This work demonstrates a convenient strategy for the interconversion of the organic carbon transfer process (OCTP) and oxidative mineralization process (OMP) in atomic cobalt mediated Fenton-like systems via flexible strain engineering. CoN1O2 active sites anchored on carbon nanospheres of varying curvatures were used to activate peroxymonosulfate (PMS) for the differentiated removal of phenol (PhOH). While over 80% of PhOH was removed in all systems, the low curvature catalyst recovered over 90% of PhOH as polymers, whereas the high curvature catalyst achieved efficient mineralization and avoided performance deterioration. Combined characterization and calculations reveal that strain-induced curvature regulates the catalytic mechanism by modulating both the geometric and electronic structures. Geometrically, co‑occupation of PhOH and PMS on the active sites promotes direct two‑electron transfer for OCTP, whereas mutually exclusive occupation generates singlet oxygen via single‑electron transfer for OMP. Electronically, the strong strain reduces the lowest unoccupied molecular orbital energy by weakening the ligand field strength, enhancing electron accessibility and driving the mechanistic transition. This work provides an experimental knob for regulating the carbon cycle in heterogeneous Fenton-like reactions, enabling tunable water purification for diverse application needs.

Sulfadiazine (SDZ), a widely used antibiotic, poses a significant threat to aquatic ecosystems due to its environmental persistence. Advanced oxidation processes (AOPs), particularly those combining photocatalysis with peroxymonosulfate (PMS) activation, offer a promising solution for its removal. This study aimed to construct a novel 2D/2D Z-scheme heterojunction photocatalyst, CuFe-LDH/BiOBr (4-CFB), and evaluate its synergistic performance with PMS for the efficient degradation of SDZ under visible light. The 4-CFB composite was synthesized via electrostatic self-assembly and comprehensively characterized using SEM, HRTEM, XRD, XPS, ESR, and DRS. The optimal composite (4-CFB) exhibited exceptional catalytic activity, achieved a rate constant (0.21 min-1) 3 and 10.5 times higher than that of CuFe-LDH (0.07 min-1) and BiOBr (0.02 min-1), respectively. It demonstrated excellent stability during multiple reuse cycles, minimal metal leaching (Cu2+ < 1.1 mg/L), and broad-spectrum efficacy against various antibiotics. Mechanistic studies revealed that the direct Z-scheme heterojunction drove efficient charge separation, while the Fe(II)/Fe(III) redox cycle alongside oxygen vacancies proved critical for activating PMS, where singlet oxygen (1O2) and holes (h+) emerged as the primary drivers of SDZ degradation. The Vis/PMS/4-CFB system presents a highly efficient, stable, and environmentally compatible strategy for antibiotic wastewater remediation.

The widespread occurrence of sulfadiazine (SDZ) in aquatic environments poses significant ecological risks, necessitating the development of efficient removal technologies. This study successfully synthesized orthorhombic Mo and S co-doped Cu-BTC (Mo/Cu-S-BTC) cages to activate H2O2 for SDZ degradation via a Fenton-like process. Comprehensive characterization confirmed the successful formation of a composite where MoS2 nanosheets were in-situ grown on the Cu-BTC-derived framework, creating a hierarchical and mesoporous structure. The optimized Mo/Cu-S-BTC exhibited superior catalytic performance, achieving 98.4 % SDZ removal with a reaction rate constant (0.13 min-1) 3.7-33.3 times higher than those of its precursors (Cu-BTC, Cu2S-BTC, and MoS2), demonstrating a strong synergistic effect. The system operated effectively over a wide pH range (5-9) and showed strong resistance to common inorganic anions and humic acid. Mechanistic investigations revealed that 1O2 was the primary reactive species. The catalytic cycle involved the synergistic redox action of Mo and Cu sites, where Mo(IV)/Mo(VI) redox pairs facilitated center dot O2-/O2 generation, and Cu(I)/Cu(II) cycles promoted center dot OH formation, with S2- aiding Cu(I) regeneration. Furthermore, the catalyst demonstrated excellent reusability and minimal metal leaching over four consecutive cycles. These findings highlight Mo/Cu-S-BTC as a highly efficient and stable catalyst for H2O2 activation, providing a promising strategy for remediating antibiotic contaminated water.

