甲基叔丁基醚降解菌的驯化与筛选

为了筛选降解甲基叔丁基醚(MTBE)的优势菌种,调查了不同来源土壤土著菌的降解潜力.应用不同的驯化方式以MTBE为惟一碳源,在好氧的条件下,驯化、筛选出高效降解混合菌株,为现场应用打好基础.并从中分离得到6株高降解性的单一菌株,对其进行了初步鉴定,为进一步研究其降解途径做好准备.对单一菌株与混合菌株的降解效果进行了比较.结果表明,混合菌株的降解效果要明显高于单一菌株.     

UV/Fenton氧化降解水溶液中甲基叔丁基醚的试验研究

采用UV／Fenton技术对污染水体中的甲基叔丁基醚（MTBE）进行了氧化降解试验。结果表明，在室温条件下，当H2O2为10mmol／L，FC＋为2mmol／L，pH为2．4时，起始摩尔浓度为1mmol／L的MTBE在30min内可去除99％；结果还显示了MTBE的降解分两个阶段，第一阶段是在UV／Fe^2＋／H2O2下的快速降解，第二阶段由于Fe^2＋的大量消耗而降解相对较慢。     

多孔碳表面自养硝化生物膜的培养及其性能研究

在pH值7．5～7．8、温度28℃、DO≥3mg／L的条件下，分别以NaNO2和K2HPO4为氮源和磷源，按N：P=50：1的比例混合，对自养硝化菌进行液相培养并在一种新型材料多孔碳的表面挂膜，进而对其特征、性能等进行了研究。实验得到了稳定的自养硝化生物膜；当NO2^-浓度为206．82mg／L时，生物膜的稳定硝化速率可达260mg/L·d；经鉴定，硝化速率最高的N-20菌株属硝化杆菌属(Nitrobacter sp．)。     

多孔碳表面自养硝化生物膜的培养及其性能研究

在pH值7.5～7.8、温度28℃、DO≥3mg/L的条件下,分别以NaNO2和K2HPO4为氮源和磷源,按N∶P=50∶1的比例混合,对自养硝化菌进行液相培养并在一种新型材料多孔碳的表面挂膜,进而对其特征、性能等进行了研究。实验得到了稳定的自养硝化生物膜;当NO-2浓度为206.82mg/L时,生物膜的稳定硝化速率可达260mg/L·d;经鉴定,硝化速率最高的N20菌株属硝化杆菌属(Nitrobactersp.)。     

生物膜电极反应器降解苯胺的研究

生物膜电极反应器是结合生物膜法和电催化技术而发展的新型废水处理技术.研究了生物膜电极上的苯胺降解,对电流强度、温度、葡萄糖协同作用等因素的影响进行了观察.结果表明,生物膜电极反应器最高的电流强度为5 mA,运行的最适温度为36 ℃.葡萄糖对苯胺的生物膜电极降解的协同作用在进水COD为2 000 mg/L后达到最大.色谱/质谱联用检测苯胺降解中间产物为4-羟基-α-氨基戊酸.生物膜电极上的苯胺降解在阴极发生,降解开环途径与常规降解途径不同.     

生物膜电极法降解氯苯、二氯苯的研究

研究证实,氯苯和二氯苯在生物膜电极下降解速率显著快于常规方法.质谱分析可知,氯苯的中间产物存在苯酚、乙酸,二氯苯的3种同分异构体中间产物均存在氯酚、苯酚和乙酸.中间产物表明,氯苯、二氯苯的生物膜电极降解途径完全不同于常规生物降解途径,而阴极的还原气氛对脱氯起到关键性影响.     

生物膜氧化沟污水处理性能的研究

生物膜氧化沟是在普通氧化沟内放置合适填料，使之成为活性污泥法与生物膜法相结合的混合污水处理工艺。本研究通过清水试验，选择出了生物膜氧人诉合适填料及其安装方式，并同时比较了生物膜氧化沟和普通氧化沟的传质效果，水流阻力、水力混合特性。通过污水试验，确定了生物膜氧化沟的填料最佳填充率。并比较了生物膜氧化沟和普通氧化沟的去除ＣＯＤ、ＳＳ、ＴＮ效率及两者的污泥性能。     

宁波市大气可吸入颗粒物PM1o和PM2.5的源解析研究

在宁波市布设4个代表性点位,于2010年春季、夏季和冬季进行大气PM10和PM2.s的采样,同时采集了多种颗粒物源样品,建立了PM10、PM2.5和源样品的化学成分谱.采用化学质量平衡模型(CMB)对宁波市PM10、PM2.5进行源解析.结果表明,城市扬尘、煤烟尘、机动车尾气尘是宁波市PM10、PM2.5的3大污染源,...     

