Chlorination Treatment Research Articles

The occurrence and removal of selected fluoroquinolones in urban drinking water treatment plants.

Fluoroquinolones (FQs) are a widely prescribed group of antibiotics. They enter the aqueous environment, where they are frequently detected, and can lead to a threat to human health. Drinking water treatment plants (DWTPs) play a key role in removing FQs from potable water. This study investigated the occurrence and removal of four selected FQs (norfloxacin (NOR), ciprofloxacin (CIP), enrofloxacin (ENR), and ofloxacin (OFL)) in three urban DWTPs in China. The treatment efficacy for each system was simultaneously evaluated. Two of the examined DWTPs used conventional treatment processes. The third used conventional processes followed by additional treatment processes (ozonation-biologically activated carbon (ozonation-BAC) and membrane technology). The average concentrations of the four FQs in the source water and the finished water ranged from 51 to 248ng/L and from <5 to 46ng/L, respectively. Based on residual concentrations, the conventional treatment system had a low removal of FQs. In contrast, the addition of advanced treatment processes such as the ozonation-BAC and membranes, substantially improved the removal of FQs. The finding of this study has important implications: even though coagulation-sedimentation and chlorination treatment processes can remove most target FQs, the typical practice of advanced treatment processes is necessary for the further removal.

Application of ozone treatment in cooling water systems for energy and chemical conservation

In this study, a complete set of recirculating cooling water system and the required instruments were built in a semi-industrial-scale and a 50 g/h ozone generation plant and a chlorine system were designed for cooling water treatment. Both chlorination and ozonation treatment methods were studied and the results were analyzed during two 45-days periods. The concentrations of ozone and chlorine in recirculating water were constant at 0.1 mg/lit and 0.6 mg/lit, respectively. In ozone treatment, by increasing the concentration cycle to 33%, the total water consumption decreased by 26% while 11.5% higher energy efficiency achieved thanks to a better elimination of bio-films. In case of Carbon Steel, the corrosion rate reached to 0.012 mm/yr and 0.025 mm/yr for the ozonation and chlorination processes, respectively. Furthermore, consumptions of the anti-corrosion and anti-sedimentation materials in the ozone cooling water treatment were reduced about 60% without using any oxidant and non-oxidant biocides. No significant changes in sediment load were seen in ozonation compared to chlorination. The Chemical Oxygen Demand of the blow-down in ozonation method decreased to one-sixth of that in the chlorination method. Moreover, the soluble iron and water turbidity in the ozonation method were reduced by 97.5% and 70%, respectively. Although no anaerobic bacteria were seen in the cooling water at the proper concentration range of ozone and chlorine, the aerobic bacteria in chlorine and ozone treatment methods were 900 and 200 CFU/ml, respectively. The results showed that the payback time for the ozone treatment is about 2.6 years.

DVC-FISH and PMA-qPCR techniques to assess the survival of Helicobacter pylori inside Acanthamoeba castellanii

Free-living amoebae (FLA) are ubiquitous microorganisms commonly found in water. They can act as Trojan Horses for some amoeba-resistant bacteria (ARB). Helicobacter pylori is a pathogenic bacteria, suggested to be transmitted through water, which could belong to the ARB group. In this work, a co-culture assay of H. pylori and Acanthamoeba castellanii, one of the most common FLA, was carried out to identify the presence and survival of viable and potentially infective forms of the bacteria internalized by the amoeba. Molecular techniques including FISH, DVC-FISH, qPCR and PMA-qPCR were used to detect the presence of internalized and viable H. pylori. After 24 h in co-culture and disinfection treatment to kill extra-amoebic bacteria, viable H. pylori cells were observed inside A. castellanii. When PMA-qPCR was applied to the co-culture samples, only DNA from internalized H. pylori cells was detected, whereas qPCR amplified total DNA from the sample. By the combined DVC-FISH method, the viability of H. pylori cells in A. castellanii was observed. Both specific techniques provided evidence, for the first time, that the pathogen is able to survive chlorination treatment in occurrence with A. castellanii and could be very useful methods for performing further studies in environmental samples.

