Enhanced iodinated disinfection byproducts formation in iodide/iodate-containing water undergoing UV-chloramine sequential disinfection: Machine learning-aided identification of reaction mechanisms.

Restricted to the complex nature of dissolved organic matter (DOM) in various aquatic environments, the mechanisms of enhanced iodinated disinfection byproducts (I-DBPs) formation in water containing both I and IO (designated as I/IO in this study) during the ultraviolet (UV)-chloramine sequential disinfection process remains unclear. In this study, four machine learning (ML) models were established to predict I-DBP formation by using DOM and disinfection features as input variables. Extreme gradient boosting (XGB) algorithm outperformed the others in model development using synthetic waters and in cross-dataset generalization of surface waters.

Far-UVC direct photolysis of iohexol and acetochlor: an experimental and mechanism study.

Recently, the emission of 222 nm Far-UVC krypton chloride (KrCl*) excimer lamps, has gained widespread attention in the field of water treatment. This study compared the degradation kinetics of IOX and ACE under UV and UV irradiation. The results demonstrated that UV irradiation exhibited higher efficiency, increasing the removal rates of IOX and ACE from 72.

Mixed chlorine/chloramines in disinfected water and drinking water distribution systems (DWDSs): A critical review.

Mixed chlorine/chloramines are commonly occurring in real drinking water distribution systems (DWDSs) but often overlooked. This review provides a comprehensive overview of the occurrences, characteristics, analysis methods, and control strategies of mixed chlorine/chloramines in DWDSs. The characteristics of mixed chlorine/chloramine species are summarized for treated water in drinking water treatment plants (DWTPs), secondary disinfection facilities, and DWDSs where different disinfectants could be blended.

Overlooked Role of Fungi in Drinking Water Taste and Odor Issues.

Taste and odor (T&O) are among the most frequently encountered aesthetic issues in drinking water. While fungi have been reported to produce offensive odors, their contribution to T&O in drinking water remains understudied and often overlooked. In this study, the profiles of fungal community and odorants produced by 10 native fungal isolates were investigated in 36 samples collected from two drinking water treatment plants and a premise plumbing system.

Wavelength dependency and photosensitizer effects in UV-LED photodegradation of iohexol.

Iodinated X-ray contrast media (ICM) are ubiquitously present in water sources and challenging to eliminate using conventional processes, posing a significant risk to aquatic ecosystems. Ultraviolet light-emitting diodes (UV-LED) emerge as a promising technology for transforming micropollutants in water, boasting advantages such as diverse wavelengths, elimination of chemical additives, and no induction of microorganisms' resistance to disinfectants. The research reveals that iohexol (IOX) degradation escalates as UV wavelength decreases, attributed to enhanced photon utilization efficiency.

Degradation kinetics and disinfection by-products formation of benzophenone-4 during UV/persulfate process.

The degradation kinetics, reaction pathways, and disinfection by-products formation of an organic UV filter, benzophenone4 (BP4) during UV/persulfate oxidation were investigated. BP4 can hardly be degraded by UV alone, but can be effectively decomposed by UV/persulfate following pseudo-first order kinetics. BP4 degradation rate was enhanced with increasing persulfate dosage and decreasing pH from 8 to 5.

Insight into mixed chlorine/chloramines conversion and associated water quality variability in drinking water distribution systems.

Mixed chlorine/chloramines are common in drinking water distribution systems (DWDSs); however, their transformation and impact on chemical and microbial characteristics are not well understood. We systematically investigated water quality parameters associated with mixed chlorine/chloramine species conversion in 192 samples (including raw, finished, and tap water) collected throughout the year in a city in East China. Various chlorine/chloramine species (free chlorine, monochloramine [NHCl], dichloramine [NHCl], and organic chloramines [OC]) were detected in both chlorinated and chloraminated DWDSs.

Occurrence of fungal spores in drinking water: A review of pathogenicity, odor, chlorine resistance and control strategies.

Fungi in drinking water have been long neglected due to the lack of convenient analysis methods, widely accepted regulations and efficient control strategies. However, in the last few decades, fungi in drinking water have been widely recognized as opportunity pathogens that cause serious damage to the health of immune-compromised individuals. In drinking water treatment plants, fungal spores are more resistant to chlorine disinfection than bacteria and viruses, which can regrow in drinking water distribution systems and subsequently pose health threats to water consumers.

Chlorine dioxide-based oxidation processes for water purification：A review.

Chlorine dioxide (ClO) has emerged as a broad-spectrum, safe, and effective disinfectant due to its high oxidation efficiency and reduced formation of organochlorinated by-products during application. This article provides an updated overview of ClO-based oxidation processes used in water treatment. A systematic review of scientific information and experimental data on ClO-based water purification procedures is presented.

