Carbon source shaped microbial ecology, metabolism and performance in biofilm system for simultaneous phosphorus...

The application of biofilm-based phosphorus enrichment technology has been hampered by the limited information on the performance, microbial interactions and metabolic patterns of dominant functional bacteria, especially those fed with complex carbon sources conditions. In this study, three representative carbon sources contained in real sewage, i.e., volatile fatty acids (VFAs), glucose, and amino acids were selected as the complex carbon sources. The comparison in phosphorus removal/enrichment performance, carbon utilization, and metabolic characteristics were performed during the biofilm system changed the sole carbon source (acetate sodium) feeding to complex carbon source feeding gradually. The performance reduction and instability were observed in initial stage of complex carbon source feeding, while the phosphorus removal/enrichment efficiency improved significantly after long-term acclimation by extending the anaerobic HRT. The concentration of phosphorus enrichment solution exceeded 50 mg/L, meanwhile the total nitrogen and total phosphorus removal efficiencies over 82 % and 97 %, respectively. Intriguing, intracellular organic phosphorus (OP) contents fluctuated with phosphorus uptake and release, which may be a hint of the important role of OP in PAOs energy conversion. Complex carbon sources induced the succession of biofilm community, especially the enrichment of hydrolytic fermentation bacteria, and a more intricate microbial interaction network among functional microbiota. The co-occurrence of the EMP and ED pathways during glycolysis implied more extensive carbon utilization pathways, and amino acids was speculated to complement intracellular energy metabolism via the tricarboxylic acid cycle (TCA). This study demonstrated that the biofilm systems have great potential to simultaneously achieve phosphorus removal and enrichment by using complex carbon sources in sewage wastewater.