Start-up of anammox systems with different feeding patterns: System performance, microbial community and potential microbial interactions

Successful start-up of the anaerobic ammonium oxidization (anammox) system is the main challenge for its application. Two anammox biofilm systems with pulse feeding pattern (AN-P) and constant feeding pattern (AN-C) were operated, and the performance of nitrogen removal and microbial interactions among anammox bacteria, heterotrophs, and other microorganisms were investigated. The total nitrogen removal percentage reached 82% (AN-P) and 82.4% (AN-C) in 13 days and 32 days, respectively. AN-P could start up and reach steady state quicker than AN-C. Candidatus Kuenenia was the dominant functional microorganism in both reactors. Heterotrophs (Pseudomonas and Hyphomicrobium) might play important roles in nitrogen and carbon metabolisms. N-decanoyl-DL-homoserine lactone and N-dodecanoyl-DL-homoserine lactone were detected, and acyl homoserine lactone-based quorum sensing system existed in the anammox system. Complex microbial interactions, including competition, cooperation and cross-feeding co-existed in the anammox system and affected system performance.