Chlorination Of Natural Waters Research Articles

ANALYSIS OF APPLYING SURFACE WATER TREATMENT TECHNOLOGY WHEN USING CHLORINE DIOXIDE AT WATER SUPPLY PLANTS

The results of the conducted research made it possible to establish that in EU countries chlorine dioxide (CD) is more often used for secondary or final disinfection of drinking water. By-products of this process are chlorites and chlorates, which are subject to control in the drinking water of all EU countries. Aldehydes and carboxylic acids can also be formed in drinking water, which leads to a decrease in the microbiological stability of tap water. Ozonation and filtration using a carbon filter are used in the final stage of drinking water purification, which contributes to a significant reduction in the dose of CD and water contamination with toxic chlorites. In the case of pre-oxidation of water with sodium hypochlorite, the largest amount of chlorites and chlorates is formed, while in the case of using potassium permanganate for the same purpose, the need for CD and the amount of chlorites and chlorates in drinking water reduced. Chlorination of natural water that has undergone CD pre-oxidation leads to complete oxidation of the chlorites that have formed, increases the effectiveness of disinfection, and provides a bacteriostatic effect in the distribution network. During 2021-2022, when using CD for the treatment of drinking water at the Dniprovska WTP in Kyiv it was established that the process of treating natural water with CD is accompanied by the formation of its by-products, mainly toxic chlorites, the levels of which depend on the applied doses of CD and are the lowest in winter, while the largest ones are observed in summer and do not always reach regulatory values (0,2 mg/l) and range up to 0,7 mg/l, which corresponds to the WHO recommended standard for this substance in drinking water. Italian scientists focus their attention on the fact that during the first years of using CD at each water supply station, optimal conditions must be ensured for the safe and effective use of this reagent. Therefore, CD is becoming widespread in the EU countries and Ukraine for the treatment of tap drinking water; it is an alternative method of water effective disinfection at water supply stations with traditional surface water purification technology. Using such a method for treating surface water requires a preliminary pilot experiment and should be carried out along with an analysis of the feasibility of using the methods for preliminary and/or final purification of drinking water from organic substances and additional disinfection. Today, based on experimental and natural studies, it is relevant to expand knowledge about the properties of CD in the case of its use in drinking water supply for the treatment of surface water with a high content of organic substances.

Synergistic Bacterial Inactivation by Silver Ions and Free Chlorine in Natural Waters

Synergistic Bacterial Inactivation by Silver Ions and Free Chlorine in Natural Waters

Assessment of carcinogenic risk from exposure to chlororganic compounds of water of systems of centralized water supply

Introduction. The problem of providing the population with drinking water with guaranteed quality, safety, and physiological usefulness is highly relevant for many regions of Russia. The use of chlorination for disinfection of the water is a potential cause of the formation of excess concentrations of organochlorine compounds in it, including trihalogenomethanes, which leads to elevated levels of carcinogenic risk. The study’s object was: data on the content in water of centralized water supply systems of carcinogenic organochlorine compounds - chloroform, dichlorobromomethane and chlorodibromomethane. Material and methods. information on the incidence of the population of malignant neoplasms; the results of an experiment to evaluate the effectiveness of the preliminary ammonization method. The paper used methods of health risk assessment, variation statistics, and mathematical modeling. Results. The use of preliminary ammonization in Taganrog prevents the formation of trihalogenomethanes and ensures the maintenance of an individual multi-route carcinogenic risk at an acceptable level (9.933 · 10-6). Systematic unreasonable hyper chlorination of river water without prior ammoniation is the main reason for the excess content of chlororganic compounds and the high level of individual carcinogenic risk in the Primorsky rural settlement of the Neklinovsky District - up to 3.234 · 10-3 in 2015. Modeling on the basis of experimental chlorination of natural water indicates the high efficiency of preliminary ammonization in the disinfection mode, which ensures the content of free total active chlorine in tap water in the range from 0.8 to 1.2 mg/l. Conclusion. The high efficiency of the application of preliminary ammonization of natural water to prevent the formation of trihalogenomethanes and reduce carcinogenic risk has been confirmed. The priority factor for the formation of excess amounts of organochlorine compounds in drinking water is its hyper chlorination. Promising measures to reduce the carcinogenic risk of trihalogenomethanes in tap water include the systematic monitoring of their content, the use of preliminary ammonization, the exact dosage of chlorine, the deep purification of the source water before chlorination, the replacement of primary chlorination with ultraviolet disinfection, and others.

