Start-up and community analysis of simultaneous partial nitrificatioand anammox (Snap) process by immobilization

Abstract

In this study, partial-nitrification and anammox biomass were co-immobilized by polyvinyl alcohol and sodium alginate (PVA-SA) to treat the ammonium-rich wastewater. The enriched partial nitrification and anammox sludge entrapped in the beads. The beads were round in shape with 4–5 mm in diameter and not agglomerated with each other. The ammonium removal efficiency of 80% achieved within ten days. The nitrogen loading rate varied from the start (37 mg/L/d) to the end of experiment (75 mg/L/d). The enriched sludge,suitable environment inside of the beads for growth of bacteria, and low diffusion constraints were the possible reasons for the fast start-up of PN-anammox system. The necrosis/apoptosis analysis confirmed that there was no observed death phenomena inside of the gel beads in a normal operation of the reactor. The microbial community analysis showed that the dominance of phyla Proteobacteria (35.35%) while the abundance of phyla Planctomycetes was 2.42%. Likewise, at the genus level, Candidatus Brocadia accounts for 1.33% while Nitrosomonas was 0.89%, but the highest shared observed from the genus Burkholderia. The use of immobilization technology in the application of the SNAP process may represent a valuable alternative to other technologies such as granulation, suspended cell growth and biofilm system.