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Inhibitory effect of free ammonia on the activity of nitrifying bacteria and recoverability |
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Abstract In order to investigate the inhibition of free ammonia (FA) on nitrifying bacteria (ammonia-oxidizing bacteria, AOB and nitrite-oxidizing bacteria, NOB), after the nitrite pathway was stably achieved in an sequencing batch reactor (SBR) by synergetic interaction of FA and process control, the inhibitory effect of FA on AOB and NOB was investigated at different FA concentrations (1.0,5.3,16.6,13.4,9.9,5.2,1.0mg/L) levels. It demonstrated that, at FA concentration of 13.4mg/L, nitrite accumulation rate (NiAR) gradually increased, nitrate accumulation rate (NaAR) decreased, and chen the nitrite pathway was successfully established in the SBR. Further study showed that this level of FA had a certain inhibitory effect on the activity of AOB and NOB. Compared to AOB, NOB was more sensitive to FA. AOB activity could recovered quickly, while the NOB activity was completely inhibited all along. Thereafter, when the FA concentration was gradually decreased to 1.0mg/L (the lowest level in this study), AOB maintained good activity, however, the NOB activity had not recovered. Therefore, under the concentration of FA used in this experiment, AOB inhibition by FA was reversible, while NOB activity was non-reversible.
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Received: 04 April 2014
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