建筑物对高架点源大气污染物扩散影响的模拟研究

运用数值方法对城市中高架点源排放大气污染物的扩散规律进行了模拟研究,在计算区域内建立了三维数学模型,并将拉格朗日法描述的颗粒轨道模型耦合到风场。本研究计算了地面风速为3 m/s时的大气流场,并模拟研究了该风场条件下气体污染物的扩散和固体颗粒污染物的运动轨迹。通过分析模拟结果,给出了高架点源中排放的气体污染物的扩散区域和固体颗粒污染物运动轨迹的变化规律。     

贝壳粉型煤固硫剂固硫的实验及机理研究

以贝壳粉作为型煤固硫剂,用正交实验的方法研究了影响贝壳粉固硫率的主要影响因素,在高温(1 150℃)时固硫效率达到56.6%,比CaCO3的固硫率提高40%以上,具有较好的高温固硫性。分析得知,贝壳的主要成分为CaCO3,其含钙量在40%左右,贝壳中又含有较高的Na等碱金属元素以及Fe,Al和Si等。用X射线粉末衍射法分析了高温(1 150℃)型煤样生成的灰渣,分析了贝壳粉作为型煤固硫剂在高温下具有较高固硫率的机理。发现CaAlSi2O8为主的复合晶体在高温下包裹在CaSO4的表面,抑制了CaSO4的热分解从而有效地提高了固硫率。     

A fuel-based approach for emission factor development for highway paving construction equipment in China

The objective of this paper is to develop and demonstrate a fuel-based approach for emissions factor estimation for highway paving construction equipment in China for better accuracy. A highway construction site in Chengdu was selected for this study with NO emissions being characterized and demonstrated. Four commonly used paving equipment, i.e., three rollers and one paver were selected in this study. A portable emission measurement system (PEMS) was developed and used for emission measurements of selected equipment during real–world highway construction duties. Three duty modes were defined to characterize the NO emissions, i.e., idling, moving, and working. In order to develop a representative emission factor for these highway construction equipment, composite emission factors were estimated using modal emission rates and the corresponding modal durations in the process of typical construction duties. Depending on duty mode and equipment type, NO emission rate ranged from 2.6–63.7mg/s and 6.0–55.6g/kg–fuel with the fuel consumption ranging from 0.31–4.52 g/s correspondingly. The NO composite emission factor was estimated to be 9–41mg/s with the single-drum roller being the highest and double-drum roller being the lowest and 6–30g/kg-fuel with the pneumatic tire roller being the highest while the double-drum roller being the lowest. For the paver, both time-based and fuel consumption-based NO composite emission rates are higher than all of the rollers with 56mg/s and 30g/kg-fuel, respectively. In terms of time–based quantity, the working mode contributes more than the other modes with idling being the least for both emissions and fuel consumption. In contrast, the fuel-based emission rate appears to have less variability in emissions. Thus, in order to estimate emission factors for emission inventory development, the fuel-based emission factor may be selected for better accuracy.

Implications: The fuel-based composite emissions factors will be less variable and more accurate than time-based emission factors. As a consequence, emissions inventory developed using this approach will be more accurate and practical.     

海绵铁还原耦合活性炭吸附-微波再生技术降解甲基橙

采用海绵铁(s-Fe0)还原耦合活性炭(GAC)吸附-微波(MW)再生技术降解甲基橙(MO)溶液,重点考察了s-Fe0投加量、粒径、微波功率等因素对MO去除效果的影响。结果表明,s-Fe0投加剂量为15.0 g/L、粒径为3～5 mm、超声波功率为200 W,反应1 h,MO的去除率为94.2%。其次,采用GAC吸附-MW再生技术(800 W,照射1 min)循环处理上述脱色后的MO废水。结果表明,GAC吸附可有效降低废水的生物毒性及残留的染料、TOC和总铁离子浓度,且MW辐射可有效再生吸附饱和的GAC颗粒。因此,s-Fe0还原耦合GAC吸附-MW再生技术可以有效降解MO染料,具有处理效果好、实现资源循环利用等优点。     

广州市白云人工湖生态修复工程设计

广州市白云湖是广州市最大的人工生态服务湖泊,通过对白云湖生态修复工程进行设计,采用了炭素纤维生态草、微纳米气泡发生装置及纯氧发生器和人工干预与生物处理相结合生态浮床等环保新技术对白云湖水体进行综合生态修复,并对白云湖水质进行跟踪监测。结果显示,白云湖水质提升工程实施之后,白云湖各项水质指标都有一定的改善。白云湖生态修复工程的设计经验对于类似人工水体的水质改善和生态修复工程建设具有参考意义。     

浊度与微生物指标在污水再生处理系统中的去除特性及相关性

本研究考察了污水再生处理系统对颗粒物(包括浊度和粒径分布)和微生物指标(包括隐孢子虫、贾第鞭毛虫、粪大肠菌群和SC噬菌体)的去除特性以及不同指标间的相关关系。研究结果表明,污水再生处理系统对浊度的平均去除率为3.53-log,其中二级生化处理及砂滤对浊度的去除率较高,分别为1.52-log和1.35-log。粒径分析结果表明,絮凝沉淀后粒径均值达到最大值223.2μm;而再生水中粒径均值最小,仅为5.8μm。污水再生处理系统对各微生物指标的去除率为2.96-log~4.11-log。各处理单元中,二级生化处理单元对粪大肠菌群和SC噬菌体的去除率较高,分别为2.81-log及2.14-log;而砂滤对SC噬菌体去除效果较差,仅为0.18-log。从再生处理工艺整体上看,水样浊度、粪大肠菌群、SC噬菌体和两虫浓度具有显著相关性。而对于单个取样点,除污水厂进水中SC噬菌体和两虫浓度表现出一定相关性外,其他情况下各指标与两虫浓度间均无显著相关关系。     

两种填埋结构中氨氮的空间变化规律研究

依据准好氧填埋和厌氧填埋的原理,构建了准好氧和厌氧填埋的实验室模拟装置,研究了2种填埋结构渗滤液中氨氮的空间分布规律。结果表明,准好氧填埋结构3层渗滤液中氨氮浓度都呈不断稳定下降的趋势,29周时上层、中层和下层渗滤液中氨氮浓度分别从填埋初的931.8、1796和3019 mg/L下降到25.6、328.9和820.1 mg/L;厌氧填埋结构3层渗滤液中氨氮浓度下降趋势不明显且波动性较大。准好氧填埋与厌氧填埋结构渗滤液中氨氮浓度表现出明显的空间层次效应,为下层>中层>上层。     

铅胁迫对小麦幼苗抗氧化酶活性的影响

通过营养液培养实验,研究小麦幼苗在遭受铅胁迫后,地上部及根系抗氧化酶活性的变化.试验表明:小麦幼苗受到铅胁迫后,地上部及根系的超氧化物歧化酶(SOD)活性均显著增加,根系中过氧化氢酶(CAT)的活性也比对照有所增加,但不如SOD酶变化剧烈,表明SOD酶活性是比较敏感的生物指标(biomarker).但是,小麦幼苗地上部及根系的丙二醛(MDA)含量仍均比对照显著升高,表明小麦幼苗的膜系统受到了一定程度的破坏.试验同时还反映出,铅胁迫对小麦幼苗根系的影响远远强于地上部.