ASSR-mediated sludge yield reduction couples deterministic enrichment of Nitrospira with metabolic resource partitioning

  • Huanzhong Deng
  • , Junling Yang
  • , Ruohong Li
  • , Kewen Li
  • , Hui Lu
  • , Bing Lin
  • , Xingquan Xu
  • , Jiajun Liao
  • , Congrong Ye
  • , Jie Deng
  • , Bo Wu*
  • , Lianpeng Sun
  • *Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The anaerobic side-stream reactor (ASSR) process offers a microbiome-driven strategy for sustainable wastewater treatment, yet the ecological mechanisms governing its sludge yield reduction efficiency remain unresolved. Here, we demonstrate that a pilot-scale anaerobic-anoxic-oxic (AAO) system with integrated anaerobic side-stream reactor (ASSR) (designated AAO-ASSR/SR) reduced sludge production by 43.6 % compared to a conventional AAO system (designated AAO/CK), while maintaining effluent quality. Through integrated multi-omics and ecological modeling, we revealed the core microbiome-driven mechanism for ASSR-mediated sludge yield reduction. This mechanism is characterized by three key features: (1) enhanced microbial stability via cooperative networks, (2) deterministic assembly selecting slow-growing keystone taxa (e.g., Nitrospira, 18.6 % abundance in SR), and (3) metabolic resource partitioning from biomass synthesis to amino acid cross-feeding. Functional metagenomics revealed that Nitrospira (phylum Nitrospirota, comprising >99 % Nitrospira) and Novosphingobium (phylum Proteobacteria) mediated increased amino acid metabolism and reduced ATP biosynthesis in SR, contrasting with Bacteroidota-dominated biomass synthesis in CK through enhanced protein, nucleotide metabolism and ATP biosynthesis. By coupling deterministic microbial assembly with functional repartitioning, this work contributes to establish a design principle for targeted microbiome engineering in low-sludge systems, advancing sustainable wastewater management through ecological optimization of microbial resource allocation.

Original languageEnglish
Article number125031
JournalWater Research
Volume290
DOIs
StatePublished - 15 Feb 2026

Keywords

  • Anaerobic side-stream reactor (ASSR)
  • Deterministic assembly
  • Microbial cooperation
  • Nitrospira
  • Sludge yield reduction

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