Stability and microbial community structure of a partial nitrifying fixed-film bioreactor in long run |
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Authors: | Biswas Rima Bagchi Samik Bihariya Priyanka Das Arnab Nandy Tapas |
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Institution: | a Wastewater Technology Division, National Environmental Engineering Research Institute, Council of Scientific and Industrial Research, Nagpur-440020, India b Germplasm Evaluation Division, National Bureau of Plant Genetic Resources (IARI), PUSA Campus, New Delhi-110012, India |
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Abstract: | A partial nitrification system was investigated for 471 days under DO varying concentrations for assessing its stability and population dynamics. Within 130 days of operation at feed DO concentration of 1.0 ± 0.1 mg/L, more than 85% of nitrite was accumulated. Efficiency deteriorated when the feed DO concentration was increased to 4.2 ± 0.3 mg/L. Nitrite accumulation could not be re-established on decreasing feed DO to 1.0 ± 0.1 mg/L. Even at DO concentration of <0.05 mg/L, nitrate production was observed; a condition termed as anoxic nitrification. NOB was detected in the biomass even under this condition by Fluorescence in-situ hybridization (FISH) analysis. Through 16S rRNA gene sequencing a major fraction of unknown bacterial sequences closely resembling haloalkalophilic bacteria of marine origin were detected. The study indicated that these bacterial species might play a role in anoxic nitrification and that NOB could survive extreme low DO condition. |
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Keywords: | Partial nitrification Dissolved oxygen FISH 16S rRNA gene sequencing |
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