Effect of the form of granular sludge and temperature on anammox immobilized fillers: From performance to microbial community analysis.

Abstract

The immobilized carrier was prepared with complete anaerobic ammonia oxidation granular sludge (AnGS) and crushed AnGS, respectively. We evaluated the effects of granular form and continuous temperature changes on nitrogen removal by immobilized anaerobic ammonium oxidation (anammox) filler. The results showed that the rate of nitrogen removal of crushed and encapsulated AnGS was 20% higher than that of direct encapsulated AnGS. However, the latter had higher thresholds of tolerance to Fe2+ and Cu2+. In addition, the immobilization reduced the activation energy of anammox. Above 12.5\xa0°C, the immobilized filler was efficient at removing nitrogen removal through the dual adjustment of temperature-hydraulic retention time. From 12.5\xa0°C to 23\xa0°C, the temperature had a greater influence on the nitrogen removal effect than the HRT. In contrast, HRT had a dominant influence from 23\xa0°C to 32\xa0°C. Anammox activity was severely inhibited below 12.5\xa0°C. High-throughput sequencing analysis showed that the community structure migrated with the changes in temperature. The anammox functional bacteria Candidatus Kuenenia (18.31-39.73%) were the dominant genus at medium and high temperatures, and it was replaced by Chryseobacterium (24.19%) at 8.5\xa0°C. In addition, an RDA analysis showed that Candidatus Brocadia was more adaptable to low temperatures than Candidatus Kuenenia. In addition, Bellilinea was more sensitive to temperature than Candidatus Kuenenia. Thus, the temperature could be appropriately lowered to avoid overbreeding. The results of this study optimized the operation of an anammox immobilized system and promote its further application.