微纳米曝气技术对城市景观水体修复的影响

以微纳米曝气为主要曝气方式,鼓风微孔曝气方式作对比,处理广西大学东校园景观湖湖水,考察微纳米曝气方式在污染景观水体中氧传质系数变化及其对污染物的去除效果。结果表明,对污染景观水体曝气过程中,微纳米曝气氧总体积传质系数高于鼓风微孔曝气,且与景观水的污染程度成负相关。微纳米曝气具有很好的氧传递性,平均气含率为1.09%。该曝气法对污染景观水体中多种污染物有良好的去除效果,实验结束时,微纳米曝气对化学需氧量(COD)、总磷(TP)、氨氮(NH_4~+-N)和总氮(TN)的去除率分别为67.59%、17.30%、70.20%和66.75%,水体中叶绿素a上升了14.03%,是一种有效改善景观水体水质的曝气方式。     

扬水曝气技术对周村水库藻类的控制

扬水曝气作为湖泊、水库水体修复技术之一,在国内多个水源水库水质改善工程中得到应用。为进一步研究扬水曝气技术对湖库藻类的控制效果及其机理,在对北方温带季节性分层水库-周村水库垂向水体的理化指标及藻类参数进行常年监测的基础上,于2015年8月—9月扬水曝气运行前后对垂向水体理化指标及浮游植物生物量、群落结构及丰度进行了连续监测和对比分析。结果表明,扬水曝气破坏了水体分层,藻类生物量锐减,多样性水平提高,藻类密度垂向差异消失,优势种群由威胁性较大的蓝藻、绿藻变为威胁性较小的硅藻,水体生态状况良好。扬水曝气系统对氮营养盐含量、热分层结构和光照条件的影响是促进了藻类群落结构改变的主要原因。     

黑藻根际对沉积物中氨氧化细菌和古菌的影响

氨氧化反应对水生态系统氮循环和氮的去除有重要作用,沉水植物通过根系泌氧促进沉积物中硝化反应并对氨氧化细菌和古菌的分布产生影响。本研究以轮叶黑藻为实验对象,利用微电极研究沉积物-水界面的溶解氧变化,研究了黑藻根系对沉积物中氨氧化细菌和古菌数量的影响。结果表明,黑藻通过根系泌氧增加沉积物-水界面的溶解氧量和表层沉积物有氧层厚度,有氧层厚度增加了3 mm以上;种植黑藻后,根际沉积物中氨氧化细菌数量逐渐增加,氨氧化古菌数量前30天增加随后减少,氨氧化细菌与氨氧化古菌amoA基因拷贝数的比值由0.51增加到6.75,说明黑藻根际沉积物更适宜氨氧化细菌的生存。     

Biostyr曝气生物滤池的沿程微生物多样性

采用高通量测序Illumina MiSeq方法对Biostyr曝气生物滤池(BAF)沿程微生物多样性进行研究,分析了滤池内不同高度样品中菌群类别、群落组成及不同样品间物种差异及进化关系等;同时测定各高度样品的COD、NH_4~+-N和磷变化规律,与微生物特性进行了对应性分析。结果表明,Biostyr曝气生物滤池优势菌群主要为拟杆菌、疣微菌门、厚壁菌门和变形菌门,滤池沿程微生物的变化主要表现在数量上的变化,而群落结构的变化不明显,这是沿程理化条件变化引发微生物在空间上发生变化的结果。     

陕北石油污染区土壤细菌群落结构解析

为了解陕北地区石油污染对土壤微生物群落结构的影响,采用高通量测序对石油污染土壤中细菌群落结构进行研究,考察了石油污染土样的理化性质、可培养微生物数量及细菌群落结构,探讨石油污染程度与细菌群落结构间的关系。结果表明,石油污染土样中残油量为28.7~870.0mg/kg,相对于未污染土样,石油污染土样的总碳随残油量的增加呈增加趋势。石油污染土样中可培养细菌数量大于未污染土样,而可培养放线菌数量则相反。细菌群落结构分析表明,石油污染土样中细菌群落数量显著低于未污染土样,操作分类单元(OTU)数从未污染土样的7 707个最低下降到2 034个,且物种丰富度显著降低,其中厚壁菌门、放线菌门及变形菌门为优势菌群,随土壤残油量增加,厚壁菌门、变形菌门及拟杆菌门比例显著上升,而酸杆菌门、芽单胞菌门等比例则显著降低。     

