臭氧氧化降解苊的中间产物分析

苊属于EPA优先污染物名单上的物质,其在染料、化工等行业有着广泛的应用.它具有水溶性低、易蓄积、难生物降解的特点.臭氧氧化法可以对其有效的降解,但是过量的臭氧也难以实现对苊的矿化,在苊浓度下降的同时将生成中间产物.中间产物包括多种含一个苯环的酯和直链的酸、醇、酯等.     

超声清洗MBR生物膜--臭氧化技术在中水回用中的应用

超声清洗MBR生物膜-臭氧化技术,是在传统的二级生化污水处理技术的基础上,采用膜生物技术、臭氧化工艺和现代超声波清洗膜元件技术,进行生活污水回用处理的新兴技术.膜生物(MBR)技术具有出水水质好,一次性投资低,占地面积小,运行费用低等优点;利用现代超声波技术清洗膜元件,既可以彻底清除粘附在膜内、外壁上的污染物,又可以避免化学清洗对膜造成的危害,及清洗剂对环境的污染;采用臭氧化工艺,利用臭氧的强氧化性,可以彻底消除细菌、臭味、色度等可能对回用人群造成的危害,使处理后的水成为真正安全的回用水.     

基于人工神经网络模型预测ABR反应器处理效率

ABR反应器的处理效率受多方面的因素影响，本文通过BP人工神经网络，利用ABR反应器进水CODcr浓度、容积负荷、温度、稳定运行时间四个参数对其反应器处理效率进行预测。结果表明，BP人工神经网络可较好的用于ABR反应器处理效率的预测，具有较高的精度，在实际生产中，可以运用人工神经网络，对ABR反应器的运行参数进行调整，使之达到最优化的运行状态。     

Effects of temperature and discharge parameters on ozone concentration of negative corona discharge

The relationship of the ozone generation and the heating power, corona wire surface temperature, discharge electrode and netting electrode was studied during the negative corona discharge. The experimental results showed that the ozone concentration reduced with applied voltage decrease. With heating power increase, the ozone concentration of unit current decreased at exponential rate and it almost change no longer over 0.40 W. Under given temperature, the lower the applied voltage was, the smaller the ozone concentration was; while under given applied voltages, only over 11 kV could decrease with the surface temperature increase. The ozone concentration decreased with the lengthening of corona wire, and could reduced to 10 ppb under experimental condition of 14.2 kV; it also decreased with the shortening of wire diarmeter,and could decrease 67% at best in the given condition. Moreover, it decreased with the increasing size of netting electrode mesh. At the anion current of 1.65 μA, the ozone concentration of 5.0 x 5.0 cm^2 is only 41% of that of 3.3 x 3.3 cm^2 .     

Traffic congestion and ozone precursor emissions in Bilbao (Spain)

GOAL. SCOPE. BACKGROUND: In urban environments, the measured levels of ozone are the result of the interaction between emissions of precursors (mainly VOCs and NOx) and meteorological effects. In this work, time series of daily values of ozone, measured at three locations in Bilbao (Spain), have been built. Then, after removing meteorological effects from them, ozone and traffic data have been analyzed jointly. The goal was to identify traffic situations and link them to ozone levels in the area of Bilbao. METHODS: To remove meteorological effects from the selected ozone time series, the technique developed by Rao and Zurbenko was used. This is a widely used technique and, after its application, the fraction obtained from a given ozone time series represents an ozone forming capability attributable to emissions of precursors. This fraction is devoid of any meteorological influence and includes only the apportion of periodicities above 1.7 years. In the case of Bilbao, the ozone fractions obtained at three locations have been compared on that time scale with traffic data from the area. RESULTS AND DISCUSSION: For the 1993-1996 period, a regression analysis of the ozone and traffic fractions due to periodicities above 1.7 years (long-term fractions), shows that traffic is the main explanatory factor for ozone with R2 ranging from 0.916 to 0.996 at the three locations studied. Analysis of these longterm fractions has made it possible to identify two traffic regimes for the whole area, associated to different profiles of ozone forming capability. The first one favors low ozone forming capability, and is associated with a situation of fluent traffic. The second one shows high ozone forming capability and represents congestion. Joint analysis of raw data of ozone and traffic do not show any clear pattern due to the strong masking effects that seasonal-meteorological effects (mainly radiation) have on the measured ozone signal. If only immission data of ozone are available, as in this case, a comparison between ozone and traffic can only be made on the long-term time scale, since that is the only fraction embedded in the ozone time series that can exclusively be attributed to emissions of precursors. This fact stresses the need to study the different fractions embedded in the time series of ozone measured levels separately. CONCLUSION: Though the coefficients obtained in the regression are only valid for the 1993-1996 period, these traffic regimes represent long-term targets (congestion or fluent traffic) that can inspire policies for a joint management of the traffic and pollution by ozone in the area of Bilbao beyond that period. RECOMMENDATIONS AND OUTLOOK: The results of this work show the need of a joint management of ozone and traffic in Bilbao. Since an accurate knowledge of traffic was not available, the use of emission factors to relate traffic and actual ozone levels has not been possible. For this reason, this study has focused on the long-term fractions of traffic and ozone. In the future, if a more accurate knowledge of traffic is available, it will be possible to find relationships between traffic and ozone on all time scales.     

