Authors
Enlei Liang, Ji Shen, Tongyue Song, Xuezhuang Liu, Yinuo Liu, Jianming Su, Yue Gu, Yingxin Zhao
Published in
Bioresource technology. Pages 135648. Aug 16, 2026. Epub Aug 16, 2026.
Abstract
Excess sludge production and subsequent treatment remain major challenges in activated sludge-based wastewater treatment. However, biological strategies for efficient in-situ sludge reduction remain limited. In this study, a composite bio-promoter was developed to support low-MLVSS operation. At 15% lower MLVSS, the bioreactor maintained 88.37% ammonia nitrogen removal, while the observed sludge yield decreased by 19.78% within a cycle. Long-term operation showed that bio-promoter addition activated the metabolic activity and key enzyme functions, thereby reducing the net sludge increase by 13.46%. The lower sludge production response was accompanied by higher biomass-specific nitrifying activity. The specific oxygen uptake rate of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria increased by 7.39% and 11.55%, respectively. The specific activities of ammonia monooxygenase and hydroxylamine oxidase increased by 13.66% and 27.71%, respectively. Metagenomics analysis revealed that Nitrosomonas and Nitrospira became the dominant functional bacteria in the community. The relative abundance of key nitrification genes amoA and hao increased by 6.25% and 40.80%, respectively, suggesting that the bio-promoter enhanced the functional activity of retained nitrifying biomass and helped maintain nitrification under reduced sludge concentration. This study created a novel bio-promoter technology scheme for in-situ sludge reduction and provided a theoretical basis and practical strategy for achieving energy-saving and efficient operation.
PMID:
42604702
Bibliographic data and abstract were imported from PubMed on 17 Aug 2026.
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