Hi Felipe, Biological oxygen ...

Hi Felipe, Biological oxygen demand removal and nitrification is normally done in the same basin, although the biological oxygen demand will essentially be satisfied first before nitrification will commence. If the hydraulic retention is too short, all the BOD may not be removed and nitrification will not happen (typical hydraulic retention would be in the order of 20 hours for domestic sewage depending on process configuration). Nitrification is subject to possible inhibition by some pollutants and is sensitive to temperature. Low temperatures will required a longer sludge age. With temperatures in the region of 15C to 25C typical sludge age could be in the order of 6 -12 days (high temp) to 12-20 days (low temp) depending on other nitrification inhibitors (inhibition more probable in industrial type effluents), MBBR should assist nitrification due to the fact that a nitrifying culture could establish on the media and counteract lack of nitrification due to short sludge ages in conventional mixed liquor suspended solids activated sludge units,