Ambient Air Quality at the Site of a Former Manufactured Gas Plant

Prior to the 1950's, manufactured gas was commerciallyproduced from the pyrolysis of coal, coke, and oil atfacilities that are termed manufactured gas plants (MGPs). The constituents of residual coal tar present on many MGPsites are an environmental health concern because of theirtoxicity and the possibility for their off-site migration viawater and air. Atmospheric concentrations of five volatileorganic compounds (VOCs, e.g., benzene), sixteen polycyclicaromatic hydrocarbons (PAHs, e.g., naphthalene), and particulate matter less than 10 microns in aerodynamicdiameter (PM₁₀) were measured at the site of a former MGP. Air samples were obtained before, during, and after excavationof subterranean coal tar at the site. The results of thisinvestigation indicate that subterranean coal tar was not aprimary source of VOCs and PAHs in the local atmosphere beforeor after remediation of the site. However, excavation,treatment, blending, and transfer of the coal tar duringremediation generated concentrations of selected aromatic andsemi-volatile organic compounds that were substantiallygreater than typical ambient levels. In addition, these datasuggest that blending and mixing of coal tars could lead toexceedance of the U.S. National Ambient Air Quality Standardfor PM₁₀, although additional research is required to fullyevaluate this possibility. Nuisance odors associated with thesite remediation were likely the result of naphthalene andpossibly isomers of xylene. Air pollutant concentrationsmeasured adjacent to the excavation area and at the siteperimeter during remediation activities were less than therelevant occupational and environmental exposure limits.     

三维电极氧化法在城市污泥稳定化中的实验研究

以Ti/RuO2网状电极为工作电极,研究三维电极氧化法在城市污泥处理中的效果,探讨了外加电压、电解时间、污泥浓度、活性炭填充层高度等因素的影响.结果表明:极板间距为3cm,电压为20V,曝气量为3L·h-1,活性炭厚度为1.2cm,电解浓度为1.59%的混合污泥,挥发性悬浮物质(VSS)的去除率可达40%以上,VSS/TSS降至41%以下.加入Na2SO4调节浓度为2.06%的污泥,电导率为6ms·cm-1,VSS去除率可达42%左右.     

生物滴滤器处理高温甲苯废气的探讨

以甲苯为目标污染物,设计可控温的双塔生物滴滤器为净化装置,考察了高温条件下挥发性有机物的生物处理性能,镜检确定了高温条件下降解甲苯的优势菌种。结果表明:(1)液相驯化菌种对气相甲苯适应性较差,挂膜120～140h可形成稳定的生物膜;(2)随甲苯废气温度升高,甲苯去除效率下降,40℃效率最高,60℃仍有一定的去除能力;(3)短杆菌和球形菌为降解甲苯的优势菌种,球形菌是高温优势菌;(4)温度高于40℃时降解产物中检测到有机中间产物。     

回灌渗滤液pH和VFA浓度对填埋层初期甲烷化的影响

采用人工配制渗滤液回灌模拟填埋柱的方法,研究了回灌渗滤液中pH和VFA对填埋层甲烷化的影响.实验结果表明,回灌渗滤液酸性条件(pH=6)下,且回灌渗滤液中存在一定量的VFA时,填埋层仍可迅速甲烷化;并且VFA浓度越低,填埋层甲烷化过程稳定时间越短.回灌渗滤液pH为7时,保证填埋层仍能快速进入甲烷化阶段的最高VFA浓度不应超过4000 mg·L-1(以C计).研究结果表明,生物反应器填埋初期,以回灌为目标的渗滤液预处理工艺的出水水质要求可适当降低,这既有利于控制渗滤液预处理的成本,也可避免预处理后渗滤液中有机酸浓度过低,导致填埋层可转化为甲烷的有机碳过量流失.     

