Chlorine Consumption Research Articles

Variability of residual chlorine in swimming pool water and determination of chlorine consumption for maintaining hygienic safety of bathers with a simple mass balance model.

Trial-and-error chlorination as a conventional practice for swimming pool water disinfection may fail to consistently maintain the pool's residual chlorine within regulatory limits. This study explored the variability of residual chlorine and other common water quality parameters of two sample swimming pools and examined the potential of using a mass balance model for proactive determination of chlorine consumption to better secure the hygienic safety of bathers. A lightly loaded Pool 1 with a normalized bather load of 0.038 bather/m3/day and a heavily loaded Pool 2 with a normalized bather load of 0.36 bather/m3/day showed great variances in residual free and combined chlorine control by trial-and-error methods due to dynamic pool uses. A mass balance model based on chemical and physical chlorine consumption mechanisms was found to be statistically valid using field data obtained from Pool 1. The chlorine consumption per capita coefficient was determined to be 4120 mg/bather. The predictive method based on chlorine demand has a potential to be used as a complementary approach to the existing trial-and-error chlorination practices for swimming pool water disinfection. The research is useful for pool maintenance to proactively determine the required chlorine dosage for compliance of pool regulations.

Biobleaching of Kraft pulp using fungal xylanases produced from sugarcane straw and the subsequent decrease of chlorine consumption

Xylanase extract, produced by T. reesei QM9414 in a culture with sugarcane straw (SS) as substrate, was studied in the biobleaching of Kraft pulp associated with chemical bleaching. The biobleaching parameters optimization showed that 30 U/g of xylanases, at pH 5, at 50 °C, during 30 min, are the best conditions to bleach the crude Kraft pulp (3% of consistency). lA decrease of 12.5% of Kappa number, as well as the release of 1 g/lL of sugar, and the presence of chromophores compounds (237 nm) are also observed. After this xylanase biobleaching the final chlorine dioxide consumption decrease in 10%, maintaining the same brightness as in the control on the subsequent chemical process. SEM shows the effect on the pulp surface. These results clearly demonstrated that the T. reesei QM9414 xylanase is an eco-friendly and economical alternative for paper production.

Analysis of water supply system maintenance costs from the aspect of water quality

Abstract There is no current obligation in pipeline dimensioning practice to consider free residual chlorine (FRC) consumption. The only requirements are the hydraulic parameters defined by the ‘codes of practice’ and legal regulations. The objective of this paper is to give insight into the potential additional (hidden) costs that can arise when maintaining water supply systems, i.e., parts that, from the water quality aspect, can often be considered over-dimensioned. An algorithm is used to analyse FRC consumption that is implemented in EPANET 2.0 software. EPANET 2.0 is proven to be able to yield reliable descriptions of FRC consumption in parts of water supply systems. Here it is simplified for use in relation to a single pipeline as an example.

Quantifying chlorine-reactive substances to establish a chlorine decay model of reclaimed water using chemical chlorine demands

In order to guarantee the water quality of reclaimed water in pipeline system, a chlorine bulk-decay model is required for simulation and prediction of chlorine profiles in networks. Conventional chlorine decay models of drinking water are not applicable to reclaimed water due to its complex and varying water quality. In this study, the chlorine decay of reclaimed water was investigated under different operational conditions. Based on these results, different chlorine-reactive substances (CRSs) in reclaimed water were quantified by total chlorine demand (TCD), instantaneous chlorine demand (ICD) and lasting chlorine demand (LCD), respectively. A stoichiometric model (CRS model) of chlorine decay of reclaimed water was established using ICD, TCD and reaction rate constant (k) as key independent parameters. The experimental data were fitted to the CRS model with promising results under various initial chlorine concentrations (3–10 mg-Cl2/L) and temperatures (8–35 °C). The ICD, TCD and k of different reclaimed water samples were in the range of 0.23 to 2.85 mg-Cl2/L, 1.07 to 4.73 mg-Cl2/L, and 0.04 to 4.06 L/(mg·h), respectively. Furthermore, the ICDs, TCDs and k could be determined directly by measuring the chlorine consumption at 5 min (ΔCCl,5min) and 8 h (ΔCCl,8h) after the addition of chlorine into reclaimed water, and the UV254 of reclaimed water, respectively. The relationships between ICD, TCD, k and the corresponding water quality indexes were further validated. In this way, the chlorine decay profile of reclaimed water could be predicted rapidly and precisely by measuring the ΔCCl,5min, ΔCCl,8h, and UV254 of reclaimed water.

