Exploring the feasibility of high rate enhanced biological phosphorus removal system driven by diverse carbon source

Abstract

The limited understanding of the mechanism and metabolism with short sludge retention time (SRT) conditions remain a significant challenge, hindering the integration of enhanced biological phosphorus removal (EBPR) into high-rate A/B processes. Previous short-SRT EBPR studies mainly relied on volatile fatty acid (VFA), whereas the diversity of carbon sources in real wastewater treatment plants (WWTP) is much broader and also includes sugars and amino acids. In this study, a long-term EBPR process with a short SRT was established using mixed carbon sources representative of domestic wastewater, achieving reliable and efficient chemical oxygen demand (COD) and phosphorus (P) removal. Through long-term operation of 680 days, P removal efficiencies were obtained at 97.7 % ± 2.3, 97.6 % ± 4.4 and 92.6 % ± 10.2 with the SRT of 8 days, 5 days and 3 days, respectively. High COD removal efficiency at each stage was also attained. This work demonstrated that mixed carbon sources, such as glucose and VFAs were more favourable for energy transformation by selected phosphorus accumulating organisms (PAOs), compared to amino acids or glycerol. Tetrasphaera-PAOs and Comamonas-PAOs were the two dominant PAOs, and clade shift was observed within Tetrasphaera-PAOs. In summary, this work provides valuable insights into the feasibility of integrating EBPR with short SRT into A-stage high-rate WWTP processes.