Rapid enrichment of anammox bacteria and transformation to partial denitrification/anammox with nitrification/denitrification sludge

• Published in: The Science of the total environment 2023-01, Vol.856, p.158973-158973, Article 158973
• Main Authors: Su, Yunlong, Peng, Yongzhen, Wang, Jiao, Zhang, Qiong, Li, Xiyao, Wang, Shuying, Xue, Xiaofei, Du, Rui
• Format: Article
• Language: English
• Subjects: Functional bacteria; Mainstream municipal wastewater treatment; Nitrite accumulation; Partial denitrification; Self-enrichment of anammox bacteria
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.158973

The stable nitrite (NO2−-N) generation and rapid startup of anammox-based process are the main bottlenecks hindering its application in mainstream municipal wastewater treatment. In this study, a Partial-Denitrification (PD) system reducing nitrate (NO3−-N) to NO2−-N was rapidly developed within 40 days, using the nitrification/denitrification sludge from wastewater treatment plant. The NO3−-N to NO2−-N transformation ratios achieved 80.6 %. Significantly, a fast self-enrichment of anammox bacteria in this system was subsequently obtained, resulting in the successful transformation to an efficient PD/Anammox (PD/A) process after 79-day operation. The total nitrogen removal efficiency increased from 12.4 % to 90.0 % with influent ammonia and nitrate of 45.9 mg N/L and 62.2 mg N/L, corresponding to the anammox activity significantly increasing to 6.0 mgNH4+-N/g VSS/h without seeding anammox sludge. Abundance of anammox increased from 6.7 × 108 to 2.0 × 1011 copies/g dry sludge. High-throughput sequencing results showed that Candidatus Brocadia was the only known anammox genus and accounted for 1.08 % during the PD/A stage. Functional bacteria for PD, assumed to be the Thauera, was enriched from 1.99 % to 60.06 % but decreased to 32.49 % during the improvement of anammox activity. It demonstrated that the PD system with stable NO2−-N accumulation enabled a rapid self-enrichment of anammox bacteria and sufficient nitrogen removal with ordinary nitrification/denitrification sludge. This provides new insights into the scaling application of anammox by integrating PD with shortened startup periods and improved TN removal efficiency. [Display omitted] •PD was established within 40 days with NO3− to NO2− of 80.6 % using excess sludge.•Anammox was significantly self-enriched in PD system by three orders of magnitude.•Increasing activity of Anammox facilitated efficient establishment of PD/A process.•Candidatus Brocadia was detected as a known anammox genus enriched in PD reactor.