The microbial community in a high-temperature enhanced biological phosphorus removal (EBPR) process

An enhanced biological phosphorus removal (EBPR) process operated at a relatively high temperature, 28 °C, removed 85% carbon and 99% phosphorus from wastewater over a period of two years. This study investigated its microbial community through fluorescent in situ hybridization (FISH) and clone library generation. Through FISH, considerably more Candidatus “Accumulibacter phosphatis” (Accumulibacter)-polyphosphate accumulating organisms (PAOs) than Candidatus ‘Competibacter phosphatis’ (Competibacter)-glycogen accumulating organisms were detected in the reactor, at 36 and 7% of total bacterial population, respectively. A low ratio of Glycogen/Volatile Fatty Acid of 0.69 further indicated the dominance of PAOs in the reactor. From clone library generated, 26 operational taxonomy units were retrieved from the sludge and a diverse population was shown, comprising Proteobacteria (69.6%), Actinobacteria (13.7%), Bacteroidetes (9.8%), Firmicutes (2.94%), Planctomycetes (1.96%), and Acidobacteria (1.47%). Accumulibacter are the only recognized PAOs revealed by the clone library. Both the clone library and FISH results strongly suggest that Accumulibacter are the major PAOs responsible for the phosphorus removal in this long-term EBPR at relatively high temperature.