活性污泥-生物膜一体化反应器对废水中苯酚的降解性能

利用活性污泥-生物膜一体化反应器处理含苯酚废水,考察了反应器对苯酚和COD的处理效果以及反应器运行中生物膜干质量(SS)、挥发性干质量(VSS)、活性生物量、脱氢酶活性(DHA)、胞外聚合物(EPS)的变化,探究了生物膜特性与废水处理效果之间的关系。结果表明：在进水苯酚质量浓度由50 mg·L⁻¹逐步提高到500 mg·L⁻¹的过程中,苯酚和COD去除率均呈先降后升的趋势;当进水苯酚质量浓度为250 mg·L⁻¹时,反应器能适应苯酚冲击,苯酚和COD去除率分别稳定在97%和60%以上;当进水苯酚质量浓度为500 mg·L⁻¹时,苯酚去除率可达到99%,同期SS、VSS、活性生物量及DHA(22.03~57.07 mg·g⁻¹)的变化亦反映出生物膜性能的提升,说明反应器对苯酚质量浓度变化的适应能力较强。此外,EPS质量分数为42.99~310.51 mg·g⁻¹,蛋白质(PN)与多糖(PS)的质量比为0.67~1.39,且当初始苯酚质量浓度为250 mg·L⁻¹时,PN/PS值最高,EPS亲水性低,生物膜可高效降解苯酚。以上研究结果表明,逐渐提高进水苯酚质量浓度能有效提高活性污泥－生物膜一体化反应器对苯酚的适应性和降解率。     

ZSM-5沸石的制备及其对甲基叔丁基醚的吸附性能研究

采用无模板剂水热合成法和晶种诱导水热合成法成功制备了ZSM-5沸石.使用X射线衍射(XRD)、扫描电子显微镜(SEM)和BET比表面积测试等手段对合成产物进行了表征,结果显示,两种ZSM-5沸石晶体粒径均在微米级,孔道均以0.60～1.00nm的微孔为主,晶种诱导合成ZSM-5沸石微孔体积更大.采用气相色谱法分析了ZSM-5沸石对甲基叔丁基醚(MTBE)的吸附性能.结果表明,晶种诱导合成的ZSM-5沸石对MTBE的吸附容量较无模板剂合成ZSM-5沸石高,原因是两种ZSM-5沸石孔道分布有差异.研究还显示,晶种诱导合成ZSM-5沸石对MTBE的吸附容量随其投加量的增大而减小,存在明显的固体浓度效应;吸附体系达吸附平衡较慢,说明MTBE在ZSM-5沸石微孔道的扩散是影响吸附平衡的控制因素;该沸石再生方便,对处理初始质量浓度为200～1000μg/L的MTBE溶液具有较好的再生吸附性能.     

Microbial degradation of methyl tert-butyl ether and tert-butyl alcohol in the subsurface

The fate of fuel oxygenates such as methyl tert-butyl ether (MTBE) in the subsurface is governed by their degradability under various redox conditions. The key intermediate in degradation of MTBE and ethyl tert-butyl ether (ETBE) is tert-butyl alcohol (TBA) which was often found as accumulating intermediate or dead-end product in lab studies using microcosms or isolated cell suspensions. This review discusses in detail the thermodynamics of the degradation processes utilizing various terminal electron acceptors, and the aerobic degradation pathways of MTBE and TBA. It summarizes the present knowledge on MTBE and TBA degradation gained from either microcosm or pure culture studies and emphasizes the potential of compound-specific isotope analysis (CSIA) for identification and quantification of degradation processes of slowly biodegradable pollutants such as MTBE and TBA. Microcosm studies demonstrated that MTBE and TBA may be biodegradable under oxic and nearly all anoxic conditions, although results of various studies are often contradictory, which suggests that site-specific conditions are important parameters. So far, TBA degradation has not been shown under methanogenic conditions and it is currently widely accepted that TBA is a recalcitrant dead-end product of MTBE under these conditions. Reliable in situ degradation rates for MTBE and TBA under various geochemical conditions are not yet available. Furthermore, degradation pathways under anoxic conditions have not yet been elucidated. All pure cultures capable of MTBE or TBA degradation isolated so far use oxygen as terminal electron acceptor. In general, compared with hydrocarbons present in gasoline, fuel oxygenates biodegrade much slower, if at all. The presence of MTBE and related compounds in groundwater therefore frequently limits the use of in situ biodegradation as remediation option at gasoline-contaminated sites. Though degradation of MTBE and TBA in field studies has been reported under oxic conditions, there is hardly any evidence of substantial degradation in the absence of oxygen. The increasing availability of field data from CSIA will foster our understanding and may even allow the quantification of degradation of these recalcitrant compounds. Such information will help to elucidate the crucial factors of site-specific biogeochemical conditions that govern the capability of intrinsic oxygenate degradation.     

