Wastewater treatment plants simultaneously emit greenhouse gases and rely on external carbon sources, presenting both a challenge and an opportunity for carbon circularity. We develop a comprehensive life-cycle assessment of 32 Waste-to-Chemical pathways that integrate thermochemical and electrochemical conversions in sequential or parallel architectures to convert CH4 and CO2 into reusable carbon sources for in-plant utilization. Sequential thermochemical-electrochemical coupling consistently delivers the strongest climate benefit, with formate identified as the optimal product, reducing emissions up to ~35% reduction relative to direct-emission baselines. We further validate this pathway experimentally using commercially available Pd/Al2O3 catalysts for CH4 thermochemical oxidation and Bi2O3 catalysts for CO2 electroreduction in a porous solid electrolyte reactor. Residual heat generated during CH4 oxidation enhances downstream CO2 electroreduction, enabling 97.2 ± 1.2% Faradaic efficiency toward separation-free formate at 150 mA cm−2 and 45 °C. These results validate that commercially relevant catalysts and thermally coupled operation can deliver experimentally validated performance aligned with system-level projections. This framework establishes a scalable strategy for embedding carbon circularity into wastewater infrastructure and transforming wastewater treatment plants into distributed platforms for low-carbon chemical production.

The abuse of antibiotics leads to widespread antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in water systems, threatening public health. Existing disinfection technologies have limitations including the generation of toxic disinfection byproducts (DBPs) and inefficiency in eliminating intracellular ARGs. Herein, we provide an effective and toxic-DBP-free disinfection approach to remove ARB/ARGs by reactive species generated via activation of sodium percarbonate (SPC) inside and outside cells with naturally abundant sunlight. Combining in situ characterization and theoretical calculation, we reveal that CO3•–, •OH, and O2•– are generated both intra- and extracellularly. SPC passively diffusing into cells complexes with intracellular substances (e.g., heme, Fe–S cluster protein, and cytochrome c) to produce various reactive species in situ under sunlight irradiation, leading to the locally increased oxidation levels within cells. These reactive species synergistically contribute to the collapse of the antioxidant system, resulting in effective ARB inactivation and ARGs degradation. Owing to its limited reactivity toward background substances in water and effective intracellular oxidation mechanisms, the SPC/sunlight system demonstrates efficient ARB disinfection capabilities without any toxic DBPs generation in real water. This study presents a green, cost-effective, and toxic-DBP-free alternative for efficient ARB/ARGs removal with deep insights into intracellular oxidation mechanisms.

Hydrogen peroxide (H2O2) photosynthesis from H2O and O2 using covalent organic frameworks (COFs) is a sustainable approach, yet its efficiency is restricted by a sluggish water oxidation reaction (WOR) due to insufficient water adsorption and charge separation. Herein, we propose a facile and universal polar center spatial-manipulation strategy to enable efficient H2O2 photosynthesis by COFs via converting high-polarity C═N linkages into 4-carboxyl-quinolyl linkages with weakened-polarity quinoline backbones and ultra-polar carboxyl side chains (forming COF-TBC). This polar-center side-shifting strategy concurrently enhances water adsorption (via the polar carboxyl side chain) and water activation (enabled by efficient exciton formation and separation along the low-polarity quinoline backbone) by COF-TBC, lowering the energy barrier of the rate-determining WOR and achieving outstanding and stable H2O2 photosynthesis from O2 and H2O without sacrificial agents (5624 µmol g−1 h−1, accumulating to 41 mM, solar-to-chemical efficiency of 0.72%). The polar-center side-shifting strategy can be extended to modify other COFs for enhancing H2O2 photosynthesis, indicating its universality. COF-TBC maintains high H2O2 yield in complex real-water matrices and can be integrated into membrane-based and continuous-flow reactors for successive H2O2 generation under natural sunlight. COF-TBC also exhibits efficient photocatalytic performance toward organic contaminant degradation and microorganism inactivation, highlighting its broad potential for water purification.

Freeze–thaw (FT) cycle, a ubiquitous and important physical process in natural environments, may influence the horizontal gene transfer (HGT) process of antibiotic-resistant genes (ARGs), yet its impact and underlying mechanisms remain unclear. This study investigated the impact and mechanisms of FT cycles on ARG conjugative transfer among intra- and interspecies under different solution ionic strength conditions. The results showed that despite ionic strengths and species pairs, different FT treatment cycles induced diverse influences on ARG conjugation frequency with inhibition effect of 1 FT cycle (decreased by 3.5–76-fold) and facilitation effect of 2 and 3 FT cycles (promoted by 2–27-fold). The reduced conjugation frequency after 1 FT treatment cycle is mainly attributed to energy deficiency caused by the starvation process during FT treatment. The enhanced cell–cell adhesion induced by the increased hydrophobicity and secretion of bacterial extracellular polymeric substances (EPS) facilitated the formation of conjugative pilus, primarily promoting the ARG conjugative transfer process after 2 and 3 FT treatment cycles. The results of our study clearly show that FT cycles (intensified by the ongoing climate change) exhibit profound influence on the dissemination of ARGs, which helps understand and predict ARG risks in different natural environments.

