氯化镁复配硫酸铝混凝性能及絮体特性

在研究氢氧化镁混凝特性的基础上,复配氯化镁和硫酸铝作为混凝剂,以高岭土配水水样为研究对象,运用iPDA在线监测技术对混凝过程絮体形成进行监测,探讨了单独使用氯化镁和硫酸铝以及二者复配使用的混凝效果和絮体特性,确定复配使用的各种条件。结果表明,对于浊度20 NTU,pH 11.5的高岭土配水水样,氯化镁、硫酸铝最佳投加量分别为7.2 mg/L(Mg2+计)和3 mg/L(Al3+计);硫酸铝跟氯化镁复配使用时,先投加硫酸铝,间隔30 s后投加氯化镁,混凝效果较好;在镁离子最佳投加量7.2 mg/L时,铝和镁最佳质量比在1∶3~1∶2之间;镁铝复配时其FI值明显大于单独作用时,即絮体尺寸大小:二者复配硫酸铝氯化镁,而且复配条件下Zeta电位值在零电势左右浮动,浮动范围小,更利于聚集沉淀;镁铝复配时发生了协同效应,弥补了单独使用氯化镁混凝过程的不足。     

微生物絮凝剂与聚合氯化铝复配处理涂料废水的响应面优化

采用响应面分析法对聚合氯化铝(PAC)与污泥生产的微生物絮凝剂复配处理涂料废水的过程进行了优化,设定的响应值为COD和色度去除率。实验分别拟合了关于COD去除率和色度去除率的二次模型,根据响应值的分布情况,确定涂料废水的最佳絮凝条件为微生物絮凝剂浓度47 mg/L,PAC浓度39 mg/L,pH为8.2,CaCl2浓度0.38 g/L,搅拌速度210 r/min。最佳絮凝条件下,微生物絮凝剂对涂料废水中COD和色度的去除率分别达到77.6%和68.9%。     

Tetra-detector size exclusion chromatography characterization of molecular and solution properties of soluble microbial polysaccharides from an anaerobic membrane bioreactor

Characterization of the molecular properties of soluble microbial products (SMP) is critical for understanding the membrane filtration and fouling mechanisms in anaerobic and aerobic membrane bioreactors (AnMBR & MBR). In this study, the distributions of the absolute molecular weight and intrinsic viscosity of SMP polysaccharides from an AnMBR were effectively determined by a high performance size exclusion chromatography (HPSEC) that was coupled with the refractive index (RI), diode array UV (DAUV), right and low angle light scattering (LS), and viscometer (Vis) detectors. Based on the tetra-detector HPSEC determined absolute molecular weights and intrinsic viscosity, a universal calibration relationship for the SMP polysaccharides was developed and the molecular conformations, average molecular weights, and hydrodynamic sizes of the SMP polysaccharides were also explored. Two factors which can be derived from the tetra-detector HPSEC analysis were proposed for the characterization of the viscous and osmotic pressure properties of the SMP polysaccharides. In addition, it was also extrapolated how to analyze the resistance characteristics of the concentration polarization layers formed in membrane filtration based on the molecular properties determined by the tetra-detector HPSEC analysis.

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Remediation of acid mine drainage (AMD)-contaminated soil by Phragmites australis and rhizosphere bacteria

Experiments were conducted to assess the impact of citric acid (CA) and rhizosphere bacteria on metal uptake in Phragmites australis cultured in a spiked acid mine drainage (AMD) soil. Rhizosphere iron-oxidizing bacteria (Fe(II)OB) enhanced the formation of Fe plaque on roots, which decreased the uptake of Fe and Mn. CA inhibited the growth of Fe(II)OB, decreased the formation of metal plaque, raised the metal mobility in soil, and increased the accumulation of metals in all tissues of the reeds. The higher the CA dosage, the more metals accumulated into reeds. The total amount of metals in reeds increased from 7.8?±?0.5?×?10^?6 mol plant^?1 (Mn), 1.4?±?0.1?×?10^?3 mol plant^?1 (Fe), and 1.0?±?0.1?×?10^?4 mol plant^?1 (Al) in spiked soil without CA to 22.2?±?0.5?×?10^?6 mol plant^?1 (Mn), 3.5?±?0.06?×?10^?3 mol plant^?1 (Fe), and 5.0?±?0.2?×?10^?4 mol plant^?1 (Al) in soil added with 33.616 g C₆H₈O₇·H₂O for per kilogram soil. CA could be effective at enhancing the phytoremediation of metals from AMD-contaminated soil.     

Distribution of antibiotic-resistant bacteria in chicken manure and manure-fertilized vegetables

Veterinary manure is an important pollution reservoir of antibiotics and antibiotic-resistant bacteria (ARB). However, little is known of the distribution of ARB in plant endophytic bacteria and the number/types of ARB in chicken manure. In this study, 454-pyrosequencing was used to investigate the distribution and composition of ARBs in chicken manure and fertilized vegetables. The prevalence of ARB in the samples of the chicken manure compost recovered from farms on which amoxicillin, kanamycin, gentamicin, and cephalexin were used was 20.91–65.9 % for ARBs and 8.24–20.63 % simultaneously resistant to two or more antibiotics (multiple antibiotic resistant bacteria (MARB)). Antibiotic-resistant endophytic bacteria were widely detected in celery, pakchoi, and cucumber with the highest rate of resistance to cephalexin. The pyrosequencing indicated that the chicken manure dominantly harbored Firmicutes, Bacteroidetes, Synergistetes, and Proteobacteria and that Bacteroidetes was significantly enhanced in farms utilizing antibiotics. In the total cultivable colonies, 62.58–89.43 % ARBs and 95.29 % MARB were clustered in Bacteroidetes with the dominant species (Myroides ordoratimimus and Spningobacterium spp., respectively) related to human clinical opportunistic pathogens.     