地下水环境中甲基叔丁基醚运移过程的动力学模型

建立了地下水环境中甲基叔丁基醚(MTBE)运移过程的变系数动力学模型,并对模型进行了验证和参数灵敏度分析.模拟结果表明,地下水流速和阻滞系数对于MTBE的运移过程影响最为显著,而水动力弥散系数的影响较小,忽略其变化不会对预测地下水环境中污染物运移的环境动力学行为造成太大误差.由此得到的结论可定量研究MTBE在地下水环境中的对流.扩散特征,还可为MTBE污染地下水的预测预报、修复治理等研究提供科学依据.     

无铅汽油添加剂甲基叔丁基醚(MTBE)的环境化学行为及其分析方法

本文简要介绍了无铅汽油添加剂MTBE的物理化学性质、环境化学行为、地下水的污染状况和对动物的潜在致癌毒理 ,并对其分析方法作了综述 ,指出了我国开展MTBE有关研究的重要性。     

Influences of metals on kinetics of methyl tert-butyl ether biodegradation by Ochrobactrum cytisi

The influence of zinc, manganese, and nickel on the degradation of MTBE (methyl tert-butyl ether), by an aerobic MTBE-degrading strain, Ochrobactrum cytisi, were investigated. The result showed that unlike previous findings, O. cytisi was able to degrade MTBE through direct metabolism when MTBE was present as the only carbon source. The degradation rate of MTBE was rapid, completed within 80 h. MTBE biodegradation by this strain was stimulated at low concentrations of Zn(2+) (1-5 mg l(-1)) and Mn(2+) (1-5 mg l(-1)) but inhibited at high concentrations of Zn(2+) (20 mg l(-1)) and Mn(2+) (20 mg l(-1)), and at low concentration of Ni(2+) (1-4 mg l(-1)). Kinetic parameters for MTBE degradation in the presence or absence of metals were obtained through nonlinear regression and a least-square minimization procedure. In all cases, a good agreement was achieved between kinetic simulations and experimental results.     

区域大气环境中PM2．5／PM10空间分布研究

提出了一种利用移动监测技术研究区域大气环境中PM2.5／PM10空间分布的方法,并在2004年12月进行了宁波市全市域PM2.5／PM10空间分布的研究。数据显示：相同路径所代表的地区PM2.5和PM10具有很好的相关性,多数路径上PM2.5与PM10数据的相关系数平方在0．95以上,而不同路径上PM2.5与PM10的比值不同。文中给出了宁波市PM2.5／PM10污染的空间分布图,直观地显示出PM2.5／PM10污染的空间分布情况,突出了污染的重点点位和地区。     

中国甲基叔丁基醚污染现状及防治对策研究

甲基叔丁基醚(MTBE)因作为汽油添加剂大量使用而广泛存在于不同环境介质中。通过调研中国部分城市大气、土壤和水体环境介质中的MTBE污染情况,分析了中国目前MTBE的污染现状及影响。结果显示,中国城市区域附近不同环境介质中普遍存在MTBE污染,一般区域MTBE污染程度较轻,加油站周边环境中MTBE污染相对较重。部分加油站区域大气中的MTBE浓度已经超过可接受的健康风险水平;加油站周边地下水中的MTBE检出率较高,对地下水水质安全具有一定威胁。最后,对中国MTBE污染防治工作进行了总结并给出了相关建议。     

Biotic and abiotic transformations of methyl tertiary butyl ether (MTBE)

