A novel shortcut nitrogen removal process using an algal-bacterial consortium in a photo-sequencing batch reactor (PSBR)

- Shortcut nitrogen removal process using an algal-bacterial consortium.
- Photo-sequencing batch reactor conditions produced high NO2− in light period.
- Uncoupling SRT and HRT process produced well settling biomass.
- Over 90% of total nitrogen was removed without aeration other than mixing.
- Potential treatment of high NH4+ strength wastewater with low energy inputs.

Removal of nitrogen from anaerobically digested swine manure centrate was investigated in a photo-sequencing batch reactor (PSBR) with alternating light and dark periods. Microalgal photosynthesis was shown to provide enough oxygen for complete nitritation during the light period. With addition of an organic carbon source during the dark period, the reactor removed over 90% total nitrogen (TN) without aeration other than by mixing. Overall, 80% of the TN removal was through nitritation/denitritation and the rest was due to biomass uptake. The high concentrations of ammonia and nitrite and low dissolved oxygen concentration in the PSBR effectively inhibited nitrite oxidizing bacteria, resulting in stable nitritation. The hybrid microalgal photosynthesis and shortcut nitrogen removal process has the potential to substantially reduce aeration requirements for treatment of anaerobic digestion side streams. The PSBR also produced well settling biomass with sludge volume index of 62 ± 16 mL mg−1.

Shortcut nitrogen removal using an algal-bacterial consortium.168