Investigation of the influence of chlorine-containing disinfectant type on the quality of drinking water and the effectiveness of water treatment technology

Introduction. Effectiveness and applicability of chlorine-containing disinfectants used in the practice of water treatment were studied for the purpose of solving urgent environmental problems associated with the formation of secondary pollutants generated during the chlorination of natural water. Such contaminations are mostly represented by organohalogen compounds producing strong negative effect on the physiological state of living organisms, including human beings. To solve this problem, it is proposed to use technical grade sodium hypochlorite instead of traditional liquid chlorine when selecting disinfectants for natural water. Technical grade sodium hypochlorite is obtained by saturating solutions of diaphragmatic sodium hydroxide with chlorine gas at the stage of liquefaction of chlorine and caustic soda production. Sodium hypochlorite solution is significantly less toxic, non-flammable and not explosive. Materials and methods. A comparative study was conducted as to changes in the content of organohalogen compounds and heavy metals in water treated with sodium hypochlorite and liquid chlorine of one year duration. Analyses of water samples of water treated with liquid chlorine and sodium hypochlorite were made to measure concentrations of heavy metals, organohalogen compounds and other drinking water quality indicators, as specified by current regulations. Results. The obtained data demonstrate that the use of sodium hypochlorite for disinfection provides a higher quality of drinking water, therefore, it is advisable to replace liquid chlorine with technical grade sodium hypochlorite in the process of water treatment as potable water. Conclusions. The results of the study formed the basis for numerous industrial tests and subsequent implementation in existing water treatment plants in many large cities of Russia.

Formation of disinfection by-products under influence of shale gas produced water

Accidental spills and surface discharges of shale gas produced water could contaminate water resources and generate health concerns. The study explored the formation and speciation of disinfection by-products (DBPs) during chlorination of natural waters under the influence of shale gas produced water. Results showed the presence of produced water as low as 0.005% changed the DBP profile measurably. A shift to a more bromine substitution direction for the formation of trihalomethanes, dihaloacetic acids, trihaloacetic acids, and dihaloacetonitriles was illustrated by exploring the individual DBP species levels, bromine substitution factors, and DBP species fractions, and the effect was attributable to the introduction of bromide from produced water. The ratio of dichloroacetic and trichloroacetic acids also increased, which was likely affected by different bromination degrees at elevated bromide concentrations. Increasing blend ratios of produced water enhanced the formation of DBPs, especially the brominated species, while such negative effects could be alleviated by pre-treating the produced water with ozone/air stripping to remove bromide. The study advances understandings about the impacts of produced water spills or surface discharges regarding potential violation of Stage 2 DBP rules at drinking water treatment facilities.

Colonial cell disaggregation and intracellular microcystin release following chlorination of naturally occurring Microcystis

Colonial cell disaggregation and release of intracellular microcystin were evaluated following chlorine treatment of naturally occurring Microcystis. Microscopic observations of water samples collected from Lake Mead, Nevada, USA, confirmed the presence of colonial Microcystis with cells protected by an outer sheath up to 30 μm thick. During chlorination, two stages of cell decomposition were observed, stage 1: colonial cell disaggregation, and stage 2: unicellular degradation. Following a [Cl2]0:DOC0 ratio of 0.15 (t = 20 min, pH = 8.2–8.5) in unfiltered Lake Havasu samples, total particle count increased from (1.0 ± 0.11) × 105 to 4.2 × 105 particles/mL and fluorescent particle count increased from (1.2 ± 0.50) × 104 to 1.2 × 105 particles/mL, illustrating colonial cell disaggregation. Although total and fluorescent particles increased, the concentration of chlorophyll-a (Chl-a) decreased from 81 μg/L to 72 μg/L, and continued to decrease at higher [Cl2]0:DOC0 ratios. The preliminary second order rate constant for the reaction between Microcystis and chlorine in natural waters was estimated using either Chl-a (k = 15 M−1 s−1) or fluorescence particle count (k = 38 M−1 s−1) as an indicator of cell damage following colonial disaggregation (i.e., at [Cl2]0:DOC0 ratio ≥0.15). Complete release of intracellular microcystin-LR (MC-LR) was observed in both Lake Havasu and Lake Mead samples when applying a [Cl2]0:DOC0 ratio of 0.30 (t = 20 min), which was equivalent to a chlorine exposure of 8 min-mg/L for Lake Havasu samples. With chlorination, DOC increased by 3–18% indicating release of either colony-bound or cell-bound DOC. The results demonstrated the ability of chlorine to disaggregate/inactivate natural Microcystis colonies, and identified oxidation conditions resulting in complete release of intracellular MC-LR.