Insufficient oxygen mass transfer and inadequate charge separation are two critical factors restricting the photocatalytic efficiency of covalent organic frameworks (COFs) for water purification. Here, we develop a facile strategy to simultaneously boost oxygen mass transfer and charge separation in COFs through constructing efficient oxygen capture tentacles via replacing conventional pyridine groups with nicotinic-acid/methyl-nicotinate groups, which have tunable oxygen affinity. Molecular dynamics simulations and in situ characterizations reveal that compared to pyridine groups in COF-EP1 and nicotinic-acid groups in COF-EP2, respectively serving as weak and medium oxygen capture tentacles, methyl-nicotinate groups in COF-EP3 can serve as strong oxygen capture tentacles due to their superb oxygen affinity, which can enhance oxygen interaction energies and thus promote oxygen mass transfer. Owing to the optimal charge polarization, methyl-nicotinate groups in COF-EP3 also strengthen internal electric fields to facilitate charge separation. COF-EP3 thus achieves exceptional photocatalytic degradation performance towards sulfadiazine (99.5% removal in 25 min, k = 0.21 min−1), which is 16.2 and 2.8 times higher than that of COF-EP1 (k = 0.013 min−1) and COF-EP2 (k = 0.076 min−1), respectively. Besides, COF-EP3 exhibits high sulfadiazine degradation performance in complicated water matrices, continuous-flow system, and scaled-up reactor, demonstrating its practical application potential.

The effects and mechanisms of carbon (C)- and nitrogen (N)-deficient nutrient conditions (prevalent in natural environment) on bacterial mobile performance in porous media are unclear. This study systematically investigated the transport/retention performance of Gram-negative Escherichia coli and Gram-positive Bacillus subtilis experiencing different nutrient conditions (i.e. nutrient-sufficient, C-deficient, or N-deficient conditions) in column, parallel plate flow chamber (PPFC) and microfluidic chamber systems. We found that compared to those in nutrient-sufficient condition, bacteria (regardless of their type) exposure to C-deficient nutrient condition exhibited 7–14% reduced mobility in porous media, whereas those experienced N-deficient condition had 7–20% enhanced transport in both simulated electrolyte solutions and real groundwater samples. The underlying mechanisms driving to different mobile performance of bacteria exposure to different nutrient conditions were correlated with the composition of proteins (one major component of extracellular polymeric substances (EPS)). Compared to nutrient-sufficient condition, C-deficient condition increased EPS hydrophobicity via enhancing hydrophobic amino acids contents and altering secondary structure within proteins thus decreased bacterial transport, while N-deficient condition decreased EPS hydrophobicity through decreasing the abundance of hydrophobic amino acids within proteins and increased cell mobility. The results showed that via changing cell surface hydrophobicity, exposure bacteria to different nutrient conditions could induce different mobile performance of bacteria.

Antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARGs) pose global threats to human health and ecological safety. Activation of percarbonate (PC) by eco-friendly bismuth oxyiodide (BiOI) is a promising ARB/ARGs removal technique, yet its efficiency is hindered by the insufficient exposure of reactive Bi sites. Herein, we provide a facile protocol to fabricate BiOI with remarkable PC activation efficiency (BOI-C) for the ultrafast ARB/ARGs removal via modulating reactive Bi sites through introducing optimal Bi3-oxygen vacancy (OV) sites on the unsaturated facets. We show that BOI-C with optimal amount of Bi3-OV site can efficiently activate 50 µM PC to rapidly disinfect 7-log ARB to the limit of detection within only 4 min. Moreover, this reaction system can effectively degrade the released ARG and suppress the horizontal gene transfer process, greatly decreasing the risks of ARG dissemination. Negligible toxic halogen-containing disinfection byproducts is generated during the disinfection process, indicating the outstanding ecological safety of BOI-C/PC system. The reaction system can also effectively disinfect ARB under complex water chemistries including a broad pH range (3–9), high ionic strengths (up to 150 mM), copresence of natural organic matter (up to 10 mg L−1), and diverse actual water samples including tap water, lake water, groundwater and aquaculture tailwater. Furthermore, it can also be assembled into a filtration system for successive ARB disinfection, demonstrating the feasibility for practical application. The catalytic system also exhibits excellent ARB disinfection performance across various bacterial strains and effective degradation performance towards different types of emerging organic pollutants, suggesting its universal decontamination capability. Combining in-situ characterizations and theoretical calculations, we reveal that Bi3-OV sites on the unsaturated facets of BOI-C facilitate the p-p interaction with peroxy O atoms of PC molecules and trigger the electron transfer as well as the subsequent cleavage of peroxy bonds, generating abundant CO3•− for the ultrafast ARB disinfection. The results of this study show that BOI-C/PC system can be employed to effectively remove antibiotic resistance in real water.