CEPT-曝气生物滤池低温下处理模拟灰水的应用研究

实验研究了在冬季低温条件（2～10℃）下,化学温凝预处理曝气生物滤池(CEPT/BAF)工艺处理模拟灰水的效果。考查了混凝预处理效果、BAF的出水水质与滤料高度的关系、水力负荷对出水COD的影响、直链烷烃苯磺酸钠(LAS)对出水NH₃-N等的影响。研究表明：经过预处理(PAC为40 mg/L)后的模拟灰水,BAF的有机负荷去除率达到40%～55%;COD、LAS的去除主要发生在滤料前端1.2 m处,去除率达到70%,去除率与滤料高度近似呈指数关系下降;在COD负荷、水力负荷不变的情况下,当进水LAS从23 mg/L降到9 mg/L时,BAF的NH₃-N的去除率则从41%上升到72%,说明较高浓度的LAS对亚硝化及硝化细菌有一定影响。模拟灰水经过化学混凝/曝气生物滤池处理之后,出水水质NH₃-N、COD和LAS分别在10、40和4 mg/L以下。     

Highly elevated levels of perfluorooctane sulfonate and other perfluorinated acids found in biota and surface water downstream of an international airport, Hamilton, Ontario, Canada

Per- and poly-fluorinated compounds (PFCs), which include perfluorinated carboxylates (PFCAs) and sulfonates (PFSAs) and various precursors, are used in a wide variety of industrial, commercial and domestic products. This includes aqueous film forming foam (AFFF), which is used by military and commercial airports as fire suppressants. In a preliminary assessment prior to this study, very high concentrations (> 1 ppm wet weight) of the PFSA, perfluorooctane sulfonate (PFOS), were discovered in the plasma of snapping turtles (Chelydra serpentina) collected in 2008 from Lake Niapenco in southern Ontario, Canada. We presently report on a suite of C₆ to C₁₅ PFCAs, C₄, C₆, C₈ and C₁₀ PFSAs, several PFC precursors (e.g. perfluorooctane sulfonamide, PFOSA), and a cyclic perfluorinated acid used in aircraft hydraulic fluid, perfluoroethylcyclohexane sulfonate (PFECHS) in surface water from the Welland River and Lake Niapenco, downstream of the John C. Munro International Airport, Hamilton, Ontario, Canada. Amphipods, shrimp, and water were sampled from the Welland River and Lake Niapenco, as well as local references. The same suite of PFCs in turtle plasma from Lake Niapenco was compared to those from other southern Ontario sites. PFOS dominated the sum PFCs in all substrates (e.g., > 99% in plasma of turtles downstream the Hamilton Airport, and 72.1 to 94.1% at all other sites). PFOS averaged 2223 (± 247.1 SE) ng/g in turtle plasma from Lake Niapenco, and ranged from 9.0 to 171.4 elsewhere. Mean PFOS in amphipods and in water were 518.1 (± 83.8) ng/g and 130.3 (± 43.6) ng/L downstream of the airport, and 19.1 (± 2.7) ng/g and 6.8 (± 0.5) ng/L at reference sites, respectively. Concentrations of selected PFCs declined with distance downstream from the airport. Although there was no known spill event or publicly reported use of AFFF associated with a fire event at the Hamilton airport, the airport is a likely major source of PFC contamination in the Welland River.     

Effect of salinity and sediment characteristics on the sorption and desorption of perfluorooctane sulfonate at sediment-water interface

This study investigated the influence of solution salinity, pH and the sediment characteristics on the sorption and desorption of perfluorooctane sulfonate (PFOS). The results showed that the sorption of PFOS onto sediment increased by a factor of 3 as the CaCl₂ concentration increased from 0.005 to 0.5 mol L⁻¹ at pH 7.0, and nearly 6 at pH 8.0. Desorption hysteresis occurred over all salinity. The thermodynamic index of irreversibility (TII) values increased with increasing concentration of CaCl₂. Maximum irreversibility was found in the sorption systems with CaCl₂ in the concentration of 0.5 mol L⁻¹. The results suggested that PFOS can be largely removed from the water with increasing salinity, and get trapped onto sediments irreversibly. These phenomena could be explained by salting-out effect and Ca-bridging effect. Studies also suggested that the content of total organic carbon is the dominant psychochemical properties of sediment controlling the sorption of PFOS.     

