地表载荷对硬岩区埋地管道应力应变影响分析

为研究地表载荷对硬岩区埋地管道力学性能的影响,建立了管-土耦合三维数值模型,分析了地表载荷大小、作用面积、管道压力、管道径厚比及回填土弹性模量对管道应力分布、塑性应变、椭圆度的影响。结果表明:地表压载作用下,高应力区首先出现在管道顶部且呈椭圆形;随着地表载荷及其作用面积的增大,管道高应力区逐渐扩大,管道截面左右两侧也出现应力集中;随着回填土弹性模量、管道壁厚及内压的增加,管道顶部高应力区及最大等效应力均减小。塑性应变首先出现在管顶,且塑性区随地表载荷、载荷作用长度增加而增大,随回填土体弹性模量及管道壁厚增大而逐渐减小;当内压为0~4MPa时,管道塑性应变及塑性区随内压的增大而减小。管道椭圆度随回填土体弹性模量、管道内压、壁厚增加而逐渐减小,随地表压载增大而增大。     

水胺硫磷降解优势菌的筛选及其降解条件的研究

本文从已驯化好的活性污泥菌是悬液中分离筛选出水胺硫磷的降解优势菌，并对其降解条件进行了实验研究，当温度为２５℃，ＰＨ为６．５～７．５，水胺硫磷进水浓度１３５ｍｇ／Ｌ，停留时间为１２ｈ，在供氧条件下，水胺硫磷降解率可达７２．３％，而混合菌在最佳条件下，其水胺硫磷降解率为５５．８％，本文还要菌种进行了鉴定。     

有机物对亚硝化颗粒污泥中功能菌活性的影响

为探明易降解有机物短期冲击对全自养亚硝化颗粒污泥(PNG)中不同功能菌活性的影响,本研究采用多批次连续实验,系统考察了PNG在有机物胁迫与恢复阶段,氮素转化性能与溶解氧(DO)利用情况的演化规律.结果表明,基质C/N比越高,亚硝态氮比累积速率[q(NO-2-N)]的降幅就越大.期间,异养菌(He B)活性的增强,加快了PNG对DO的消耗速率,使得氧亲和力较差的亚硝酸盐氧化菌(NOB)活性得到了有效抑制.当重新采用无机碳源配水时,q(NO-2-N)数值明显增大,同时He B与NOB的活性均处于较低水平.因此,易降解有机物对全自养PNG系统的冲击具有一定可逆性,该过程有助于巩固氨氧化菌(AOB)的相对优势,提升亚硝化反应的稳定性.     

Nano-sized Fe2O3/Fe3O4 facilitate anaerobic transformation of hexavalent chromium in soil–water systems

The purpose of this study is to investigate the effects of nano-sized or submicro Fe_2O_3/Fe_3O_4 on the bioreduction of hexavalent chromium(Cr(VI)) and to evaluate the effects of nano-sized Fe_2O_3/Fe_3O_4 on the microbial communities from the anaerobic flooding soil.The results indicated that the net decreases upon Cr(VI) concentration from biotic soil samples amended with nano-sized Fe_2O_3(317.1 ± 2.1 mg/L) and Fe_3O_4(324.0 ± 22.2 mg/L) within21 days,which were approximately 2-fold of Cr(VI) concentration released from blank control assays(117.1 ± 5.6 mg/L).Furthermore,the results of denaturing gradient gel electrophoresis(DGGE) and high-throughput sequencing indicated a greater variety of microbes within the microbial community in amendments with nano-sized Fe_2O_3/Fe_3O_4 than the control assays.Especially,Proteobacteria occupied a predominant status on the phylum level within the indigenous microbial communities from chromium-contaminated soils.Besides,some partial decrease of soluble Cr(VI) in abiotic nano-sized Fe_2O_3/Fe_3O_4 amendments was responsible for the adsorption of nano-sized Fe_2O_3/Fe_3O_4 to soluble Cr(VI).Hence,the presence of nano-sized Fe_2O_3/Fe_3O_4 could largely facilitate the mobilization and biotransformation of Cr(VI) from flooding soils by adsorption and bio-mediated processes.     