京杭运河杭州段水体污染和细菌群落结构特征

为了解人类活动对城市河道水体污染和细菌群落的影响,选取京杭运河杭州段进行了分季节采样研究。测定了水体的环境与水质参数,分析了细菌丰度、胞外酶活性和群落结构变化。结果显示,从上游到下游,水体中高锰酸盐指数、氨氮、总氮以及细菌丰度和β-葡萄糖苷酶活性大体呈递增趋势,冬季水体总体污染水平及细菌丰度均显著高于其他季节。水体中细菌的主要种类集中在变形菌门(Proteobacteria)、放线菌门(Actinobacteria)、拟杆菌门(Bacterioidetes)、厚壁菌门(Firmicutes)和蓝藻门(Cyanobacteria),所占比例分别为37.8%、24.3%、18.9%、10.8%和8.1%,属于黄杆菌(Flavobacterium)、厚壁菌(Firmicutes bacterium)和放线菌(Actinobacterium)的细菌是水体中大多数时间的优势细菌。限制性排序分析显示,水体细菌群落结构从上游到下游差异明显,高锰酸盐指数和总氮是关键影响因子。杭州市区由人类活动产生的污染物输入是京杭运河杭州段的主要污染源,水体细菌群落对水体污染物的变化有着明显的响应。     

光合产电微生物群落构建及光照培养对其产电性能的影响

采用淡水沉积物为接种来源,培养出光合产电微生物群落。将其与藻阴极联用组建了完整的光合作用微生物燃料电池时,功率密度达到(157.5±3.1)m W/m2。采用循环伏安法及电化学阻抗谱对该群落的电化学性能进行了测试。PCR-DGGE及紫外可见吸收光谱分析显示,该群落含有Ectothiorhodospiraceae科及Chloroflexi门不产氧光合细菌、产电菌Arcobacter butzleri、发酵细菌及其他细菌。对该群落进行长期黑暗培养或长期光照培养时,其产电性能均得到了提高,但功率密度测试显示,光照培养微生物燃料电池最大功率密度为(180.1±8.7)m W/m2,高于黑暗培养的微生物燃料电池(160.7±11.4)m W/m2。电化学测试也显示,光照培养的阳极产电性能优于黑暗培养的阳极。     

处理畜禽废水的序批式生物膜反应器中的细菌多样性

采用序批式生物膜反应器(SBBR)处理畜禽废水,在室温(9～18℃)下,采用8 h/周期、交替停曝气的模式运行,控制曝气阶段DO浓度在2 mg/L,可实现明显的亚硝酸盐积累,氨氮及总氮的去除率分别可达(95.1±0.8)%和(87.2±0.6)%。为揭示SBBR中细菌种群构成及其动态变化规律,采用PCR-DGGE技术进行了细菌多样性分析,并构建了系统发育树,结果表明:与接种污泥相比,驯化期生物膜中细菌种群丰富度未发生明显变化,运行期交替曝气、停曝模式有助于提高生物膜中细菌的多样性指数,但受运行模式及氨氮负荷变化影响,运行期氨氧化菌多样性指数略低于驯化期;生物膜内存在一些具有反硝化功能的变形菌和特殊的氨氧化细菌,在本实验条件下未发现厌氧氨氧化菌,说明主要脱氮机理为同时短程硝化反硝化。     