Water Purification by a Lamp Discharge-Electronic Ballast System Using a Full Bridge Inverter

The presence of pathogenic microorganisms in the water poses a risk to the health of consumers of all ages. Water conventional chemical treatments are not always a good solution. Difficult to implement, they have the double disadvantage of denaturing the organoleptic qualities of water: by acting on its physico-chemical composition and rejection of polluted water. Chlorination treatment is generally used to solve the bacteriological quality problems of both unconventional drinking water and treated wastewater. The use of chlorination is increasingly avoided due to the production of chlorinated products of carcinogenic and to the little action on the virus. The search for alternative solutions has summarized in several studies. The use of “ultraviolet irradiation” is still interesting alternative solution. Sterilization system using UV radiation is recommended in health services, hospitals, pharmacies, agriculture, aquariums, water extraction fromwells orrainwater, etc. UV radiationhas a fast acting, efficient, safe and constitutes an economic process that respects the environment. In recent years, high-frequency electronic ballasts for discharge lamps have been presented as a substitute for the magnetic ballast. because of their superior qualities such as high system performance (improved power factor), weight light, the light produced per watt, long service life, the function of lighting control, non-flashing, non-presence of audible noise and more technical aspects and requirements, special attention must be given to costs of an electronic ballast. This paper presents the design of a high frequency current power supply (electronic ballast based PWM inverter) to power a low-pressure UV lamp Mercury-Argon which has a germicidal effect for water treatment. So, the main purpose is to generate maximum UV at 253.7nm (germicidal effect) and this is achieved by having at the ballast output a sinusoidal current with a frequency of 50 KHz and rms value of 0.65 A.

Microbial disinfection of seawater using hydrodynamic cavitation

Hydrodynamic cavitation has been effectively proven to be an efficient advanced oxidation process on an industrial scale. The utility of hydrodynamic cavitation for microbial disinfection of seawater has been reported in this work. Seawater is used as cooling water in refineries and nuclear power plants or as ballast water in the shipping industry. Various norms and regulations of the International Maritime Organization (IMO) make it compulsory for ship owners to treat the ballasting seawater before discharging it into the sea. Also, if the seawater is not properly treated, it causes biofouling which affects the performance of cooling tower and other heat transfer equipments. It has been observed through our study that, hydrodynamic cavitation can be effectively used for microbial disinfection of seawater. Effectiveness of different types of cavitating devices for the extent of disinfection was studied. It was conclusively proved that, slit type of geometry consumes 40% less energy compared to cylindrical geometry for similar extent of seawater disinfection. A combination of the conventional treatments of water disinfection such as chlorination and thermal treatment with hydrodynamic cavitation was found to increase the overall rate of disinfection significantly. Rate of reaction almost doubles when 5ppm hypochlorite was used as disinfectant with the combination of cavitation compared to when only 5ppm of hypochlorite was used. Similarly the rate of disinfection increases 2.5times at 50°C in combination with cavitation compared to when, only 50°C was maintained and disinfection was carried out.

¿Cumplir con la legislación nos garantiza consumir agua segura?

Current legislation on microbiological control of water for human consumption in our country, and in many others, does not include the search of human-pathogenic parasites or viruses. Even though water purification methods used for the removal of bacteria from water do also remove the great majority of parasitic forms, some of their resistance elements are not affected by chlorination treatments. Groundwater obtained from shallow wells in semi-rural areas may also constitute a risk since they are very susceptible to contamination.The aim of this work was to quantify parasitic elements and viruses present in water for human consumption in the Province of Salta, in Argentina. For that, 60 L water samples were collected in six points located in the Province, including two sources of water: the distribution network and shallow wells. Samples were collected during dry and wet seasons. Ultrafiltration techniques were used to concentrate the water in pathogens. Optical microscopy using a Neubauer chamber for the quantification of parasite elements and real-time PCR for the quantitative detection of viruses were used.We found a great variety of protozoa genera in both groundwater and in the distribution network. Only in groundwater samples we found helminths and in one of them also adenovirus. Results showed that there is little relation between the presence of bacterial indicators (established by legislation) and pathogens as parasites and viruses. Numerous water samples that are within the limits established by legislation (for which they would be considered acceptable as water for human consumption) had pathogenic parasites or viruses. This shows the urgent need to update the current legislation to include parasitic indicators that allow certifying that the water is safe for human consumption, therefore decreasing the risk of waterborne diseases.

