Volatile organic compound concentrations, emission rates, and source apportionment in newly-built apartments at pre-occupancy stage

The present study investigated the indoor concentrations of selected volatile organic compounds (VOCs) and formaldehyde and their indoor emission characteristics in newly-built apartments at the pre-occupancy stage. In total, 107 apartments were surveyed for indoor and outdoor VOC concentrations in two metropolitan cities and one rural area in Korea. A mass balanced model was used to estimate surface area-specific emission rates of individual VOCs and formaldehyde. Seven (benzene, ethyl benzene, toluene, m,p-xylene, o-xylene, n-hexane, and n-heptane) of 40 target compounds were detectable in all indoor air samples, whereas the first five were detected in all outdoor air samples. Formaldehyde was also predominant in the indoor air samples, with a high detection frequency of 96%. The indoor concentrations were significantly higher than the outdoor concentrations for aromatics, alcohols, terpenes, and ketones. However, six halogenated VOCs exhibited similar concentrations for indoor and outdoor air samples, suggesting that they are not major components emitted from building materials. It was also suggested that a certain portion of the apartments surveyed were constructed by not following the Korean Ministry of Environment guidelines for formaldehyde emissions. Toluene exhibited the highest emission rate with a median value of 138 μg m⁻² h⁻¹. The target compounds with median emission rates greater than 20 μg m⁻² h⁻¹ were toluene, 1-propanol, formaldehyde, and 2-butanone. The wood panels/vinyl floor coverings were the largest indoor pollutant source, followed by floorings, wall coverings, adhesives, and paints. The wood panels/vinyl floor coverings contributed nearly three times more to indoor VOC concentrations than paints.     

污泥焚烧灰固化处理技术研究

研究了硅酸盐水泥、高铝水泥、高岭土和β-萘系减水剂在污泥焚烧灰固化技术中的应用效果。考察了污泥焚烧灰固化块(以下简称固化块)的抗压强度,测定了固化块的重金属浸出毒性,并采用X射线衍射(XRD)和扫描电镜(SEM)分析固化块组成和微观结构。结果表明,4种物质对提高固化块的抗压强度均具有较好的效果,硅酸盐水泥、高铝水泥、高岭土和β-萘系减水剂的适宜掺量分别为10、30、20、1.0g(以100g污泥焚烧灰中掺加的质量计)。XRD和SEM分析结果显示,经固化处理后制得的固化块结构密实,存在石英(SiO2)、水化硅铝酸钙(CaAl2Si2O8)和水化硅酸铝钙(Ca2Al2SiO7)等物质,其中水化硅铝酸钙等凝胶物质有利于提高固化块的抗压强度。     

CABR处理分散式生活污水抗短期有机负荷潜能

为考察填料式厌氧折流板反应器（CABR）处理分散式生活污水抗短期有机负荷冲击的稳定性,从宏观运行性能、中间产物累积以及微观微生物活性3个层次来研究不同温度下短期有机负荷冲击对CABR运行性能影响。结果表明：宏观运行性能指标TCOD沿程变化曲线在28℃时受到有机负荷冲击仍呈现＂L＂型,容积负荷去除率也由基准条件下0.27kg/（m3.d）提高至0.73 kg/（m3.d）,但随温度的下降,沿程曲线逐渐接近＂／＂型,容积负荷去除率的增加幅度也逐渐变小。中间产物积累指标中VFA/碱度比值小于0.11～0.14时,TCOD去除率可达80%以上;SMP/SCOD比值沿水流方向呈上升趋势表明CABR抗负荷冲击性能较佳。而微观微生物酶活性受基质浓度提高的促进效应和温度下降的抑制效应相互作用表现各异。总体而言,在高温（28℃）条件下,分散式生活污水的有机负荷冲击不会对CABR出水造成显著影响,但在中温（18℃）和低温（10℃）条件下,CABR抗有机负荷冲击的稳定性随温度的下降而下降。     

利用给水厂污泥制备透水砖的实验研究

以给水厂污泥、粉煤灰和普通砂为主要原料,添加一定量的粘结剂制备透水砖。探讨了污泥掺加量、烧结温度和成型压力对透水砖基本性能的影响,结果表明,当污泥掺量为30%～40%,添加30%～35%,粒径为1.0～1.4 mm普通砂颗粒时,在30 MP压力下成型、1 150℃下烧结制备出的成品抗压强度达36.53 MP,透水系数为1.08×10-2cm/s,满足JC/T945-2005《透水砖》相关要求。     

垃圾焚烧底灰固化污水厂污泥的岩土工程性质实验

对污水处理厂污泥采用垃圾焚烧底灰进行固化处理,分别测试不同掺量和不同养护龄期时固化体的岩土工程性质,通过测试发现,固化体重度基本位于11～13 kN/m3之间,与垃圾焚烧底灰的重度相近;固化体含水率随着垃圾焚烧底灰掺量的增大而急剧减小;抗剪强度指标和无侧限抗压强度随垃圾焚烧底灰的掺量增加和养护龄期的增长而增大,其内摩擦角位于10°～30°之间。建立的固化强度预测模型,可对不同掺量和龄期的固化污泥强度进行预测。     