The widespread occurrence of sulfadiazine (SDZ) in aquatic environments necessitates efficient remediation technologies. Advanced oxidation processes based on peroxymonosulfate (PMS) activation are promising but hindered by challenges like metal leaching and low efficiency in monometallic systems. Herein, a novel amorphous cobalt-doped FeOOH/tubular carbon nitride (Co-FeOOH/TCN) was synthesized to overcome these limitations. The TCN support provided a high-surface-area, conductive scaffold that inhibited metal aggregation and facilitated electron transfer, while the Co-FeOOH enhanced PMS adsorption and activation. The optimized CoFeOOH/TCN demonstrated exceptional performance, achieving 97.5% degradation of SDZ within 10 min with a rate constant of 0.53 min-1, outperforming Cu/Mn-doped variants by 53 fold. Quenching experiments, EPR spectroscopy, and chemical probing revealed that both radical species including SO4 center dot-, center dot OH and O2- as well as non-radical species such as 1O2, M(IV)=O, and electron transfer process contributed to SDZ degradation, with non-radical mechanisms being predominant at a contribution of 76.8%. The system exhibited high efficiency across a broad pH range of 3-11 and strong resilience to common aquatic anions. In summary, this work presents triple aspect novelties. These include an amorphous Co-FeOOH/TCN structure, a non-radical dominated mechanism, and a superior normalized rate constant that outperforms state of the art catalysts.

Herein, we developed a novel UV/EDTA-Fe(II) system that integrated EDTA-Fe(II) complexation with UV photoactivation to unlock the Fe(III)/Fe(II) redox cycle for efficient antibiotic degradation. The system achieved 99.43% removal of Achromycin V and exhibited broad-spectrum degradation against cefalexin, sulfamethoxazole, and acetaminophen. The degradation efficiency was strongly governed by the standard one-electron reduction potentials of the ligand-Fe(III)/ligand-Fe(II) redox couple, which are modulated by the O and N-donor sites. Density functional theory (DFT) calculations elucidated that the EDTA-Fe(II) complex initially bound O2 to form a [(EDTA)Fe2+-O2]2− intermediate. Upon UV excitation, this intermediate converted to the excited [(EDTA)Fe2+-O2]⁎2−, which subsequently underwent metal-to-ligand charge transfer (MLCT) to yield [(EDTA)Fe3+]− and O2•− via the Fe-O bond breakage. The resulting [(EDTA)Fe3+]− functioned as a “photocatalyst” under UV irradiation, facilitating the Fe(III)/Fe(II) redox cycle via ligand-to-metal charge transfer (LMCT) while transferring electrons to O2 to produce O2•− and •OH. Notably, O2•− dismutated to produce 1O2 as the primary reactive species, implying a thermodynamically favorable “O2→O2•−→1O2” cascade. This work establishes a promising strategy for designing 1O2-mediated advanced oxidation processes (AOPs) with high anti-interference activity and long‑term stability, effectively overcoming the inherent limitations of conventional Fe-based AOPs.