N‐halamine‐modified polyglycolide (PGA) multifilament as a potential bactericidal surgical suture: In vitro study

ABSTRACTIn this study, new cationic homopolymer and anionic copolymer were synthesized, and deposited onto polyglycolide sutures using a layer‐by‐layer assembly technique. The coated sutures were rendered antibacterial by chlorinating with dilute solution of household bleach solution at pH 7. The chlorination treatment transformed the NH groups of anionic copolymer into N‐halamine structures. The N‐halamine‐modified sutures were challenged with Staphylococcus aureus and Escherichia coli O157:H7 bacteria at different contact times. The suture with chlorine loading of 0.22% completely inactivated both bacterial strains in 30 min contact time. Fourier transform infrared spectroscopy, scanning electron microscopy, and analytical titration confirmed the successful deposition of the N‐halamine multilayers. The effect of layer‐by‐layer coatings of polyelectrolytes on the chlorine loading and antibacterial efficacy of sutures was evaluated. The straight‐pull and knot‐pull strength tests performed on the sutures reported slight decline in tensile properties after chlorination treatment. The in vitro hemolysis and cytocompatibility tests revealed that the N‐halamines‐based antibacterial sutures were biocompatible. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42483.

Secondary formation of disinfection by-products by UV treatment of swimming pool water

Formation of disinfection by-products (DBPs) during experimental UV treatment of pool water has previously been reported with little concurrence between laboratory studies, field studies and research groups. In the current study, changes in concentration of seven out of eleven investigated volatile DBPs were observed in experiments using medium pressure UV treatment, with and without chlorine and after post-UV chlorination.Results showed that post-UV chlorine consumption increased, dose-dependently, with UV treatment dose. A clear absence of trihalomethane formation by UV and UV with chlorine was observed, while small yet statistically significant increases in dichloroacetonitrile and dichloropropanone concentrations were detected. Results indicate that post-UV chlorination clearly induced secondary formation of several DBPs. However, the formation of total trihalomethanes was no greater than what could be replicated by performing the DBP formation assay with higher chlorine concentrations to simulate extended chlorination. Post-UV chlorination of water from a swimming pool that continuously uses UV treatment to control combined chlorine could not induce secondary formation for most DBPs. Concurrence for induction of trihalomethanes was identified between post-UV chlorination treatments and simulated extended chlorination time treatment. Trihalomethanes could not be induced by UV treatment of water from a continuously UV treated pool. This indicates that literature reports of experimentally induced trihalomethane formation by UV may be a result of kinetic increase in formation by UV. However, this does not imply that higher trihalomethane concentrations would occur in pools that apply continuous UV treatment.The bromine fraction of halogens in formed trihalomethanes increased with UV dose. This indicates that UV removes bromine atoms from larger molecules that participate in trihalomethane production during post-UV chlorination.Additionally, no significant effect on DBP formation was observed due to photo-inducible radical forming molecules NO3− (potentially present in high concentrations in pool water) and H2O2 (added as part of commercially employed DBP reducing practices).

Assessment of the effect of UV and chlorination in the transformation of fragrances in aqueous samples

The removal and transformation of 15 common fragrance allergens and two polycyclic musks in water samples were studied using UV irradiation and chlorination treatments. The monitoring of the reaction was carried out by a HS-SPME method coupled to GC–MS analysis. Different behaviours were observed depending on the compound and the treatment applied. Elimination experiments showed that all target compounds were affected by at least one of the two treatments. A total of 15 UV transformation products were detected and chemical structures were proposed for five of them. In the chlorination experiments, only galaxolide and benzyl cinnamate transformation products were observed.

Treatment, residual chlorine and season as factors affecting variability of trihalomethanes in small drinking water systems

Seasonal variability in source water can lead to challenges for drinking water providers related to operational optimization and process control in treatment facilities. The objective of this study is to investigate seasonal variability of water quality in municipal small water systems (<3000 residents) supplied by surface waters. Residual chlorine and trihalomethanes (THM) were measured over seven years (2003–2009). Comparisons are made within each system over time, as well as between systems according to the type of their treatment technologies. THM concentrations are generally higher in the summer and autumn. The seasonal variability was generally more pronounced in systems using chlorination plus additional treatment. Chloroform, total THM (TTHM) and residual chlorine concentrations were generally lower in systems using chlorination plus additional treatment. Conversely, brominated THM concentrations were higher in systems using additional treatment. Residual chlorine was highest in the winter and lowest in the spring and summer. Seasonal variations were most pronounced for residual chlorine in systems with additional treatment. There was generally poor correlation between THM concentrations and concentrations of residual chlorine. Further study with these data will be beneficial in finding determinants and indicators for both quantity and variability of disinfection byproducts and other water quality parameters.

