# Nitrogen removal performance and the biocenosis with microalgae consortium Nitrosifying and anammox bacteria in an upflow reactor

## TL;DR

A new system using algae and bacteria successfully removes 87.4% of nitrogen from wastewater.

## Contribution

The ALGAMMOX system combines microalgae and anammox bacteria for efficient nitrogen removal.

## Key findings

- The ALGAMMOX system achieved 87.40% nitrogen removal efficiency.
- Candidatus Brocadia and Nitrosomonas were key bacteria in the system.
- Chlamydomonas, Bacillariaceae, and Pinnularia were dominant algae.

## Abstract

This study introduced an innovative pathway utilizing an algal anaerobic ammonium oxidation (ALGAMMOX) system to treat ammonium wastewater. Lake bottom sludge and anammox sludge were used to cultivate functional microorganisms and microalgae for nitrogen removal in an upflow reactor made of transparent materials. The results showed that the ALGAMMOX system achieved 87.40 % nitrogen removal when the influent NH4+-N concentration was 100 mg-N/L. Further analysis showed that anammox bacteria Candidatus Brocadia (8.87 %) and nitrosobacteria Nitrosomonas (3.74 %) were crucial contributors, playing essential roles in nitrogen removal. The 16S rRNA gene showed that the anammox bacteria in the sludge transitioned from Candidatus Kuenenia to Candidatus Brocadia. The 18S rRNA gene revealed that Chlamydomonas, Bacillariaceae and Pinnularia were the dominant microalgae in the system at a relative abundance of 7.99 %, 3.64 % and 3.14 %, respectively. This novel approach provides a theoretical foundation for ammonium wastewater treatment.

•The ALGAMMOX system was successfully established inoculating lake sediment and anammox sludge.•Chlamydomonas, Bacillariaceae and Pinnularia became the dominant algae in ALGAMMOX system.•The highest TN removal efficiency was 87.40 % in the ALGAMMOX system.•The anammox bacteria transitioned from Candidatus Kuenenia to Candidatus Brocadia.

The ALGAMMOX system was successfully established inoculating lake sediment and anammox sludge.

Chlamydomonas, Bacillariaceae and Pinnularia became the dominant algae in ALGAMMOX system.

The highest TN removal efficiency was 87.40 % in the ALGAMMOX system.

The anammox bacteria transitioned from Candidatus Kuenenia to Candidatus Brocadia.