活性污泥改性及其在废水处理中的应用

介绍了活性污泥的生物、化学组成,以及活性污泥改性方法,阐述了现有方法的研究现状及优缺点,比较了各种活性污泥在废水处理中的应用效果,分析结果认为活性污泥改性对废水处理具有广阔的应用前景.     

氧化改性活性炭吸附脱除游离态汞

煤是一种主要化石能源，燃煤烟气中汞排放引起的污染现已达到严重危害人类健康的程度，主要原因是其中的游离态汞（Hg^0）由于低熔点、高平衡蒸气压以及低水溶性而难以由传统的烟气净化装置中去除。燃煤烟气中汞的治理势在必行。本文在研究国内外含汞废气治理技术的基础上，对活性炭分别进行了浓HNO3和H2O2氧化改性，研究其对游离态汞的吸附效率和吸附等温线。结果表明，改性后的活性炭对汞的吸附能力明显增强。     

ON THE EVALUATION OF OPERATIONAL CLOUD SEEDING PROJECTS1

ABSTRACT Operational cloud seeding projects, those designed to produce a desired change in the weather and that are nonexperimental in nature, continue to be pursued widely in the United States. A recurring question by scientists, project sponsors, and cloud seeders has been, “was the weather altered and if so, by how much?” Evaluation of such projects is now recognized as having scientific benefits, and a four-year study has addressed various techniques and statistical methods to perform evaluations and to learn more about how to modify the weather. Most such evaluations hinge on some type of space-time comparisons, but valid comparisons can be obtained only avoiding biases in the project design and operation. Through simulated changes in weather conditions, it was determined that the principal component regression techniques were used to evaluate selected rain and hail modification projects, revealing modification in certain projects and none in others. Various relevant issues have been examined such as use of other weather variables (covariates) to increase detection power, the validity of using historical data as controls for discrete operational periods, possible randomization options during cloud seeding operations, and analyses of individual rain events versus that based on monthly or seasonal units.     

STORM CHARACTERISTICS OF CONVECTIVE-SCALE PRECIPITATION1

A classification scheme for convective precipitation, having applications in both analysis and modeling of meteorological and hydrological events, is presented. The method is based upon observations of rainfall at the ground, radar scans of storm events, and visible and infrared satellite imagery of larger storm systems. Empirical and theoretical frequency distributions are derived for total storm rainfall, rainfall duration and time between storms for each of the convective categories. This stratification is directly applicable to the experimental design and evaluation of weather modification projects and may be useful for the development and interpretation of meteorological and hydrological models. When atmospheric conditions limit storm development to cells, rainfall was seldom observed. Small clusters also produce small amounts of rainfall but have a longer lifetime than cells and are likely candidates for cloud seeding attempts to encourage their growth to large clusters. Large and nested clusters usually produce large amounts of natural precipitation. A few large storms account for most of a season's rainfall.     

PAA改性纳米铁强化还原降解水中亚甲基蓝

利用纳米零价铁去除水中各类污染物是近年来的研究热点,但纳米零价铁颗粒在水中的团聚会导致反应活性降低,研究通过在纳米铁颗粒制备过程中添加分散剂聚丙烯酸(PAA),提高其分散性,强化其在水中反应活性,合成改性纳米零价铁颗粒(PAA-Fe),并首次用于降解水中的亚甲基蓝.对其SEM、TEM、XRD和比表面积表征结果表明,与未改性原始纳米零价铁颗粒相比,PAA-Fe颗粒表面较光滑,团聚减少、颗粒粒径减小,比表面积增大.改性剂PAA添加浓度为0.1 g·L-1时,经过60 min降解反应,PAA改性纳米铁颗粒对亚甲基蓝的脱色率为98.84%,较未改性颗粒脱色率提高了27.32%.改性纳米铁颗粒对亚甲基蓝的脱色效果受初始溶液的p H值、初始溶液的浓度、PAA-Fe投加量和反应温度影响.PAA-Fe与亚甲基蓝的脱色反应符合假一级反应动力学规律.     

不同类型LDHs对垂直流人工湿地无烟煤基质的覆膜改性及其脱氮效果研究

选取垂直流人工湿地无烟煤基质,采用不同类型金属化合物(CaCl2、ZnCl2、MgCl2、FeCl3、AlCl3、CoCl3)两两组合方式,在碱性环境下共沉淀生成9种不同类型的层状双金属氢氧化物LDHs并覆膜于基质表面;构建基质试验柱,分别对未改性及9种LDHs覆膜改性无烟煤基质进行模拟垂直流人工湿地脱氮效果研究.结果表明,9种不同组合方式生成的LDHs均能有效地进行无烟煤基质覆膜改性;Mg2+参与合成的改性基质对TN和氨氮均有很好的去除效果,其中MgCo-LDHs改性基质对TN的平均去除率超过80%,对氨氮的平均去除率达到了85%;Mg2+和Fe3+参与合成的改性基质对氨氮的去除效果优良,其中CaFe-LDHs和MgFe-LDHs改性基质的平均去除率达到了85%以上.     

