Improvement in nitrogen removal and changes in community structure in a sequencing batch reactor bioaugmented with P. stutzeri strain XL-2

Abstract

The aim of this work was to study the bioaugmentation of P. stutzeri strain XL-2 in activated sludge to improve nitrogn removal from wastewater with the guide of growth kinetics. When 4250 mg/L COD and 80 mg/L NH₄⁺-N were applied, the TN removal efficiency in a bioaugmented sequencing batch reactor (SBR_XL) achieved 95%, while that in the control reactor (SBR_C) without strain XL-2 was only 84% (P < 0.05). The microbial community analysis demonstrated that strain XL-2 was successfully bioaugmented in SBR_XL, and increasing influent COD concentration promoted its abundance. Influent COD concentration played a dominant role in affecting community structure, while the bioaugmentation of strain XL-2 had much less impact on the community structure. Combined with principal coordinates analysis, redundancy analysis and FAPROTAX, the improvement of TN removal was mainly achieved by the bioaugmentation of strain XL-2, which played a major role in promoting aerobic denitrification.

Keywords: Bioaugmentation; Heterotrophic nitrification and aerobic denitrification; Microbial community structure; Nitrogen removal; Sequencing batch reactor.