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Investigation of trihalomethane formation after chlorine dioxide preoxidation followed by chlorination of natural organic matter

Özdemir Kadir

Environment Protection Engineering

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2021

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Vol. 47, nr 2

125--137

EN

Chlorine dioxide (ClO2) is widely used as powerful oxidant to remove taste, odor and pathogenic microorganisms with chlorine during water treatment. In this study, the formation of trihalomethanes (THMs) was investigated in sequential ClO2 and chlorination processes. During the study, water samples were collected from Terkos Lake water (TLW) and Büyükçekmece Lake water (BLW) in Istanbul. To understand the relationship between the formation of THMs and the characteristics of natural organic matter (NOM), changes in the molecular weight (MW) of NOM fractions before and after ClO2 oxidation were characterized with the ultrafiltration technique. The NOM fraction with MW <1 kDa is the dominant fraction among all the fractionated water samples. ClO2 oxidized NOM to more hydrophilic and smaller organic fractions as seen in the NOM fraction with MWCO <1 kDa. ClO2 preoxidation reduced THM concentrations but produced chlorite (ClO2 –) and chlorate (ClO3 –). The increase in ClO2 doses enhanced the reduction percentages of THMs during subsequent chlorination in water samples without or with bromide application. Bromine incorporation was higher in ClO2ClO2 preoxidized TLW and BLW samples. As a result, the findings of this study demonstrated that ClO2 preoxidation prior to chlorination is an applicable strategy for control of THMs in water treatment.

2

Chlorine decay and formation of THM in Malaysia's water distribution system

Rashid Aina Izzati Muhammad, Rohani Rosiah, Jaafar Othman, Muhammad Nur Shazwani

Environment Protection Engineering

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2021

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Vol. 47, nr 4

19--41

EN

Chlorine is a popular disinfectant used in Malaysia in the treatment process of drinking water supply because of its effectiveness. The concentration of chlorine deteriorates upon travelling in the system due to its reaction with organic matter to produce carcinogenic substances known as disinfection by-products (DBP) such as trihalomethanes (THM). This study was conducted to investigate chlorine decay and THM formation in a state's drinking water distribution system in Malaysia specifically across a 24.9 km distance. EPANET 2.0 Software program was used to perform hydraulics and water quality analysis using the extended period simulation (EPS) for 24 hours demand pattern. A simulation of the water distribution system was performed to identify the formation of THM and its relationship between chlorine and total organic carbon (TOC). The value of THM was maintained at a lower level at the water treatment plant (WTP) than at the endpoint of the distribution system. At the endpoint, which was at the targeted industrial area, the level of THM was found to increase and the obtained data showed that its formation occurred along the investigated distribution system. THM formation manifested as the natural organic matter (NOM) presence along the pipe continuously reacted with chlorine which was dosed in the distribution system.

3

Modeling of trihalomethane compounds formation in Baghdad water supply network

Ewaid Salam H., Al-Farhani Bassam F., Abed Salwan A., Al-Ansari Nadhir

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2020

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Vol. 29, No. 2

136--144

EN

This study was conducted to measure the concentrations of four trihalomethane compounds (THMs) in raw, treated, and drinking water of seven water purification plants and the residential neighborhoods nearby in Baghdad. About 350 samples gathered between January and October 2017 and analyzed by the gas chromatography method. Results showed that THM annual levels in tap water ranged between 12 and 97.3 µg·l–1 in winter and summer consecutively, with a mean concentration of 60 µg·l–1, these concentrations did not exceed the level recommended by the WHO and the Iraqi standards. Statistical modeling by SPSS software for the formation of THM (the dependent factor) in the water supply network was undertaken using the measured water quality parameters (as independent factors) and utilizing multiple regression analysis. The model obtained has a high correlation (r = 0.842) and approved that the most affecting parameters on THM formation are total organic carbon, temperature, turbidity, total solids, and chlorine dose. The model that was derived may be used for the purposes of choosing appropriate THM-reduction procedures and the use of chlorine for improving the method of disinfection.