WITHDRAWN: Formation of TCNM from polyDADMAC during UV irradiation combined with chlorination treatment

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Quantitative Detection of &amp;lt;i&amp;gt;Helicobacter pylori&amp;lt;/i&amp;gt; by Real Time PCR in Drinking Water—Environmental and Public Health Risk Significance

Helicobacter pylori (H. pylori) is bacteria considered to be present in half of the population and it is a public health problem worldwide. Most patients infected with H. pylori show no clinical symptoms; nonetheless, approximately 10% to 20% of these patients will develop peptic ulcers and 1% will develop gastric cancer. The International Agency for Research on Cancer has classified H. pylori as a Group 1 carcinogen, recognized as the only bacteria capable of producing cancer. Samples of drinking water (n = 44) from aqueducts with chlorination treatment in selected areas with high prevalence of gastric cancer were analyzed in Costa Rica. Samples of drinking water from Panama (n = 44) from aqueducts supplying untreated water for human consumption in the province of Chiriqui were also analyzed. The molecular marker of H. pylori, glmM, was used, and to optimize the Real Time PCR (qPCR) technique, annealing temperature, concentration of primers and probe were standardized; also, by analyzing different standard curves, the best reaction conditions that allowed detecting and quantifying the gene were determined. The LightCycler® 480 II (LC480II) equipment from Roche Diagnostics GmbH was used, as well as the Absolute Quantification Analysis by means of the Second Derivative Maximum Method. In the case of the samples from Costa Rica, it was determined that 79.5% were positive for H. pylori; removing outlier high average, quantification of bacteria was determined in 3.6 × 103 copies/100 mL. For Panama it was determined that 86% of the samples were found positive for the presence of H. pylori; removing outlier high average quantification of bacteria was determined at 3.3 × 102 copies/100 mL. The difference in values between the aqueducts in both countries revealed an environmental distribution of the bacteria of epidemiological interest in each case.

Surface Modification and Performance Enhancement of Carbon Derived from Chromium Carbide for Supercapacitor Applications

Modified-chromium carbide-derived carbons have been successfully prepared by chemical extraction of chromium atom from chromium carbide via chlorination and subsequent treatment with 16 M HNO3. The pore structure and physicochemical properties of the as-prepared modified chromium carbide-derived carbons were characterized by nitrogen adsorption/desorption isotherm, X-ray photoelectron spectroscopy, X-ray diffraction, and contact angle measurements. The electrochemical performance was investigated by cyclic voltammetry, galvanostatic charge/discharge tests, electrochemical impedance spectroscopy, and cycle life measurements. The results show that the functionalities have been introduced to the surface of the chromium carbide-derived carbon after modification with nitric acid, and that the modified chromium carbide-derived carbon presents better electrochemical performance due to the improved wettability and pseudocapacitance. Particularly, the modified chromium carbide-derived carbon treated with HNO3 in 100°C (C(Cr3C2)-M100) obtained a specific capacitance of 206.5 F g−1 at a current density of 1 A g−1, whereas it was only 91 F g−1 for the pristine chromium carbide-derived carbon. In addition, the supercapacitor using C(Cr3C2)-M100 as electrode material had small resistance and excellent cyclic stability with high capacitance retention of 90%. The remarkable improvement of the electrochemical performance makes the modified chromium carbide-derived carbon a promising candidate for supercapacitors.

折点氯化法处理含氨氮废水及工艺设计方案

本文根据湿法生产车间废水特点，研究了采用折点氯化法处理含氨氮工业废水的可行性，重点考察了废水中氨氮含量、次氯酸钠溶液浓度等对处理效果的影响，同时考察了次氯酸钠的用量。试验结果表明：折点氯化法处理废水中的氨氮工艺路线成熟，对不同浓度的氨氮废水都有效果，最佳条件为：进水氨氮浓度小于400 mg/L，次氯酸钠浓度大于8%，则吨水耗次氯酸钠40~60 L。最后，针对车间废水特点设计了可行的处理方案。 According to the characteristics of the wastewater in workshop of wet method, the feasibility of break point chlorination treating industrial wastewater containing ammonia nitrogen was studied. This paper focused on the content of ammonia nitrogen in wastewater; the effect of concentration of sodium hypochlorite solution on the treatment was studied, and at the same time, the dosage of sodium hypochlorite was investigated. The test results showed that: the process route of break point chlorination treatment of wastewater containing ammonia nitrogen is mature, having the effect on different concentrations of wastewater containing ammonia nitrogen. The optimum conditions are as follows: the influent concentration of ammonia nitrogen is less than 400 mg/L; the concentration of sodium hypochlorite is more than 8%, and then ton of water consumption of sodium hypochlorite is 40 - 60 L. Finally, aiming at the characteristics of wastewater, feasible treatment scheme is designed.

