活性炭纤维载体生物膜法处理洗车废水研究

为了实现洗车废水的循环使用,进行了以聚丙烯腈基活性炭纤维(PAN-ACF)为生物膜载体处理洗车废水的实验研究。以LAS、COD和NH3-N等指标考察了活性炭纤维生物膜反应器对洗车废水的处理效果。结果表明:在常温下、pH=6.5~7,当进水流量在30 mL/min时,反应器达到最佳运行参数,活性炭纤维载体生物膜法对LAS、COD和NH3-N等的去除率分别达到了97%、80%和60%。出水水质完全达到《生活杂用水水质标准》(CJ/T48-99)中洗车用水主要水质指标的规定。此外,实验表明PAN-ACF作为生物膜载体具有很好的生物亲和性和再生性。     

表面活性剂对紫背浮萍吸收氮磷的影响

采用室内培养方法,以氨氮和总磷以及植物生长量作为观测指标,分别研究了阴离子型表面活性剂LAS、阳离子型表面活性剂CTMAB和非离子型表面活性剂Tween-80对紫背浮萍吸收氮磷及植株生长的影响。结果表明,无表面活性剂影响时紫背浮萍在模拟富营养化水体中生长良好并表现出很强的氮磷去除能力;LAS和CTMAB浓度低于1 mg/L时,紫背浮萍对总磷的吸收比对氨氮的吸收更易受影响;当浓度达到10 mg/L时,LAS和CTMAB的存在使紫背浮萍明显受到损伤,氮磷吸收率出现负值,而非离子型表面活性剂毒性相对最小,对紫背浮萍吸收氮磷的影响明显低于阴离子型和阳离子型的表面活性剂。     

印染废水处理工艺改造及其效益分析

通过实验数据分析,对本源微生物菌剂处理印染废水的有效性进行了检验。在此基础上,确定了先生物处理后絮凝的处理方式。进而分析了印染废水原处理工艺中存在的问题,并对其进行了改造,即:以本源微生物菌剂为母菌接种于印染废水中,并结合生物铁填料对其进行处理。工艺改造成功启动后,稳定运行结果显示:复合生化池和接触氧化池的处理工艺对色度和COD的平均去除率分别为:55.69%、55.63%和78.53%、78.21%;出水pH、色度和COD的平均值分别为6.6、13倍和93 mg/L,全部满足标准要求。该工艺大大减少了污泥量,且降低了处理费用。     

单纤维过滤介质表面尘粒捕集的随机模拟

基于控制面概念和粒子运动轨迹计算,建立单纤维过滤介质表面尘粒捕集的三维随机计算模型,采用Ku-wabara流场表征单纤维表面的气流绕流特征。计算分析了St数、无量纲粒径及单纤维过滤模型填充密度对沉积物形态结构和积尘状态下单纤维捕集效率的影响。结果指出,St数对沉积物形态结构具有显著作用,随St数减小,沉积物由紧密的堆积结构演变为分叉显著的树枝状结构。模拟结果还发现,无论过滤条件如何变化,无量纲单纤维捕集效率随捕集粒子数呈近似线性增加关系。     

Deposition of artificial radionuclides from atmospheric Nuclear Weapon Tests estimated by soil inventories in French areas low-impacted by Chernobyl

Soil inventories of anthropogenic radionuclides were investigated in altitudinal transects in 2 French regions, Savoie and Montagne Noire. Rain was negligible in these 2 areas the days after the Chernobyl accident. Thus anthropogenic radionuclides are coming hypothetically only from Global Fallout following Atmospheric Nuclear Weapon Tests. This is confirmed by the isotopic signatures (²³⁸Pu/^239+240Pu; ¹³⁷Cs/^239+240Pu; and ²⁴¹Am/^239+240Pu) close to Global Fallout value. In Savoie, a peat core age-dated by ²¹⁰Pb_ex confirmed that the main part of deposition of anthropogenic radionuclides occurred during the late sixties and the early seventies. In agreement with previous studies, the anthropogenic radionuclide inventories are well correlated with the annual precipitations. However, this is the first time that a study investigates such a large panel of annual precipitation and therefore of anthropogenic radionuclide deposition. It seems that at high-altitude sites, deposition of artificial radionuclides was higher possibly due to orographic precipitations.     

Prediction of the PCDD/F and dl-PCB 2005-WHO-TEQ content based on the contribution of six congeners: Toward a new screening approach for fish samples?

Current European Union regulation regarding polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) in food and feed is based on Toxic Equivalent Quotient (TEQ) concept. For confirmatory purpose, the isotope-dilution method associated to a measurement by gas chromatography coupled with high resolution mass spectrometry is usually the method of choice for precisely measuring the 29 target congeners in three separated fractions. Time and cost related to these analyses are very significant. Various kinds of screening concepts can be considered. In the present study, we elaborated and validated a prediction model for the 2005 World Health Organization TEQ in fish, based on the measurement of 4 PCDD/F and 2 non-ortho dl-PCB congeners, potentially analyzable in a single extracted fraction by gas chromatography coupled with mass spectrometry. Large independent datasets have been used for model elaboration (n = 108) and validation (n = 363, n = 357 and n = 6).     

