Microbial synergies and dynamics in biological nutrient removal processes
Date of Issue2019-04-08
Interdisciplinary Graduate School (IGS)
Nanyang Environment and Water Research Institute
Integrating multiple processes is one of the solutions for the higher requirement of modern biological nutrient removal processes. However, many challenges are also associated. This study aimed to investigate the microbial synergy and dynamics in both full-scale mixed-culture context, and lab-scale pure-culture strains. The first reported full-scale Simultaneous Nitrification-Denitrification with Phosphorus Removal (SNDPR) under tropical climate was confirmed in a local water reclamation plant through plant data analysis, batch experiment and microbial analysis. The potential contribution factors were also suggested. Considering the wide range of relative abundance in nitrifying community, Nitrosomonas europaea and Nitrobacter winogradskyi were chosen to represent pure culture ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) and cocultured in nine chemostat reactors with different initial inoculum conditions to study their abundance dynamic. Results showed that different initial AOB/NOB ratio converged to similar values after 2 ~ 4 weeks’ cultivation with AOB dominant in the full-nitrification system, indicating that operation conditions were decisive for nitrifiers’ community structure and AOB dominance was not an indication for partial-nitrification. In addition, proximity of AOB and NOB cells was observed in the coculture clusters with layered floc structure frequently appeared. The potential chemotaxis feature, which was hypothesized to contribute to the floc structure and interaction, was studied with a series of capillary assays. As an independent mechanism from the metabolic activity, the chemotaxis of AOB and NOB was studied for the first time and generated innovated research direction for biological nutrient removal.