Abstract
Activated sludge samples were used to analyse microbial community structures from the anoxic and aerobic zones of a laboratory-scale modified Ludzack-Ettinger system. Fluorescent in situ hybridization and denaturing gradient gel electrophoresis were applied for analysis. With the help of DNA specific fluorochrome DAPI, approximately 75 to 80% of total cells were detected, hybridised with a specific eubacterial probe for the anoxic and aerobic zones. Results corroborate the dominance of the alpha and gamma subclasses of the Proteobacteria in the anoxic zone whilst the aerobic zone was dominated with the beta subclass of the Proteobacteria. Genetic diversity of the microbial community present in each of the anoxic and aerobic zones was employed by the DGGE technique. Results were obtained from the application of fluorescent in situ hybridisation (FISH) and PCR-DGGE yields a more precise understanding of the microbial community structure and genetic diversity present in domestic wastewater of a laboratory scale treatment process. Nitrogen mass balances indicated an upset in the nitrogen levels for wastewater batches two and seven. The carbon mass balance fell in the range of 92.4 and 105.9% and the nitrogen mass balance fell in the range of 98.4 and 160.0%. Key words: Fluorescent in situ hybridisation (FISH), denaturing gradient gel electrophoresis (DGGE), COD and nitrogen mass balances.
Highlights
The growth of the world population, the development of various industries and the use of fertilizers and pesticides in modern agriculture has overloaded the water resources and the atmosphere and the soil with pollutants (Shah et al, 2013)
These results suggest that a high denitrification potential of the modified Ludzack-Ettinger (MLE) process is prominent; complete denitrification is not possible due to the absence of secondary reactors, which is clearly shown in the effluent results
For each one thousand cells of Methanosaeta sp., there was just one single cell of Methanosarcina sp. present in the sludge. These results indicate that, the closed fermentation of POME led to the domination of Methanosaeta sp. in particular M. concilii emphasizing on the importance of the substrate
Summary
The growth of the world population, the development of various industries and the use of fertilizers and pesticides in modern agriculture has overloaded the water resources and the atmosphere and the soil with pollutants (Shah et al, 2013). Many factors can prevent the formation of the number and intensity of the bands in the DGGE gel, representing the exact number and abundance of species in a microbial community can be difficult DGGE is a sensitive and a rapid technique that detects most singe-base variations when a G-C clamp is added to one of the primers in the PCR process. This provides a profile of changes that occur within a microbial community or. A combination of molecular techniques, FISH and PCR-DGGE was used to monitor the microbial composition and examine the microbial community population shifts within a steady state laboratory-scale parent anoxic and aerobic activated sludge system
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