炼油废水微生物燃料电池启动及影响因素

以炼油废水为碳源,构建双室填料型微生物燃料电池,考察接种液、外接电阻等电池启动条件,以及电导率、pH值和缓冲溶液强度等溶液性质对电池产电性能的影响。利用微生物燃料处理炼油废水,COD去除率(52±4)%,含油量去除率(81.8±3)%;利用废水中存在的原生菌即可启动电池,但启动期长,外加接种液可快速启动电池;启动时外接电阻的大小对电池稳定运行后的输出功率有明显影响,对电池内阻影响相对较小,当启动外接电阻为2 000Ω,电池输出功率最大,为288 mW/m3;随阳极溶液电导率电池增大,电池内阻降低,输出功率升高;pH值变化对电池阳极电势影响较大,进而影响电池输出,当溶液pH为9时,电池输出电压最大(388 mV),pH过高或过低均不利于电池产电;随着缓冲强度的增大,电池输出电压增大,且PBS缓冲强度的增大可从电导率增大和改善质子传递条件两方面提高电池的输出功率。     

基于响应面法的污泥快速固化效能综合影响

针对现有污泥固化技术存在的固化养护时间长、低温条件下固化效能低等问题。研究提出污泥快速（3d）固化技术,采用响应曲面分析方法,重点考察了石灰、组分A、硅酸盐水泥、粉煤灰和温度等5因素对固化效能的综合影响,研究结果表明,石灰、组分A、硅酸盐水泥、粉煤灰和养护温度等因素对3d固化体的无侧限抗压强度和含水率的线性效应显著,石灰和组分A、石灰和养护温度对无侧限抗压强度的交互影响显著,石灰和粉煤灰、组分A和养护温度、硅酸盐水泥和粉煤灰对含水率的交互影响显著;得出了5因素对固化体3d无侧限抗压强度和含水率影响的定量模型,可对污泥快速固化进行优化和预测;并利用XRD和SED对污泥固化块的化学成分和微观结构进行了分析。     

Forensic Applications of Nitrogen and Oxygen Isotopes in Tracing Nitrate Sources in Urban Environments

Ground and surface waters in urban areas are susceptible to nitrate contamination from septic systems, leaking sewer lines, and fertilizer applications. Source identification is a primary step toward a successful remediation plan in affected areas. In this respect, nitrogen and oxygen isotope ratios of nitrate, in conjunction with hydrologic data and water chemistry, have proven valuable in urban studies from Austin, Texas, and Tacoma, Washington. In Austin, stream water was sampled during stremflow and baseflow conditions to assess surface and subsurface sources of nitrate, respectively. In Tacoma, well waters were sampled in adjacent sewered and un-sewered areas to determine if locally high nitrate concentrations were caused by septic systems in the un-sewered areas. In both studies, sewage was identified as a nitrate source and mixing between sewage and other sources of nitrate was apparent. In addition to source identification, combined nitrogen and oxygen isotopes were important in determining the significance of denitrification, which can complicate source assessment by reducing nitrate concentrations and increasing i 15 N values. The two studies illustrate the value of nitrogen and oxygen isotopes of nitrate for forensic applications in urba areas.     

改性污泥替代垃圾填埋场覆土的研究

以市政污泥为研究对象,采用固化剂对污泥进行改性,通过分析不同固化剂添加比例下固化产物的抗压强度和渗透系数,比较不同养护时间下污泥固化产物浸出液的COD、氨氮和重金属性质,探讨市政污泥固化产物作为垃圾填埋场覆土可行性。实验结果表明：固化剂添加比例为30％的固化产物抗压强度高于50kPa,其渗透系数达到10^-7cm／s数量级,基本满足覆土材料的标准要求。污泥固化产物重金属的最大浸出量远远低于《污水综合排放标准》（GB8978-88）中一级排放标准。随养护时间延长,固化产物浸出液COD和氨氮浸出浓度亦呈下降趋势,重金属Pb、Cd浸出量明显减少,浸出比例小于1％。养护有利于降低固化产物的浸出污染程度,30％的污泥固化产物养护3d后可作为垃圾填埋场日覆盖材料。     

Fly and bottom ashes from biomass combustion as cement replacing components in mortars production: Rheological behaviour of the pastes and materials compression strength

In the present research mortar pastes obtained by replacing a commercial cement with the equivalent mass of 5, 10, 20 and 30 wt.% of fly ash or bottom ash from fir chips combustion, were prepared and rheologically characterized. It was observed that the presence of ash modifies their rheological behaviour with respect to the reference blend due to the presence, in the ashes, of KCl and K₂SO₄ which cause precipitation of gypsum and portlandite during the first hydration stages of the pastes. Hydrated materials containing 5 wt.% of ash display compression strength and absorption at 28 d of same magnitude as the reference composition; conversely, progressive increase of ash cause a continuous decline of materials performances. Conversely, samples tested after 180 d display a marked decline of compression strength, as a consequence of potassium elution and consequent alkali-silica reaction against materials under curing.