The widespread use and improper discharge of tetracycline (TC) pose significant threats to environmental safety and human health, necessitating the development of efficient removal technologies. Herein, a core-shell heter-ostructure, Cu2S@Co3S4, was successfully synthesized via a hydrothermal method for activating H2O2 to degrade TC. Comprehensive characterization confirmed the well-defined cubic morphology and intimate interfacial contact between the Cu2S core and Co3S4 shell. The optimized Cu2S@Co3S4 demonstrated outstanding catalytic performance, remarkably removing over 97% of TC within 30 min and achieving a rate constant of 0.11 min1. This surpassed pure Co3S4 (0.004 min1) and Cu2S (0.030 min1) by factors of 27.5 and 3.6, respectively. The system demonstrated high efficiency across a broad pH range (5-11) and showed strong resistance to common interfering ions. Mechanistic investigations, including quenching experiments, EPR analysis, and DFT calcula-tions, revealed that 1O2 was the predominant reactive species. The internal electron transfer from (CuS)-S-2 to Co3S4 enhanced H2O2 adsorption and activation, facilitating efficient electron transfer from TC to the surface-activated H2O2 complex. Besides, the redox cycles of Cu+/Cu(2+)and Co2+/Co3+, promoted by low-valence sulfur, sustained catalytic activity. Degradation pathways were proposed, and toxicity assessment indicated the effective detox-ification of TC. This work provides a highly efficient and stable heterostructured catalyst and offers deep insight into the H2O2 activation mechanism dominated by O-1(2) for antibiotic wastewater remediation

In this study, a cobalt single-atom anchored Ti3C2Tx (CoSA-Ti3C2Tx) was fabricated via a straightforward sodium borohydride reduction approach, specifically designed to activate peracetic acid (PAA) for the efficient degradation of organic pollutants. Comprehensive characterizations (HAADF-STEM, XRD, XPS, XAFS) confirmed the atomic dispersion of Co atoms, The unique cooperative neighboring Co single atoms with Co-O-Co configuration enables a synergistic effect between the adjacent single-atom cobalt sites. The CoSA-Ti3C2Tx exhibited superior performance in activating PAA for the degradation of sulfadiazine (SDZ), achieving a reaction rate constant of 0.08 min-1, significantly surpassing that of PAA alone (0.006 min-1) and Ti3C2Tx/PAA system (0.005 min-1) under identical pH and temperature conditions. The catalytic system demonstrated high efficiency over a broad pH range (3-11) and showed strong resistance to interference from common aqueous anions. Mechanistic investigations, including quenching experiments, EPR, and electrochemical analysis, revealed that organic radicals were the dominant reactive species. DFT calculations further elucidated that the unique Co sites significantly enhanced PAA absorption, elongated the O-O bond of PAA, and facilitated electron transfer, thereby promoting efficient PAA activation. This work provides a novel and robust single-atom catalyst for PAAbased AOPs and offers profound atomic-level insights into the activation mechanism.

Perchlorate (ClO4-) is a persistent and hazardous water pollutant that disrupts thyroid function. Hydrogels, with their tunable functionality and high capacity, offer a promising alternative, but their application for perchlorate removal remains largely unexplored. A novel hydrogel was synthesized via free-radical copolymerization of methacryloxyethyl trimonium chloride (MTAC) and N, N'-methylenebis (acrylamide) (MBA). The material was characterized using SEM, EDS, FTIR, XRD, and XPS. The MTAC hydrogel exhibited a high adsorption capacity for ClO4-, with experimental data best fitted by the Langmuir isotherm, showing a maximum capacity of 425.22 mg/ g at 298 K. The adsorption process is primarily driven by strong electrostatic interactions from quaternary amine groups, supplemented by ion exchange and hydrogen bonding. The adsorption energy reached -3.59 eV. The adsorption process was fast, spontaneous, and exothermic, remaining effective over a wide pH range (5-9) and in the presence of common competing anions. The hydrogel demonstrated excellent regenerability over five cycles. MTAC/Sodium alginate (SA) beads were used in fixed bed packing, which achieved a treatment capacity of 5346 bed volumes, reducing ClO4- from 500 mu g/L to below the drinking water standard (70 mu g/L). Furthermore, the column facilitated easy regeneration and exhibited an enrichment factor as high as 122.9 fold. This work successfully developed a MTAC-based hydrogel for the removal of ClO4-. The hydrogel demonstrated high capacity and regenerability in real water samples and column experiments, making it an ideal candidate material for practical end-of-pipe water treatment applications.

