Response of aerobic granular sludge to organic loading rate under micro-electric stimulation environment

Highlights

	● The role of OLR on AGS under a complicated environment is rarely established.
	● The dynamic OLR affected the behaviors of AGS and reactor performance.
	● The variation of EPS content and constitutions was revealed.
	● The main function microbes under the OLR-varied condition were identified.

Abstract

Aerobic granular sludge (AGS) is a neoteric wastewater treatment technology. The organic loading rate (OLR) exhibits a critical effect on the AGS formation process. The special role of OLR on AGS is rarely established, especially in a complicated environment. This work explored the influence of OLR on the AGS system under a micro-electric stimulation environment. The dynamic OLR affected the behaviors of AGS and reactor performance. AGS cultured under a dynamic OLR environment showed a more compact structure and the AGS system displayed an excellent capacity in removing pollutants. The stable texture of AGS is related to the extracellular polymeric substance (EPS). The main constitutions of EPS include tryptophan protein, tyrosine protein, humic acid-like substance, and fulvic acid-like substance. The OLR-varied environment may provide a selective condition, impacting the microbial population. The prevail bacteria were Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium (21.98%), Lactococcus (23.93%), and Chryseobacterium (5.58%) in OLR-varied AGS system. The evolution of the microbial population induced the change in bacterial community functions, such as carbohydrate metabolism, replication and repair, and membrane transport functions. This work provides valuable insights into the OLR on AGS processes, helping to the stability of AGS-based systems.

Graphical abstract

Keywords

Biological treatment technology / Aerobic granular sludge / Organic loading rate / Microbial community structure / Metabolism function

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CRediT Authorship Contribution Statement

Yabin Li: Conceptualization, Methodology, Data curation, Funding acquisition, Writing - original draft-editing. Lanlan Qin: Software, Validation, Formal analysis. Xiran Li: Formal analysis, Investigation, Data curation, Supervision. Xiaolong Tang: Methodology, Investigation. Xia Zhao: Conceptualization, Resource, Funding acquisition, Project administration, Writing-review and editing. Xiaoning Jia: Methodology, Software. Xiuqin Kong: Methodology, Validation.

Conflict of Interests

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this work.

Acknowledgments

This work was supported by the National Natural Science Foundation of China (No. 22166023), the Industrial Support Plan Project of Colleges and Universities in Gansu Province (No. 2023CYZC-30), the Gansu Leading Talents Program (No. 2024), the Key Research and Development Program of Gansu Province (No. 24YFFA053), the Science and Technology Plan Project of Gansu Province (No. 24JRRA198), the Innovation Fund Project for University Teachers of Gansu Province (No. 2024), the Youth Scientific and Technological Talent Innovation Project of Lanzhou (No. 2024-QN-174), the Program for Hongliu Outstanding Young Talents in Lanzhou University of Technology (2024), the Open Project of State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology (No. QA202445), and the Science and Technology Development Plan Project of Lanzhou (No. 2024-2-4).

Electronic Supplementary Material

Supplementary material is available in the online version of this article at https://doi.org/10.1007/s11783-025-1984-9 and is accessible for authorized users.

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