<b>Artificial neural networks to control chlorine dosing in a water treatment plant

Artificial neural networks in the multivariable control of chlorine dosing in the post-chlorination stage in a water treatment plant in the Greater Sao Paulo, Brazil, are analyzed. The plant has constant fluctuations in chlorine demand caused by natural influences related to raw water from surface source. Modeling and computer simulation were implemented in MATLAB/Simulink ® environment, according to the physical and operational characteristics of the water treatment plant. Moreover, a Proportional-Integral (PI) controller was incorporated to provide better stability. Simulation results showed improved stability of free residual chlorine when compared to method currently employed, i.e. Proportional-Integral-Derivative (PID) controller that would reduce chlorine consumption in water treatment process.

Analysis of the chlorine consumption for oxidation of the cyanobacteria species Microcystis aeruginosa

Este estudo avaliou o consumo de cloro da espécie Microcystis aeruginosa presente nas florações em mananciais de abastecimento, pois a legislação exige a manutenção mínima de 0,2 mg.L-1 de cloro residual livre ou 2 mg.L-1 de cloro residual combinado e um residual de 3 a 5 mg.L-1 após 7 dias. Em escala de laboratório realizaram-se análises com cloro gasoso: 8 doses para ensaios de 30 minutos e 24 horas; e outras 7 para ensaios de 7 dias. Os resultados, em média, demonstraram alto consumo de cloro, podendo ter relação com a formação de subprodutos da cloração no tratamento de água.

Mystery of the high chlorine consumption in disinfecting a chemically enhanced primary saline sewage

Stonecutters Island Sewage Treatment Works is one of the largest sewage treatment plants in the world and consists mainly of a chemically enhanced primary treatment (CEPT) unit and a disinfection unit. It has long been realized that most of the dosed chlorine (15 mg/L) is lost at the beginning part of the disinfection unit during disinfection of the CEPT effluent. Lab-scale tests were therefore conducted in this study to determine the causes. Because ferric chloride is used in CEPT, ferrous iron in the CEPT effluent (from the reduction of ferric iron) was initially thought to be the main chlorine consumer. However, the chlorine consumption by ferrous iron was found to be 1.2 mg/L at most. Suspended solids and sulfide also did not contribute significantly to the chlorine consumption. Batch tests were therefore conducted to evaluate the effects of mixing condition and chlorine stock solution concentration on the chlorine consumption. Less chlorine was consumed upon increased mixing. Using a high-concentration chlorine stock solution (25000 mg/L) resulted in a 3-times-higher chlorine consumption in the absence of mixing than using a low-concentration chlorine stock solution (2500 mg/L). By correlating the losses of ammonia and total nitrogen with the chlorine consumption, we hypothesized that the use of a high-concentration chlorine stock solution under poor mixing leads to a localized high ratio of chlorine to ammonia, resulting in breakpoint chlorination and an unusually excessive chlorine consumption. A novel apparatus was developed to quantify the nitrogen gas generated during chlorination of a simulated wastewater, and the mass balance of nitrogen-containing species (i.e., ammonia, nitrogen gas, nitrite and nitrate) during the chlorination was inspected. The good fit between the measured chlorine consumption and that back-calculated from nitrogen-containing species verified our hypothesis. Finally, it needs mentioning that the high chlorine consumption and the breakpoint chlorination may occur during chlorine disinfection of any sewage effluents with relatively high ammonia levels; thus it is suggested that either not-too-high concentrations of chlorine stock solutions or sufficient mixing should be applied during disinfection of the sewage effluents.

Influence of dentine debris and organic tissue on the properties of sodium hypochlorite solutions.

