Nitrification denitrification enhanced biological phosphorous removal (NDEBPR) occurs in a lab-scale alternating hypoxic/oxic membrane bioreactor

Strict anaerobic or anoxic maintenance of the system and process susceptibility to low organic loading are major concerns in nitrification denitrification enhanced biological phosphorous removal (NDEBPR). The study has initiated NDEBPR in a lab-scale alternating hypoxic/oxic membrane bioreactor by developing an enhanced mixed microbial culture capable of removing 97 ± 2% COD, 99 ± 0.84% NH3-N, 90 ± 3% TN, and 96 ± 1% TP- PO 4 3 - with 20-day SRT. The viable cells ranging from 1.6 × 108 to 2.0 × 108 cells/ml estimated from the total bacterial genomic DNA (6.43–7.83 μg DNA/ml) represented only 5% of the MLVSS indicating low microbial biomass concentration. Reducing the organic load from 1250 to 750 mg COD/ml as glucose did not deteriorate the effluent quality (3.77 ± 1.0 mg N-TN/l; 0.08 ± 0.24 mg NH3-N/l; and 0.32 ± 0.10 mg PO 4 3 - -P / l ). These observations are characteristics of activated sludge that harbors denitrifying polyphosphate accumulating organisms (DPAOs). The results showed that NDEBPR can be achieved under alternating hypoxic/oxic conditions.