Extracellular polymeric substances and microbial community shift during the start-up of a single-stage partial nitritation/anammox process

A sequencing batch reactor (SBR) was operated to investigate variations of extracellular polymeric substances (EPS) and microbial community during the start-up of the single-stage partial nitritation/anammox (SPN/A) process at intermittent aeration mode. The SPN/A system was successfully started on day 34, and the nitrogen removal efficiency and total nitrogen loading rate were 82.29% and 0.31 kg N/(m3 center dot day), respectively. Furthermore, the relationship between the protein secondary structures and microbial aggregation was strongly related. The alpha-helix/ (beta-sheet + random coil) ratios increased obviously from 0.20 +/- 0.03 to 0.23 +/- 0.01, with the sludge aggregation mean size increased from 56 to 107 mu m during the start-up of SPN/A. During the start-up of SPN/A, Candidatus Kuenenia was the primary anammox bacteria, whereas Nitrospira was the main functional bacteria of nitrite-oxidizing bacteria. Correlation between the microbial community and EPS components was performed. The EPS and microbial community played important roles in keeping stable nitrogen removal and the formation of sludge granules.Practitioner PointsIntermittent aeration strategy promoted SPN/A system start-up.EPS composition and protein secondary structure were related with the sludge disintegration and aggregation.Microbial community shift existed and promoted the stability of sludge and reactor performance during SPN/A start-up. This study found that the ratios of PN/PS and alpha-helix/ (beta-sheet + random coil) ratios changed obviously with the process of sludge disintegration and aggregation. The Pearson correlation analysis revealed that the composition of EPS and microbial community had potential effects on the stability of the SPN/A system.image