现代竹结构房屋室内空气品质的实测与研究

首次对湖南大学现代竹木及组合结构研究所肖岩教授课题组研发的一栋现代竹结构房屋室内空气品质在竹材板裸露的最不利状况下进行了实测.利用甲醛分析仪检测和大气采样仪采样及气相色谱仪分析,可以判断常见的有害物质有无并测得浓度.结果表明,这种建筑在竹板材裸露而没有粘贴防火石膏板材的条件下,室内空气中含有微量的污染物质,而且根据房间的大小和通风状况有显著性差异.但即使在竹胶合板材裸露而没有内装修的条件下,各种有机污染物质的浓度都很低,完全满足国家相关空气质量标准的要求.     

挥发性有机化合物处理技术的研究进展

简要介绍了挥发性有机化合物（VOCs）的来源、危害以及控制的意义,对VOCs现有处理技术从回收方法和消除方法两个方面进行了详细评述,并指出其优势和不足。同时,着重阐述了光催化氧化法以及变压吸附技术的研究进展,并提出了进一步研究的方向。     

生物过滤法处理挥发性有机物的模型

介绍了生物过滤法处理挥发性有机物模型的研究现状,论述了过滤机理、污染物传递、生物膜增长与脱落、填料和生物膜表面形态学等方面的模型情况,指出了生物过滤法处理挥发性有机物模型的研究趋势,有助于理解生物过滤过程的内在规律和指导优化生物过滤系统的设计与运行。     

基于氢火焰离子化检测仪响应因子的设备泄漏排放核算

氢火焰离子化检测仪(FID)是检测设备泄漏挥发性有机物(VOCs)的主要仪器。通过变异系数分析了FID响应因子与FID型号、被测气体种类和被测气体浓度的关系,并进行了实例验证。分析结果表明,FID响应因子与各因素关联强度的排序为:被测气体种类FID型号被测气体浓度。响应因子应用实例的验证结果表明:对于芳烃重整装置145个接触甲苯、二甲苯两组分物料的泄漏设备,响应因子修正后的排放量计算值仅为修正前的18.68%;MTBE装置涉甲醇设备的甲醇排放量计算值修正后为修正前的3倍左右。在此基础上,就设备泄漏VOCs污染源,提出通过响应因子实现排放量精细化核算的建议。     

微波解吸-催化燃烧净化甲苯研究

以甲苯为目标污染物,采用活性炭做吸附剂对含甲苯废气进行吸附;吸附完成后利用微波辐照进行解吸;另外采用浸渍法制备Cu-Mn复合氧化物催化剂并对微波解吸后的废气进行催化燃烧处理从而达到对污染物进行彻底净化的目的.实验中甲苯的浓度由气相色谱(GC)测定.结果表明,采用微波解吸后,在以氮气为载气的解吸气体中加入空气来提供氧气从而实现催化燃烧是可行的,解吸气与空气配比为1∶1(体积比)时效果最好,此时对应的催化空速为2.67 s-1.解吸温度会影响解吸气体中的甲苯浓度进而影响催化燃烧效率,实验结果表明400℃解吸比较理想.当催化燃烧温度保持在300℃时,系统对甲苯的最终净化效率可以维持在90%以上,其中大部分时间是在95%以上.     

Characteristics of volatile compounds removal in biogas slurry of pig manure by ozone oxidation and organic solvents extraction

Biogas slurry is not suitable for liquid fertilizer due to its high amounts of volatile materials being of complicated composition and peculiar smell. In order to remove volatiles from biogas slurry efficiently, the dynamic headspace and gas chromatography-mass spectrometry were used to clear the composition of volatiles. Nitrogen stripping and superfluous ozone were also used to remove volatiles from biogas slurry. The results showed that there were 21 kinds of volatile compounds in the biogas slurry, including sulfur compounds, organic amines, benzene, halogen generation of hydrocarbons and alkanes, some of which had strong peculiar smell. The volatile compounds in biogas slurry can be removed with the rate of 53.0% by nitrogen stripping and with rate of 81.7% by the oxidization and stripping of the superfluous ozone. On this basis, the removal rate of the volatile compounds reached 99.2% by chloroform and n-hexane extraction, and almost all of odor was eliminated. The contents of some dissolved organic compounds decreased obviously and however main plant nutrients had no significant change in the biogas slurry after being treated.