的增加,此部分大分子有机物浓度直接影响了污泥混合液的可滤性.过高的曝气强度也导致了污泥絮体中1~10μm细小颗粒和EPS含量的增加. 相似文献
93.
产品碳足迹评价中,数据种类、来源、获取途径和量化方法的选择不同将直接影响到评价结果的可靠与否.本文建立了结合敏感度和DQI-Monte Carlo不确定度分析的产品碳足迹评价数据质量分析模型.首先通过敏感度分析识别出产品碳足迹评价中的主要数据,再采用DQI-Monte Carlo不确定度分析方法对主要数据进行数据质量判定,甄选出影响评价结果可靠性的关键数据,并由此有针对性地提出数据质量改进意见,从而有效地优化数据收集方案,减少碳足迹评价结果的不确定度.建立的方法应用于我国某塑料软包装印刷企业的印刷前阶段碳足迹评价中. 相似文献
94.
Decomposition mass loss and pyrolysis products analyses of particles sampled at various locations along the tailpipe of a Euro-IV diesel engine were performed using a thermogravimetry in conjunction with Fourier transformation infrared spectrometry-mass spectrum. Diesel particles were collected at the same location with and without diesel oxidation catalyst (DOC) mounted on the test engine separately. The three poles in thermal gravity-differential thermal gravity images suggested that the decomposition process of diesel particles could be divided into three stages which correspond to the decompositions of lower boiling substances, higher boiling substances and soot respectively. It is noticed that no matter whether DOC was mounted or not, the further the particles were sampled away from the engine block, the lower the peak temperatures and the heavier the mass losses within the first two stages, which indicated that the soluble organic fraction in the particle samples increased and therefore lowering the activation energy of thermal decomposition. Hydroxyl, ammonia, CxHy fragments, benzene, toluene, and phenol were found to be the primary products of particle decomposition, which didn't change with the location of particle sample point. The employment of DOC increased the activation energy for particle oxidation and resulted in a higher peak temperature and lower mass loss within the first-stage. Moreover, the CO stretching bands of aldehyde and ketone at 1771 cm?1 was only detected without a DOC, while the NO2 peak at 1634 cm?1 was solely noticed with the presence of DOC. Compared to the first-stage pyrolysis products, more polycyclic aromatic hydrocarbons and less CxHy fragments were seen in the second-stage. 相似文献
95.
用硫酸铝PAM混合絮凝剂净化乳制品行业废水,寻找一种最佳的处理方案。通过多组实验显示:硫酸铝投入量280mg/L,pH值为6—7,水温20℃,搅拌速度为40~70r/min时,经处理的废水外观清晰、透明度高,COD去除率均在80%左右,对保障乳品行业的可持续发展起到科学的借鉴作用。 相似文献
96.
Part V—sorption of pharmaceuticals and personal care products 总被引:5,自引:0,他引:5
Background, aim, and scope Pharmaceuticals and personal care products (PPCPs) including antibiotics, endocrine-disrupting chemicals, and veterinary pharmaceuticals
are emerging pollutants, and their environmental risk was not emphasized until a decade ago. These compounds have been reported
to cause adverse impacts on wildlife and human. However, compared to the studies on hydrophobic organic contaminants (HOCs)
whose sorption characteristics is reviewed in Part IV of this review series, information on PPCPs is very limited. Thus, a
summary of recent research progress on PPCP sorption in soils or sediments is necessary to clarify research requirements and
directions.
Main features We reviewed the research progress on PPCP sorption in soils or sediments highlighting PPCP sorption different from that of
HOCs. Special function of humic substances (HSs) on PPCP behavior is summarized according to several features of PPCP–soil
or sediment interaction. In addition, we discussed the behavior of xenobiotic chemicals in a three-phase system (dissolved
organic matter (DOM)–mineral–water). The complexity of three-phase systems was also discussed.
Results Nonideal sorption of PPCPs in soils or sediments is generally reported, and PPCP sorption behavior is relatively a more complicated
process compared to HOC sorption, such as the contribution of inorganic fractions, fast degradation and metabolite sorption,
and species-specific sorption mechanism. Thus, mechanistic studies are urgently needed for a better understanding of their
environmental risk and for pollution control.
