Anammox bacteria community and nitrogen removal in a strip-like wetland in the riparian zone

Abstract

A strip-like wetland was constructed in the riparian zone for investigation of ammonium nitrogen (NH₃-N) removal in the Peach River. An inner zeolite layer was set in the wetland to adsorb NH₃-N and further to remove total nitrogen (TN). An oxygen-deficient condition with dissolved oxygen of 0.87–1.60 mg L⁻¹ was observed in the zeolite layer, which benefits anaerobic ammonium oxidation (anammox) bacteria survival. The community structure of anammox bacteria was analyzed in the zeolite layer. The analysis shows that the anammox bacterial sequences are grouped into three known distinct clusters: Candidatus Brocadia fulgida, Candidatus Brocadia anammoxidans and Candidatus Jettenia asiatica. The intensified test driven by artificial pumping shows that average removal rates of NH₃-N and TN are 41.6 mg m⁻³d⁻¹ and 63.2 mg m⁻³d⁻¹, respectively. The normal test driven by natural hydrodynamics also verifies that NH₃-N removal mainly happens in the zeolite layer. Microbial mechanism of TN removal in the wetland involves both the autotrophic and heterotrophic process. These results suggest that the strip-like RW can be a cost-effective approach for NH₃-N removal and can potentially be extended to similar rivers as no extra energy is required to maintain the wetland operation.

Keywords:

• Ammonium nitrogen
• anammox
• zeolite
• riparian wetland

Acknowledgments

This research was jointly supported by National Natural Science Foundation of China (50979007) and National High-Tech Research and Development (863) Programme (2008AA06Z301).