Wet deposition of mercury within the vicinity of a cement plant before and during cement plant maintenance

Hg species (total mercury, methylmercury, reactive mercury) in precipitation were investigated in the vicinity of the Lehigh Hanson Permanente Cement Plant in the San Francisco Bay Area, CA., USA. Precipitation was collected weekly between November 29, 2007 and March 20, 2008, which included the period in February and March 2008 when cement production was minimized during annual plant maintenance. When the cement plant was operational, the volume weighted mean (VWM) and wet depositional flux for total Hg (Hg_T) were 6.7 and 5.8 times higher, respectively, compared to a control site located 3.5 km east of the cement plant. In February and March, when cement plant operations were minimized, levels were approximately equal at both sites (the ratio for both parameters was 1.1). Due to the close proximity between the two sites, meteorological conditions (e.g., precipitation levels, wind direction) were similar, and therefore higher VWM Hg_T levels and Hg_T deposition likely reflected increased Hg emissions from the cement plant. Methylmercury (MeHg) and reactive Hg (Hg(II)) were also measured; compared to the control site, the VWM for MeHg was lower at the cement plant (the ratio = 0.75) and the VWM for Hg(II) was slightly higher (ratio = 1.2), which indicated the cement plant was not likely a significant source of these Hg species to the watershed.     

含钛炉渣制备光催化剂处理模拟甲基橙废水

以含钛炉渣为原料制得光催化剂PTC,PTC不仅对紫外光具有较大的吸收,且在可见光范围内也有明显的吸收。PTC是一种比表面积较大的多微孔材料。PTC对模拟甲基橙废水脱色的最佳工艺条件:PTC加入量为0.50g/L,废水pH为2。加入强氧化剂H2O2能提高模拟甲基橙废水的总脱色率,在初始质量浓度为50m g/L的模拟甲基橙废水中H2O2加入量为6m g/L时,废水总脱色率达80.96%,比不加H2O2时的废水总脱色率提高了31.36%。     

Improving ozone modeling in complex terrain at a fine grid resolution: Part I – examination of analysis nudging and all PBL schemes associated with LSMs in meteorological model

Meteorological variables such as temperature, wind speed, wind directions, and Planetary Boundary Layer (PBL) heights have critical implications for air quality simulations. Sensitivity simulations with five different PBL schemes associated with three different Land Surface Models (LSMs) were conducted to examine the impact of meteorological variables on the predicted ozone concentrations using the Community Multiscale Air Quality (CMAQ) version 4.5 with local perspective. Additionally, the nudging analysis for winds was adopted with three different coefficients to improve the wind fields in the complex terrain at 4-km grid resolution. The simulations focus on complex terrain having valley and mountain areas at 4-km grid resolution. The ETA M–Y (Mellor–Yamada) and G–S (Gayno–Seaman) PBL schemes are identified as favorite options and promote O₃ formation causing the higher temperature, slower winds, and lower mixing height among sensitivity simulations in the area of study. It is found that PX (Pleim–Xiu) simulation does not always give optimal meteorological model performance. We also note that the PBL scheme plays a more important role in predicting daily maximum 8-h O₃ than land surface models. The results of nudging analysis for winds with three different increased coefficients' values (2.5, 4.5, and 6.0 × 10^?4 s^?1) over seven sensitivity simulations show that the meteorological model performance was enhanced due to improved wind fields, indicating the FDDA nudging analysis can improve model performance considerably at 4-km grid resolution. Specifically, the sensitivity simulations with the coefficient value (6.0 × 10^?4) yielded more substantial improvements than with the other values (2.5 and 4.5 × 10^?4). Hence, choosing the nudging coefficient of 6.0 × 10^?4 s^?1 for winds in MM5 may be the best choice to improve wind fields as an input, as well as, better model performance of CMAQ in the complex terrain area. As a result, a finer grid resolution is necessary to evaluate and access of CMAQ results for giving a detailed representation of meteorological and chemical processes in the regulatory modeling. A recommendation of optimal scheme options for simulating meteorological variables in the complex terrain area is made.     

Levels,congener profile and inventory of polychlorinated biphenyls in sediment from the Songhua River in the vicinity of cement plant,China: a case study

This study investigated the contamination levels, homologue, and congener profiles and evaluated the residue inventory of polychlorinated biphenyls (PCBs) in sediment of the Songhua River in the vicinity of cement plant. The total concentration of detected 35 PCB congeners ranged from 1.12 to 2.19 ng/g dry weight (dw) in sediment, with a mean value of 1.56 ng/g dw, and the concentration of PCBs decreased in the following order: the downstream?>?cement plant?>?upstream. The results of total organic carbon (TOC)-normalized PCB concentrations indicate that the sediments have low potential ecological risk in this area. The study results on homologue and congener of PCBs show that the emissions from cement production could be the major sources of PCBs in sediment, and the low-chlorinated PCBs will be exchanged among air, water, and sediment with increasing temperature during summer and flow to downstream with water during the wet season. The spatial density and total burden of PCBs in the surface sediments were 17.2 ng/cm² and 1.2 kg, respectively. To our knowledge, this study is the first to explore the pollution characteristics of unintentionally produced PCB emissions from cement industry by means of monitoring sediment samples.