Nitrogen Removal Characteristics and Comparison of the Microbial Community Structure in Different Anaerobic Ammonia Oxidation Reactors

Liqiu Zhang,Shugeng Li,Zhongxuan Geng,Hainan Yao,Wei Lv

doi:10.3390/w11020230

Abstract

Nitrogen removal characteristics and the comparison of the microbial community structure were investigated in different anaerobic ammonia oxidation (Anammox) reactors: an anaerobic sequencing batch reactor (ASBR) and a biofilter reactor. The Anammox systems were inoculated with sludge from the second settling tank of a wastewater treatment plant in Guangzhou, China. After successful start up of Anammox, the microbial community structure of different Anammox reactors were studied through high-throughput sequencing. The results showed that anaerobic ammonium oxidation in the ASBR reactor could successfully start up after 134 days, while Anammox in the biofilter could start up after 114 days. In both systems, total nitrogen removal was at 80% after more than 200 days of operation. The diversity of denitrifying microorganisms was high in both reactors, with Planctomycetes as the main taxa. Anammox bacteria belonging to the genera Candidatus Anammoxoglobus and Kuenenia, were dominant in the ASBR, while all three genera of Candidatus, Anammoxoglobus, Kuenenia, and Brocadia, could be detected in the biofilter reactor. Therefore, the biofilter starts up faster than the ASBR, and contains richer species, which makes it more suitable to domesticate Anammox bacteria.

Highlights

Anaerobic ammonium oxidation (Anammox) was discovered and named in 1995 by researchers of the Delft University of Technology, Netherlands [1]
The anaerobic sequencing batch reactor (ASBR) reactor was operated over 246 days, with a start up period of 134 days
These results indicated that Anammox bacteria were not the dominant bacteria in the system and that nitrite-oxidizing bacteria (NOB) and denitrifying bacteria were more concentrated than the Anammox bacteria at that time

Summary

Introduction

Anaerobic ammonium oxidation (Anammox) was discovered and named in 1995 by researchers of the Delft University of Technology, Netherlands [1]. It is an alternative nitrogen removal process oxidizing NH4 + –N into nitrogen, using NO2 - –N as an electron acceptor. The bacteria involved in this process, Anammox bacteria, are anaerobic autotrophic bacteria, and Anammox is an anaerobic process and does not require an additional carbon source [2]. In this sense, it has been recognized as the most cost effective biological nitrogen removal approach.

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