Page 11 - Simplified Wastewater Treatment Fundamentals_BNR

Biological Nutrient Reduction (BNR)

BNR incorporates older sludge ages. BNR Sludge Retention Time (SRT) can be 6 to 20 or

more days. Older sludge age helps slower growing autotrophic bacteria populations

develop. Autotrophic bacteria feed on ammonia and other forms of nitrogen.

BNR treatment requires more than one community of organisms to remove nitrogen in all

of nitrogen’s available forms.

BNR F/M ratios are lower than carbon-based activated sludge (0.2 to 0.06) because there

are far more organisms needed to remove nutrients.