A novel anammox granules-circulating expanded granular sludge bed reactor for the efficient circulation and retention of floating anammox granules. (November 2019)

• Record Type: Journal Article
• Authors: Ni, Lingfeng; Lin, Ximao; Yan, Hexiang; Wang, Yayi
• Is Part Of: Chemosphere. Volume 235(2019)
• Page Start: 316
• Page End: 326
• Publication Date: 2019-11
• Subjects: Anammox granules -- Granules floatation -- Expanded granular sludge bed reactor -- Three-phase separator -- Sludge circulation; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2019.06.176
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: In application of anammox process, the operation of the conventional expanded granular sludge bed reactor (EGSBconv. ) is severely limited by the blocking and decay of floating anammox granules.To address this emerging issue, a novel three-phase separator configuration was designed and an anammox granules circulating EGSB (EGSBGC ) was proposed in this study. In the EGSBGC, an influent scour on floating granules, whose effect was confirmed by simulation with a three-dimensional flow model, was obtained by integrating the external three-phase separator with the influent and the external cycle. After 166-d operation, the nitrogen removal efficiency of the EGSBGC reached 75.6%, being 1.28-times that of the EGSBconv. (58.9%). The sludge concentration in the main body of the EGSBGC reached 3112 ± 65 mg/L, compared with 2613 ± 42 mg/L in the EGSBconv. ( p < 0.05). Moreover, the severe granules blockage and decay problem that is frequently encountered in the EGSBconv. no longer occurred in the EGSBGC . The relative abundance of anammox bacteria in granules from the three-phase separator of the EGSBGC was 29.7%, significantly higher than that from the EGSBconv. (16.1%, p < 0.05). The blockage and decay of granules in the three-phase separator of the EGSBconv. led to an obvious proliferation of heterotrophic bacteria, with their relative abundance increased by 9.4% compared with the seed sludge (38.6% vs. 29.2%). This study proposed a practical three-phase separator configuration to sustain efficient and stable operation of anammox processes toward the promotion of granules circulation, retention and reaction. Graphical abstract: Image 1 Highlights: EGSBGC promoted circulation and avoided blockage of granules by influent scour. High separating efficiency was proved by three-dimensional flow model analysis. EGSBGC nitrogen removal efficiency was 1.28-times that of EGSBconv. after 166 d. Sludge concentration enhanced in the EGSBGC main body but reduced in EGSBconv. Granules blockage and decay in EGSBconv. caused heterotrophic bacteria proliferation.