Investigation of bacterial and fungal communities in indoor and outdoor air of elementary school classrooms by 16S rRNA gene and ITS region sequencing

The advent of high-throughput sequencing methods allowed researchers to fully characterize microbial community in environmental samples, which is crucial to better understand their health effects upon exposures. In our study, we investigated bacterial and fungal community in indoor and outdoor air of nine classrooms in three elementary schools in Seoul, Korea. The extracted bacterial 16S rRNA gene and fungal ITS regions were sequenced, and their taxa were identified. Quantitative polymerase chain reaction for total bacteria DNA was also performed. The bacterial community was richer in outdoor air than classroom air, whereas fungal diversity was similar indoors and outdoors. Bacteria such as Enhydrobacter, Micrococcus, and Staphylococcus that are generally found in human skin, mucous membrane, and intestine were found in great abundance. For fungi, Cladosporium, Clitocybe, and Daedaleopsis were the most abundant genera in classroom air and mostly related to outdoor plants. Bacterial community composition in classroom air was similar among all classrooms but differed from that in outdoor air. However, indoor and outdoor fungal community compositions were similar for the same school but different among schools. Our study indicated the main source of airborne bacteria in classrooms was likely human occupants; however, classroom airborne fungi most likely originated from outdoors.     

强化生物脱氮分步进水型序批式反应器

介绍了分步进水型序批式反应器（SFSBR）工艺的运行方式、工艺特点、关键参数和研究进展，并分析了该工艺的应用前景。与传统SBR工艺相比，SFSBR反应阶段包含多个缺氧／厌氧-好氧子循环，并在各缺氧阶段始端进水，使进水中的有机物作为反硝化细菌碳源转化前一好氧阶段产生的硝态氮，提高了反硝化碳源补给率，强化了整个系统的生物脱氮能力。SFSBR工艺不仅适用于新建污水处理厂，而且适用于传统SBR工艺的改造和功能扩展，在实际工程中的推广应用可操作性强。     

聚季胺盐投加方式对厌氧污泥颗粒化的影响研究

投加阳离子聚合物是加速厌氧污泥颗粒化的有效方法,根据静态试验得出的聚季胺盐投加总量,选定了聚季胺盐的几种投加方式（不同的投加量和投加时间间隔）,研究其对实验室规模下的厌氧序批式反应器（ASBR）中污泥颗粒化的影响.试验以污水厂的厌氧污泥为对象,以污泥颗粒的粒径、沉速及出水COD等作为评价污泥颗粒化进程的指标,分析了各投加方式对污泥颗粒化进程的影响,并挑选出适宜的絮凝剂投加方式.结果表明,不同投加方式对ASBR污泥颗粒化进程有不同影响,建议采用每次投加量为0.16～0.32 mg/gMLSS,投加时间间隔为2～5 d,分5～10次投加的方式.     

Growth and control of filamentous microbes in activated sludge: an integrated hypothesis

Since its initial development and application, the activated sludge process has undergone a continual evolution aimed at maximizing process efficiency and controlling population selection. Organic loading rate, dissolved oxygen concentration and reactor configuration have been implicated as key process variables affecting sludge settleability, their combined effects determining which microbe or microbes are best able to grow and survive in a given system. Using available pure and mixed culture observations, a conceptual hypothesis centered around three model organisms has been developed to explain the growth and control of filamentous organisms in activated sludge. Organism selection in continuously fed systems has been hypothesized to be dominated by filamentous organisms with high sustainable growth rates at low reactor substrate concentrations/organic loading rates and filaments best able to compete for dissolved oxygen at elevated reactor substrate concentrations/organic loading rates. Intermittently fed systems, on the other hand, enrich for nonfilamentous organisms which both rapidly extract substrate from solution and maintain peak activity during extended periods of endogeneous metabolism. While both types of reactor induced feeding patterns can control filamentous organism growth, intermittently fed systems are capable of operation over a wider range of operating conditions by accentuating differences in organism physiology. Additional selection pressures such as substrate composition, non-ideal reactor hydraulics and time-variable influent waste streams were also discussed in relation to their impact on idealized systems.     

多层砖房震害预防方法的可靠性分析

对几种震害预测方法进行了回顾。对其中典型的不同的五种方法进行了地震动参数、抗力参数、修正系数、判别参数及方法性与可靠性进行了初步的对比研究。最后,对其中的4种方法运用层次分析法判断了它们之间的可靠程度并给出了可靠性排序。结果表明,这些方法对多层砖房震害预测结果的可靠程度差不多,其中高小旺提出的方法最为复杂,其可靠程度也最高。利用给出的排序结果,可以用作多种方法震害预测的结果评定的权系数。     

通过控制泥龄实现亚硝酸盐型同步硝化反硝化

采用序批式活性污泥法处理人工配制的城市生活污水，通过控制泥龄成功地实现了亚硝酸盐型同步硝化反硝化，曝气过程中NO2^-N／NOx^-N值始终保持在84．48％以上，曝气结束时大约有80．39％的氨氮通过同步硝化反硝化途径被去除。在适宜的曝气量下，利用排泥的方法控制反应器内适宜的泥龄，可以实现稳定的亚硝酸盐型同步硝化反硝化。     

Sequencing Batch Reactor Technology: Concepts, Design and Experiences (Abridged)

The sequencing batch reactor is a specific fill-and-draw version of the activated-sludge process. In contrast to the continuous-flow alternative, metabolic reactions and solid-liquid separation are carried out in one tank and in a well-defined and continuously repeated time sequence.
This paper reviews the historical development of sequencing batch reactor technology and describes the different modes of operation. Mass-balance equations are introduced to allow for a quantitative comparison of sequencing batch reactor and continuous-flow technologies and for the design of such systems. The initial design dynamic simulation and in-situ adjustment of the cycle program under the actual process conditions can be used conveniently to further optimize the sequencing batch reactor plant.     

好氧MBR与序批式MBR处理生活污水的比较

比较了中试规模的好氧式膜生物反应器及序批式膜生物反应器处理生活污水的效果。结果表明，两者对COD及氨氮的去除效果相当，且都具有良好的抗冲击负荷能力；在总氮去除上，序批式膜生物反应器优于好氧式膜生物反应器；在稳定运行阶段，当好氧式膜生物反应器及序批式膜生物反应器处理同等水量时，过膜阻力增加率分别为1．68和1．03kPa／m。通过测定膜丝上多糖的含量分析了两者在膜污染速率上存在差异的原因，发现序批式膜生物反应器膜丝上的多糖含量要少于好氧式膜生物反应器。     

用厌氧产氢反应器出水培养好氧颗粒污泥的研究

以厌氧产氢反应器出水为底物，在序批式反应器中研究了好氧颗粒污泥的培养过程。结果表明，以厌氧产氢反应器出水为底物，在60d内能够培养出粒径大、沉降性能优异且对污染物去除能力强的好氧颗粒污泥。在活性污泥的颗粒化过程中，伴随着污泥体积指数的减小。污泥的粒径和沉速增大，反应器内的污泥浓度增加，从而提高了反应器的处理效能。