외식업체에서 제공하는 잠재적 위험 식품의 미생물적 품질향상을 위한 중점관리점 관리방안

The purpose of this study was to present management guidelines for critical control points by analyzing microbiological hazardous elements through screening Potentially Hazardous Foods (PHF) menus in an effort improve the microbiological quality of foods prepared by restaurant operations. Steamed spinach with seasoning left at room temperature presents a range of risk temperatures which microorganisms could flourish, and it exceeded all microbiological safety limits in our study. On the other hand, steamed spinach with seasoning stored in a refrigerator had Aerobic Plate Counts of 2.86±0.5 log CFU/g and all other microbiological tests showed that their levels were below the limit. The standard plate counts of raw materials of lettuce and tomato were 4.66±0.4 log CFU/g and 3.08±0.4 log CFU/g, respectively. Upon washing, the standard plate counts were 3.12±0.6 log CFU/g and 2.10±0.3 log CFU/g, respectively, but upon washing after chlorination, those were 2.23±0.3 log CFU/g and 0.72±0.7 log CFU/g, respectively. The standard plate counts of baby greens, radicchio and leek were 6.02±0.5 log CFU/g, 5.76±0.1 log CFU/g and 6.83±0.5 log CFU/g, respectively. After 5 minutes of chlorination, the standard plate counts were 4.10±0.6 log CFU/g, 5.14±0.1 log CFU/g and 5.30±0.3 log CFU/g, respectively. After 10 minutes of chlorination treatment, the standard plate counts were 2.58±0.3 log CFU/g, 4.27±0.6 log CFU/g, and 4.18±0.5 log CFU/g, respectively. The microbial levels decreased as the time of chlorination increased. This study showed that the microbiological quality of foods was improved with the proper practices of time-temperature control, sanitization control, seasoning control, and personal and surface sanitization control. It also presents management guidelines for the control of potentially hazardous foods at the critical control points in the process of restaurant operations.

Formation pathways of brominated products from benzophenone-4 chlorination in the presence of bromide ions

The brominated products, formed in chlorination treatment of benzophenone-4 in the presence of bromide ions, were identified, and the formation pathways were proposed. Under disinfection conditions, benzophenone-4 would undertake electrophilic substitution generating mono- or di-halogenated products, which would be oxidized to esters and further hydrolyzed to phenol derivatives. The generated catechol intermediate would be transformed into furan-like heterocyclic product. The product species were pH-dependent, while benzophenone-4 elimination was chlorine dose-dependent. When the chlorination treatment was performed on ambient water spiked with benzophenone-4 and bromide ions, most of brominated byproducts could be detected, and the acute toxicity significantly increased as well.

Copper release from copper nanoparticles in the presence of natural organic matter

Copper nanoparticles (CuNPs) are widely used and inevitably released into aqueous environments, causing ecological and health risks. Ubiquitous natural organic matter (NOM) might affect the copper release behaviors from CuNPs and their toxicity. This work aims to elucidate how NOM affects copper release from CuNPs, with a focus on the impacts of NOM properties and the NOM-CuNPs interaction mechanism. The copper release kinetics and different copper fractions induced by representative NOMs were characterized. The presence of NOM led to a more dispersive state of CuNPs clusters. Copper release mainly resulted from complexation reactions between CuNPs and functional groups of NOM. Humic substances were more effective in releasing copper than sodium alginate and bovine serum albumin, due to a higher amount of functional groups and lower molecular weight, which facilitated the contact and complexion reactions. Chlorination treatment of NOM significantly decelerated copper release due to the destruction of functional groups and less attachment of NOM. However, the copper releasing ability of humic acid was not substantially affected by Ca2+-induced coagulation. This study provides better understanding about the persistence and transformation of CuNPs in aquatic environments.

Enhanced formation of disinfection byproducts in shale gas wastewater-impacted drinking water supplies.