改性芦苇生物炭对水中低浓度磷的吸附特征

为吸附处理低浓度含磷废水和实现芦苇资源化利用,将湿地植物芦苇制备成生物炭,通过负载氯化铁进行改性,探究了改性芦苇生物炭对水体中磷的吸附特征.结果表明,改性后芦苇生物炭的含铁量为11.98 mg·g~(-1),是改性前的44.7倍;改性芦苇生物炭p H_(pzc)为7.49,当溶液p H为7.0时,吸附效果最好;在磷溶液浓度为4.0 mg·L~(-1)、温度为298K时,改性芦苇生物炭平衡吸附量为0.658 mg·g~(-1),是未改性生物炭吸附量的34.6倍.研究不同温度下的吸附等温线,Langmiur方程很好地拟合不同温度的吸附等温线,该吸附是单层吸附,温度升高有利于吸附.吸附热力学研究表明,ΔG~θ0、ΔH~θ0和ΔS~θ0,说明该吸附是自发、熵增的吸热过程.假二级方程很好地拟合改性芦苇生物炭吸附磷的动力学数据,初始吸附速率随初始浓度的增大而增大,该吸附主要受颗粒内扩散控制.该研究为改性芦苇生物炭用于污水处理厂和水体深度除磷提供基础数据.     

BS+CTMAB复配修饰在黄棕壤吸附苯酚上的应用

本文基于两性修饰剂十二烷基二甲基甜菜碱(BS-12)和阳离子型表面修饰剂十六烷基三甲基溴化铵(CTMAB)复配修饰蒙脱石吸附苯酚的最佳修饰比例基础上,分别以蒙脱石含量为43%和6%的2种黄棕壤制备了2个系列的BS-12+CTMAB复配修饰土样.以两性复配修饰蒙脱石作对比,研究了2种两性复配修饰黄棕壤对苯酚的吸附特征,分析了温度、pH值和离子强度对两性复配修饰黄棕壤吸附苯酚的影响,并探讨了两性复配修饰蒙脱石与两性复配修饰黄棕壤以及两性复配修饰黄棕壤之间吸附苯酚的差异性.结果表明,和两性复配修饰蒙脱石相同,复配修饰增强了两性修饰黄棕壤对苯酚的吸附能力,30℃时吸附量呈215BS+215CT(215%BS-12+215%CTMAB)215CT(215%CTMAB)215BS(215%BS-12)CK1(蒙脱石含量为43%未修饰黄棕壤)和33BS+33CT(33%BS-12+33%CTMAB)33CT(33%CTMAB)33BS(33%BS-12)CK2(蒙脱石含量为6%未修饰黄棕壤)顺序.Henry模型适用于描述苯酚在黄棕壤各供试土样中的吸附;2种修饰黄棕壤对苯酚吸附量均随温度、pH值的升高而降低,在低浓度范围内,随离子强度的增大而升高,和修饰蒙脱石吸附苯酚的规律相同;土样阳离子交换量(CEC)是决定两性复配修饰蒙脱石与黄棕壤以及2种两性复配修饰黄棕壤之间吸附苯酚存在差异的根本原因.     

玻璃纤维编织管覆膜改性及其动态膜生物反应器研究

对玻璃纤维编织管进行了覆膜改性,并依托于玻璃纤维编织管开发了一种新型的栅式膜组件及其动态膜生物反应器.研究表明,覆膜改性前,玻纤编织管动态膜组件的稳定通量仅为4 L/(m2.h),跨膜压差为0.02 MPa;覆膜改性后,玻纤编织管动态膜组件的膜通量可达到16 L/(m2.h),跨膜压差为0.01 MPa;经过水力清洗和碱洗后再次运行,膜通量可达到17.1 L/(m2.h),而跨膜压差最低仅为0.003 MPa.覆膜膜液浓度为1∶4时反应器在膜通量为14.29 L/(m2.h)时稳定运行长达51 d.按阻力增长速率计算,膜通量可保持稳定运行275 d左右.同时出水效果良好,COD和NH4+-N的处理效果平均值分别为81.96%和83.66%,其中动态膜的去除率分别为21.01%和3.61%.此外,覆膜改性的玻纤编织管估算价格约为40~60元/m2,低于传统有机膜.     

改性海带对铜离子的吸附性能

为了开发对重金属离子有很高吸附性能的生物吸附剂,文章对天然海带进行化学处理,研究了改性海带对铜离子的吸附能力。结果表明,天然海带、HCl处理后的海带及NaOH处理后的海带对铜离子的吸附量分别为59.3,38.6和88.0mg/g。化学改性提高了海带对铜离子的吸附能力,在废水处理中有很高的应用价值。