To address the limitations of traditional bacterial-algal symbiotic systems in treating wastewater with high ammonia-nitrogen levels. A novel symbiotic system consisting of heterotrophic nitrifying-aerobic denitrifying (HN-AD) bacteria and Chlorella was established to treat synthetic high-ammonia wastewater exposed to continuously accumulated polyethylene microplastics (PE-MP). The consortium maintained partial functionality within a range of 3.0g·L-1, while coordination deteriorated under high loading conditions. At 3.5g·L-1, NH4+-N and total phosphorus removal rates decreased by 16.52% and 16.83%, respectively, compared to the control group. Ammonia monooxygenase (AMO) and nitrate reductase (NR) activities decreased by 75.8% and 63.7%, respectively, while nitrification activity and chlorophyll a content decreased by 40% and 15.8%, respectively. Metagenomic analysis revealed that the relative abundance of Azospirillum decreased by 18.8% compared to the control group, while that of Rhodococcus increased by 5.0%. The relative abundance of the key genes napAB and nasCDE decreased by 54.3% and 41.6%, respectively. The reductions in galU and ugd relative abundances coincided with a decline in EPS production and a 59%–65% decrease in PN/PS. Metabolomics revealed changes in nitrogen and phosphorus metabolism, along with reduced levels of EPS-related metabolites. These results identified a performance shift at approximately 3.0g·L-1 under these specific continuous exposure conditions and provide insights for optimizing bacterial-algal wastewater treatment systems.

Perfluorooctanoic acid (PFOA), with high toxicity and resistance to degradation, has been widely detected in various wastewaters, posing a potential threat to environmental health. This study found that far-ultraviolet light (UV222) markedly enhanced the mineralization rates of PFOA in secondary effluent by driving the silver oxide (Ag2O)/peroxymonosulfate (PMS) system. The photocatalysis in Ag2O, radiation activation of PMS by the high photon energy of UV222, activation of PMS by Ag2O, and Ag2+ formation by electron transfer formed multiple pathways for radical generation. Characterization results indicated that UV222 inhibited the transformation of Ag+ crystal structures, enabling stable cycling between Ag/Ag+/Ag2+ states. Degradation product analysis and ECOSAR assessment revealed that the majority of PFOA was degraded into small-molecule products, thereby reducing the ecological toxicity risk. The free radical pathway, primarily utilizing sulfate radicals as the active species, serves as the main mechanism for defluorinating PFOA. This system successfully overcame the limitations associated with the Fenton-like process, including pH constraints, elevated oxidant doses, and ionic interference, while also demonstrating notable antibacterial performance and detoxification capabilities. These findings enhance the understanding of UV222-driven technologies and offer an efficient and sustainable strategy for the treatment of PFASs.

The widespread occurrence of carbamazepine (CBZ) in aquatic environments necessitates efficient water treatment technologies. This study developed a cobalt-doped iron oxychloride (Co-FeOCl) catalyst via a facile calcination method to activate peracetic acid (PAA) for enhanced degradation of CBZ. The incorporation of Co into the FeOCl structure dramatically boosted the catalytic performance, with 0.5Co-FeOCl exhibiting superior activity compared to pristine FeOCl. The 0.5Co-FeOCl/PAA system achieved an apparent rate constant of 0.039 min-1, 19.5 and 5.6 times higher than that of the PAA alone (0.002 min-1) and FeOCl/PAA (0.007 min-1) systems, respectively. Mechanistic investigations revealed that the degradation was primarily driven by organic radicals (CH3C(O)OO center dot and CH3C(O)O center dot) and high-valent metal species (Co(IV) and Fe(IV)). The Co doping established synergistic Fe(II)/Fe(III)-Co(II)/Co(III) redox cycles, effectively accelerating the rate-limiting Fe(III) reduction step and facilitating continuous generation of reactive species. XPS analysis confirmed an increased surface Fe(II) content after reaction, supporting this synergistic mechanism. Density functional theory (DFT) calculations proved that Co sites exhibit superior adsorption capacity for PAA compared to Fe sites on three main facets. This work not only presents 0.5Co-FeOCl as a highly efficient and stable catalyst for PAA activation but also provides fundamental insights into the synergistic mechanisms in bimetallic/PAA systems for remediating refractory organic pollutants.