To determine the free available chlorine of 2.5% sodium hypochlorite (NaOCl) alone and combined with 9% etidronic acid (HEDP) in the presence of inhibitors, organic tissue and organic tissue plus dentine debris; to evaluate the influence of dentine debris on the tissue-dissolving capacity of both NaOCl solutions; and to determine the antimicrobial action of these solutions when in contact with organic tissue and organic tissue plus dentine debris. The available chlorine of the solutions over time in the absence and presence of the inhibitors was measured using a titration method. The organic tissue dissolution by the solutions alone and in the presence of dentine powder was evaluated by weighing bovine tissue specimens before and after exposure to the solutions for 3 and 10min. For the antimicrobial activity, biofilms of Enterococcus faecalis were exposed to the solutions for 3min in the absence and presence of organic tissue and organic tissue+dentine debris. The biovolume and percentage of damaged membrane cells of the biofilm were measured by means of confocal microscopy and the live/dead technique. Nonparametric tests were used to determine statistical differences (P<0.05). Both inhibitors consumed the free available chlorine of the solutions over time. The presence of dentine debris significantly reduced the tissue dissolution capacity of the NaOCl solutions (P<0.05). The percentages of biovolume reduction were not affected by the presence of the inhibitors in the two NaOCl solutions, whereas the percentage of damaged membrane cells was significantly reduced (P<0.001). Overall, a similar behaviour was observed in the NaOCl and NaOCl/HEDP groups. The presence of organic tissue and organic tissue+dentine debris favoured rapid consumption of the free chlorine of NaOCl and NaOCl/HEDP. This resulted in a decreased ability to dissolve organic tissue without affecting the short-term antimicrobial activity.

PPCP Degradation by Chlorine-UV Processes in Ammoniacal Water: New Reaction Insights, Kinetic Modeling, and DBP Formation.

The combination of chlorine and UV (i.e., chlorine-UV process) has been attracting more attention in recent years due to its ready incorporation into existing water treatment facilities to remove PPCPs. However, limited information is available on the impact of total ammonia nitrogen (TAN). This study investigated two model PPCPs, N,N-diethyl-3-toluamide (DEET) and caffeine (CAF), in the two stages of the chlorine-UV process (i.e., chlorination and UV/chlor(am)ine) to elucidate the impact of TAN. During chlorination, the degradation of DEET and CAF was positively correlated with the overall consumption of total chlorine by TAN. Reactive nitrogen intermediates, including HNO/NO- and ONOOH/ONOO-, along with •OH were identified as major contributors to the removal of DEET and CAF. During UV irradiation, DEET and CAF were degraded under UV/chlorine or UV/NH2Cl conditions. •OH and •Cl were the major reactive species to degrade DEET and CAF under UV/NH2Cl conditions, whereas •OCl played a major role for degrading CAF under UV/chlorine conditions. Numerical models were developed to predict the removal of DEET and CAF under chlorination-UV process. Chlorinated disinfection byproducts were detected. Overall, this study presented kinetic features and mechanistic insights on the degradation of PPCPs under the chlorine-UV process in ammoniacal water.

Investigating the management performance of disinfection analysis of water distribution networks using data mining approaches

Chlorination, the basic treatment utilized for drinking water sources, is widely used for water disinfection and pathogen elimination in water distribution networks. Thereafter, the proper prediction of chlorine consumption is of great importance in water distribution network performance. In this respect, data mining techniques-which have the ability to discover the relationship between dependent variable(s) and independent variables-can be considered as alternative approaches in comparison to conventional methods (e.g., numerical methods). This study examines the applicability of three key methods, based on the data mining approach, for predicting chlorine levels in four water distribution networks. ANNs (artificial neural networks, including the multi-layer perceptron neural network, MLPNN, and radial basis function neural network, RBFNN), SVM (support vector machine), and CART (classification and regression tree) methods were used to estimate the concentration of residual chlorine in distribution networks for three villages in Kerman Province, Iran. Produced water (flow), chlorine consumption, and residual chlorine were collected daily for 3years. An assessment of the studied models using several statistical criteria (NSC, RMSE, R2, and SEP) indicated that, in general, MLPNN has the greatest capability for predicting chlorine levels followed by CART, SVM, and RBF-ANN. Weaker performance of the data-driven methods in the water distribution networks, in some cases, could be attributed to improper chlorination management rather than the methods' capability.

Role of drinking water biofilms on residual chlorine decay and trihalomethane formation: An experimental and modeling study

PVC pipe loops were constructed to simulate household premise plumbing. These pipe loops were exposed to water treated by physical processes at three water treatment plants in Xiamen, China from August 2016 to June 2017. After the biofilms were allowed to develop inside the pipes, these pipes were deconstructed and exposed to organic-free chlorine solution buffered at pH 6.8 ± 0.2 for 48 h. The decay of chlorine by these biofilms was higher than by the effluent waters that were used to grow the biofilms. A chlorine consumption mass balance model elucidated the role of both the diffusion of chlorine into the biofilm and the reaction of chlorine with the biofilm matrix. Comparable concentrations of trihalomethanes were quantified from the reaction between chlorine and source water organic matters, and chlorine and the biofilm, further emphasizing the role of biofilms in the safety of disinfected drinking water. These findings imply that when chlorine is used in the drinking water distribution system, the ubiquitous presence of biofilms may cause the depletion of chlorine and the formation of non-negligible levels of toxic disinfection byproducts.

