Nanoarchitectured structure and population dynamics of anaerobic ammonium oxidizing (anammox) bacteria in a wastewater treatment plant

[Display omitted] •Nanoarchitectured structure of ammonium-oxidizing (anammox) system was studied in a full scale wastewater treatment plant.•New designed primers successfully quantified two dominant anammox bacteria.•Formation of anammox granule was highly related to composition of anammox structure and ammonium removal efficiency. Studies on microbial community and population dynamics are essential for the successful development, monitoring and operation of biological wastewater treatment systems. Especially for novel or sustainable systems such as the anaerobic ammonium oxidizing (anammox) process that are not yet well explored. Here we collected granular microbial sludge samples and investigated a community of anammox bacteria over a period of four years, divided into eight stages in a full scale simultaneous partial nitrification, anammox and denitrification (SNAD) process for treating landfill leachate. Specific qPCR primers were designed to target and quantify the two most abundant anammox species, Candidatus Kuenenia stuttgartiensis (KS) and Candidatus Brocadia anammoxidans (BA). The two species were monitored and could explain the dynamic shift of the anammox community corresponding to the operating conditions. Using the newly designed KS-specific primer (KSqF3/KSqR3) and BA-specific primer (BAqF/BAqR), we estimated the amounts of KS and BA to be in the range of 6.2 × 106 to 5.9 × 108 and 1.1 × 105 to 4.1 × 107 copies μg−1 DNA, respectively. KS was found to be the dominant species in all anammox granules studied and played an important role in the formation of granules. The KS/BA ratio was positively correlated to the size of granules in the reactor and ammonia nitrogen removal efficiency of the treatment plant.