Anaerobic ammonium oxidation (anammox), as an efficient and low-carbon method for nitrogen removal from wastewater, faces the challenge of slow enrichment of functional bacteria. In this study, the enrichment of anammox bacteria Candidatus Brocadia was successfully accelerated by co-culturing with the quorum-sensing strain Pseudomonas aeruginosa and anoxic sludge from a pig farm. Experimental results showed that the R2, which had Pseudomonas aeruginosa added, exhibited chemical reaction ratios R_S (NO₂⁻-N consumption/NH₄⁺-N consumption) and R_P (NO₃⁻-N production/NH₄⁺-N consumption) closer to the theoretical values of the anammox reaction since Phase Ⅱ. Bacterial community analysis indicated that the abundance of Candidatus Brocadia in R2 reached 1.63% in cycle 20, significantly higher than the 0.45% in R1. More quorum-sensing signaling molecules, primarily C6-HSL, were detected in R2. C6-HSL was positively correlated with processes such as the secretion of anammox extracellular polymers (EPS) and the regulation of nitric oxide reductase (Nir), which may explain the reason behind the accelerated increase in the abundance of Candidatus Brocadia through co-culturing. Moreover, the metabolism of the dominant genus Paracoccus within the two groups of reactors also showed positive regulation by C6-HSL, with its abundance trend similar to that of Candidatus Brocadia, jointly completing the nitrogen removal process in the reactors. However, it is still unknown which genera secrete large amounts of C6-HSL after inoculation with Pseudomonas aeruginosa. This research provides a novel and low-cost method for the enrichment of anammox bacteria.

This study investigates how 0.8 V applied voltage modulates phenazine biosynthesis, quorum sensing (QS), and microbial interactions in Pseudomonas aeruginosa PAO1-inoculated microbial electrolysis cell (MEC) reactors. Voltage stimulation significantly enhanced phenazine derivatives (PYO: 8.65-fold; 1-OH-PHZ: 14.98-fold) and QS signals (C4-HSL: 2.88-fold; 3-OXO-C12-HSL: 2.21-fold), correlating with upregulated biosynthetic genes (phzG: 14.8-fold; rhlI: 15.2-fold). Electrical stimulation amplified QS cross-regulation, reinforcing Las-mediated positive feedback on Rhl/PQS systems while attenuating Rhl’s inhibition of PQS. Untargeted metabolomic analysis demonstrated significant alterations in bacterial metabolic activity under electrical stimulation, identifying 140 differential metabolites. Among these, indole, a signaling molecule with QS-like functionality, exhibited the highest VIP score as an upregulated metabolite, and another indole derivative, brassicanal A, was also elevated. KEGG pathway enrichment analysis highlighted that these metabolites were primarily associated with amino acid metabolism and transport, while anthranilic acid and L-tryptophan—key metabolites linked to both indole-related pathways and phenazine biosynthesis—were also identified. Correlation analysis between differential metabolites with microbial communities confirmed that Delftia and Burkholderiales were strongly associated with phenazine biosynthesis and QS activity in P. aeruginosa PAO1. These findings highlight voltage as a key driver of metabolic rewiring and microbial niche partitioning, optimizing MEC reactor performance for wastewater treatment. This work provides foundational insights into electro-stimulated biofilm engineering through targeted QS and metabolic pathway regulation.

Heterogeneous Fenton process is a promising water treatment technology for sterilization and degradation of organic pollutants, due to the strong oxidation of hydroxyl radicals (OH˙) generated. However, the low H₂O₂ activation efficiency and the instability of catalyst leading to low OH˙ production restricted development of this technology. Herein, we synthesized a novel porous activated carbon-loaded nano silver oxide (nAg₂O/AC) catalyst to enhance the activation of H₂O₂ for removing bacteria (E. coli) and micropollutants (Tetracycline, TC) from water. In the nAg₂O/AC Fenton system, reductive hydroxyl groups on AC accelerated Ag(I)/Ag cycle through mediated electron transfer, which markedly increased H₂O₂ activation efficiency to 73.7% (About 2.9 times that of traditional Fenton). Hence, nAg₂O/AC Fenton achieved up to 6.0 log and 100% removal efficiency for E. coli and TC, respectively. The OH˙ as the major oxidizing species in nAg₂O/AC Fenton system was detected and verified by radical scavenging tests and electron spin resonance (ESR) measurement. After 4 and 5 cycles of experiments, the removal of E. coli and TC still reached 5.2 log and 96%, respectively, confirming good stability of nAg₂O/AC for considerable application prospects. This study concluded that nAg₂O/AC is a promising H₂O₂ catalyst for simultaneous removal of bacteria and micropollutants in aqueous environment.

Electrolytic hydrogen production from water is a cost-effective renewable energy technology, but its development is severely constrained by high energy consumption, precious metal catalysts, and low-value products of anode. Given that inexpensive glycerol exhibits a significantly lower redox potential than water, this study developed a 3D coral-like nickel–molybdenum sulfur bifunctional nanocatalyst (Ni–Mo–S/NF) based on nickel foam, which served as both the anode and cathode in an alkaline glycerol electrolyte, enabling the simultaneous production of high-value formate at the anode and high-purity hydrogen at the cathode. Notably, in a two-electrode system, the alkaline glycerol electrolyzer required only 1.37 V to achieve a current density of 10 mA cm⁻², which was 280 mV lower than that of an alkaline aqueous solution system, indicating an about 17% reduction in energy consumption compared to conventional water electrolysis. Meanwhile, this system reached a faradaic efficiency of 95.0% for formate production and 99.6% for hydrogen evolution. Benefiting from the outstanding performance of the noble-metal-free Ni–Mo–S/NF catalyst, the proposed technology for simultaneous formate and hydrogen production via glycerol electrooxidation offers a novel pathway for the green production of high-value chemicals and energy-saving hydrogen generation.

Nitrous oxide (N₂O) is not only recognized as a potent greenhouse gas, but it is also used in industry as a clean energy source. In this study, different electrode materials of carbon felt and graphite were equipped in the ΔnosZ P. aeruginosa/microbial electrolysis cell (MEC) systems to explore the optimization mechanism for long-term N₂O recovery during incineration leachate treatment. The carbon felt group showed a better performance in N₂O recovery across 45 days of operation. The N₂O conversion efficiency was above 80% and the proportion of N₂O in biogas accounted for 80.6% in the carbon felt group. qRT-PCR analysis was conducted to evaluate the expression of genes involved in denitrification (norB) and electroactivity (phzG, phzM, and phzH) of ΔnosZ P. aeruginosa. The results showed a significant upregulation in the suspended biomass (day 21) and the electron-attached biomass (day 45) from the carbon felt-equipped reactor, which was highly related to the opportunity of biomass exposed to the phenazine derivatives. By the carbon felt optimization in the system, 82.6% of the Pseudomonas genus survived after 45 days of operation. These results indicate that the carbon felt electrode has a more sustainable performance for N₂O recovery in the ΔnosZ P. aeruginosa/MEC system.