Acid-resistant nanofiltration (NF) membrane can effectively separate and recycle valuable cations from acidic wastewater. This places higher demands on both the acid resistance stability and the positively charged surface of the NF membrane. However, the application of NF membrane under harsh acidic conditions is often hindered by the dual drawback of a weak surface positive charge and low permeation flux. In this study, a positively charged NF membrane was successfully fabricated via post-polymerization solid-liquid surface amidation, which incorporated a Gemini quaternary ammonium salt (GQAS) monomer into the membrane structure. The preparation conditions were optimized to enhance both separation performance and permeation flux, resulting in the optimal GQAS0.2/PEI-PSA membrane. Subsequent characterization and performance evaluation elucidated the structure-performance relationship of the GQAS0.2/PEI-PSA membrane. The results indicated the membrane surface exhibited a highly positive charge, resulting in a MgCl2 rejection of 90.3% and an excellent permeation flux of 180.5 L & sdot;m-2 & sdot;h-1 & sdot;MPa-1. Furthermore, the membrane also demonstrated remarkable acid resistance, it retained a MgCl2 rejection of 89.1% and a permeation flux of 170.1 L & sdot;m-2 & sdot;h-1 & sdot;MPa-1 after immersion in a 20 wt % H2SO4 solution for 15 days, These results validate the substantial potential of the GQAS0.2/PEI-PSA membrane for applications involving acidic wastewater.

Aged nanoplastics, characterized by their small size, abundant oxygen-containing functional groups, are high colloidal stability. These features make them difficult to remove by conventional membrane processes. Efficient removal usually requires membranes with very small pore sizes. This requirement causes a severe permeability and selectivity trade-off. Herein, a hierarchical PEG-PA/Fe3O4@PNF composite membrane was rationally engineered via electrospinning coupled with interfacial polymerization to achieve efficient removal of aged polystyrene nanoplastics (PSNPs). The membrane features a three-layer architecture consisting of a PEG-modified polyamide (PEG-PA) selective layer, a Fe3O4-loaded polyacrylonitrile nanofibrous (Fe3O4@PNF) adsorption layer, and a nonwoven support, enabling the integration of surface sieving and depth adsorption within a single membrane. PEG modification markedly improved surface hydrophilicity, reducing the water contact angle from 28.07° to 9.84%. As a result, water flux increased by 54.2% while simultaneously enhancing antifouling performance. Meanwhile, Fe3O4 nanoparticles introduced abundant adsorption sites that effectively captured aged PSNPs through specific coordination interactions. Density functional theory (DFT) calculations further supported this proposed mechanism. Benefiting from the synergistic coupling of selective sieving and adsorption, the optimized membrane achieved an aged PSNP removal efficiency of 99.89% while maintaining a water flux of approximately 1142–1059 L m−2 h−1 at 0.4 MPa (the pure-water flux is 1199 L m−2 h−1 under the same pressure). Moreover, the membrane maintained a high removal efficiency under neutral and alkaline conditions (pH 7–11), exhibited good tolerance toward common inorganic ions except phosphate, and demonstrated satisfactory reusability. This study presents an effective strategy for integrating selective separation and targeted adsorption into thin-film composite membranes. The proposed design also provides new insights into the efficient remediation of aged nanoplastics with broad size distributions in complex aqueous environments.