The disposal and leaks of hydraulic fracturing wastewater (HFW) to the environment pose human health risks. Since HFW is typically characterized by elevated salinity, concerns have been raised whether the high bromide and iodide in HFW may promote the formation of disinfection byproducts (DBPs) and alter their speciation to more toxic brominated and iodinated analogues. This study evaluated the minimum volume percentage of two Marcellus Shale and one Fayetteville Shale HFWs diluted by fresh water collected from the Ohio and Allegheny Rivers that would generate and/or alter the formation and speciation of DBPs following chlorination, chloramination, and ozonation treatments of the blended solutions. During chlorination, dilutions as low as 0.01% HFW altered the speciation toward formation of brominated and iodinated trihalomethanes (THMs) and brominated haloacetonitriles (HANs), and dilutions as low as 0.03% increased the overall formation of both compound classes. The increase in bromide concentration associated with 0.01-0.03% contribution of Marcellus HFW (a range of 70-200 μg/L for HFW with bromide = 600 mg/L) mimics the increased bromide levels observed in western Pennsylvanian surface waters following the Marcellus Shale gas production boom. Chloramination reduced HAN and regulated THM formation; however, iodinated trihalomethane formation was observed at lower pH. For municipal wastewater-impacted river water, the presence of 0.1% HFW increased the formation of N-nitrosodimethylamine (NDMA) during chloramination, particularly for the high iodide (54 ppm) Fayetteville Shale HFW. Finally, ozonation of 0.01-0.03% HFW-impacted river water resulted in significant increases in bromate formation. The results suggest that total elimination of HFW discharge and/or installation of halide-specific removal techniques in centralized brine treatment facilities may be a better strategy to mitigate impacts on downstream drinking water treatment plants than altering disinfection strategies. The potential formation of multiple DBPs in drinking water utilities in areas of shale gas development requires comprehensive monitoring plans beyond the common regulated DBPs.

Morphological and chemical study of CdTe thin films annealed in CHClF2–O2 gas mixture

The effect of annealing in CHClF2–O2 gas mixture on morphological and chemical properties of CdTe thin films deposited by conventional close space sublimation (CSS) has been investigated. Annealing was done at 400°C for 5min in a mixture of CHClF2 and O2 with partial pressures of 50 and 160mbar, respectively, and to reach a total pressure of 800mbar the annealing chamber was filled with Ar. After annealing, residuals at the surface of films were not removed in order to be study. High Resolution Scanning Electron Microscopy (HR-SEM) and X-ray Photoelectron Spectroscopy (XPS) were employed for analysis. The annealing promotes the etching of the CdTe grains at faces and edges; as a consequence, the surface became smooth with a compact structure. The main improvement on morphology by the inclusion of O2 during the annealing was the reduction of the grain boundary width of films. Chemical analysis of samples annealed in CHClF2 with and without mixed oxygen showed that the oxygen in the gas mixture acts as a catalyst in the decomposition of the CHClF2. Annealing with the CHClF2–O2 mixture reduces the oxidized compounds at the surface of films and promotes incorporation of Cl in the bulk. The experimental results give a clear demonstration why CdS/CdTe solar cells fabricated using CHClF2–O2 during chlorination treatments have better performance, as referred in a previous work.

Comparison between chlorination and ozonation treatments for the elimination of the emerging contaminants amitriptyline hydrochloride, methyl salicylate and 2-phenoxyethanol in surface waters and secondary effluents

BACKGROUND A new class of micropollutants, generally called emerging contaminants (ECs), is increasingly found in surface waters and wastewaters. Owing to their potential ecologic and health risks, ECs must be removed using different procedures, such as chemical oxidation processes. RESULTS The oxidation of the selected ECs amitriptyline hydrochloride, methyl salicylate and 2-phenoxyethanol has been investigated by means of two known oxidizing agents: chlorine and ozone. The efficiencies of elimination of each system have been compared, and apparent second-order rate constants of the reactions involved are determined. The variation of these kinetic parameters with pH is also evaluated, which enables determination of the intrinsic rate constant values for the oxidation reactions of the neutral and dissociated species. In addition, the simultaneous oxidation of these selected ECs in different water systems (ultrapure water, surface water from a reservoir and two secondary effluents) is studied, and the influence of operating conditions on the removal efficiency is established. CONCLUSION The reaction rates between chlorine or ozone and neutral and dissociated species revealed that the ozonation process is around three orders of magnitude higher than chlorination. © 2014 Society of Chemical Industry