Effect of wastewater composition on microbial populations in biological phosphorus removal processes

Bench-scale sequential batch reactors (SBRs) were fed with glucose- and acetate-containing synthetic wastewaters to evaluate microbial population dynamics and types of phosphorus-accumulating organisms (PAOs) using a cellular fatty acid profile analysis. The phosphorus content in the sludge was 38% (w/w) for the acetate-fed SBR and 20% (w/w) for the glucose-fed SBR with a VSS/TSS ratio of 50%. Glucose-fed PAOs were found to remove phosphorus with accumulation of glycogen in cells without synthesizing poly-β-hydroxybutyrate (PHB) at influent phosphorus concentration < 20 mg-P/L and nitrate concentration < 2 mg-N/L. From the fatty acid profile biomarker study, it was found that the glucose-fed SBR maintained the same fatty acid profile before and after biological phosphorus removal (BPR) occurred while the acetate-fed SBR had a different fatty acid profile. The microbial population in the glucose-fed SBR was significantly different in terms of metabolic behavior and cellular fatty acid profile from that introduced in the acetate-fed SBR. Fatty acid a15:0 (anteiso methyl-branching) was abundant in the glucose-fed PAOs. Among the five PAO candidates (Acinetobacter, Pseudomonas, Arthrobacter, Aeromonas, and Micrococcus), only Arthrobacter spp. had the biomarker of fatty acid a15:0, indicating that Arthrobacter spp. may be one of the PAOs existing in the glucose-fed bioreactors.