The absence of nitrite (NO2-) in ammonium wastewater has impeded the widespread application of conventional anammox processes in resource-efficient and energy-saving modes. Recently, microbial electrolysis cells (MEC) employing anodes as electron harvesters have demonstrated the ability to oxidize ammonium (NH4+) with electroactive biofilm of highly enriched anammox cultures. This discovery has prompted the exploration of anodic anammox process as a promising approach for sustainable ammonium wastewater treatment by inoculating anammox granular sludge in single-stage MEC reactors. This study shows that NH4+ can be fully autotrophically converted to dinitrogen gas by anammox granular sludge in a MEC system with a titanium anode, achieving a removal rate of 7.2 g N/(m(-3).d(-1)) without the accumulation of nitrite and nitrate. Biotic and abiotic control experiments confirm that anodic anammox is indeed an electrochemical biological process. Electrochemical analyses and in situ Raman spectroscopy further reveal that outer membrane cytochrome c mediates the extracellular electron transfer (EET), and that the addition of NO2- does not inhibit the anodic reaction activity. Metatranscriptomic analysis also indicates that genes related tocytochrome c are enriched in the MEC. The results suggest that titanium anodes enhance the activity of electroactive microorganisms to conduct EET, thereby facilitating efficient NH4+ removal through multiple pathways. This paper demonstrates for the first time the feasibility of the anodic anammox process and provides valuable insights into the integration of MEC with anammox as an alternative technology for biological nitrogen removal.

This study describes the synthesis of a BiOCOOH/TiO2 heterojunction photocatalyst using a hydrothermal method, with the incorporation of citric acid to modulate the morphology. The modified composite photocatalyst demonstrated a degradation efficiency of 98.11% for Rhodamine B (RhB) within 40 min, a significant improvement compared to the unmodified material. The addition of citric acid was discovered to alter the material's morphology, increase its specific surface area, and enhance photocatalytic activity. The material's crystal structure, morphology, composition, optical properties, surface potential, adsorption capacity, and photoelectric performance were comprehensively characterized using a range of techniques including XRD, SEM, TEM, EDS, BET, UV-vis DRS, EIS, Mott-Schottky tests, and FT-IR. Moreover, the study explored the impact of catalyst dosage, initial pollutant concentration, solution pH, and salt effects on photocatalytic performance, confirming the material's versatility and recyclability. Finally, by conducting radical trapping experiments and analyzing the band structure, a possible photocatalytic mechanism was proposed. When exposed to light, the heterointerface created by the intimate interaction of BiOCOOH and TiO2 serves as a pathway for charge transfer. The presence of the built-in electric field facilitates the recombination of electrons in the conduction band of TiO2 and holes in the valence band of BiOCOOH at the heterogeneous interface. Simultaneously, the electrons in the conduction band of BiOCOOH and holes in the valence band of TiO2 are effectively stored, maintaining the redox potential of the entire system at a high level. This process promotes the degradation of RhB. Furthermore, the introduction of citric acid significantly boosts the photocatalytic activity by regulating the morphology of the material and increasing its specific surface area. This adjustment provides additional adsorption sites for dye molecules, aiding in the separation of photogenerated charge carriers, which, in turn, accelerates the degradation of Rhodamine B. The findings of this study offer valuable theoretical and experimental support for the development and production of innovative and highly efficient photocatalysts.