Understanding the coagulant activity of zirconium oxychloride to control THMs formation using response surface methodology

In the present study, impact of coagulant activity of zirconium oxychloride and aluminium sulphate on the kinetics of chlorine consumption and trihalomethanes (THMs) formation has been delineated. Zirconium Oxychloride showed rapid chlorine decay within the first 30 min, which further achieved steady rate after 60 min, but in case of aluminium sulphate chlorine consumption has been increased drastically throughout the chlorine decay. Zirconium oxychloride has effectively reduced significant amount of slow reducing agents (SRA) as well as fast reducing agents (FRA), which correspond to the rate of reduction in phenolic groups from water enriched with Natural Organic Matter (NOM) which eventually decreased trihalomethane mediated cancer risk by ~ 2.3 times among adults as compared to aluminium sulphate. Result depicts the outstanding coagulant activity of zirconium oxychloride as it tends to surpass aluminium sulphate in reducing NOM “measured as Absorbance Slope Index (ASI)” and phenol by 57.98% and 49.02% respectively from NOM enriched chlorinated water, which also resembles the THMs removal trend observed during cancer risk assessment.

Effects of phosphate-enhanced ozone/biofiltration on formation of disinfection byproducts and occurrence of opportunistic pathogens in drinking water distribution systems

The effects of ozone-biologically activated carbon (O3-BAC) treatment with various phosphate doses (0, 0.3 or 0.6 mg/L) were investigated on the formation of disinfection by-products (DBPs) and occurrence of opportunistic pathogens (OPs) in drinking water distribution systems (DWDSs) simulated by annular reactors (ARs). It was found that the lowest DBPs and the highest inactivation of OPs such as Mycobacterium spp., Mycobacterium avium, Aeromonas spp., Pseudomonas aeruginosa and Hartmanella vermiformis, occurred in the effluent of the AR with 0.6 mg/L phosphate addition. Based on the results of different characterization techniques, for the AR with 0.6 mg/L phosphate-enhanced O3-BAC treatment, dissolved organic carbon in the influent exhibited the lowest concentration and most stable fraction due to the improved biodegradation effect. Moreover, the total amount of suspended extracellular polymeric substances (EPS) in the bulk water of the AR decreased greatly, resulting in the lowest chlorine consumption and DBPs formation in the AR. In Fourier transform infrared spectra of the suspended EPS, the amide II band (1600-1500 cm−1) disappeared and the protein/polysaccharide ratio decreased remarkably, indicating the destruction of protein and a decrease in hydrophobicity. Moreover, β-sheets and α-helices in the protein secondary structures were degraded while the random coils increased sharply as phosphate addition increased to 0.6 mg/L, inhibiting microbial aggregation and hence weakening the chlorine-resistance capability. Thus, most of the OPs in suspended biofilms were more easily inactivated by residual chlorine, resulting in the lowest OPs occurrence in the effluent of the AR. Our findings indicated that enhancing the efficiency of the BAC filter by adding phosphate is a promising method for improving water quality in DWDSs.

Formation of chlorinated haloacetic acids by chlorination of low molecular weight compounds listed on pollutant release and transfer registers (PRTRs)

Anthropogenic compounds accidentally released to the environment could be important precursors of disinfection byproducts (DBPs) in drinking water treatment processes. In this study, the haloacetic acid formation potentials (HAAFPs) of 155 anthropogenic compounds listed on the Japanese pollutant release and transfer register (PRTR) system were evaluated. The results showed that phenolic and aromatic amine compounds were important HAA precursors, and chlorinated phenols showed high HAAFPs (>400 μg/mgC). Moreover, trichlorfon and ethyl chloroacetate (HAAFP of 104.9 and 602.3 μg/mgC, respectively) were also important HAA precursors because of their ability to undergo hydrolysis. Although most anthropogenic compounds with high HAAFPs showed high chlorine consumptions, no clear correlation between HAAFPs and chlorine consumptions was found in this study. In addition, the quantitative structure-activity relationship (QSAR) approach was a useful tool for predicting the chlorine consumption of organic compounds but was not effective for predicting HAAFPs based on the information currently available. A scenario study assuming a hypothetical accidental release predicted that the release of 3,4-dichloroaniline (HAAFP of 407.6 μg/mgC) would lead to a violation of the current drinking water quality standards for HAAs in Japan.