An environmentally friendly flow system for high-sensitivity spectrophotometric determination of free chlorine in natural waters

A green and highly sensitive analytical procedure was developed for the determination of free chlorine in natural waters, based on the reaction with N,N-diethyl-p-phenylenediamine (DPD). The flow system was designed with solenoid micro-pumps in order to improve mixing conditions by pulsed flows and to minimize reagent consumption as well as waste generation. A 100-cm optical path flow cell based on a liquid core waveguide was employed to increase sensitivity. A linear response was observed within the range 10.0 to 100.0 µg L − 1 , with the detection limit, coefficient of variation and sampling rate estimated as 6.8 µg L − 1 (99.7% confidence level), 0.9% ( n = 20) and 60 determinations per hour, respectively. The consumption of the most toxic reagent (DPD) was reduced 20,000-fold and 30-fold in comparison to the batch method and flow injection with continuous reagent addition, respectively. The results for natural and tap water samples agreed with those obtained by the reference batch spectrophotometric procedure at the 95% confidence level.

Transformation of 17α-Ethinylestradiol during Water Chlorination: Effects of Bromide on Kinetics, Products, and Transformation Pathways

Kinetics, products, and pathways of 17alpha-ethinylestradiol (EE2) transformation during chlorination of water with and without bromide (Br(-)) were studied to evaluate the effect of chlorination on the fate of steroid estrogens. Br(-) can be important for the fate of EE2 during chlorination because of a rapid conversion of Br(-) to bromine by chlorine and a approximately 1000 times higher reactivity of bromine than chlorine toward EE2. Experimental data and model calculations for EE2 chlorination show that 4-chloro EE2 and 2,4-dichloro EE2 are the major initial transformation products in absence of Br(-). With increasing concentration of Br(-), the bromo-analogous of the chloro EE2s becomes significant as additional initial transformation products. Those initial transformation products of EE2 are generally quickly further transformed to products with a destroyed phenolic moiety. Transformation of EE2 during chlorination becomes considerably faster at Br(-) concentrations higher than 0.25 microM (20 microg L(-1)). However, in presence of model dissolved organic matter such as glycine or phenol, the accelerating effect of Br(-) diminishes due to a more rapid consumption of bromine than chlorine by these compounds. A kinetic model was developed which allows to predict EE2 transformation during chlorination of natural waters and wastewaters in presence of Br(-) and low concentrations of ammonia (<10 microM). It could be demonstrated in these systems that bromine produced from Br(-) is mainly responsible for EE2 transformation.

Haloacetic acid and Trihalomethane Formation from the Chlorination and Bromination of Aliphatic β-Dicarbonyl Acid Model Compounds

While it is known that resorcinol- and phenol-type aromatic structures within natural organic matter (NOM) react during drinking water chlorination to form trihalomethanes (THMs), limited studies have examined aliphatic-type structures as THM and haloacetic acid (HAA) precursors. A suite of aliphatic acid model compounds were chlorinated and brominated separately in controlled laboratory-scale batch experiments. Four and two beta-dicarbonyl acid compounds were found to be important precursors for the formation of THMs (chloroform and bromoform (71-91% mol/mol)), and dihaloacetic acids (DXAAs) (dichloroacetic acid and dibromoacetic acid (5-68% mol/mol)), respectively, after 24 h at pH 8. Based upon adsorbable organic halide formation, THMs and DXAAs, and to a lesser extent mono and trihaloacetic acids, were the majority (> 80%) of the byproducts produced for most of the aliphatic beta-dicarbonyl acid compounds. Aliphatic beta-diketone-acid-type and beta-keto-acid-type structures could be possible fast- and slow-reacting THM precursors, respectively, and aliphatic beta-keto-acid-type structures are possible slow-reacting DXAA precursors. Aliphatic beta-dicarbonyl acid moieties in natural organic matter, particularly in the hydrophilic fraction, could contribute to the significant formation of THMs and DXAAs observed after chlorination of natural waters.

A membrane introduction flame ionization/electron capture detection (MIFID/ECD) system for the rapid, real-time screening of volatile disinfection byproducts and hydrocarbon contaminants in water

Described is a system that employs an online membrane introduction (MI) interface coupled with parallel flame ionization and electron capture detectors (FID/ECD). We report the use of a MIFID/ECD system as an online method to detect total volatile organic halides (ΣVOXs) and volatile organic compounds (ΣVOCs) as aggregate parameters in environmental water samples at sub parts-per-billion levels without the need for sample handling or analyte pre-concentration. The instrument provides rapid screening and real-time monitoring capabilities of important classes of water contaminants in a simple system without the vacuum requirements of MS detectors. Furthermore, the MIFID/ECD instrument was successfully employed as a real-time reaction monitor for the photodegradation of toluene by an advanced oxidation process and the formation of volatile disinfection byproducts in the chlorination of natural waters. The results of these experiments compare favorably to those obtained using membrane introduction mass spectrometry (MIMS).