四氯化碳的生产与应用及其淘汰策略

四氯化碳是一种消耗臭氧层物质,其生产和消费都面临着严峻的淘汰形势.简要叙述了四氯化碳的生产技术,以四氯化碳为原料生产大宗化学品和精细化学品的转化技术,四氯化碳作为化工助剂在我国的应用情况以及相应的淘汰方法和技术进展.     

复杂地形空气污染预报模式的研究

本文依据一个同时包括地形、热力以及摩擦等因素在内的，能够较真实地反映复杂地形情况下，大气运动基本特征的近地层水平流场二维数值模式，将其扩展成三维模式。在此基础上，从平流扩散方程出发，建立了一个与上述流场相应的浓度场预报模式。经与实测值比较，该预报模式具有较好的可靠性和适用性     

EuroBionet: a pan-European biomonitoring network for urban air quality assessment

EuroBionet, the 'European Network for the Assessment of Air Quality by the Use of Bioindicator Plants', is an EU-funded cooperative project currently consisting of public authorities and scientific institutes from 12 cities in 8 countries. In 2000, the bioindicator plants tobacco (Nicotiana tabacum Bel W3), poplar (Populus nigra 'Brandaris'), spiderwort (Tradescantia sp. clone 4430), Italian rye grass (Lolium multiflorum italicum) and curly kale (Brassica oleracea acephala) were exposed to ambient air at 90 monitoring sites according to standardised methods. Visible injuries and growth parameters were assessed and the accumulation of toxic substances in leaves determined. The exposure of tobacco resulted in a gradient with low levels of ozone-induced foliar injury in N and NW Europe, and medium to high values in the southern and central regions. The results of heavy metal and sulphur analyses in rye grass samples generally showed low to very low sulphur and low to medium heavy metal concentrations in leaves. In some cities, however, local hot spots of heavy metal contamination were detected. Analyses of the PAH contents in curly kale leaves gave low to medium values, with locally elevated levels at traffic-exposed sites.     

Ozone patterns for three metropolitan statistical areas in North Carolina, USA

As part of an effort by the state of North Carolina to develop a State Implementation Plan (SIP) for 1-h peak ozone control, a network of ozone stations was established to monitor surface ozone concentrations across the state. Between 19 and 23 ozone stations made continuous surface measurements between 1993 and 1995 surrounding three major metropolitan statistical areas (MSAs): Raleigh/Durham (RDU), Charlotte/Mecklenburg (CLT), and Greensboro/High Point/Winston-Salem (GSO). Statistical averages of the meteorological and ozone data were performed at each Metropolitan Statistical Area (MSA) to study trends and/or relationships on high ozone days (days in which one of the MSA sites measured an hourly ozone concentration90.0 ppbv). County emission maps of precursor gases, wind roses, total area averages of ozone, total downwind averages of ozone deviations, upwind averages of ozone, and a modified delta ozone analysis were all obtained and analyzed. The results of this study show a reduction in the delta ozone relative to an earlier study at RDU, but no average significant change at CLT (no comparison can be made for GSO). The statistical data analyses in this study are used to quantify the importance of local contributions and regional transport, to ozone air pollution in the MSAs.