Effective range of chlorine transport in an aquifer during disinfection of wells: From laboratory experiments to field application

Microbiological contamination usually leads to erratic operation of drinking water wells and disinfection is required after disasters and sometimes to restore proper well performance for aquifer storage and recovery (ASR) and subsurface iron removal (SIR) wells. This study focused on estimating the fate of chlorine around an infiltration well and improving the knowledge about processes that control the physical extent of the disinfected/affected radius. Closed bottle batch tests revealed low chlorine consumption rates for filter gravel and sand (0.005 mg/g/d) and higher rates for clay (0.030 mg/g/d) as well as natural aquifer material (0.054 mg/g/d). Smaller grain sizes <1 mm showed 10- to 70-times higher initial chlorine consumption rates within the first hour after contact compared to the median consumption rates. Initial chlorine concentration most likely does not impact disinfection ability at grain sizes >1 mm, but results in more effective disinfection for very fine material <0.063 mm. Column studies focused on the adaptation of the lab results to an actual SIR waterworks in Khabarovsk, Russia. Results reinforced the previous lab results with low 1st-order decay constants of 16 d−1 for filter material and much higher values of 254 d−1 for natural aquifer material. Application of the chlorine consumption rates to an example well consistently indicated that the filter gravel pack consumes <1% of infiltrated chlorine. The disinfection zone at the example well seems to extend to maximum 3.5 m into the aquifer. Excessive chlorine dosage of >10 mg/l would not further extend the disinfected radius. A preferable way to increase the range of chlorine application is to increase the total infiltrated volume and time. Three approaches are proposed for adapting lab results to actual infiltration wells, that are in principle applicable to any other site.

Influence of different organic materials on chlorine concentration and sanitization of slightly acidic electrolyzed water

The objective of the present study was to determine the effect of organic materials on chlorine concentration through in vitro assays to identify the most critical organic material affecting the sanitization of slightly acidic electrolyzed water (SAEW) during washing process. Organic materials (100–1000 mg/L) were added into SAEW solution and consumption of free chlorine was recorded. Inactivation of pathogens was performed in present of these organic materials. Depletion of free chlorine and sanitization efficacy of SAEW were determined during vegetables and meats samples washing processes. Results of this study showed that protein compounds had more detrimental effects on sanitization efficacy than lipids and carbohydrates. In the presence of carbohydrate and lipid compounds, pathogen population were decreased below the detection limits within 3 min. However, SAEW effect was decreased with increasing protein concentration. During simulation of washing processes, free chlorine was more quickly consumed in reactions containing organic materials for meats compared to those for vegetable produce. However, such difference in chlorine depletion did not significantly influence bacterial reduction between meats and vegetable produce. These results indicate that the optimization of SAEW washing should consider both the amount and the type of organic materials constituting the fresh produce.

PILOT PLANT PENGOLAHAN AIR MINUM DENGAN PROSES BIOFILTRASI DAN ULTRAFILTRASI

Until now, the drinking water companies in Indonesia still use chlorine for disinfection processes. In addition, the chlorine also uses for removal Fe, Mn and ammonia. If the raw water contains high concentration of ammonia, chlorine will react with ammonia form chloramines which have lower strength of disinfection power. The higher concentration of ammonia in raw water caused the higher consumption of chlorine. The reaction of chlorine with certain organic compounds as humic substances will to produce chloro-organo compounds like chlorophenols which become serious problems to day because trihalomethane and also chlorophenols compounds are carcinogenic substances.To overcome the problems one of alternative is using the combination of biofiltration and ultrafiltration to process the drinking water. Biofltrations process is treatment of raw water biologically using fixed bed biofilter reactor witch filled with honeycomb plastic supporting media for removal Fe, Mn, ammonia detergent, and also organic substances. Ultrafiltration (UF) is filtration process using hollow fiber membranes that have effective pore sizes of 0.1 – 0.01 µm. The ultrafiltration units are capable of separating some large molecular weight dissolved organics, colloids, macromolecules and suspended solids from raw water. The ultrafiltration process is designed to remove colloidalized particles in the range from 0.1-0.01µm.By combining the biofiltration and ultrafiltration processes, hence will be got technological alternative of drinking water process which capable to degrade an organic matter, ammonia, detergent and can remove the colloidal or suspended matter effectively without chemicals instead of conventional process. Kata Kunci : Pengolahan Air Minum, Biofiltrasi, Membran, Ultrafiltrasi, Pilot Plant

