Biological Nitrogen Removal in a Photosequencing Batch Reactor with an Algal-Nitrifying Bacterial Consortium and Anammox Granules

This study demonstrates the feasibility of combining microalgae, ammonia-oxidizing bacteria (AOB), and Anammox in a photosequencing batch reactor. Alternating light and dark periods were applied to achieve biological nitrogen removal without mechanical aeration or external electron donor addition. This process is termed ALGAMMOX (algal anaerobic ammonium oxidation) and differs from the SHARON-Anammox process in that oxygen is generated during light periods through microalgal photosynthesis, replacing mechanical aeration. Results from bench-scale ALGAMMOX experiments with high-ammonia strength wastewater (COD/TN from 1 to 3) showed that influent ammonia was converted to nitrite during light periods at a rate of 7.0 mg of NH₄ ⁺-N L^-1 h^-1. Nitrite was subsequently reduced by an average of 82% during the dark (anoxic) periods due to Anammox activity. Further studies are needed to optimize the system to maximize nitrogen removal rates and to assess long-term process stability.