磁场强化全程自养脱氮工艺的启动

为强化全程自养脱氮（CANON）工艺的脱氮性能,利用膜生物反应器（MBR）启动CANON工艺,并对其施加静态磁场进行强化,分析磁场作用下CANON工艺脱氮效果,并对其影响机理进行解析。结果表明:适宜强度的磁场强化了CANON工艺的脱氮效率,并缩短了工艺启动周期。磁场作用下,CANON工艺后期平均氮去除负荷为49.5 g/（m3·d）,相比于对照提高了1.45倍。在低温条件下,磁场的存在能使CANON工艺保持较高的反应活性,其平均氮去除负荷为对照组的2.88倍。磁场促进了污泥胞外聚合物的合成与分泌,提高了蛋白的含量,同时降低了反应器内体系Zeta电位,有利于污泥的聚集,使其内部形成不同的氧分区,促进了CANON工艺中不同微生物的共存,从而强化了CANON工艺的脱氮效率。     

ABR启动期运行效能及互营产甲烷菌群的分布特征

为探讨厌氧折流板反应器（ABR）启动期运行效能和互营产甲烷菌群的空间分布特征,考察了ABR反应器处理制糖废水启动期的运行特征,并采用聚合酶链式反应-变性梯度凝胶电泳（PCR-DGGE）技术分析了互营产甲烷菌群在ABR各格室的分布规律.结果表明,在污泥驯化阶段,ABR的COD去除率为61.5%,出水挥发酸总量高达1808mg/L.经过2个阶段的调控运行后,ABR出水挥发酸明显降低,甲烷含量增加至55%以上,COD去除率达到了94.8%.而且ABR第2~4格室形成了沉降性能良好的颗粒污泥.PCR-DGGE检测结果表明,该ABR系统中的主要产氢产乙酸菌为Syntrophobacter和Pelotomaculum,主要分布在ABR系统第3,4格室.ABR第1,2格室的产甲烷菌主要为耐酸的氢营养型产甲烷菌（Methanoregula和Methanosphaerula）,而乙酸营养型产甲烷菌（Methanosaeta和Methanothrix）主要分布在第3,4格室.ABR系统中产甲烷菌的多样性要明显高于产氢产乙酸菌,说明当系统受到冲击时,产氢产乙酸作用比产甲烷作用更易成为限速步骤.     

青藏高原不同海拔梯度厌氧氨氧化细菌丰度及其生物多样性空间分布

厌氧氨氧化作为新型微生物氮循环过程,已经成为国内外研究热点.目前对厌氧氨氧化细菌的研究主要集中在海洋生态系统中,而在陆地生态系统外源氮污染物较少的地区是否存在厌氧氨氧化过程且其在氮循环中发挥的作用,还很少有相关报道.本研究应用分子生物学技术研究了氮污染负荷较低的青藏高原地区不同海拔湿地和旱地土壤样品中厌氧氨氧化细菌的丰度及其生物多样性.结果表明,在青藏高原地区,普遍存在厌氧氨氧化细菌.使用厌氧氨氧化细菌特异性引物HSBeta396f/HSBeta742r进行定量发现,厌氧氨氧化细菌丰度随着海拔的升高而降低.垂向尺度上,海拔较低地区表层样品厌氧氨氧化细菌丰度高于底层样品,海拔较高地区则相反.通过构建厌氧氨氧化细菌系统发育分析发现,青藏高原地区厌氧氨氧化细菌的生物多样性较高,且多数可能属于新型厌氧氨氧化细菌.该区域湿地沉积物样品厌氧氨氧化细菌生物多样性明显低于旱地土壤样品.湿地沉积物样品厌氧氨氧化细菌生物多样性与海拔无明显关系,但旱地土壤样品厌氧氨氧化细菌生物多样性随着海拔的增高有上升趋势.     

不同水深梯度对4种挺水植物生长繁殖的影响

选择了水葱（Scirpus validus）、菖蒲（Acorus calamus）、香蒲（Typha orientalis）、茭草（Zizania caduciflora）4种常见的挺水植物,研究了静水条件下不同水深梯度（0cm（对照）、30cm（浅水处理）、60cm（深水处理））对4种挺水植物生长和繁殖的影响.试验结...     

专家试制“反磁体斗篷” 让物体在磁场中隐形

据英国广播公司（BBC）9月26日报道,科学家们正试图研制能对磁场隐形的“反磁体斗篷”,其可让磁场对物体“视而不见”。科学家们表示,这种设备可广泛应用于安全和医疗等领域。西班牙巴塞罗那自治大学的阿尔巴多·桑切斯教授解释称,光和磁是同一种物理力的两个方面,因此,对光隐形的斗篷的很多基本原则同样也适用于研制对磁场隐形的斗篷。     

高梯度磁场中磁性可吸入颗粒物脱除试验研究

在高梯度磁场中,分别对钡铁氧体、Fe3O4和γ-Fe2O3等3种磁性可吸入颗粒物进行了脱除实验研究.通过改变外加磁场磁通密度、格栅排数、气溶胶流量、磁性可吸入颗粒物的种类,研究其脱除效率的变化规律.确定影响磁性可吸入颗粒物脱除效率的因素.结果表明:外加磁场的磁通密度越大,颗粒物的脱除效率越高,但有一定限度;格栅排数增加后,颗粒物的脱除效率得到提高;随着流量的增加,颗粒物的脱除效率有所下降;磁性颗粒的磁化率越大.颗粒脱除效率越高.     