南京某城市污水二级处理系统中酞酸酯类的分布及去除特征

以南京某城市污水厂污水和污泥中的酞酸酯类（PAEs）为研究对象，分别采用固相萃取-气相色谱-质谱联用（SPE—Gc．Ms）和超声提取．气相色谱．质谱联用（USE—GC—Ms）检测其中的优先控制污染物邻苯二甲酸二甲酯（DMP）、邻苯二甲酸二乙酯（DEP）、邻苯二甲酸二丁酯（DBP）和邻苯二甲酸单（2-乙基己基）酯（MEHP），研究其在厌氧／好氧（A／O）污泥处理过程中的分布特征及降解规律。研究结果表明，各类PAEs在该污水厂的污水和污泥中均有检出，二级处理出水中4种酞酸酯类物质的浓度在0．151—2．419μg／L。污水中4种酞酸酯的分布规律为MEHP〉DBP〉DMP〉DEP，污泥中4种酞酸酯的分布规律为MEHP〉DBP〉DEP〉DMP。该污水厂二级处理工艺对4种PAEs的去除效果较明显，去除效率DBP〉DEP〉DMP〉MEHP．     

竹制填料生物接触氧化工艺处理污染河水简

针对受污染的湖溪河水质特征，以传统弹性塑料填料做对比，研究以竹球和竹丝为填料的生物接触氧化工艺，考察填料的挂膜时间、生物量和污水处理效果；确定连续曝气和间歇曝气时反应器的最优运行工况：连续曝气时为HRT=7.5 h，DO=3 mg/L；间歇曝气时为厌氧1.2 h、好氧6.3 h交替运行。实验结果表明，与弹性塑料填料相比，竹制填料挂膜速度快，竹球填料的水处理效果最好；连续曝气最优工况下竹球填料反应器中COD、TN、NH₃-N和TP的平均去除率分别为66.7%、47.9%、57.1%和30.6%；间歇曝气最优工况下竹球填料反应器中COD、TN、NH₃-N和TP的平均去除率分别64.08%、39.95%、60.7%和54.68%；竹制填料可替代传统的塑料填料作为生物接触氧化工艺的载体填料。     

煤基腐殖酸对外源砷胁迫下玉米生长及生理性状的影响简

为了筛选用于砷污染土壤治理的煤基腐殖酸，采用盆栽实验研究了施用不同种类和浓度的煤基腐殖酸及EDTA对外源砷胁迫下玉米株高、株鲜重、株干重、根干重、砷积累量、叶片抗氧化酶（POD，SOD和CAT）活性和脯氨酸含量的影响。结果表明，11种供试煤基腐殖酸均促进了玉米生长，提高了叶片POD、SOD和CAT活性。其中6和10号腐殖酸可降低土壤砷活性和显著抑制玉米吸收和积累砷，而8和9号腐殖酸增加了土壤活性砷和显著促进了玉米对砷的吸收和累积，且不同程度地强于EDTA。除8和9号外，其余腐殖酸均可明显降低玉米叶片脯氨酸的含量。EDTA可显著促进玉米吸收和积累砷，且加剧了砷对玉米的危害。因此，8和9号供试煤基腐殖酸可以替代EDTA活化土壤砷，与植物配合以提高砷污染土壤的植物修复速度和效果，而6和10号供试煤基腐殖酸则可用于土壤砷钝化剂，以保证作物产品的安全。     

CuO/γ-Al2O3类Fenton试剂降解丁基黄药

CuO/γ-Al2O3类Fenton试剂是降解丁基黄药的优良试剂。该试剂与传统的Fenton试剂相比,提高了反应的pH值,可在较高pH(4~5)条件下反应,而传统的Fenton试剂的适宜pH值一般在3以下。采用单因素实验和正交实验相结合的方法研究了pH、催化剂投加量、过氧化氢投加量以及反应时间对丁基黄药降解效果的影响,并对催化剂的使用寿命进行了探讨。研究结果表明,反应的最佳条件为:pH为4~5,催化剂投加量为6 g/L,过氧化氢用量为30 mg/L,反应30min。在此反应条件下,丁基黄药的降解率达98%以上;影响丁基黄药降解效果的因素大小顺序为:pH>反应时间>H2O2用量>催化剂投加量,其中pH对CuO/γ-Al2O3类Fenton试剂降解丁基黄药的影响最为显著。     

煅烧的水滑石同时去除水体中砷和氟

为探讨水滑石类材料对水体中氟、砷离子的同时去除效果,采用共沉淀法合成(Mg∶Al=2∶1)纳米类水滑石(LDHs),用傅立叶转换红外光谱、电子扫描透射电镜、X射线晶体衍射等手段对合成的材料进行了表征,并研究纳米材料在不同初始浓度、pH、吸附时间、阴离子干扰条件下其同时除砷氟性能。结果表明,煅烧后的水滑石(LDOs)对砷最大吸附量为51.02 mg/g,对氟最大吸附量为36.63 mg/g。吸附动力学实验表明,煅烧水滑石对砷的吸附在前6 h内基本完成,对氟的吸附在前10 h内基本完成。砷氟共存溶液保持pH=4~10及pH=6~8时,水滑石分别对砷、氟保持良好的吸附效率。对比不同阴离子对水滑石共除砷氟效率的影响,水滑石除砷速率受到阴离子影响力大小为:HPO2-4CO2-3NO-3Cl-SO2-4;水滑石除氟速率受到阴离子影响力大小为:CO2-3HPO2-4SO2-4Cl-NO-3。材料再生循环利用4次后,对砷和氟的吸附效率均能达到90%以上。实验结果表明,所合成的水滑石是一种优秀的能共除砷氟的吸附剂。