Enrichment of Anaerobic Ammonium Oxidation (Anammox) bacteria for Biological Nitrogen removal of wastewater

Anaerobic ammonium oxidation (anammox) bacteria enrichment was explored for the potential application of ammonium rich wastewater removal. Samples of sludge from mature and young landfill leachate treatment plants were screened and used as inocula for anammox enrichment cultures. Enrichments were monitored for N-NH3, N-NO2- and N-NO3- to detect anammox potential activity. Six of the twelve enrichment cultures showed anammox activity after more than five months of enrichment period. All enrichment cultures that gave positive results were obtained from bottom part of sequencing batch reactor (SBR) lagoon indicating localization of anammox bacteria in anaerobic condition. Polymerase Chain Reaction (PCR) with specific primers targeting anammox and planctomycete were able to amplify the 16S rRNA sequence for anammox bacteria under PCR optimum condition. However, only three of six positive samples were successfully sequenced. DNA sequence analysis using NCBI (BLAST) and RDP showed that the anammox bacterial sequences of the investigated samples were identified as Candidatus Kuenenia stuttgartiensis with similarity of 100% (NCBI) and 99.3% (RDP).