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.

Coconut shell biochar and bamboo biochar were added to the bedding courses of permeable pavements to improve nitrogen removal efficiency. This was expected to be particularly effective for innovative permeable pavements that increase evaporation of stored rainwater. The effects of the rainfall intensity and ambient temperature on nitrogen removal were assessed. The NO3−-N removal rate for the pavements with biochar added and the blank controls were 48.6%–54.0% and 10.8%, respectively, at a rainfall intensity of 10 mm/h and temperatures of 22–28 °C. The total nitrogen removal rates for the pavements with biochar added and the blank controls were 52.6%–57.7% and 20%, respectively. Adding coconut shell and bamboo biochar improved denitrification without causing organic matter to be leached. Increasing the rainfall intensity and decreasing the temperature caused less nitrogen to be removed. The total nitrogen balance indicated that the innovative pavements and conventional pavements with the same biochar amendments removed 781.58 and 733.30 mg of nitrogen, respectively, suggesting that adding biochar improved the performances of the innovative pavements more than the conventional pavements. Quantitative polymerase chain reaction assays of bedding course samples indicated that adding biochar markedly increased the abundances of denitrifying microorganisms.

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.