不同功能区表层土中全氟化合物污染指纹及其来源解析

为探究区域功能对其表层土中全氟化合物(perfluorinated compounds,PFCs)污染指纹与含量水平的影响,采用固相萃取分离富集、高效液相色谱-质谱联用与源解析相结合的方法,分析了深圳市公园、居民小区、十字路口、工厂周边4个功能区和城市背景共76份表层土中14种PFCs的含量.结果表明,深圳市表层土总PFCs(ΣPFCs)含量受区域功能影响显著,呈工厂周边(P<0.001)>>十字路口(P<0.01)>>居民小区(P<0.05)>>公园>城市背景的分布.其中工厂周边、居民小区、公园表层土中PFCs呈中链(P<0.05)>>长链>短链的分布,而十字路口则呈中链≈短链(P<0.05)>>长链的分布.同时,以全氟辛烷磺酸、全氟辛酸、全氟十三酸为主要标志物的3个主成分可以解释深圳表层土超过81%的ΣPFCs,十字路口以及电镀、油漆厂周边表层土呈现出较清晰的PFCs污染指纹.     

SDS对两性修饰膨润土吸附Cd2+的影响

采用十二烷基磺酸钠(SDS)复配修饰十二烷基二甲基甜菜碱(BS-12)修饰的两性修饰膨润土,以批处理法研究了不同修饰比例、温度、pH和离子强度下,SDS对两性修饰膨润土吸附Cd2+的影响,并从吸附等温线、温度效应和热力学角度探讨了吸附机制.结果表明,SDS复配修饰显著增强了两性修饰膨润土对Cd2+的吸附能力,修饰土对Cd2+的吸附量呈现BS+150SDS(BS-12+150%SDS)>BS+100SDS(BS-12+100%SDS)>BS+50SDS(BS-12+50%SDS)>BS+25SDS(BS-12+25%SDS)>BS(BS-12)>CK(原土)的顺序.修饰土对Cd2+的吸附等温线符合Langmuir模型.SDS复配修饰后,温度效应由CK和BS两性修饰土的增温正效应逐渐向BS+150SDS两性复配修饰土的增温负效应转变.pH对修饰土吸附Cd2+影响不大.离子强度增加,修饰土对Cd2+的吸附能力下降,但SDS修饰比例增加可以减弱离子强度对修饰土吸附Cd2+的影响.热力学参数结果表明,修饰土对Cd2+吸附是熵增控制的自发性过程,当SDS复配修饰比例<100%CEC时,修饰土对Cd2+吸附为焓增、熵增过程;当SDS复配修饰比例≥100%CEC时,修饰土对Cd2+吸附为焓减、熵增过程.     

全氟辛烷磺酸对赤子爱胜蚓的抗氧化酶、代谢酶和DNA损伤的影响

非致死浓度下全氟辛烷磺酸(PFOS)对土壤生物的毒性作用研究在国内外鲜见报道.因此,本文采用人工土壤培养法,通过亚急性试验,研究了PFOS对赤子爱胜蚓(Eisenia fetida)生长抑制、谷胱甘肽硫转移酶(GST)、过氧化氢酶(CAT)及DNA损伤的影响.结果表明,PFOS暴露急性期和亚急性期,非致死浓度PFOS显著抑制蚯蚓生长(p=0.000),生长抑制率随着暴露浓度、暴露时间的增大而逐渐增大,42 d时250 mg·kg^-1处理组的生长抑制率最大(55.86%).PFOS暴露急性期和亚急性期,非致死浓度PFOS对GST和CAT活性没有显著性影响(GST:p=0.067;CAT:p=0.123),采用GST和CAT酶活性评价非致死浓度PFOS对蚯蚓的生态毒性时,需要参考其他指标进行综合分析.PFOS暴露急性期,非致死浓度PFOS可致体腔细胞DNA损伤;PFOS暴露亚急性期,体腔细胞DNA损伤随着暴露时间的增加而逐渐得到恢复.     

