Alternative electron acceptors in microbial coal-conversion wastewater treatment

1996 ◽  
Vol 46 (5-6) ◽  
pp. 604-609 ◽  
Author(s):  
F. Eismann ◽  
F. Becker ◽  
P. Kuschk ◽  
U. Stottmeister
Keyword(s):  
Wastewater Treatment ◽  
Electron Acceptors ◽  
Coal Conversion

Quantification of functional groups in activated sludge by microautoradiography

2002 ◽  
Vol 46 (1-2) ◽  
pp. 389-395 ◽  
Author(s):  
J.L. Nielsen ◽  
P.H. Nielsen
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Functional Groups ◽  
Wastewater Treatment Plant ◽  
Municipal Wastewater ◽  
Heterotrophic Bacteria ◽  
Treatment Plant ◽  
Electron Acceptors ◽  
Ammonia Oxidizing Bacteria ◽  
Number Of Bacteria

Different functional groups of bacteria in activated sludge from a Danish municipal wastewater treatment plant were investigated and quantified on the basis of their ability to take up acetate under different electron acceptor conditions. The number of bacteria in the different functional groups was quantified by microautoradiography or by fluorescence in situ hybridization (FISH). Uptake of radiolabeled acetate was tested under conditions where oxygen, nitrate, ferric iron, and sulfate served as electron acceptors and under methanogenic conditions. Ammonia-oxidizing bacteria and nitrite-oxidizing bacteria were enumerated by applying oligonucleotide probes (FISH). 80% of the total DAPI count hybridised with a mixture of bacterial probes. Most baceria were able to take up acetate with oxygen or nitrate as electron acceptors (74 and 71% of all DAPI-stained bacteria, respectively). The very similar numbers indicate that the alternating aerobic and anoxic conditions in the wastewater treatment plant investigated favoured the presence of facultative aerobic and denitrifying heterotrophic bacteria. The number of bacteria able to take up acetate under anaerobic conditions was around 8% of the total DAPI count. About half of these were able to take up acetate and store it and were thus probably phosphate-accumulating organisms. The remaining 4% of anaerobic acetate-consuming bacteria were mainly iron reducers. By incubating the sludge samples with specific inhibitors against sulfate reduction and methanogenic activity, it was found that sulfate reducers and methanogenic bacteria constituted approximately 1% and less than 0.5% of the total DAPI count, respectively.

scholarly journals Integrated ‘omic’ analyses provide evidence that aCa. Accumulibacter phosphatis strain performs denitrification under micro-aerobic conditions

2018 ◽  
Author(s):  
Pamela Y. Camejo ◽  
Ben O. Oyserman ◽  
Katherine D. McMahon ◽  
Daniel R. Noguera
Keyword(s):  
Wastewater Treatment ◽  
Phosphorus Removal ◽  
Cost Effective ◽  
Transcript Abundance ◽  
Electron Acceptors ◽  
Nitrogen And Phosphorus ◽  
Aerobic Conditions ◽  
Anoxic Conditions ◽  
Omics Analysis ◽  
Accumulibacter Phosphatis

ABSTRACTThe unique and complex metabolism ofCandidatusAccumulibacter phosphatis has been used for decades for efficiently removing phosphorus during wastewater treatment in reactor configurations that expose the activated sludge to cycles of anaerobic and aerobic conditions. The ability of Accumulibacter to grow and remove phosphorus during cyclic anaerobic and anoxic conditions has also been investigated as a metabolism that could lead to simultaneous removal of nitrogen and phosphorus by a single organism. However, although phosphorus removal under cyclic anaerobic and anoxic conditions has been demonstrated, elucidating the role of Accumulibacter in this process has been challenging, since experimental research describes contradictory findings and none of the published Accumulibacter genomes show the existence of a complete pathway for denitrification. In this study, we use an integrated omics analysis to elucidate the physiology of an Accumulibacter strain enriched in a reactor operated under cyclic anaerobic and micro-aerobic conditions. The reactor’s performance suggested the ability of the enriched Accumulibacter (clade IC) to simultaneously use oxygen and nitrate as electron acceptors under micro-aerobic conditions. A draft genome of this organism was assembled from metagenomic reads (hereafter referred to as Accumulibacter UW-LDO-IC) and used as a reference to examine transcript abundance throughout one reactor cycle. The genome of UW-LDO-IC revealed the presence of a full denitrification pathway. The observed patterns of transcript abundance showed evidence of co-regulation of the denitrifying genes along with acbb3cytochrome, which is characterized as having high affinity for oxygen, thus supporting the hypothesis that UW-LDO-IC can simultaneously respire nitrate and oxygen. Furthermore, we identified an FNR-like binding motif upstream of the coregulated genes, suggesting transcriptional level regulation of the expression of both denitrifying and respiratory pathways in Accumulibacter UW-LDO-IC. Taken together, the omics analysis provides strong evidence that Accumulibacter UW-LDO-IC simultaneously uses oxygen and nitrate as electron acceptors under micro-aerobic conditions.IMPORTANCECandidatusAccumulibater phosphatis is widely found in full-scale wastewater treatment plants, where it has been identified as the key organism for biological removal of phosphorus. Since aeration can account for 50% of the energy use during wastewater treatment, micro-aerobic conditions for wastewater treatment have emerged as a cost-effective alternative to conventional biological nutrient removal processes. Our study provides strong genomics-based evidence that Accumulibacter is not only the main organism contributing to phosphorus removal under micro-aerobic conditions, but also that this organism simultaneously respires nitrate and oxygen in this environment, consequently removing nitrogen and phosphorus from the wastewater. Such activity could be harnessed in innovative designs for cost-effective and energy-efficient optimization of wastewater treatment systems.

Electronic structure studies of conducting polymers by electron energy-loss spectroscopy

1996 ◽  
Vol 54 ◽  
pp. 160-161
Author(s):  
J. Fink
Keyword(s):  
Electronic Structure ◽  
Conducting Polymers ◽  
Conjugated Polymers ◽  
Electron Acceptors ◽  
Electron Donors ◽  
Light Emitting ◽  
One Dimensional ◽  
New Class ◽  
Electrical Conductivities ◽  
Electron Energy Loss

Conducting polymers comprises a new class of materials achieving electrical conductivities which rival those of the best metals. The parent compounds (conjugated polymers) are quasi-one-dimensional semiconductors. These polymers can be doped by electron acceptors or electron donors. The prototype of these materials is polyacetylene (PA). There are various other conjugated polymers such as polyparaphenylene, polyphenylenevinylene, polypoyrrole or polythiophene. The doped systems, i.e. the conducting polymers, have intersting potential technological applications such as replacement of conventional metals in electronic shielding and antistatic equipment, rechargable batteries, and flexible light emitting diodes.Although these systems have been investigated almost 20 years, the electronic structure of the doped metallic systems is not clear and even the reason for the gap in undoped semiconducting systems is under discussion.

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