Glycine adversely affects enhanced biological phosphorus removal

Yucheng Tian; Hang Chen; Liping Chen; Xuhan Deng; Zekun Hu; Cenchao Wang; Chaohai Wei; Guanglei Qiu; Stefan Wuertz

doi:10.1016/j.watres.2021.117894

Glycine adversely affects enhanced biological phosphorus removal

Water Res. 2022 Feb 1:209:117894. doi: 10.1016/j.watres.2021.117894. Epub 2021 Nov 23.

Authors

Yucheng Tian¹, Hang Chen¹, Liping Chen¹, Xuhan Deng¹, Zekun Hu¹, Cenchao Wang¹, Chaohai Wei², Guanglei Qiu³, Stefan Wuertz⁴

Affiliations

¹ School of Environment and Energy, South China University of Technology, Guangzhou 510006, China.
² School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; Key Laboratory of Pollution Control and Ecological Restoration in Industrial Clusters, Ministry of Education, Guangzhou 510006, China.
³ School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore; Key Laboratory of Pollution Control and Ecological Restoration in Industrial Clusters, Ministry of Education, Guangzhou 510006, China. Electronic address: qiugl@scut.edu.cn.
⁴ Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore; School of Civil and Environmental Engineering, Nanyang Technological University, Singapore 639798, Singapore. Electronic address: swuertz@ntu.edu.sg.

PMID: 34890912
DOI: 10.1016/j.watres.2021.117894

Abstract

Enhanced biological phosphorus removal (EBPR) is used extensively in full-scale wastewater treatment plants for the removal of phosphorus. Despite previous evidence showing that glycine is a carbon source for a certain lineage of polyphosphate accumulating organisms (PAOs) such as Tetrasphaera, it is still unknown whether glycine can support EBPR. We observed an overall adverse effect of glycine on EBPR using activated sludge from both full-scale wastewater treatment plants and lab-scale reactors harboring distant and diverse PAOs and glycogen accumulating organisms (GAOs), including Candidatus Accumulibacter, Thiothrix, Tetrasphaera, Dechloromonas, Ca. Competibacter, and Defluviicoccus, among others. Glycine induced phosphorus (P) release under anaerobic conditions without being effectively taken up by cells. The induced P release rate correlated with glycine concentration in the range of 10 to 50 mg C/L. PAOs continued to release P in the presence of glycine under aerobic conditions without any evident P uptake. Under mixed carbon conditions, the occurrence of glycine did not seem to affect acetate uptake; however, it significantly reduced the rate of P uptake in the aerobic phase. Overall, glycine did not appear to be an effective carbon source for a majority of PAOs and GAOs in full-scale and lab-scale systems, and neither did other community members utilize glycine under anaerobic or aerobic conditions. Metatranscriptomic analysis showed the transcription of glycine cleavage T, P and H protein genes, but not of the L protein or the downstream genes in the glycine cleavage pathway, suggesting barriers to metabolizing glycine. The high transcription of a gene encoding a drug/metabolite transporter suggests a potential efflux mechanism, where glycine transported into the cells is in turn exported at the expense of ATP, resulting in P release without affecting the glycine concentration in solution. The ability of glycine to induce P release without cellular uptake suggests a way to effectively recover P from P-enriched waste sludge.

Keywords: Enhanced biological phosphorus removal (EBPR); Glycine; Glycogen accumulating organisms (GAOs); P release; P removal; Polyphosphate accumulating organisms (PAOs).