Correlation between water quality parameters and microbial populations at full-scale enhanced phosphorus removal wastewater treatment plants in South Korea

Optimizing enhanced biological phosphorus removal in wastewater treatment plants (WWTPs) can lead to energy savings of 5-30%. However, the understanding of phosphorus-removing microbes remains incomplete. Polyphosphate-accumulating organisms (PAOs), particularly Candidatus Accumulibacter, dominate lab-scale reactors but are not always prevalent in full-scale facilities. Other significant PAOs include Tetrasphaera and Dechloromonas. In contrast, glycogen-accumulating organisms (GAOs) negatively affect phosphorus removal efficiency. Factors such as the influent carbon source, total organic carbon (TOC)/P ratio, and temperature influence the competition between PAOs and GAOs. This study investigated the influence of microbial communities on phosphorus removal in six full-scale WWTPs in Gyeongsangbuk-do, Republic of Korea. Next-generation sequencing (NGS) provided insights into microbial interactions with physicochemical conditions. NGS analysis revealed that in the six full-scale plants, Tetrasphaera had an abundance of up to 1.39%, and Dechloromonas up to 1.19%. For GAOs, Defluviicoccus reached an abundance of 3.35%, and Propionivibrio reached 1.48%. The correlation between operational parameters and PAO/GAO ratios indicated that the chemical oxygen demand had a very strong correlation (0.94) with both the removal efficiency and the removal amount related to the read abundance of PAOs (%). For the read abundance of GAOs (%), the TOC removal amount showed a very strong correlation (0.97).