水环境中PFOA和PFOS的质量浓度分布及其生态毒性

全氟辛酸类物质（PFOA）以及全氟辛烷磺酸类物质（PFOS）是不易降解、具有持久性的污染物,环境中存在的这些痕量物质对水生生物和人体造成潜在威胁.根据目前国内外已有的研究结果,系统论述了水环境中PFOA和PFOS的来源、毒性及其在部分国家和地区的污水处理厂、湖泊、河流、海岸带以及自来水中的污染现状.根据德国对污水处理厂...     

无机阴离子对TiO_2-膨润土紫外光降解SDBS的影响

TiO2-膨润土光催化降解水溶液中阴离子表面活性剂十二烷基苯磺酸钠(SDBS)的效率较高,Cl-、SO42-、NO3-、HCO3-、H2PO4-是水体中常见的阴离子,这些阴离子对降解效果的影响直接影响该技术的实际应用。分别投加36 mmol/L上述阴离子的钠盐到SDBS水溶液中,紫外光照射溶液2 h,比较投加与不投加的SDBS去除效果差异,结果表明:(1)水溶液中上述阴离子对TiO2-膨润土降解SDBS的效果都有不利影响,其中HCO3-影响最大,其次是H2PO4-,再次是NO3-,SO42-和Cl-。紫外光照射2 h后,投加HCO3-、H2PO4-、NO3-、SO42-、Cl-的水溶液中SDBS的浓度分别比不投加的高2.63倍、1.63倍、0.73倍、0.52倍和0.46倍。原因有三方面:这几种无机阴离子与有机分子竞争表面活性位置;在接近催化剂颗粒表面的地方产生高极性环境;溶液pH值的改变。(2)投加这些无机阴离子的溶液COD值比不投加的都高,反应2 h投加Cl-、SO42-、NO3-、HCO3-、H2PO4-分别比不投加的溶液COD值高6.62倍,0.26倍,0.03倍,0.29倍,0.45倍。     

大连沿海常见海产品PFOS和PFOA的暴露水平调查

文章应用液相色谱-质谱分析方法,对2009年春季大连沿海常见海产品体内PFOS和PFOA的暴露水平进行了调查。鱼、蟹、乌贼和海胆肌肉中PFOS的平均暴露水平分别为0.40 ng/g,0.07 ng/g,0.09 ng/g及0.12 ng/g(湿重),而PFOA的平均暴露水平分别为0.06ng/g,0.01 ng/g,0.06 ng/g及0.10 ng/g(湿重)。鱼类肝脏中PFOS和PFOA的平均暴露水平分别为0.90 ng/g和0.24 ng/g。调查结果表明,大连沿岸常见海产品体内普遍检测到PFOS和PFOA,并且肝脏中PFOS和PFOA暴露水平均高于肌肉组织。通过比较发现,大连沿岸鱼类样品中PFOS的暴露水平低于美、日等国家的沿岸海域鱼类的暴露水平。     

A case study of aggregation behaviors of titanium dioxide nanoparticles in the presence of dodecylbenzene sulfonate in natural water

The present work aims to ascertain the mechanisms of surfactant (dodecylbenzene sulfonate; DBS) effects on the aggregation behaviors of TiO₂ nanoparticles (TiO₂-NPs) in natural water samples. Aggregation experiments were conducted at a TiO₂-NPs concentration of 10 mg/L in deionized water and in natural water samples via dynamic light scattering and Zeta potential determination. Average attachment efficiency was calculated to compare the aggregation behaviors of nanoparticles in the two aqueous media. Results showed that the effects of DBS on aggregation could be interpreted by both Derjaguin–Landau–Verwey–Overbeek (DLVO) and non-DLVO mechanisms. In natural water samples, aggregation did not occur rapidly and was able to develop slowly under all conditions, and the roles of DBS were obvious at high DBS concentration owing to the impacts of inherent components of natural water samples, such as colloids and natural organic compounds. Future aggregation studies should concentrate on multi-factor, multi-colloidal and dynamic aspects under similar environmental conditions.