饮用水管网生物膜细菌群落特征及其对腐蚀的影响

通过454高通量测序对北方A和B两实际饮用水管网系统中生物膜细菌群落特征进行表征,并研究了其对管网腐蚀产物组成的影响。结果表明,A管网生物膜细菌群落丰度和多样性高于B管网生物膜。在门水平上,两管网生物膜细菌群落主要为变形菌门Proteobacteria,但B管网生物膜中的相对丰度(67.10%)高于A(46.50%)。在纲水平上,A管网生物膜主要为β-变形菌纲Betaproteobacteria,B管网生物膜中主要为β-变形菌纲Betaproteobacteria和δ-变形菌纲Deltaproteobacteria。在属水平上,A管网生物膜中腐蚀相关菌群主要为硝酸盐还原菌和铁还原菌,其腐蚀产物主要为α-Fe OOH和Fe_3O_4,而B管网生物膜中硫酸盐还原菌特别是脱硫弧菌属Desulfovibrio含量较高,其可能与管垢中绿锈含量高有关。     

抗生素菌渣堆肥进程中微生物群落的变化

将青霉素菌渣、林可霉素菌渣与牛粪等原料分别进行好氧堆肥实验,以考察堆肥过程中不同菌渣对微生物群落的影响。在堆制的41d里,根据温度变化分阶段采集堆肥样品,采用稀释倒平板法测定细菌、放线菌和真菌的数量。结果表明,菌渣不同,其堆肥中的微生物群落变化趋势不同。青霉素菌渣堆肥中细菌数量变化趋势为高一低,真菌数量变化趋势为高一低．高,放线菌数量为逐渐增加;林可霉素菌渣堆肥过程中细菌数量变化趋势为低一高一低,放线菌和真菌数量变化趋势为高．低．高。依据真菌菌落形态观察,菌渣堆肥中的真菌种类比对照牛粪堆肥单一,表明两种菌渣对堆肥中的微生物多样性均产生了不利影响。林可霉素菌渣堆肥初始时的细菌数量比对照低1个数量级,放线菌数量在整个堆肥进程中都明显低于对照,堆肥结束时,随着菌渣含量的增加,放线菌数量逐渐下降,高温期真菌数量下降幅度随着菌渣含量增加而加大,表明林可霉素菌渣对细菌、放线菌和真菌均有不同程度的抑制。堆肥化后菌渣中林可霉素残留量的减少表明,在一定条件下堆肥处理可以将抗生素菌渣无害化和资源化。     

Photocatalytic bacterial inactivation by polyoxometalates

The photocatalytic inactivation (PCI) of Escherichia coli (Gram-negative) and Bacillus subtilis (Gram-positive) was performed using polyoxometalate (POM) as a homogeneous photocatalyst and compared with that of heterogeneous TiO₂ photocatalyst. Aqueous suspensions of the microorganisms (10⁷–10⁸ cfu ml⁻¹) and POM (or TiO₂) were irradiated with black light lamps. The POM-PCI was faster than (or comparable to) TiO₂-PCI under the experimental conditions employed in this study. The relative efficiency of POM-PCI was species-dependent. Among three POMs (H₃PW₁₂O₄₀, H₃PMo₁₂O₄₀, and H₄SiW₁₂O₄₀) tested in this study, the inactivation of E. coli was fastest with H₄SiW₁₂O₄₀ while that of B. subtilis was the most efficient with H₃PW₁₂O₄₀. Although the biocidal action of TiO₂ photocatalyst has been commonly ascribed to the role of photogenerated reactive oxygen species such as hydroxyl radicals and superoxides, the cell death mechanism with POM seems to be different from TiO₂-PCI. While TiO₂ caused the cell membrane disruption, POM did not induce the cell lysis. When methanol was added to the POM solution, not only the PCI of E. coli was enhanced (contrary to the case of TiO₂-PCI) but also the dark inactivation was observed. This was ascribed to the in situ production of formaldehyde from the oxidation of methanol. The interesting biocidal property of POM photocatalyst might be utilized as a potential disinfectant technology.     