Consumption of Free Chlorine in an Aqueduct Scheme with Low Protection: Case Study of the New Aqueduct Simbrivio-Castelli (NASC), Italy

The safety of high quality drinking water supply relies on the quantities to be delivered, on the complexity of the water supply systems, and on the widespread phenomena of the contamination of water bodies. These parameters indicate the need for the development of an application that will allow the quick acquisition of data on strategic management. This is requires both the analysis of factors related to the hydraulic operation of the plants and the characteristics of water quality. The present paper aims to evaluate the use of models that predict data for water quality in a distribution system. The assessment is made in order to consider the use of the model as a support tool for the management system of a supply network and to optimize the quality of the provided service. The improvement of the control system related to the operations of disinfection, in particular, in the case of long pipelines, is absolutely mandatory in order to ensure the safety of public health and respect for the environment at high levels.

Chlorination of bisphenol S: Kinetics, products, and effect of humic acid.

Bisphenol S (BPS), as a main alternative of bisphenol A for the production of industrial and consumer products, is now frequently detected in aquatic environments. In this work, it was found that free chlorine could effectively degrade BPS over a wide pH range from 5 to 10 with apparent second-order rate constants of 7.6-435.3 M-1s-1. A total of eleven products including chlorinated BPS (i.e., mono/di/tri/tetrachloro-BPS), 4-hydroxybenzenesulfonic acid (BSA), chlorinated BSA (mono/dichloro-BSA), 4-chlorophenol (4CP), and two polymeric products were detected by high performance liquid chromatography and electrospray ionization-tandem quadrupole time-of-flight mass spectrometry. Two parallel transformation pathways were tentatively proposed: (i) BPS was attacked by stepwise chlorine electrophilic substitution with the formation of chlorinated BPS. (ii) BPS was oxidized by chlorine via electron transfer leading to the formation of BSA, 4CP and polymeric products. Humic acid (HA) significantly suppressed the degradation rates of BPS even taking chlorine consumption into account, while negligibly affected the products species. The inhibitory effect of HA was reasonably explained by a two-channel kinetic model. It was proposed that HA negligibly influenced pathway i while appreciably inhibited the degradation of BPS through pathway ii, where HA reversed BPS phenoxyl radical (formed via pathway ii) back to parent BPS.

Comparison of the effects of chloramine and chlorine on the aromaticity of dissolved organic matter and yields of disinfection by-products

This study compared effects of chlorination and chloramination on the chromophores of dissolved organic matter (DOM) and attendant formation of disinfection by-products (DBPs) in raw and treated surface waters. Comparison of the differential absorbance spectra of chloraminated and chlorinated waters shows that interactions of chloramine with DOM chromophores result in changes that are in many respects similar to those observed for chlorine although the extent of degradation of DOM chromophores and the attendant decrease of DOM aromaticity by chloramine are less pronounced than that caused by free chlorine. The degradation of DOM chromophores caused by the examined disinfectants indicated that in both cases a gradual decrease of DOM took place. Decreases of DOM aromaticity estimated based on the changes of DOM absorbance at 254 or 280 nm were correlated with chlorine consumption in a similar way for both examined disinfectants. Correlations between changes of DOM absorbance and yields of dihaloacetic acids (DHAA) were also similar for chlorination and chloramination. This was interpreted to indicate that the generation of DHAA proceeds via the degradation of the reactive sites associated with DOM chromophores irrespective of whether these sites are engaged by chlorine or chloramine. Correlations between the decrease of DOM aromaticity and formation of other DBP (e.g. trihalomethanes - THM, trihaloacetic acids - THAA and dihaloacetonitriles - DHAN) for chloramine and chlorine were also observed but, as opposed to the observations for DHAA, the correlations between degradation of DOM aromaticity and yields of THM, THAA or DHAN were different for chlorination and chloramination.