Human activities have led to an increase in atmospheric carbon dioxide (CO2) concentration, which can enhance the flux of CO2 from air to water, thus impacting algal growth. Phosphorus (P) is a key factor influencing the formation of cyanobacteria blooms. Nutrient utilization is closely related to carbon (C) metabolism, but the effects of elevated CO2 on microalgae under different P sources are rarely studied. In this study, we investigated the growth and physiological and biochemical responses of Microcystis aeruginosa (M. aeruginosa) under ambient (400 ppm) and elevated (550 ppm) CO2 levels in P-free, dissolved inorganic P (DIP, 1 mg P/L), and dissolved organic P (DOP, 1 mg P/L) groups. The bioavailability of DIP to M. aeruginosa was greater than that of DOP, and elevated CO2 increased both the uptake of DIP and DOP. Elevated CO2 promoted the growth (increasing by 9.0%-14.2%), photosynthesis, and CO2 fixation of M. aeruginosa under different P sources (P-free, DIP, DOP), and increased total microcystin-LR content (increasing by 5.4%-12.6%), which increased the risk of microcystin-LR release into the environment. Furthermore, elevated CO2 aggravated the stress effect of DOP, leading to an increase in protein content and proportion of humic acid substances in the extracellular polymeric substances. Our study provides a theoretical basis for understanding the impact of elevated CO2 on cyanobacteria bloom under different P sources, and provides a new insight for the control of eutrophic waters under the background of climate change.

In recent years, advanced oxidation processes (AOPs) based on peracetic acid (PAA) have garnered significant attention for the removal of emerging organic pollutants due to their high efficiency. However, traditional iron-based catalysts used for PAA activation face challenges related to structural instability and high iron leakage. To tackle these issues, this study employed a silicon (Si) doping strategy and synthesized Fe2SiO4-NC using Fe-ZIF-8 as a precursor to activate PAA for the removal of tetracycline (TC). The morphology and physicochemical properties of the catalyst were characterized. Density Functional Theory (DFT) calculations revealed that the introduction of Si reduced the formation energy and orbital transition energy, thereby enhancing structural stability and catalytic activity. The degradation tests indicated that 40 μM of TC was completely removed within 10 min using 0.06 g/L of Fe2SiO4-NC and 0.15 mM of PAA, achieving a kobs value of 0.40 min-1. Additionally, the Fe2SiO4-NC exhibited exceptional recyclability and stability, achieving over 90 % TC removal across six consecutive cycles, with Fe ion leakage below 0.3 mg/L. Quenching tests and mechanism analysis indicated that organic radicals of CH3C(O)OO• played the predominant role in the degradation. Fe redox cycles and surface Si-OH groups were found to promote the activation of PAA. Notably, this work lies in the rational integration of Si doping and Fe-ZIF-8-derived structure to engineer catalyst Fe2SiO4-NC with extremely low metal leaching and high PAA activation efficiency, which provides critical insights into the design of Fe-based catalysts with high structural stability and activity.

Widespread eutrophication is recognized to have caused severe algal blooms. Meanwhile, the algal cells and their organic matter attract much attention since they are significant precursors for the formation of disinfection byproducts (DBPs) in water treatment. Halonitromethanes (HNMs), as a typical nitrogen-containing DBPs (NDBPs), are more toxic than other DBPs. Bromide ion (Br-) is ubiquitous in water and has been verified to enhance the toxicity levels of HNMs. Consequently, this study chose Microcystis aeruginosa as a typical alga to explore the formation patterns of HNMs in the presence of Br- during UV/chloramine disinfection. Results revealed that intracellular organic matter (IOM) of Microcystis aeruginosa generated more HNMs compared to extracellular organic matter (EOM), and all detected HNMs presented an initially upward then downward trend over time. With the increase of Br- dosage, the concentration of bromine-containing HNMs increased. Besides, the total amount and toxicity of HNMs were elevated by higher Br- : Cl-2 mass ratio, UV intensity, and Microcystis aeruginosa concentration but suppressed by higher pH. The potential formation paths of HNMs from Microcystis aeruginosa during UV/chloramine disinfection were also deduced. The formation mechanisms involved halogenation, imidization, alcoholization, dealdehydation, N-nitration, oxidation, and addition reactions. Finally, the formation patterns of HNMs in actual water were identical to those in deionized water (DW). The results of this study provided theoretical bases for understanding the HNMs formation in algal-rich water involving Br- during UV/chloramine disinfection.