Stability and microbial community structure of a partial nitrifying fixed-film bioreactor in long run.
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.
Wastewater Technology Division, National Environmental Engineering Research Institute, Council of Scientific and Industrial Research, Nagpur, India. ra_biswas@neeri.res.in
Rima
R
Biswas
Samik
S
Bagchi
Priyanka
P
Bihariya
Arnab
A
Das
Tapas
T
Nandy
D001420:Bacteria, Aerobic / Q000145:classification* / Q000302:isolation & purification / Q000378:metabolism*; D057919:Biological Oxygen Demand Analysis / Q000379:methods*; D019149:Bioreactors / Q000382:microbiology*; D008567:Membranes, Artificial; D009584:Nitrogen / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*
D008567:Membranes, Artificial; D009584:Nitrogen; D010100:Oxygen