Efficient nitrogen removal from ammonia rich wastewater using aerobic granular sludge (AGS) reactor: Selection and enrichment of effective microbial community

Xin Zou; Mengjiao Gao; Yiduo Yao; Yihui Zhang; Hengbo Guo; Yang Liu

doi:10.1016/j.envres.2024.118573

Efficient nitrogen removal from ammonia rich wastewater using aerobic granular sludge (AGS) reactor: Selection and enrichment of effective microbial community

Environ Res. 2024 Feb 29;251(Pt 1):118573. doi: 10.1016/j.envres.2024.118573. Online ahead of print.

Authors

Xin Zou¹, Mengjiao Gao², Yiduo Yao¹, Yihui Zhang¹, Hengbo Guo¹, Yang Liu³

Affiliations

¹ Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta, T6G 1H9, Canada.
² Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta, T6G 1H9, Canada; College of Environment and Ecology, Chongqing University, Chongqing, China.
³ Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta, T6G 1H9, Canada; School of Civil & Environmental Engineering, Queensland University of Technology, Brisbane, Queensland, Australia. Electronic address: yang.liu@ualberta.ca.

PMID: 38431070
DOI: 10.1016/j.envres.2024.118573

Abstract

Anaerobically digested sludge supernatant, characterized by its high ammonia and low biodegradable chemical oxygen demand (COD) content, has raised concerns when returned to mainstream treatment lines due to potential impacts on effluent quality. Addressing this, an aerobic granular sludge (AGS) reactor adopted nitritation/denitritation with external COD addition was utilized and achieved a considerable nitrogen treatment capacity of 4.2 kg N/m³/d, reaching over 90% removal efficiencies for both ammonia and total inorganic nitrogen. This study applied progressively increased nitrogen loading to select for a microbial community that exhibited high nitrogen oxidation and reduction rates, demonstrating peak rates of 0.5 g N/g VSS/d and 3 g N/g VSS/d, respectively. The enrichment of highly efficient microbial community was achieved along with the increased biomass density peaked at 17 g/L MLVSS, with the system retaining small-sized granular sludge at 0.5 mm. The primary ammonia oxidizing bacteria was Nitrosomonas, while Thauera was the dominated denitrifiers. Quantitative polymerase chain reaction analyses reinforced the enhanced nitrogen removal capacity based on the progressively increased abundance of nitrogen cycling functional genes. The high nitrogen treatment capacity, synergistic attributes of high specific microbial activities and the substantial biomass retention, suggest the AGS's efficacy and capacity in ammonia rich wastewater treatment.

Keywords: Anaerobically digested sludge supernatant; High nitrogen loading; Nitritation/denitritation; Quantitative polymerase chain reaction (qPCR); Small-sized granular sludge; Specific microbial activity.