Disinfection by-product formation potential in response to seasonal variations in lake water sources: Dependency on fluorescent and molecular weight characteristics

Dissolved organic matter derived from aquatic plants in constructed wetlands: Characteristics and disinfection byproducts formation

Changes in algal organic matter under different pre-oxidants and dosages, and the formation potential of DBPs in algal-rich drinking water sources

Disinfection by-product formation potential in response to variability in dissolved organic matter and nutrient inputs: Insights from a mesocosm study

Assessing the potential effect of extreme weather on water quality and disinfection by-product formation using laboratory simulation

Selective removal of dissolved organic matter affects the production and speciation of disinfection byproducts

Effects of phosphate addition on the removal of disinfection by-product formation potentials by biological activated carbon filtration

Engineered biofiltration for the removal of disinfection by-product precursors and genotoxicity

This study focuses on exploring the dynamics of dissolved organic matter (DOM) using high-frequency, continuous monitoring coupled with advanced fluorescence spectroscopy and statistical modeling. By combining continuous fluorescence sondes with spot sampling, we show temporal and longitudinal dynamics of DOM over a 14-month period in two UK rivers. The integration of fluorescence excitation-emission matrix (EEM) spectroscopy and Parallel Factor Analysis (PARAFAC) enabled the identification of key fluorescent components, including humic and protein-like substances. Real-time monitoring of these two DOM components reveals significant diel and seasonal variations in both the quantities and characteristics of DOM. External carbon sources (treatment works, agricultural land use) showed increased protein-like DOM, particularly during summer, indicating the influence of labile organic matter. A new fluorescence ratio (humic DOM/protein-like DOM) proved to be a robust indicator for differentiating between microbial-derived labile DOM and more refractory humic substances, offering new insights into organic matter processing and nutrient cycling in the studied ecosystems.Modeling approaches, based on ANCOVA and logistic regression, demonstrated that allochthonous sources, precipitation, and seasonal temperature variations were key drivers of DOM dynamics. Periods of low temperature and high precipitation were characterized by a notable increase in humic-like DOM concentrations, primarily due to enhanced runoff of terrestrial organic matter into the river system. In contrast, as temperature increased, tryptophan-like DOM concentrations rose, reflecting heightened microbial activity driven by warmer conditions. The elevated temperature not only stimulated microbial metabolism but also accelerated the decomposition of organic matter, leading to the production of more labile, protein-like substances. These contrasting seasonal trends highlight the dual influence of hydrological inputs and temperature-driven biological processes on DOM patterns.

Disinfection by-products (DBPs), major health concerns in the potable reuse of municipal wastewater effluent, are process-related in wastewater treatment systems. Anammox is a promising and increasingly-applied technology for nitrogen removal in wastewater. In this study, the relationship between DBP formation potential and the anammox process has been investigated based on a lab-scale sequencing batch reactor (SBR). Excitation and emission matrix (EEM) fluorescence spectroscopy was employed to identify the compositions of the DBP precursors. The results showed that the effluents from the anammox SBR could yield both carbonaceous and nitrogenous DBPs after chlorination. Trichloromethane (TCM) was the dominant product among all DBPs detected. The anammox effluent has a low specific TCM formation potential of 0.778 μmol/mmol C and a trichloronitromethane (TCNM) formation potential of 0.0725 μmol/mmol C, leading to a TCM and TCNM formation potential ratio of 10.7. We found that substrate utilization of anammox did not enhance DBP yields, and the DBP formation potential decreased after 10 hour starvation. High pH conditions stimulated the production of TCM precursors in the anammox reactor. Humic acid-like and protein-like substances were identified in the EEM spectra of anammox effluents.