Characteristics of penicillin bacterial residue

IMPLICATIONS: During the production of penicillin, a mass of waste bacterial residue is generated. In the past, the bacterial residues have been used for food additives. Unfortunately, doubts of their suitability as a feedstock have been raised because of the small amount of antibiotics and the degradation products remaining in the bacterial residues. So, penicillin bacterial residue is one of the hazardous wastes. Therefore, penicillin bacterial residue should be managed in accordance with the hazardous waste. To get a right method, the penicillin bacterial residue was characterized.     

Characteristics of penicillin bacterial residue

A hybrid selective noncatalytic reduction/selective catalytic reduction (SNCR/SCR) system that uses two types of technology, low-temperature SCR process and SNCR process, was designed to develop nitrogen oxide (NO_x) reduction technology. SCR was conducted with space velocity (SV) = 2400 hr^?1 and hybrid SNCR/SCR with SV = 6000 hr^?1, since the study focused on reducing the amount of catalyst and both achieved 98% NO_x reduction efficiency. Characteristics of NO_x reduction by NH₃ were studied for low-temperature SCR system at 150 °C using Mn-V₂O₅/TiO₂ catalyst. Mn-added V₂O₅/TiO₂ catalyst was produced, and selective catalyst reduction of NO_x by NH₃ was experimented. NO_x reduction rate according to added Mn content in Mn-V₂O₅/TiO₂ catalyst was studied with varying conditions of reaction temperature, normalized stoichiometric ratio (NSR), SV, and O₂ concentration. In the catalyst experiment according to V₂O₅ concentration, 1 wt.% V₂O₅ catalyst showed the highest NO_x reduction rate: 98% reduction at temperature window of 200~250 °C. As a promoter of the V₂O₅ catalyst, 5 wt.% Mn was added, and the catalyst showed 47~90% higher efficiency even with low temperatures, 100~200 °C. Mn-V₂O₅/TiO₂ catalyst, prepared by adding 5 wt.% Mn in V₂O₅/TiO₂ catalyst, showed increments of catalyst activation at 150 °C as well as NO_x reduction. Mn-V₂O₅/TiO₂ catalyst showed 8% higher rate for NO_x reduction compared with V₂O₅/TiO₂ catalyst in 150 °C SCR. Thus, (5 wt.%)Mn-(1 wt.%)V₂O₅/TiO₂ catalyst was applied in SCR of hybrid SNCR/SCR system of low temperature at 150 °C. Low-temperature SCR hybrid SNCR/SCR (150 °C) system and hybrid SNCR/SCR (350 °C) showed 91~95% total reduction rate with conditions of SV = 2400~6000 hr^?1 SCR and 850~1050 °C SNCR, NSR = 1.5~2.0, and 5% O₂. Hybrid SNCR/SCR (150 °C) system proved to be more effective than the hybrid SNCR/SCR (350 °C) system at low temperature.

Implications:?NO_x control is very important, since they are the part of greenhouse gases as well as the cause of acid rain and ozone hole. A technology, so-called hybrid SNCR/SCR process, was tested using Mn-V₂O₅/TiO₂ monolithic catalyst for NO_x reduction, and the method is promising. The results of this study would provide some ideas to parties such as policy makers, environmental engineers, and so on.     

一株有机浮选药剂——黄原酸盐降解菌的特性研究

从矿山废水中经富集分离到一株能以黄原酸盐为惟一碳源的黄原酸盐降解菌，初步鉴定为铜绿假单胞菌属。菌株降解黄原酸盐的最佳条件为：pH为8，温度30℃，振荡速率120r／min。当黄原酸盐浓度达到1500mg／L时，24h后浓度降解率为95．7％，COD去除率为84．7％。黄原酸盐浓度越高，COD去除率越高。当加入0．2g／L的葡萄糖时可大大提高菌对黄原酸盐的降解率。     

一株有机浮选药剂--黄原酸盐降解菌的特性研究

从矿山废水中经富集分离到一株能以黄原酸盐为惟一碳源的黄原酸盐降解菌,初步鉴定为铜绿假单胞菌属.菌株降解黄原酸盐的最佳条件为:pH为8,温度30℃,振荡速率120 r/min.当黄原酸盐浓度达到1500 mg/L时,24 h后浓度降解率为95.7%,COD去除率为84.7%.黄原酸盐浓度越高,COD去除率越高.当加入0.2 g/L的葡萄糖时可大大提高菌对黄原酸盐的降解率.     

