Dichloroacetic acid (DCAA), trichloroacetic acid (TCAA), and bromate (BrO₃ ⁻) are disinfection byproducts (DBPs) formed during drinking water treatment and pose health risks. Rapid and reliable detection of these DBPs is essential for ensuring water safety. Non-suppressed ion chromatography (IC)-electrospray ionization mass spectrometry (IC-ESI-MS/MS) offers a promising approach for simultaneous analysis of organic haloacetic acids (HAAs) and inorganic oxyhalides, but previous methods using toxic methylamine can pose health risks. Herein, a new rapid non-suppressed IC-ESI-MS/MS method using a short AG18 guard column (13 μm, 2 mm × 50 mm) with aqueous ammonia as the alkaline modifier was developed for the simultaneous quantification of DCAA, TCAA, and BrO₃ ⁻. This method allows direct sample injection without pretreatment and achieves sub-μg L⁻¹ detection limits within 5 minutes. Aqueous ammonia (0.4 M) and acetonitrile were used as mobile phases in a gradient elution mode, providing good linearity (R² >0.995), low limits of quantification (0.48–1.13 μg L⁻¹), and high recoveries (76.3–107.3%). Intra-day (n = 9) and inter-day (3 days, n = 9) precision were validated with relative standard deviations of 5.8–8.9% and 6.4–7.7%, respectively. The method also demonstrated limited matrix interference from common water parameters such as Cl⁻, SO₄ ²⁻, HCO₃ ⁻/CO₃ ²⁻, and natural organic matter (NOM), making it suitable for real water analysis. The applicability of this method was confirmed by monitoring DBP formation during the chlorination of NOM, showing that two-step chlorine dosing strategies reduce DBP formation compared to single-stage dosing. This newly established method provides a robust and efficient tool for DBP monitoring in drinking water treatment processes.

Multifunctional water-treatment materials urgently need to be developed to avoid normal organic matter, inorganic anions, resistant bacteria, and hazardous disinfection by-products in conventional drinking water treatment strategies. While quaternary ammonium pyridine resins (QAPRs) possess porous adsorption structures and incorporate antibacterial groups, enabling simultaneous water disinfection and purification, their limited bactericidal efficacy hinders broader utilization. Therefore, a deeper understanding of the structure-dependent antimicrobial mechanism in QAPRs is crucial for improving their antibacterial performance. Hexyl (C₆) was proved to be the optimal antibacterial alkyl in the QAPRs. A new antibacterial quaternary ammonium pyridine resin Py-61 was prepared by more surficial bactericidal N⁺ groups and higher efficient antibacterial hexyl, performing with the excellent antibacterial efficiency of 99.995%, far higher than the traditional resin Py-6C (89.53%). The antibacterial resin Py-61 completed the disinfection of sand-filtered water independently to produce safe drinking water, removing the viable bacteria from 3600 to 17 CFU/mL, which meets the drinking water standard of China in GB5749-2022 (99.97%. As an integrated disinfection–purification solution, the novel antibacterial resin presents a promising alternative for enhancing safety in drinking water treatment.

Pre-ozonation can enhance the removal of algae in source water during cyanobacterial blooms; however, little is known about the influence of the co-existing allochthonous natural organic matter (NOM) on algal removal and algal organic matter (AOM) behavior during ozonation. This study aims to elucidate in the presence and absence of allochthonous NOM and the effects of varying ozone doses on Synechococcus sp. cell removal, membrane integrity, and dissolved organic matter (DOM) release and removal. The results indicate that ozone effectively disrupted algal cell membranes, reducing algal density; however, the presence of allochthonous NOM delayed cell rupture by competing for ozone due to aromatic humic-like substances. Pterin-like and protein-like fluorescent compounds were released upon cell disruption. Due to that, excess ozone led to the oxidation of the released pterin-like compounds, with characteristic fluorescence changes correlating to ozone dosage; these changes are potential to be used as an indicator to determine the optimized ozone dosage, avoiding more adverse release of intracellular AOM to form disinfection byproducts.

Effect-based toxicity assessments are crucial for evaluating the risks of disinfection byproducts (DBPs), particularly unknown species, generated during drinking water chlorination. However, the accuracy of this approach is highly dependent on unbiased sample extraction. Conventional methods often employ single, low-pH extraction, which may fail to recover pH-sensitive amphoteric DBPs derived from amphoteric precursors (e.g., nitrogenous compounds). This study investigated how extraction pH affects the measured biotoxicity of DBPs formed from three model precursors: biopterin (Bip), cytosine (Cyt), and tryptophan (Trp). Under excess chlorine conditions, all three precursors degraded rapidly. The formation of aliphatic DBPs followed the order Trp > Cyt > Bip, and the maximum toxicity of the non-volatile extracts, assessed via a Vibrio fischeri bioassay, followed the reverse order: Bip > Trp > Cyt. This toxicity profile was significantly influenced by extraction pH, with maximum toxicity observed for Bip at around pH 4.0, under weakly acidic conditions for Trp, and under neutral to alkaline conditions for Cyt. For all precursors, the total organic carbon concentration remained constant throughout chlorination, indicating negligible mineralization and the predominant formation of non-aliphatic, likely heteroaromatic, products. These findings demonstrate that conventional extractions at a single low pH can lead to the incomplete recovery of toxic DBPs from amphoteric precursors. Therefore, pH-optimized extraction protocols are necessary for a more accurate risk assessment of chlorinated drinking water.