Cold temperature drives the re-granulation of disintegrated partial nitritation granules in a continuous-flow reactor. (10th December 2022)

• Record Type: Journal Article
• Authors: Liu, Wenru; Wang, Caixia; Chen, Jie; Jiang, Kuansheng; Zhang, Liangwei; Wang, Jianfang; Wu, Peng; Ji, Xiaoming; Shen, Yaoliang; Yang, Dianhai; Shen, Yijun
• Is Part Of: Journal of cleaner production. Volume 378(2022)
• Publication Date: 2022-12-10
• Subjects: Partial nitritation -- Cold temperature -- Extracellular polymeric substance -- Aerobic granules -- Continuous-flow process; Factory and trade waste -- Management -- Periodicals; Manufactures -- Environmental aspects -- Periodicals; Déchets industriels -- Gestion -- Périodiques; Usines -- Aspect de l'environnement -- Périodiques; 628.5
• DOI: 10.1016/j.jclepro.2022.134530
• Languages: English
• ISSNs: 0959-6526

Abstract

Abstract: To investigate the effect of temperature on the recovery of aerobic granule stability, two continuous-flow reactors inoculated with disintegrated partial nitritation granules were operated at different temperatures for organic-free wastewater treatment. Granules disintegration and partial nitritation deterioration further occurred in the reactor (R1) operating at 25–28 °C. However, successful sludge re-granulation with a decrease of sludge volume index (SVI5) from 73 mL/g to 35 mL/g was observed in the reactor (R2) operated with the decreasing temperature from 20 °C to 12 °C. The reduced temperatures decreased the activity and growth rate of nitrifiers (from 47.2 mg/g VSS/h to 21.3 mg/g VSS/h), and selected the extracellular polymeric substance (EPS) producing bacteria (e.g., Flavobacterium and Rhodobacteraceae sp.). Correspondingly, an enhanced secretion of tightly-bound EPS (200.3–224.6 mg/g VSS in R2 vs 166.8–152.5 mg/g VSS in R1), particularly proteins, and an increased expression of quorum sensing-related enzyme genes (2.98% in R2 vs 2.75% in R1) were obtained. All of this contributed to the cold temperature-driven sludge re-granulation. The recovery of granular structure promoted the stable maintenance of efficient partial nitritation at low temperatures. Overall, this study gives insights into the positive role of cold temperatures on the stability of partial nitritation granules. Graphical abstract: Image 1 Highlights: Temperature effects on nitrifying granules were studied in continuous-flow reactors. Granule disintegrated at 25–28 °C, but regranulation occurred at low temperatures. Cold temperature enriched extracellular polymeric substance-producing microbes. The mechanism of cold temperature-driven sludge regranulation was proposed.