Background Methyl tertiary butyl ether (MTBE) is a fuel additive which is used all over the world. In recent years it has often been found in groundwater, mainly in the USA, but also in Europe. Although MTBE seems to be a minor toxic, it affects the taste and odour of water at concentrations of < 30 μg/L. Although MTBE is often a recalcitrant compound, it is known that many ethers can be degraded by abiotic means. The aim of this study was to examine biotic and abiotic transformations of MTBE with respect to the particular conditions of a contaminated site (former refinery) in Leuna, Germany. Methods Groundwater samples from wells of a contaminated site were used for aerobic and anaerobic degradation experiments. The abiotic degradation experiment (hydrolysis) was conducted employing an ion-exchange resin and MTBE solutions in distilled water. MTBE, tertiary butyl formate (TBF) and tertiary butyl alcohol (TBA) were measured by a gas chromatograph with flame ionisation detector (FID). Aldehydes and organic acids were respectively analysed by a gas chromatograph with electron capture detector (ECD) and high-performance ion chromatography (HPIC). Results and Discussion Under aerobic conditions, MTBE was degraded in laboratory experiments. Only 4 of a total of 30 anaerobic experiments exhibited degradation, and the process was very slow. In no cases were metabolites detected, but a few degradation products (TBF, TBA and formic acid) were found on the site, possibly due to the lower temperatures in groundwater. The abiotic degradation of MTBE with an ion-exchange resin as a catalyst at pH 3.5 was much faster than hydrolysis in diluted hydrochloric acid (pH 1.0). Conclusion Although the aerobic degradation of MTBE in the environment seems to be possible, the specific conditions responsible are widely unknown. Successful aerobic degradation only seems to take place if there is a lack of other utilisable compounds. However, MTBE is often accompanied by other fuel compounds on contaminated sites and anaerobic conditions prevail. MTBE is often recalcitrant under anaerobic conditions, at least in the presence of other carbon sources. The abiotic hydrolysis of MTBE seems to be of secondary importance (on site), but it might be possible to enhance it with catalysts. Recommendation and Outlook MTBE only seems to be recalcitrant under particular conditions. In some cases, the degradation of MTBE on contaminated sites could be supported by oxygen. Enhanced hydrolysis could also be an alternative. - * The basis of this peer-reviewed paper is a presentation at the 9th FECS Conference on 'Chemistry and Environment', 29 August to 1 September 2004, Bordeaux, France.     

Simultaneous decontamination of hexavalent chromium and methyl tert-butyl ether by UV/TiO2 process

Hexavalent chromium and methyl tert-butyl ether (MTBE) are two important environmental pollutants. Simultaneous decontamination of Cr(VI) and MTBE was studied by UV/TiO2 process. The influences of pH and the concentrations of pollutants on the kinetics of the photocatalytic reactions were evaluated. Dark adsorption tests showed that the acidic pH favored the adsorption of Cr(VI) while neutral pH favored the adsorption of MTBE. Under UV irradiation, Cr(VI) reduction was observed in Cr(VI)/TiO2 system, and MTBE oxidation was observed in MTBE/TiO2 system. The system containing Cr(VI) and MTBE by UV/TiO2 process demonstrated the synergistic effect between oxidation of MTBE and reduction of Cr(VI). The results demonstrated that two pollutants Cr(VI) and MTBE could be eliminated simultaneously by UV/TiO2 process. tert-Butyl formate, tert-butyl alcohol and acetone were identified as primary degradation products of MTBE by gas chromatography-mass spectrometry in the degradation of MTBE by UV/TiO2 process.     

冷凝湿度控制对微振荡天平监测细颗粒物性能的改进

为提高细颗粒物(PM2.5)测量的准确性,尝试采用一种新型的气溶胶冷凝湿度控制器(简称冷凝湿度控制器)作为微振荡天平法颗粒物监测仪(TEOM)的除湿方式,在广东大气超级监测站开展了TEOM自动监测(一台采用传统的加热除湿方式,记为TEOM1405;另一台采用冷凝湿度控制器除湿,记为TEOM1405+除湿)和手工监测结果的对比。结果表明,根据PM2.5日均值相关性的拟合结果,TEOM1405监测较手工监测结果总体偏低约13%,加装冷凝湿度控制器后,TEOM1405+除湿监测较手工监测结果总体偏低在5%以内。加装冷凝湿度控制器后,显著提高了PM2.5的监测准确性;在相对湿度较高、二次颗粒物生成量较少的大气环境中,TEOM1405+除湿系统对PM2.5的监测结果是可靠的,而且在降雨过程中监测结果更为稳定;但在相对湿度较高、且二次颗粒物生成量较多的大气环境中,其对PM2.5的监测性能仍待进一步考察;在PM2.5污染比较严重的高污染时段,TEOM1405、TEOM1405+除湿监测到的PM2.5日均质量浓度分别比手工监测结果偏低26%和11%,偏低较多。但这种高污染情况在珠三角地区出现的概率很低,故采用TEOM1405+除湿系统进行PM2.5长期自动监测是可取的。