Experimental study on the establishment of independent enhanced biological phosphorus removal system based on immobilized fillers for wastewater nitrogen removal

Abstract

The current sewage treatment systems are typically unable to efficiently remove both nitrogen and phosphorus simultaneously, often compromising biological phosphorus removal to ensure effective nitrogen removal. To resolve this issue, this study establishes an independent enhanced biological phosphorus removal (EBPR) system based on an immobilized fillers nitrogen removal system for treating actual rural sewage. The research focuses on the phosphorus removal performance, operational conditions, and characteristics of the independent EBPR system. When fluctuations occur in the effluent phosphorus concentration, phosphorus-accumulating organisms (PAOs) utilize only 29 % of the available carbon sources, with the remaining carbon being fully consumed by glycogen-accumulating organisms (GAOs). The presence of GAOs and low dissolved oxygen (DO) concentrations leads to deteriorating phosphorus removal performance in the system. To address this, reducing the carbon load and increasing aeration are necessary to maintain effluent phosphorus concentrations below 0.5 mg·L⁻¹. Tetrasphaera and Acinetobacter are identified as key microbial genera responsible for phosphate removal in this system. Finally, fluorescence excitation emission matrix parallel factor analysis (EEM-PARAFAC) showed that fermentation microorganisms, represented by Tetrasphaera, played a key role in the removal of tryptophan and tyrosine produced by raw wastewater and microbial metabolism.