2株苯胺降解的分离鉴定及其降解特性研究

从处理印染废水的活性污泥中分离得到2株苯胺降解菌,从菌落、细胞形态、生理生化及16S rRNA基因扩增测序等方面对2株菌进行了鉴定,并比较分析2株菌在好氧与缺氧条件下的苯胺降解、偶氮染料脱色及苯胺脱氨氧化酶基因tdnQ和黄素还原酶基因(fre)的携带情况.结果表明,2株菌属于Pseudomonas属和Shewanella属,分别命名为Pseudomonas sp.AN30和Shewanella sp.DN425.AN30菌株在振荡好氧条件下72h内对250mg/L苯胺的降解率为96.1%,DN425菌株的降解率为13.8%;在静置缺氧条件下AN30菌株的苯胺降解率为39.6%,DN425菌株的降解率仅为8.6%.DN425菌株在静置缺氧条件下4h内可将初始浓度为50 mg/L的偶氮染料酸性大红彻底脱色,而AN30菌株对酸性大红不具有脱色能力.以总DNA为模板,分别用tdnQ基因和fre基因特异性引物进行扩增,2株菌均能扩增出大小分别为380bp和630bp左右的目标条带,显示2菌株均携带有苯胺脱氨氧化酶基因和黄素还原酶基因.     

炼油厂活性污泥中硝化细菌富集条件优化及效果评价

为提高炼油厂废水中氨氮化合物的去除效率．对生物曝气池活性污泥中的硝化菌群进行培养条件优化和并富集培养。实验结果表明,在pH值为8．0,28℃环境,150r／min振荡暗培养条件下,通过不断添加富集培养基,经过6周培养后,可使湿泥中硝化细菌的数量增加24．95倍／g,硝化速率提高2．76倍,达到了富集的目的。     

Enhanced metronidazole removal by binary-species photoelectrogenic biofilm of microaglae and anoxygenic phototrophic bacteria

High efficient removal of antibiotics during nutriments recovery for biomass production poses a major technical challenge for photosynthetic microbial biofilm-based wastewater treatment since antibiotics are always co-exist with nutriments in wastewater and resist biodegradation due to their strong biotoxicity and recalcitrance. In this study, we make a first attempt to enhance metronidazole (MNZ) removal from wastewater using electrochemistry-activated binary-species photosynthetic biofilm of Rhodopseudomonas Palustris (R. Palustris) and Chlorella vulgaris (C. vulgaris) by cultivating them under different applied potentials. The results showed that application of external potentials of -0.3, 0 and 0.2 V led to 11, 33 and 26-fold acceleration in MNZ removal, respectively, as compared to that of potential free. The extent of enhancement in MNZ removal was positively correlated to the intensities of photosynthetic current produced under different externally applied potentials. The binary-species photoelectrogenic biofilm exhibited 18 and 6-fold higher MNZ removal rate than that of single-species of C. vulgaris and R. Palustris, respectively, due to the enhanced metabolic interaction between them. Application of an external potential of 0V significantly promoted the accumulation of tryptophan and tyrosine-like compounds as well as humic acid in extracellular polymeric substance, whose concentrations were 7.4, 7.1 and 2.0-fold higher than those produced at potential free, contributing to accelerated adsorption and reductive and photosensitive degradation of MNZ.     

大气环境下风电塔筒金属材料的应力腐蚀

塔筒金属材料在大气中的应力腐蚀会导致脆性断裂,从而对产生严重的后果。本文重点论述了应力腐蚀的几种腐蚀机理以及Cl-对应力腐蚀的影响,并介绍了应用较广的慢应力速率试验方法。     

Escherichia coli Concentrations in Urban Watersheds Exhibit Diurnal Sag: Implications for Water‐Quality Monitoring and Assessment

The variability of indicator bacteria over a fine resolution time scale on the order of minutes has yet to be fully understood. In this study, we collected more than 700 Escherichia coli samples at a 10‐ and 30‐min resolution in an urban watershed in Houston. A Bacteria Diurnal Sag (BDS) marked with daytime exponential decay followed by an exponential nighttime regeneration was observed. This pattern was observed during all sampled events but varied depending on other variables. The concentrations during a 24‐h period varied 1 to 5 orders of magnitude and the fecal load was at least 10 times lower than what would be obtained using a single morning E. coli measurement, the typical sampling scheme in most monitoring programs. Decay rates, ranging from 3.67 to 24.7/day, decreased E. coli concentrations to below the water‐quality standards from 14:00 to 18:00 h and were strongly influenced by water temperatures and solar radiation intensities. Rapid regeneration occurred on the order of 9.41 to 64.1/day allowing E. coli concentrations to return to their pre‐decay levels. The data indicated that four to six samples taken between 06:00 and 18:00 h may be sufficient to define the BDS depending on stream conditions, and that a threshold concentration of approximately 100 MPN/dl (most probable number in a deciliter) existed for the studied urban watershed. These findings have significant implications for water‐quality monitoring, regulation, and compliance.