Kinetics of the formation and decomposition of chlorination by-products in surface waters

The presence of organic chlorination by-products (CBPs) in drinking waters has caused great public health concerns. One of the most important factors affecting their formation during the disinfection procedure is reaction time. The kinetics of the formation of CBPs can be different for the different categories or species of compounds, depending also on the chlorine dose, organic matter content and the presence of bromide ion. Decomposition of some CBPs also occurs due to hydrolysis or reactions with residual chlorine. Therefore, the final concentrations of individual species of CBPs reaching the consumers’ tap may deviate from the predictions. The aim of the present investigation was the determination of formation or decomposition kinetics of CBPs during chlorination of natural waters. 24 CBPs were studied in chlorinated water from three different sources. Different speciation of CBPs and different formation rates were observed for different water quality regarding bromide ion presence and organic matter content. Decomposition of some CBPs occurred, specifically haloketones, BCA and DBA, after an initial formation step. The percentages of incorporation of chlorine and organic matter into CBPs indicated that other halogenated compounds not identified during the present study have also been formed during chlorination. The importance of chlorine dose for the formation of CBPs and for the incorporation of organic matter was highlighted. Moreover, linear correlations were observed between the concentrations of chloroform-MCA, chloroform-DCA and chloroform-TCA as well as between total THMs and total HAAs, in all waters studied.

Formation of Haloforms during Chlorination of Natural Waters

Recent drinking water regulations have lowered the standards for disinfection by-products and have added new disinfection by-products for regulation. Natural organic matter (NOM), mainly humic compounds, plays a major role in the formation of undesirable organic by-products following disinfection of drinking water. Many disinfection by-products have adverse carcinogenic or mutagenic effects on human health. This paper deals with the formation potencial of disinfection by-products in water samples taken from different places in the Flaje catchment.

Formation of organic by-products during chlorination of natural waters

Natural water from six sources in Mytilene, Greece, was chlorinated in order to identify and quantify some of the organic by-products formed. The compounds examined were trihalomethanes, haloacetic acids, haloacetonitriles, haloketones, chloral hydrate and chloropicrin. The factors tested were time and chlorine dose. The presence of bromide ion in some of the waters studied resulted in significant changes in the by-product speciation, with enhanced brominated species formation. In addition, UV absorbance, measured at three wavelengths, led to correlation of organic matter content with the concentrations of by-products produced. The species formed, varying among different water sources, increased with increasing chlorine dose. Most of the species also increased with increasing contact time, although there were some exceptions due to hydrolysis reactions.

Disinfection Byproduct Yields from the Chlorination of Natural Waters

Disinfection Byproduct Yields from the Chlorination of Natural Waters

Disinfection byproduct yields from the chlorination of natural waters

Yields for the formation of trihalomethane and nonpurgeable total organic-halide disinfection byproducts were determined as a function of pH and initial free-chlorine concentration for the chlorination of water from the Mississippi, Missouri, and Ohio Rivers. Samples were collected at 12 sites on the Mississippi River from Minneapolis, MN, to New Orleans, LA, and on the Missouri and Ohio Rivers 1.6 km above their confluences with the Mississippi during the summer, fall, and spring seasons of the year. Yields varied little with distance along the Mississippi River, although the dissolved organic-carbon concentration decreased considerably with distance downstream. Yields for the Missouri and Ohio were comparable to yields for the Mississippi, despite much higher bromide concentrations for the Missouri and Ohio. Trihalomethane yields increased as the pH and initial free-chlorine concentration increased. Nonpurgeable total organic-halide yields also increased as the initial free-chlorine concentration increased, but decreased as the pH increased.

