45 research outputs found
Wastewater nutrient removal in a mixed microalgae bacteria culture: effect of light and temperature on the microalgae bacteria competition
[EN] The aim of this study was to evaluate the effect of light intensity and temperature on nutrient removal and biomass productivity in a microalgaeÂżbacteria culture and their effects on the microalgaeÂżbacteria competition. Three experiments were carried out at constant temperature and various light intensities: 40, 85 and 125¿”EÂżmÂż2ÂżsÂż1. Other two experiments were carried out at variable temperatures: 23¿±¿2°C and 28¿±¿2°C at light intensity of 85 and 125¿”EÂżmÂż2ÂżsÂż1, respectively. The photobioreactor was fed by the effluent from an anaerobic membrane bioreactor. High nitrogen and phosphorus removal efficiencies (about 99%) were achieved under the following operating conditions: 85Âż125¿”EÂżmÂż2ÂżsÂż1 and 22¿±¿1°C. In the microalgaeÂżbacteria culture studied, increasing light intensity favoured microalgae growth and limited the nitrification process. However, a non-graduated temperature increase (up to 32°C) under the light intensities studied caused the proliferation of nitrifying bacteria and the nitrite and nitrate accumulation. Hence, light intensity and temperature are key parameters in the control of the microalgaeÂżbacteria competition. Biomass productivity significantly increased with light intensity, reaching 50.5¿±¿9.6, 80.3¿±¿6.5 and 94.3¿±¿7.9ÂżmgVSSÂżLÂż1ÂżdÂż1 for a light intensity of 40, 85 and 125¿”EÂżmÂż2ÂżsÂż1, respectivelyThis research work was possible because of Projects CTM2011-28595-C02-01 and CTM2011-28595-C02-02 [funded by the Spanish Ministry of Economy and Competitiveness jointly with the European Regional Development Fund and the Generalitat Valenciana GVA-ACOMP2013/203]. 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Characterization and quantification of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in a nitrogen-removing reactor using T-RFLP and qPCR
Using ammonia monooxygenase α-subunit (amoA) gene and 16S rRNA gene, the community structure and abundance of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in a nitrogen-removing reactor, which was operated for five phases, were characterized and quantified by cloning, terminal restriction fragment length polymorphism (T-RFLP), and quantitative polymerase chain reaction (qPCR). The results suggested that the dominant AOB in the reactor fell to the genus Nitrosomonas, while the dominant AOA belonged to Crenarchaeotal Group I.1a in phylum Crenarchaeota. Real-time PCR results demonstrated that the levels of AOB amoA varied from 2.9âĂâ103 to 2.3âĂâ105 copies per nanogram DNA, greatly (about 60 times) higher than those of AOA, which ranged from 1.7âĂâ102 to 3.8âĂâ103 copies per nanogram DNA. This indicated the possible leading role of AOB in the nitrification process in this study. T-RFLP results showed that the AOB community structure significantly shifted in different phases while AOA only showed one major peak for all the phases. The analyses also suggested that the AOB community was more sensitive than that of AOA to operational conditions, such as ammonia loading and dissolved oxygen
A seasonal study of the mecA gene and Staphylococcus aureus including methicillin-resistant S. aureus in a municipal wastewater treatment plant
Community shift of ammonia-oxidizing bacteria along an anthropogenic pollution gradient from the Pearl River Delta to the South China Sea
The phylogenetic diversity and abundance of ammonia-oxidizing beta-proteobacteria (beta-AOB) was analyzed along an anthropogenic pollution gradient from the coastal Pearl River Delta to the South China Sea using the ammonia monooxygenase subunit A (amoA) gene. Along the gradient from coastal to the open ocean, the phylogenetic diversity of the dominant genus changed from Nitrosomonas to Nitrosospira, indicating the niche specificity by these two genera as both salinity and anthropogenic influence were major factors involved. The diversity of bacterial amoA gene was also variable along the gradient, with the highest in the deep-sea sediments, followed by the marshes sediments and the lowest in the coastal areas. Within the Nitrosomonas-related clade, four distinct lineages were identified including a putative new one (A5-16) from the different sites over the large geographical area. In the Nitrosospira-related clade, the habitat-specific lineages to the deep-sea and coastal sediments were identified. This study also provides strong support that Nitrosomonas genus, especially Nitrosomonas oligotropha lineage (6a) could be a potential bio-indicator species for pollution or freshwater/wastewater input into coastal environments. A suite of statistical analyses used showed that water depth and temperature were major factors shaping the community structure of beta-AOB in this study area
Application of hierarchical oligonucleotide primer extension (HOPE) to assess relative abundances of ammonia- and nitrite-oxidizing bacteria
Further studies of in situ corrosion testing of miniature copper-cast iron nuclear waste canisters
To ensure the safe disposal of spent fuel in Sweden, SKB is planning to use the copper-iron canister in a granitic deep geological repository, surrounded by a compacted bentonite engineered barrier. In order to develop a deeper understanding of the internal corrosion behaviour of the design should a leak occur in the outer copper canister, a set of model canisters was set up in the Ăspöunderground laboratory in contact with bentonite with a range of densities. The environmental conditions and electrochemical corrosion behaviour were monitored using a range of techniques. Water analysis and electrochemical measurements indicated an increase in the corrosion rate of both iron and copper in contact with low density bentonite, and of iron only in experiments with no bentonite present. This behaviour may be attributable to microbial activity. The measured corrosion rate depends on the technique used and it will be necessary to confirm the measurements by removal and examination of weight loss coupons. © 2011 Institute of Materials, Minerals and Mining
Children's understanding of quantity and their ability to use graphical information
SIGLEAvailable from British Library Document Supply Centre- DSC:D181913 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Involving High School Students in Computational Physics University Research: Theory Calculations of Toluene Adsorbed on Graphene
<div><p>To increase public awareness of theoretical materials physics, a small group of high school students is invited to participate actively in a current research projects at Chalmers University of Technology. The Chalmers research group explores methods for filtrating hazardous and otherwise unwanted molecules from drinking water, for example by adsorption in active carbon filters. In this project, the students use graphene as an idealized model for active carbon, and estimate the energy of adsorption of the methylbenzene toluene on graphene with the help of the atomic-scale calculational method density functional theory. In this process the students develop an insight into applied quantum physics, a topic usually not taught at this educational level, and gain some experience with a couple of state-of-the-art calculational tools in materials research.</p></div
The atomic structures of benzene, and the methylbenzenes toluene, para-xylene, and mesitylene.
<p>The student research project focuses on toluene (top right), whereas the continuation of the project involves also benzene and para-xylene (bottom left), the so-called BTX-family, as well as mesitylene (bottom right).</p