Cyanide detoxification by recombinant bacterial rhodanese

Cyanide is a major environmental pollutant of the chemical and metallurgical industries. Although extremely toxic, cyanide can enzymatically be converted to the less toxic thiocyanate by rhodaneses (thiosulfate:cyanide sulfurtransferases, EC 2.8.1.1). We engineered a genetic system to express high levels of recombinant Pseudomonas aeruginosa rhodanese (r-RhdA) in Escherichia coli, and used this organism to test the role of r-RhdA in cyanide detoxification. Inducible expression of the rhdA gene under the control of the hybrid T7-lacO promoter yielded active r-RhdA over a 4-h period, though r-RhdA-expressing E. coli showed decreased viability starting from 1 h post-induction. At this time, Western blot analysis and enzymatic assay showed r-RhdA partition between the cytoplasm (95%) and the periplasm (5%). The accessibility of thiosulfate to r-RhdA was a limiting step for the sulfur transfer reaction in the cellular system, but cyanide conversion to thiocyanate could be increased upon permeabilization of the bacterial membrane. Specific r-RhdA activity was higher in the whole-cell assay than in the in vitro assay with pure enzyme (2154 vs. 816 micromol min-1 mg-1 r-RhdA, respectively), likely reflecting enzyme stability. The r-RhdA-dependent cyanide detoxification resulted in increased resistance of r-RhdA overexpressing E. coli to 5 mM cyanide. Bacterial survival was paralleled by release of thiocyanate into the medium. Our results indicate that cyanide detoxification by engineered E. coli cells is feasible under laboratory conditions, and suggest that microbial rhodaneses may contribute to cyanide transformation in natural environments.     

Study of bacterial activity in fabricated soils

Fabricated Soil (FS) is a natural mixture of decaying substrates rich in alumni silicate, carbon, nitrogen, phosphorus and potassium sources. This substrate usually is used for landscape rehabilitation and is an excellent source and example of environmental remediation. The structure and function of the soil food web have been suggested as prime indicators of ecosystem health (Coleman et al., 1992; Coleman, 1985; Kalevitch et al., 2004a, 2004b). Measurement of disrupted soil processes and decreased bacterial or fungal activity, along with other parameters, can serve to indicate a problem long before the natural vegetation is lost or human health problems occur (Bongers, 1990; Kalevitch et al., 2003). Fabricated soils could be a solution to the problem of soil erosion.     

Characterization of bacterial communities at heavy-metal-contaminated sites

The microbial community in soil samples from two long-term contaminated sites was characterized by using culture-dependent and culture-independent methods. The two sites investigated contained high amounts of heavy metals and were located in the upper Silesia Industrial Region in southern Poland. The evaluation of the aerobic soil microbial population clearly demonstrated the presence of considerable numbers of viable, culturable bacteria at both sites. A high fraction of the bacterial population was able to grow in the presence of high amounts of metals, i.e. up to 10 mM Zn²⁺, 3 mM Pb²⁺ or 1 mM Cu²⁺. Site 1 contained significantly (P < 0.05) lower bacterial numbers growing in the presence of 10 mM Zn²⁺ than site 2, while the opposite was observed for bacteria tolerating 1 mM Cu²⁺. This coincided with the contents of these two metals at the two sites. Ecophysiological (EP) indices for copiotrophs (r-strategists) and oligotrophs (K-strategists) pointed to high bacterial diversity at both sites. Fluorescence in situ hybridization (FISH) analysis indicated that Actinobacteria and Proteobacteria represent the physiologically active fraction of bacteria at the two sites. Shannon diversity (H′) indices for FISH-detected bacterial phylogenetic groups were not significantly different at the two sites.