Effect of salt concentration in anammox treatment using non woven biomass carrier

Effect of high salt concentration on the anammox treatment was investigated to establish an acclimation strategy under high salt concentration conditions. An anammox fixed-bed reactor with non-woven biomass carrier was used and the salt concentration was gradually increased from 2.5 g L-1 to 33 g L-1. The anammox reactor demonstrated stable nitrogen removal rate (NRR) of 1.7 kg-N m(-3) d(-1) for 65 days under a salt concentration of 30 g L-1. However, the NRR sharply declined at a salt concentration of greater than 30 g L-1. The bacterial community was examined by 16S rRNA gene analysis and DGGE after the acclimation of the anammox sludge to high salt conditions. Although the salt concentration was almost sea level, the freshwater anammox bacteria, KU2, were detected. In addition, the unidentified bacteria which perhaps belong to candidate division OPIO and Lysobacter sp. were found to coexist with anammox bacteria at a salt concentration of 30 g L-1. (c) 2009, The Society for Biotechnology, Japan. All rights reserved.