Work

The return sludge sidestream process promotes phosphorus removal stability with synergistic activity of polyphosphate accumulating organism populations

Year: 2025

Type: article

Abstract: Conflicting reports exist regarding the benefits of sidestream enhanced biological phosphorus removal (EBPR) processes as compared to conventional EBPR. This study assesses the mechanisms of P removal by different microbial populations within sidestream vs conventional EBPR. Two bioreactors were operated as either a conventional anaerobic/anoxic-aerobic (CONV) or return sludge sidestream (RSS) configuration for 180 days to evaluate the microbial community and performance. The RSS process demonstrated greater long-term P removal stability (RSS P effluent: 0.51±0.84 mgP/L, CONV: 2.42±2.53 mgP/L), with a high and stable abundance of Tetrasphaera-related polyphosphate accumulating organisms (PAOs). Metagenomics showed that the RSS process was dominated by Phycicoccus elongatus and a relatively unknown genus in the Dermatophilaceace, called JAGOME01. Interestingly, the RSS system exhibited a higher abundance of glycogen accumulating organisms (GAOs) (30.4±8.6%) as compared to the CONV (3.5±1.9%) system, implying that GAOs did not negatively impact P removal performance. Indeed, the high level of Micropruina GAOs (16.0±4.6%) in the RSS may have been beneficial for P removal, by fermenting complex carbon sources to volatile fatty acids that are taken up by Accumulibacter PAOs. Raman-FISH revealed that despite the vast difference in population abundance between the two PAOs (Tetrasphaera: 15.9±5.7%, Accumulibacter: 4.3±2.1), the higher specific P uptake capacity of Accumulibacter meant that they still accounted for 43% of the P removal in the RSS system. This study shows that P removal is carried out through different mechanisms in RSS vs CONV configurations, which improves P removal stability, where the higher diversity of PAOs can mitigate GAO growth.

Source: Journal of environmental chemical engineering

DOI: 10.1016/j.jece.2025.117331

Authors: Kylie Close, Liu Ye, Dongqi Wang, April Z. Gu, Adrian Oehmen

Institutions: The University of Queensland, Xi'an University of Technology, Cornell University

Language: English

Topic: Wastewater Treatment and Nitrogen Removal

Subfield: Pollution

Field: Environmental Science

Domain: Physical Sciences

SDGs: Clean water and sanitation, Responsible consumption and production

Open Access status: hybrid

Estimated APC paid: $3,350