Yasushi Hirukoi

Microbial Diversity in ANAMMOX granular Sludge

Hideki Harada


Anaerobic ammonium oxidation (ANAMMOX) is an microbial reaction which nitrite and ammonium is oxidized to nitrogen. The advantages of the ANAMMOX process over the traditional combination of nitrification and denitrification for wastewater treatment are no requirement for external carbon sources because the process is autotrophic. However, process startup could be hindered by the relatively low growth rate of anammox bacteria.

The successful nitrogen removal by using ANAMMOX depends on the retainment of high concentration of ANAMMOX bacteria in the reactor. To overcome this key factor, KURITA proposed the ANAMMOX reactor using anaerobic granular sludge as an initial carriers. ANAMMOX granules were formed after one year cultivation.

The microorganism carrying out the ANAMMOX reaction was identified by using sequencing and FISH approach based on 16S rRNA to get more information of ANAMMOX sludge. The application of 16S rRNA based sequencing approach elucidates that some bacteria in ANAMMOX granule were affiliated to the Planctomycetales. Moreover, novel bacteria which does not affiliate to Planctomycetales and have not been detected in the anaerobic methanogenic sludge was also detected.

The dominance of ANAMMOX bacteria-like cells in the ANAMMOX granule was distinctively revealed.