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Updated: May 31, 2026

A Novel Bioreactor for High Density Cultivation of Diverse Microbial Communities
Published on: December 25, 2015
Synergistic antibiotic-laden wastewater treatment doubles denitrification rate in a pilot mineral-based autotrophic
Yiqing Zhang1, Li Zhang1, Shujun Zhang2
1National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing, 100124, China.
Abstract:
The practical application of pyrite-based autotrophic denitrification biofilters (PADB) is limited by their low nitrogen removal rate (NRR). This study demonstrates that in a pilot-scale PADB (750 L) treating NO3--N wastewater, heterotrophic bacterial consortia (HBs) severely impair the denitrification activity of autotrophic denitrifying bacteria (ADB) through network encapsulation and metabolic shunting. However, after switching to treating composite wastewater containing antibiotics, the system achieved an antibiotic removal rate of 95.12%. And it's NRR from 32.37 to 63.15 mg N/(L·d), representing a 0.95-fold enhancement. Integrated co-occurrence network and metagenomic analyses revealed a three-stage cascade reaction underlying this improvement: (i) The antibiotic stress halted carbon-feeding from ADB and hydrolytic-acidifying bacteria to HBs (fermentation gene abundance decreased by 1.89-58.45%), depriving HBs of energetic and substrate support and resulting in their selective elimination (0.63-fold decrease in relative abundance). This relieved ADB's metabolic burden and shortened their physical distance to pyrite; (ii) Elevated electron and energy demand in ADB activated dormant genes for electron shuttle synthesis (menC/E: 0 to 342/402 TPM) and upregulated sulfur metabolism genes (∼3.9-fold), enhancing pyrite dissolution and electron harvesting; (iii) This augmented electron flow stimulated ADB's carbon fixation pathway (Calvin-Benson-Bassham cycle genes upregulated 14.89-fold) and amplified energy metabolism (1.33-1.55-fold enhancement in glycolysis and Tricarboxylic Acid cycle), supplying ample material and energy for ADB proliferation and denitrification. Consequently, ADB enrichment accelerated 509-fold, while the abundance of key denitrification genes (napA/B, nosZ) increased by 2.1-11.04-fold. These molecular and population-level changes doubled the system's NRR compared to its original level.
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