Discussion Recent research progress on nonideal sorption has not been incorporated into fate modeling of xenobiotic chemicals. A major
reason is the complexity of the three-phase system. First of all, lack of knowledge in describing DOM fractionation after
adsorption by mineral particles is one of the major restrictions for an accurate prediction of xenobiotic chemical behavior
in the presence of DOM. Secondly, no explicit mathematical relationship between HS chemical–physical properties, and their
sorption characteristics has been proposed. Last but not least, nonlinear interactions could exponentially increase the complexity
and uncertainties of environmental fate models for xenobiotics. Discussion on proper simplification of fate modeling in the
framework of nonlinear interactions is still unavailable.
Conclusions Although the methodologies and concepts for studying HOC environmental fate could be adopted for PPCP study, their differences
should be highly understood. Prediction of PPCP environmental behavior needs to combine contributions from various fractions
of soils or sediments and the sorption of their metabolites and different species.
Recommendations and perspectives More detailed studies on PPCP sorption in separated soil or sediment fractions are needed in order to propose a model predicting
PPCP sorption in soils or sediments based on soil or sediment properties. The information on sorption of PPCP metabolites
and species and the competition between them is still not enough to be incorporated into any predictive models. 相似文献
97.
Fenton 法降解抗生素磺胺间甲氧嘧啶钠 总被引:2,自引:1,他引:2
应用Fenton高级氧化技术降解水溶液中抗生素磺胺间甲氧嘧啶钠(SMMS),系统探讨了起始pH、CSMMS、CFe2+、CH2O2和温度等因素对SMMS降解效果的影响。结果表明:CSMMS=4.53 mg/L,pH=4.0,CH2O2=0.49 mmol/L,CFe2+=19.51μmol/L,T=25℃为最佳反应条件。在最佳条件下,87.4%的SMMS可以在120 min内降解。反应动力学研究表明Fenton氧化降解SMMS分为两个阶段,快速反应阶段和慢速反应阶段,并建立了两阶段动力学模型,模型拟合结果较好。研究结果为含有SMMS的污废水处理提供了基础数据和科学参考。 相似文献
98.
针对目前人们对好氧脱氮中气态产物认识不清的问题,采用SBR反应器,以人工配制的NO3--N废水为处理对象,对影响好氧脱氮的COD/N进行了深入研究,测定了三种主要含氮气态产物(NO、NO2、N2O),揭示了好氧状态下生物脱氮的途径和机理。通过对COD/N分别为9、12、15、18的系统氮元素的全程跟踪测定,得到系统内各含氮化合物的变化规律。结果表明,三种气体的产生同COD/N有着密切的关系,低C/N会导致NO、NO2和N2O的积累,最多达总脱氮量的9%。研究结果还表明当进水COD/N为15时,既保证了良好的脱氮效果且抑制了NO、NO2、N2O三种有害气体的大量产生。 相似文献
99.
Jacob Heilmann‐Clausen Elizabeth S. Barron Lynne Boddy Anders Dahlberg Gareth W. Griffith Jenni Nordén Otso Ovaskainen Claudia Perini Beatrice Senn‐Irlet Panu Halme 《Conservation biology》2015,29(1):61-68
Hitherto fungi have rarely been considered in conservation biology, but this is changing as the field moves from addressing single species issues to an integrative ecosystem‐based approach. The current emphasis on biodiversity as a provider of ecosystem services throws the spotlight on the vast diversity of fungi, their crucial roles in terrestrial ecosystems, and the benefits of considering fungi in concert with animals and plants. We reviewed the role of fungi in ecosystems and composed an overview of the current state of conservation of fungi. There are 5 areas in which fungi can be readily integrated into conservation: as providers of habitats and processes important for other organisms; as indicators of desired or undesired trends in ecosystem functioning; as indicators of habitats of conservation value; as providers of powerful links between human societies and the natural world because of their value as food, medicine, and biotechnological tools; and as sources of novel tools and approaches for conservation of megadiverse organism groups. We hope conservation professionals will value the potential of fungi, engage mycologists in their work, and appreciate the crucial role of fungi in nature. Una Perspectiva Micótica de la Biología de la Conservación 相似文献
100.
建设项目环境影响报告编制过程中常因未注意到某些关键问题的论述,而使环境影响报告缺乏科学性和可靠性,导致环境影响评价结论依据不足.为使建设项目从环境保护角度分析更具有可行性,以某橡胶制品项目为例,总结了橡胶制品工业项目环境影响评价文件中需注意的几个要点问题,为环境保护主管部门审批环境影响评价文件提供必要的依据,为此类项目更好地开展环境保护工作提供指导. 相似文献