Hi Lin, my first thought was that you may be getting some anoxic conditions within the MLSS flocs at the lower DO levels, but it seems the literature does not support this theory. The fact that you get some nitrite in the higher DO conditions seems to imply the temperature of the wastewater is quite high (>25 degrees C), which may also affect other biological processes. Lastly, having a single mixed aerator is not normally ideal for nitrification. If possible try to install baffles to divide the reactor and obtain more of a plug flow condition, but test this out on a laboratory scale first. Best wishes
Published by Ian Pearson
Hi Lin, my first thought was that you may be getting some anoxic conditions within the MLSS flocs at the lower DO levels, but it seems the literature does not support this theory. The fact that you get some nitrite in the higher DO conditions seems to imply the temperature of the wastewater is quite high (>25 degrees C), which may also affect other biological processes. Lastly, having a single mixed aerator is not normally ideal for nitrification. If possible try to install baffles to divide the reactor and obtain more of a plug flow condition, but test this out on a laboratory scale first. Best wishes