Dynamic model of algal-bacterial shortcut nitrogen removal in photo-sequencing batch reactors

This study investigated algal-bacterial shortcut nitrogen removal (SNR) in photo-sequencing batch reactors (PSBRs) for treatment of high ammonium strength wastewater using both experimental and modeling approaches. Bench-scale PSBR studies were carried out under alternating light and dark cycles, provided aerobic and anoxic conditions that promoted nitritation/ denitritation. Total nitrogen removal efficiencies >90% were achieved when favorable operating conditions, including solids retention time (SRT) and organic and inorganic carbon availability, were applied for the functional microorganisms. A dynamic model was developed to simulate conversions of species and the activity of algae, ammonia oxidizing, nitrite oxidizing and heterotrophic bacteria. In addition, biomass wasting during each cycle was estimated by the model to maintain the targeted SRT. The model was able to capture the dynamics of nitrogen removal, substrate utilization and biomass generation under varying operating conditions and can potentially be used for large scale PSBR design and optimization.