零价铁对铬污染底泥的修复及其对微生物群落结构的影响

采用实验室批次实验方法,研究了零价铁对Cr(Ⅵ)模拟污染底泥的修复作用.结果表明.添加2%(以底泥干重计)的还原铁粉在24h内可将150 mg.kg-1的Cr(Ⅵ)去除94.7%.较未加还原铁粉的Cr处理提高23.7%,较S+Cr+Fe处理(灭菌加铁)高14.2%;这说明,零价铁修复有效地促进了底泥中Cr(V1)的去除,底泥中的土著微生物也具有一定的去除Or(V1)的作用.采用变性梯度凝胶电泳(Denatured Gradient GelElectroohoresis.DGGE)和磷脂脂肪酸(Phospholipid Fatty Acid,PLFA)分析技术研究了零价铁修复对底泥微生物群落结构的影响.基于DGGE图谱的差异条带DNA序列分析和多样性指数分析表明:零价铁修复可使底泥中Cr(V1)耐受菌群减少,敏感菌群重新出现,并且可使底泥微生物的shannon多样性指数恢复至未污染对照水平.PLFA指纹图谱分析结果表明:零价铁修复可使代表细菌生物量的磷脂脂肪酸17:0的量以及Cr(V1)对底泥微生物的胁迫恢复至未污染对照水平.     

碳源对EBPR代谢过程及微生物特性的影响

采用SBR反应器,研究了乙酸和丙酸分别作为唯一进水碳源时对EBPR过程物质转化及代表性微生物变化特性的影响,并对不同碳源可能导致不同的微生物代谢过程进行了讨论.SBR的运行模式为：厌氧2 h,好氧5 h,每天运行3个周期,乙酸和丙酸进水的COD均为300 mg/Ｌ,系统先用乙酸作为碳源运行60 d,随后以丙酸作为碳源运行60 d.结果表明,在采用乙酸作为碳源时,厌氧结束放磷和消耗COD的比值为0.35,生成的PHA中以PHB为主,占92.6%,PHV只占到7.4%,没有PH2MV生成.在采用丙酸作为碳源时,厌氧结束放磷和消耗COD的比值稍低,为0.27,生成的PHA中PHV占35.8%,PHB和PH2MV分别占10.2%和54.0%.2种碳源条件下系统都具有良好的EBPR效能,出水PO^3-₄-P均在检出限以下.对不同阶段的污泥进行DGGE分析表明,系统中的微生物发生了变化;扫描电镜图片和PHA染色结果分析表明,在乙酸作为碳源时,系统中的PAOs以球菌形式存在,而在丙酸作为碳源时,系统中的PAOs以杆菌形式存在.不同碳源培养出了不同类型的PAOs,两者代谢途径不同,但都具有较好的EBPR效能.     

Effect of organic carbon on nitrification e ciency and community composition of nitrifying biofilms

The effects of organic carbon/inorganic nitrogen (C/N) ratio on the nitrification processes and the community shifts of nitrifying biofilms were investigated by kinetic comparison and denaturing gradient gel electrophoresis (DGGE) analysis. The results showed that the nitrification rate decreased with an increasing organic concentration. However, the effect became weak when the carbon concentration reached sufficiently high level. Denitrification was detected after organic carbon was added. The 12 h ammonium removal rate ranged from 85% to 30% at C/N = 0.5, 1, 2, 4, 8 and 16 compare to control (C/N = 0). The loss of nitrogen at C/N = 0.5, 1, 2, 4, (8 and 16 was 31%, 18%, 24%, 65%, 59% and 62% respectively, after 24 h. Sequence analysis of 16S rRNA gene fragments revealed that the dominant populations changed from nitrifying bacteria (Nitrosomonas europaea and Nitrobacter sp.) to denitrifying bacteria (Pseudomonas sp., Acidovorax sp. and Comamonas sp.) with C/N ratio increase. Although at high C/N ratio the denitrifying bacteria were the dominant populations, nitrifying bacteria grew simultaneously. Conrrespondingly, nitrification process coexisted with denitrification.     

Phylogenetic diversity and specificity of bacteria associated with Microcystis aeruginosa and other cyanobacteria

Interactions between bacteria and cyanobacteria have been suggested to have a potential to influence harmful algal bloom dynamics; however, little information on these interactions has been reported. In this study, the bacterial communities associated with five strains of Microcystis aeruginosa, three species of other Microcystis spp., and four representative species of non-Microcystis cyanobacteria were compared. Bacterial 16S rDNA fragments were amplified and separated by denaturing gradient gel electrophoresis (DGGE) followed by DNA sequence analysis. The similarities among bacterial communities associated with these cyanobacteria were compared to the digitized DGGE profiles using the cluster analyses. The bacterial community structure of all cyanobacterial cultures di ered. Cluster analysis showed that the similarity values among M. aeruginosa cultures were higher than those of other cyanobacterial cultures. Sequence analysis of DGGE fragments indicated the presence of bacteria including, Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Bacteroidetes and Actinobacteria in the cyanobacterial cultures. Members of the Sphingomonadales were the prevalent group among the Microcystis-associated bacteria. The results provided further evidence for species-specific associations between cyanoabcteria and heterotrophic bacteria, which are useful for understanding interactions between Microcystis and their associated bacteria.