Distinct comammox Nitrospira in high-rate down-flow hanging sponge reactor treating municipal wastewater

• Published in: Bioresource technology 2024-09, Vol.408, p.131160, Article 131160
• Main Authors: Watari, Takahiro, Kirishima, Yoshihiro, Choeisai, Pairaya, Thepubon, Thanapat, Hirakata, Yuga, Matsueda, Takashi, Nagano, Akihiro, Yamaguchi, Tsuyoshi, Okubo, Tsutomu, Hatamoto, Masashi, Yamaguchi, Takashi
• Format: Article
• Language: English
• Subjects: biomass; Complete ammonia oxidation; genes; municipal wastewater; Nitrification; Sewage treatment; Sponge-based trickling filter; wastewater treatment
• ISSN: 0960-8524; 1873-2976; 1873-2976
• DOI: 10.1016/j.biortech.2024.131160

[Display omitted] •The downflow hanging sponge reactor was operated with a short HRT.•HRT of 0.5 h was effective for high organic removal and nitrification efficiency.•Comammox bacteria are capable of enhancing nitrification in high-rate DHS reactors. A down-flow hanging sponge (DHS) reactor is a trickling filter system used for wastewater treatment, which employs sponges to retain biomass. This study assessed the process performance of a compact DHS combined with a sedimentation tank with seven phases at varying hydraulic retention times (HRT) over 500 days. The BOD of the DHS effluent was maintained at 4.0 ± 0.5 mg·L-1 for the shortest HRT 0.3 ± 0.1 h. The nitrification efficiency was considerably impacted by the reduced HRT, with NH4+-N and NO3–-N concentrations of 9.0 ± 1.2 mgN·L-1 and 2.2 ± 0.5 mgN·L-1, respectively. Nevertheless, the effluent complied with effluent discharge standards throughout the trial period. The number of comammox 16S rRNA gene copies ranged from 5.58 to 13.2 × 107 copies·mL−1, indicating that sponges biomass retained carrier can provide favorable conditions for comammox growth and could contribute to nitrification in the high-rate DHS reactor.