Processes controlling the distribution of boron and chlorine in natural waters in Iceland

The concentrations of B and Cl in natural waters in Iceland lie in the range 0.001–10 and 1–20,000 ppm, respectively. Lowest concentrations occur in surface and groundwaters in the central highlands. Highest Cl concentrations are found in high-temperature waters on the Reykjanes Peninsula and highest B concentrations in well waters from high-temperature geothermal systems in the axial zones of the active volcanic belts. The B and Cl contents of Icelandic basalts are 0.1–6.6 and 75–750 ppm, respectively. These large variations are considered to result from variable degassing during consolidation as well as concentration variations in the initial magma. Tholeftes are lowest in both elements (av. 1.2 ppm B and 170 ppm CI), transitional basalts intermediate (av. 2.1 ppm B and 240 ppm CI), and alkali-basalts highest (av. 3.8 ppm B and 340 ppm Cl). Cl B ratios in tholeiites are most often within 25–50, but somewhat lower in alkali basalts. Most geothermal waters contain B and Cl within 0.05–1 and 10–100 ppm, respectively. These rather low values are attributed to the low content of B and Cl in the basaltic rock. The B and Cl distribution in the Icelandic natural waters indicate that these elements act as essentially incompatible. Their sources of supply include (1) the atmosphere (seawater spray and aerosols), (2) the rock with which the water interacts, (3) seawater-groundwater, and (4) magma intrusions. In surface water and nonthermal groundwater the dominant source of supply of Cl is seawater spray and aerosols, but the soil and rock contribute often significantly to the B in these waters. Their Cl B ratio is similar to that of seawater (1330) or somewhat lower. Boron and Cl concentrations generally increase with water temperature. Warm waters (<50°C) usually possess Cl B ratios intermediate between those of seawater and basalt. With increasing temperature this ratio decreases and gradually approaches that of the rock. Some high-temperature geothermal waters have as low Cl B ratios as 1 and B concentrations as high as 10 ppm. The cause is either B degassing of the magmatic intrusive heat source or phase separation in the producing aquifer. Some low-temperature waters (<150°C) in low lying areas by the coast have elevated Cl concentrations due to the presence of a component of seawater-groundwater that entered the bedrock during the deglaciation period when the lowland areas were submerged. Estimation of the marine component of Cl in waters of the low-temperature systems that do not contain a seawater-groundwater component indicate that the recharge is most often local, but not distantly derived from elevated areas inland as has been inferred from their deuterium content.

Humic substance removal through surface water potabilization processes

Chlorination of natural waters during potabilization process has proven to produce trihalomethanes (THM) as well as other higher molecular weight halogenated organic compounds, presumably through reactions with humic substances present in natural waters (THM precursors). This work shows the removal of humic substances obtained by using a laboratory-scale surface water potabilization process. Monitoring of precursors removal was achieved by adding excess amounts of chlorine to water samples taken through the process, and then measuring THM formation via a purge-and-trap of volatiles concentration and gas-liquid chromatographic analysis. It was demonstrated that both preozonation followed by coagulation-flocculation-sedimentation, and activated carbon filtration, remove important amounts of THM precursor. OOn the other hand, filtration through inert media (sand, anthracite) do not exert a significant influence on THM precursors content of water. These results support the idea of the humic nature of THM precursors.

Developing Models for Predicting Trihalomethane Formation Potential and Kinetics

This article describes the overall development, including formulation and calibration, of linear and nonlinear multiple regression models for predicting total trihalomethane formation potential and kinetics during the chlorination of natural waters. The rationale behind each model formulation is discussed, and statistics relating to the calibration of each model are presented. The testing and attempted validation of these models are also addressed. Each model is subjected to a sensitivity analysis and a validation analysis using data derived from the literature.

Determination of residual chlorine in natural waters by X-ray fluorescence spectrometry

A method for the determination of total residual chlorine (TRC) in natural water is described. Potassium iodide is added to water samples on-site followed by filtration with active charcoal filters to collect iodine generated by TRC oxidation. The filters are subsequently analysed for iodine content in the laboratory by X-ray fluorescence spectrometry. The iodine recovery is better than 96%, the TRC detection limit being approximately 40 µg l–1. The within-batch relative standard deviation is 23% at 0.16 mg l–1 of TRC and 60% at lower concentrations. The method is rapid (less than 10 min per sample), virtually free from interferences and the samples remain stable for at least 1 month.

Current status of models in determining optimum chlorination practices

Interest in mathematical models for predicting the fate of chlorine in natural waters arose in the 1970's, and evolution of these models has proceeded rapidly. The crudest of the models incorporate empirical estimates of chemical reactions in a single term to predict generic chlorine products such as total residual chlorine or free residual chlorine. A second order of model complexity includes use of multifactor predictor variables to approximate losses of chlorine via chemical reaction, but predictions are still couched in terms of generic chlorine products. The most sophisticated of the current models are based on specific chemical reactions and predict the identity and quantity of some (but not all) of the products resulting from chlorination of natural waters. None of these models have been sufficiently verified, but each has some potential value for assessment of environmental effects of chlorinated discharges. Evaluation of the strengths and weaknesses of existing models is presented to stimulate further model development and to direct the focus of chemical studies toward collection of data most critical for derivation of input parameters.