Start-up and bacterial communities of single-stage nitrogen removal using anammox and partial nitritation (SNAP) for treatment of high strength ammonia wastewater

• The start-up the SNAP process was achieved from dewatered surplus activated sludge.
• High rate TN removal around 0.54 kg N m−3 d−1 was achieved in a single reactor.
• 16S rDNA amplicon pyrosequencing showed presence of AOB and AnAOB.
• Quantitative analysis of dominant bacteria groups arrangement in reactor.

In this study, a lab-scale sequencing batch biofilm reactor (SBBR) was used to start up the single-stage nitrogen removal system using anammox and partial nitritation (SNAP) process seeding from surplus activated sludge. The volumetric nitrogen loading rate (vNLR) was firstly 0.075 kg N m−3 d−1 and then gradually increased to 0.60 kg N m−3 d−1. A maximal total nitrogen (TN) removal rate of 0.54 kg N m−3 d−1 was achieved by the SNAP process after 132 days operation with NH4+-N and TN removal efficiency of 99.4% and 90.5%, respectively. This reactor may have applications for the SNAP process treating high strength ammonia wastewater. And dewatered surplus activated sludge was recommended as the seed sludge for engineering applications. The dominant bacterial strains were Xanthomonas campestris, Nitrosomonas europaea and Ignavibacterium album, corresponding to the percentage of 24%, 22% and 20%, respectively, based on the 16S rDNA amplicon pyrosequencing of the SNAP sludge.