Insight into the formation of iodinated trihalomethanes during chlorination, monochloramination, and dichloramination of iodide-containing water.

In this study, the formation of iodinated trihalomethanes (I-THMs) was systematically evaluated and compared for three treatment processes - (i) chlorination, (ii) monochloramine, and (iii) dichloramination - under different pH conditions. The results demonstrated that I-THM formation decreased in the order of monochloramination > dichloramination > chlorination in acidic and neutral pH. However, the generation of I-THMs increased in the dichloramination < chlorination < monochloramination order in alkaline condition.

Micropollutant removal and disinfection byproduct control by sequential peroxymonosulfate-UV treatment in water: A case study with sulfamethoxazole.

UV/peroxymonosulfate (UV/PMS) advanced oxidation process has attracted significant attention for removal of micropollutants in water. However, during practical water treatment applications, the PMS treatment must be performed before the UV treatment to achieve full contact. In this study, sulfamethoxazole (SMX) was selected as the target micropollutant.

Organic chloramines attenuation and disinfection by-product formation during UV, chlorination and UV/chlorine processes.

Organic chloramines (OCs) have become one of the research focuses in the field of drinking water treatment due to its limited oxidation and sterilization ability as well as potential cytotoxicity and genetic toxicity to the public. Among widespread OCs, produced by chlorinating cytosine are a typical one exists during chlorine disinfection. OCs degradation during UV, chlorination and UV/chlorine processes were systematically investigated.

Enhanced degradation of emerging contaminants by permanganate/quinone process: Case study with bisphenol A.

Permanganate (Mn(VII)) is widely used as a mild oxidant in water treatment. However, the reaction rates of some emerging contaminants with Mn(VII) are extremely low. In this study, benzoquinone (BQ), a redox mediator with the important component in dissolved organic matter (DOM), enhanced the oxidation of bisphenol A (BPA) by Mn(VII) in a wide pH range of 4.

Enhanced formation of iodinated trihalomethanes in a mixed chlorine/chloramine system and attenuation by UV-activated process.

Iodinated trihalomethanes (I-THMs) have drawn increasing concerns due to their higher toxicity than those of their chlorinated and brominated analogues. In this study, I-THM formation was firstly evaluated for three treatment scenarios - (i) chlorine alone, (ii) chloramine alone, and (iii) mixed chlorine/chloramine - in the presence and absence of UV irradiation for the iodide-containing humic acid solution or natural water. The results indicated that I-THM formation decreased in the order of mixed chlorination/chloramination > chloramination > > chlorination, which fitted the trend of toxicity evaluation results using Chinese hamster ovary cells.

The formation, analysis, and control of chlor(am)ination-derived odor problems: A review.

Odors and tastes have become universal problems related to drinking water quality. In addition to the typical odor problems caused by algae or microorganisms, the occurrence of odors derived from drinking water disinfection have attracted attention. The chlor(am)ination-derived odor substances have certain toxicity and odor-causing characteristics, and would enter the tap water through water distribution systems, directly affecting drinking water safety and customer experience.

Formation and control of organic chloramines and disinfection by-products during the degradation of pyrimidines and purines by UV/chlorine process in water.

Pyrimidine and purine bases (adenine, cytosine, guanine and thymine) are important precursors of organic chloramines (OC) and disinfection by-products (DBPs) during chlor(am)ination. In this study, OC and DBP formation derived from pyrimidine and purine bases during chlor(am)ination, post-chlor(am)ination after pretreated by UV alone and UV/chlorination were systematically investigated with ultraviolet light-emitting diodes (UV-LEDs, 265 and 275 nm) and low pressure mercury lamp (LPUV, 254 nm). The results revealed that higher OC formation was observed during chlorination than that during chloramination of pyrimidine and purine bases.

Degradation kinetics of prometryn and formation of disinfection by-products during chlorination.

Prometryn is a herbicide that is widely used and frequently detected in aqueous environment and soil. Prometryn is chemically stable, biologically toxic, and easily to accumulate in living bodies, which can cause accumulate in the environment and acute and chronic toxicity to living creatures. In this study, factors affecting the degradation kinetics of prometryn chlorination were studied, including solution pH, bromide and ammonium concentrations, and temperature.

Photodegradation pathway of iodate and formation of I-THMs during subsequent chloramination in iodate-iodide-containing water.

This study investigated the mechanisms of mixed IO/I system under UV irradiation in drinking water and compared the iodinated trihalomethanes (I-THMs) formation of a mixed IO/I system to that of single I and IO systems during subsequent chloramination. The effects of initial I/IO molar ratio, pH, and UV intensity on a mixed IO/I system were studied. The introduction of I enhanced the conversion rate of IO to reactive iodine species (RIS).