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771.
Frimmel FH 《Environmental science and pollution research international》2003,10(6):408-413
BACKGROUND: Water is the basis for life and culture. In addition to the availability of water its quality has become a major issue in industrialized areas and in developing countries as well. Water usage has to be seen as part of the hydrological cycle. As a consequence water management has to be sustainable. The aim of the contribution is to give water usage oriented quality criteria and to focus on the technical means to achieve them. MAIN FEATURES: Water is used for many purposes, ranging from drinking and irrigation to a broad variety of technical processes. Most applications need specific hygienic, chemical and/or physical properties. RESULTS: To meet these demands separation and reaction principles are applied. The reuse of water and the application of water treatment with little or no waste and by-product formation is the way to go. Membrane separation and advanced oxidation including catalytic reactions are promising methods that apply natural processes in sustainable technical performance. Thus elimination of specific water constituents (e.g. salts and metals, microorganisms) and waste water cleaning (e.g. pollutants, nutrients and organic water) can be done efficiently. OUTLOOK: Learning from nature and helping nature with appropriate technology is a convincing strategy for sustainable water management. 相似文献
772.
Background, Aims and Scope Secondary inorganic aerosol (SIA), i.e. particulate sulphate (S(VI)), ammonium and nitrate (N(V)) is formed from gaseous
precursors i.e., sulfur dioxide (S(IV)), ammonia and nitrogen oxides, in polluted air on the time-scale of hours to days.
Besides particulate ammonium and nitrate, the respective gaseous species ammonia and nitric acid can be formed, too. SIA contributes
significantly to elevated levels of respirable particulate matter in urban areas and in strongly anthropogenically influenced
air in general.
Methods The near-ground aerosol chemical composition was studied at two stationary sites in the vicinity of Berlin during a field
campaign in summer 1998. By means of analysis of the wind field, two episodes were identified which allow to study changes
within individual air masses during transport i.e., a Lagrangian type of experiment, with one station being upwind and the
other downwind of the city. By reference to a passive tracer (Na+) and estimates on dry depositional losses, the influences
of dispersion and mixing on concentration changes can be eliminated from the data analysis.
Results and Discussion Chemical changes in N(-III), N(V) and S(VI) species were observed. SIA i.e., N(V) and S(VI), was formed from emissions in
the city within a few hours. The significance of emissions in the city was furthermore confirmed by missing SIA formation
in the case of transport around the city. For the two episodes, SIA formation rates could be derived, albeit not more precise
than by an order of magnitude. N(V) formation rates were between 1.4 and 20 and between 1.9 and 59 % h-1 on the two days,
respectively, and S(VI) formation rates were > 17 and > 10 % h-1. The area south of the city was identified as a source of
ammonia.
Conclusion The probability of occurrence of situations during which the downwind site (50 km downwind of Berlin) would be hit by an
urban plume is > 7.4%. Furthermore, for the general case of rural areas in Germany it is estimated that for more than half
of these there is a significant probability to be hit by an urban plume (> 8%). The S(VI) formation rates are higher than
explainable by homogeneous gas-phase chemistry and suggest the involvement of heterogeneous reactions of aerosol particles.
Recommendation and Outlook The possible contribution of heterogeneous processes to S(VI) formation should be addressed in laboratory studies. Measurements
at more than two sites could improve the potential of Lagrangian field experiments for the quantification of atmospheric chemical
transformations, if a second downwind site is chosen in such a way that, at least under particular stability conditions, measurements
there are representative for the source area. 相似文献
773.
774.
在模拟大气环境中,紫外光照射以及纳米TiO2光催化剂的作用下,气相无机污染物SO2被完全氧化为SO2或H2SO4。本文提出了SO2的非均相光催化氧化机理,并得出光催化反应速率符合一级动力学过程;经过连续使用之后,TiO2的光催化活性降低,最后活性消失;经过水洗之后,失活的TiO2可以得到再生。失活的TiO2和新鲜的TiO2的IR和XPS光谱差异表明,失活的TiO2表面存在H2SO4,其被认为是使催化剂失活的成分。 相似文献
775.
776.
777.
研究了利用电厂粉煤灰作为非均相催化剂,催化H2O2氧化对氨基苯酚(PAP),讨论了各种因素对PAP去除率的影响.结果表明,在30℃,pH=1.5,H2O2和PAP的起始浓度分别为0.50 mol/L和0.10 mol/L,反应时间为100min,粉煤灰用量为6.0%,搅拌速度为1000r/min的条件下,粉煤灰具有良好的催化活性,能有效地催化H2O2氧化PAP,PAP的去除率可达81%左右.该法可用于预处理含PAP的工业废水. 相似文献
778.
药物合成废水处理工程 总被引:3,自引:0,他引:3
张记市 《环境污染治理技术与设备》2005,6(9):79-82
针对氯唑沙宗、枸橼酸莫沙必利化学原料药合成过程中产生的有机废水浓度高、成分复杂及处理难度大等特点(COD高达80 000 mg/L左右),采用催化氧化-生物化学方法,试验研究了药物合成废水处理.试验结果表明,该技术对合成废水的COD去除率可达98%,SS去除率可达96%,色度降到50倍左右,其去除率约为98%.该系统运行费用为0.4~0.5元/m^3废水.经过3个月的工程运行,表明催化氧化-生物化学处理药物合成废水系统是一种高效率、低能耗、运行管理方便、经济可行的处理方法.处理类似制药废水这样的高浓度有机废液,上述废水处理工艺具有广阔的应用前景. 相似文献
779.
780.
考虑到机械行业磷化废水的特点 ,利用混凝沉淀与结晶除磷的原理 ,设计成 2t h的磷化废水处理成套设备 相似文献