Microbial community analysis in the autotrophic denitrification process using spent sulfidic caustic by denaturing gradient gel electrophoresis of PCR-amplified genes

2011 ◽  
Vol 63 (3) ◽  
pp. 475-483 ◽  
Author(s):  
J. -H. Lee ◽  
S. -M. Lee ◽  
G. -C. Choi ◽  
H. -S. Park ◽  
D. -H. Kang ◽  
...  

Spent sulfidic caustic (SSC) produced from petrochemical plants contains a high concentration of hydrogen sulfide and alkalinity, and some almost non-biodegradable organic compounds such as benzene, toluene, ethylbenzene and xylenes (BTEX). SSC is mainly incinerated with auxiliary fuel, leading to secondary pollution problems. The reuse of this waste is becoming increasingly important from economic and environmental viewpoints. To denitrify wastewater with low COD/N ratio, additional carbon sources are required. Thus, autotrophic denitrification has attracted increasing attention. In this study, SSC was injected as an electron donor for sulfur-based autotrophic denitrification in the modified Ludzack-Ettinger (MLE) process. The efficiencies of nitrification, COD, and total nitrogen (TN) removal were evaluated with varying SSC dosage. Adequate SSC injection exhibited stable autotrophic denitrification. No BTEX were detected in the monitored BTEX concentrations of the effluent. To analyse the microbial community of the MLE process, PCR-DGGE based on 16 S rDNA with EUB primers, TD primers and nirK gene with nirK primers was performed in order to elucidate the application of the MLE process to SSC.

2005 ◽  
Vol 52 (1-2) ◽  
pp. 115-121 ◽  
Author(s):  
M.L. Gong ◽  
N.Q. Ren ◽  
D.F. Xing

Start-up of a continuously stirred tank reactor for bio-hydrogen production under different initial organic loading rate (OLR) of 3, 7 and 10 kgCOD/m3 d, respectively, was carried out with sewage sludge as inoculum. Molasses wastewater was used as substrate and hydraulic retention time was kept at 6 h. This study aimed to assess OLR on the formation of fermentation types and the structure of microbial communities during the start-up period. It was found that at an initial OLR of 7 kgCOD/m3 d and an initial biomass of 6.24 gVSS/L, an equilibrial microbial community of ethanol-type fermentation could be established within 30 days. The observed average specific hydrogen production rate was 276 mLH2/gVSS d, which was 40% higher than that of the one acclimated with 3 kgCOD/m3 d. Based on denaturing gradient gel electrophoresis profiles, significant microbial population shifts took place at the first 15 days, but a longer period up to 30 days was required to establish a microbial community with stable metabolic activity.


2002 ◽  
Vol 46 (11-12) ◽  
pp. 93-98 ◽  
Author(s):  
S. Yoshie ◽  
N. Noda ◽  
T. Miyano ◽  
S. Tsuneda ◽  
A. Hirata ◽  
...  

The metallurgic wastewater generated from the processes of recovering precious metals from industrial wastes contains high concentrations of nitrogen compounds such as ammonia and nitric acid and of salts such as sodium chloride and sodium sulfate. Biological nitrogen removal from this wastewater was attempted by a circulating bioreactor system equipped with an anoxic packed bed and an aerobic fluidized bed. The anoxic packed bed of this system was found to effectively remove nitrite and nitrate from the wastewater by denitrification at a removal ratio of 97%. As a result of denitrification activity tests at various NaCl concentrations, the sludge obtained from the anoxic packed bed exhibited accumulation of nitrite at 5.0 and 8.4% NaCl concentrations, suggesting that the reduction of nitrite is the key step in the denitrification pathway under hypersaline conditions. The microbial community analysis by denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S ribosomal DNA (rDNA) fragments revealed that the community diversity varied in accordance with water temperature, nitrate-loading rate and ionic strength. When particular major DGGE bands were excised, reamplified and directly sequenced, the dominant species in the anoxic packed bed were affiliated with the beta and gamma subclasses of the class Proteobacteria such as Alcaligenes defragrans and Pseudomonas spp., respectively.


2000 ◽  
Vol 42 (3-4) ◽  
pp. 17-22 ◽  
Author(s):  
M. Onuki ◽  
H. Satoh ◽  
T. Mino ◽  
T. Matsuo

In the last decade, molecular biology has made significant progress, and innovative molecular methods have become available to analyze microbial community structures. Among them, we applied the FISH (Fluorescent in situ Hybridization) method to analyze activated sludge in wastewater treatment plants (WWTPs). As a result, domain- or division-level community structures in activated sludge were determined successfully without cultivation. We also applied the PCR (polymerase chain reaction) -DGGE (Denaturing Gradient Gel Electrophoresis) method for laboratory nitrifying sludge in order to investigate more detailed microbial community structure. By this method, genus- or species-level community structures were characterized well. This method was also found to be powerful for monitoring the change of microbial community structures. For example, the behavior of Nitrosomonas group was successfully detected in the reactor with nitrification by the PCR-DGGE method.


2000 ◽  
Vol 66 (12) ◽  
pp. 5488-5491 ◽  
Author(s):  
Robert I. Griffiths ◽  
Andrew S. Whiteley ◽  
Anthony G. O'Donnell ◽  
Mark J. Bailey

ABSTRACT A rapid protocol for the extraction of total nucleic acids from environmental samples is described. The method facilitates concomitant assessment of microbial 16S rRNA diversity by PCR and reverse transcription-PCR amplification from a single extraction. Denaturing gradient gel electrophoresis microbial community analysis differentiated the active component (rRNA derived) from the total bacterial diversity (ribosomal DNA derived) down the horizons of an established grassland soil.


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