Feeding Strategies for Enrichment and Characterization of Anammox Biomass in a Sequencing Batch Reactor

Abstract

Anammox bacteria represent a promising alternative for treating ammonium-rich wastewater. In this work reported, biomass performing anaerobic oxidation of ammonium was enriched in a sequencing batch reactor, from sludge used for the treatment of high-nitrogen waste from an amino acid-producing industry. After 89 days of operation, both ammonium and nitrite were consumed. During operation under a 24-hour cycle, the applied nitrogen load (ANL) was increased from 155 to 802 mg N/L·d. This strategy resulted in efficiencies of nitrogen removal and nitrogen conversion rate of 91.7% and 98.5%, respectively. Specific anammox activity increased proportionally to ANL and it was partially inhibited at 802 mg N/L·d. Sequencing analysis using 16S rRNA anammox primers, after 170 days of operation, showed that 21 clones were grouped into two OTUs (operational taxonomic units). The identity of the 16S rRNA gene of OTU esp 1 showed similarity to Brocadia species, and OTU esp 2 displayed 99% similarity to Anammoxoglobus propionicus . After 450 days of operation, sequencing analysis using universal primers showed that 48 clones were grouped into 19 OTUs representing six major groups of bacteria: Planctomycetes , beta- Proteobacteria , green sulfur bacteria of the Chlorobi phylum, Nitrospira , Chloroflexi and OP 11. Brocadia sp. was the only anammox bacteria in the biomass at this time.