Characteristic on pollutant removal and extracellular polymeric substances distribution in different periods of an up-flow biological aerated filter

The up-flow biological aerated filter (UBAF) reactor was established to explore the pollutant removal and the extracellular polymeric substances (EPS) distribution at the initial stage of biofilm, maturity of biofilm, and stable operation periods. The parallel factor (PARAFAC) model was applied to analyze the three-dimensional fluorescence characteristics of EPS. Canonical correlation analysis (CCA) was used to study the correlation between the distribution of EPS and pollutant removal. The results showed that the removal efficiency of chemical oxygen demand (COD), ammonia nitrogen (NH4 +-N), and total phosphorus (TP) at the maturity of biofilm were higher than other periods, and reached to 95.68%±0.87%, 73.48%±4.32%, and 63.80%± 14.27%, respectively. The operation period had a significant correlation with EPS distribution. All of biofilm samples detected four kinds of fluorescent substance of tryptophan-like (C1), protein-like (C2), humilic acid (C3), and humic acids-like (C4). The CCA result showed that NH4 +-N removal had a very significant positive correlation with EPS concentration and composition (R≥0.9261).