Full nitrogen and phosphorus removal in the PASDEBPR system

• Published in: Bioresource technology reports 2024-02, Vol.25, p.101782, Article 101782
• Main Authors: Kamath, P., Rubio-Rincón, F.J., Brdjanovic, D., Lopez-Vazquez, C.M.
• Format: Article
• Language: English
• Subjects: Denitrification; Enhanced biological phosphorus removal; Microalgae-bacteria consortium; Nitrous oxide
• ISSN: 2589-014X; 2589-014X
• DOI: 10.1016/j.biteb.2024.101782

Photo-activated sludge (PAS) system aims to utilize microalgae to deliver oxygen for bacterial respiration, eliminating the need for external aeration. However, research on the treatment potential of PAS systems in the removal of nutrients is limited. In this context, a research study was devised to evaluate the possibility of developing a microalgae-bacteria consortium to achieve the simultaneous removal of organic carbon, nitrogen, and phosphorus. A successful PAS system capable of removing phosphorus was established at the end of the first phase, with an effluent phosphorus (P) concentration of 1.6 mg P L−1. In the subsequent stage, during the introduction of the nitrification-denitrification process, the system lost stability and deteriorated. Interestingly the system recovered via the sparging of nitrogen gas reaching effluent concentrations of 1.22 mg P L−1 and 0.88 mg N L−1. Thus, the system was capable of removing phosphorus and nitrogen via biological means without the need for external aeration. It is hypothesized that the inhibition caused was due to the production of a gaseous compound during the nitrification/denitrification process. [Display omitted] •Algae provided enough oxygen for the biological removal of nitrogen and phosphorus•Dark zones enhanced the simultaneous nitrification-denitrification process•Nitrous oxide plays a role in the inhibition of biological N and P removal