<p indent="0mm">Dissolved organic matter (DOM), a ubiquitous component of source water, serves as a significant precursor to hazardous disinfection byproducts (DBPs) in chlorinated drinking water. Recently, the UV/H₂O₂ advanced oxidation process (UV/H₂O₂ AOP), known for generating highly reactive hydroxyl radicals (HO^•), has become increasingly favored for micropollutant abatement in drinking water treatment plants. This process can alter the structural composition of DOM and its potential for DBP formation. However, the specific impact of UV/H₂O₂ on DBP formation from various types of DOM, particularly the production of highly toxic brominated DBPs during harmful algal bloom events in bromide (Br⁻)-enriched waters, remains poorly understood. This knowledge gap impedes the optimization of water treatment processes and the improvement of water quality. To address this gap, six DOM isolates were selected, including three natural organic matters (NOMs) and three algal organic matters (AOMs), to evaluate the influence of UV/H₂O₂ AOP on DBP formation, under both Br⁻-enriched and Br⁻-free conditions. At concentrations typical of those used <sc>(0.50 mW/cm²</sc> UV and <sc>0.3 mmol/L</sc> H₂O₂) in drinking water treatment plants, UV/H₂O₂ significantly increased the formation of DBP from both NOM and AOM. Specifically, the concentrations of DBPs formed from <italic>Microcystis aeruginosa</italic> AOM (MAAOM), <italic>Anabaena</italic> AOM (AAOM), and <italic>Chlorella</italic> AOM (CAOM) increased by 198.6%, 117.9%, and 103.4%, respectively, compared to only 33.8%, 45.5%, and 17% increments for Suwannee River NOM (SRNOM), Pahokee Peat fulvic acid (PPFA), and Elliott Soil humic acid (ESHA), respectively. Furthermore, under Br⁻-enriched conditions, UV/H₂O₂ further augmented DBP formation, predominantly as brominated DBPs. Notably, the concentrations of brominated-haloacetaldehydes (Br-HALs) produced after AOM oxidation were higher than those from NOM, especially for bromodichloroacetal and dibromochloroacetaldehyde. Due to the elevated toxicity of Br-HALs, the calculated cytotoxicity induced by DBPs from AOM was 49~81 times higher than that of the control group. Analysis using fluorescence spectroscopy showed a positive correlation between changes in the fluorescence intensities of the soluble microbial by-product-like regions before and after the oxidation of each DOM and the formation potential of HALs (<italic>R</italic>² = 0.59), suggesting that UV/H₂O₂ may alter the structures of proteins or microbial metabolites in AOM, thereby boosting HAL formation. We investigated the moieties responsible for altering HAL formation and found that UV/H₂O₂ modified the molecular structure of amino acids, facilitating HAL formation, especially Br-HALs in the presence of Br⁻. Additionally, based on the analysis of oxidation products and bromination experiments, the formation pathway of Br-HAL from histidine (HIS, representative of amino acids) was proposed: HO^• attacks the heterocycle of HIS to produce 2-oxo-HIS; during post-chlorination, Br⁻ in water can be rapidly oxidized by HOCl to active HOBr, which further reacts with 2-oxo-HIS to form Br-HAL. Finally, we proposed two strategies to control DBP formation: treatment by MIEX<x content-type="symbol">Ò</x> DOC resin prior to chlorination and switching to chloramination. The results indicate that these strategies could reduce DBP formation by 48.1%–96.7% and 83.5%–97.7%, respectively, with a more significant reduction in DBP toxicity (84.2%–98.2%) under the chloramination scenario. In conclusion, UV/H₂O₂ significantly enhances DBP formation from both NOM and AOM, with a more pronounced increase observed in AOM. Under Br⁻-enriched conditions, UV/H₂O₂-treated AOM exhibits a remarkably high potential for Br-HAL formation, contributing to an increase in the total toxicity of DBPs. This study provides substantial insights into the mechanisms of DOM oxidation and HAL formation by UV/H₂O₂, offering guidance for safer and more reliable drinking water treatment strategies during harmful algal blooms.

The quality of drinking water is crucial for public health and sustainable development. This study elucidates the interaction between per- and polyfluoroalkyl substances (PFAS) and algal organic matter (AOM) in freshwater sources, which modifies the composition and reactivity of dissolved organic matter (DOM), enhances the formation potential of disinfection by-products (DBP), and may impact drinking water treatment (DWT) systems. The study employs multi-spectroscopic analysis like excitation emission matrix-parallel factor analysis (EEM-PARAFAC), Fourier-transform infrared spectroscopy (FTIR), and DBP quantification to demonstrate that specific PFAS (hexafluoropropylene oxide dimer acid (GenX), and perfluorobutane sulfonate (PFBS)) with AOM shift DOM to protein-like dominance, reducing the humification index (HIX) by 70 % and disrupting amide I bonds. This transition elevated brominated DBPs (>90 % of total DBPs in algae-PFAS systems). Coagulation (Polyaluminum chloride, PACl, 50-200 mg/L) exhibited concentration-dependent flocculation index (FI) increases, with GenX (1 μg/L) and PFBS (10 μg/L) peaking at 1.1-1.18 % FI, enhancing floc formation within 300 s, though AOM reduced baseline FI to 0.7 %. Nanofiltration (NF-270 membrane) showed flux reductions of 36-43 % for GenX (0.1-10 μg/L) and 39-47 % for PFBS (0.1-10 μg/L) without AOM, intensifying to 46 % (GenX10) and 52 % (PFBS10) with AOM due to biopolymer release and algal stress. Combined coagulation and nanofiltration treatment reduced DBP precursors by 60-85 % and mitigated fouling. These findings reveal that PFAS-AOM complexes elevate DBP formation risks and impair DWT efficiency, emphasizing the need for integrated coagulation, filtration, and nanofiltration processes to manage water quality hazards arising from PFAS-algal-impacted water sources.

Removal of disinfection by-product precursors by ion exchange resins

Disinfection byproduct formation from chlorination of agricultural reuse water sources

Formation of disinfection by-products from microplastics, tire wear particles, and other polymer-based materials

Microplastics release precursors of chlorinated and brominated disinfection byproducts in water