4

Chlorine and chlorine dioxide oxidation of natural organic matter in water treatment plants

Özdemir Kadir

Environment Protection Engineering

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2020

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Vol. 46, nr 4

87--97

EN

The formation of trihalomethanes (THMs) during chlorine (Cl2) and chlorine dioxide (ClO2) treatment was investigated. Water samples were collected from three drinking water sources, namely, Büyükçekmece Lake water (BLW) in Istanbul City, Kızılcapınar Lake water (KLW), and Ulutan Lake water (ULW) in Zonguldak City, Turkey. The results of the study show that Cl2 treatment forms more THMs in all three water sources compared to ClO2treatment. Further, due to the Cl2treatment, the maximum THMs concentrations were observed in BLW (121.15 μg/dm3) samples, followed by KLW (97.26 μg/dm3) and ULW(88.52 μg/dm3) samples within the reaction time of 24 h for 5 mg/ dm3 of Cl2dose. However, it was found that the concentrations of THMs formed at three water sources with applied ClO2treatment under the same conditions were significantly reduced. As a result of the ClO2treatment at the end of the reaction time of 24h, THMs concentrations formed in BLW, KLW, and ULW were recorded as 30.26, 16.53, and 17.71 μg/ dm3, respectively. On chlorination, chloroform (CFM) was found the dominant THM species in all water sources. All THM species contents ranged from 1.98 μg/dm3 to 11.23 μg/ dm3 and the highest level of dibromochloromethane (BDCFM) was observed as the major THM species among all species in BLW due to the ClO2treatment. Also, the formation of inorganic DBPs such as chlorate (ClO3–) and chlorite ClO2–) was evaluated during Cl2oxidation. The levels ClO2– formed due to the ClO2 oxidation were higher than those of ClO3– levels for BLW, KLW, and ULW samples and varied from 19 to 55%, and from 37 to 60% of the applied ClO2 doses (2–10 mg/ dm3), respectively. On the other hand, ClO3– levels varied between 5 and 9% and 2 and 6% of the applied ClO2concentration for the KLW and ULW samples, respectively.

5

Wpływ warunków chlorowania wody na zawartość trihalogenometanów w wodzie do picia

Hrynaszkiewicz T., Kucharski M.

Zeszyty Naukowe Politechniki Białostockiej. Matematyka, Fizyka, Chemia

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1999

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Z. 19

169-188

PL

W przedstawionej pracy na podstawie przeprowadzonych badań zaproponowano model matematyczny do obliczania sumarycznego stężenia trihalogenometanów w wo-dzie po chlorowaniu.

EN

In this paper mathematical model for total trihalomethane concentration in water after chlorination has been proposed.

6

Badanie kinetyki powstawania trihalogenometanów. Model II. rzędu

Hrynaszkiewicz T., Kucharski M.

Zeszyty Naukowe Politechniki Białostockiej. Matematyka, Fizyka, Chemia

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1999

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Z. 19

161-168

PL

Przeprowadzone badania potwierdzają, że w początkowym przedziale czasowym (do 10 godzin) reakcja powstawania trihalogenometanów przebiega najprawdopodobniej zgodnie z modelem mieszanym I. i II. rzędu. Równocześnie ustalono, że w późniejszym okresie (powyżej 10 godzin) reakcję tę dobrze opisuje model zakładający kinetykę II. rzędu. Jako wynik badań i obliczeń zaproponowano równanie umożliwiające określanie sumarycznego stężenia trihalogenometanów z błędem względnym poniżej 1,5%.

EN

It was found that in initial time range (to 10 hours) reaction of trihalomethane formation most probably goes on according to mixed model of first and second order. Simultaneously, it was established that in future stage (after 10 hours) this reaction could be described by the model of second order kinetic. As a result of investigation and estimation the equation for trihalomethane concentration was proposed. The relative error of estimation does not exceed 1,5%.

7

Normatywy jakości wody przeznaczonej do konsumpcji

Wichrowska B.

Przemysł Spożywczy

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1998

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T. 52, nr 6

5-9

PL

Źródłem zaopatrzenia w wodę do picia są wody podziemne oraz powierzchniowe. Zarówno jedne jak i drugie, aby nadawały się do celów konsumpcyjnych, muszą być odpowiednio uzdatnione. Wody podziemne powinny być pozbawione nadmiernych ilości Fe, Mn, NH3 i NO3. W wodach powierzchniowych największy problem zdrowotny stanowią produkty powstające w trakcie uzdatniania i dezynfekcji wody chlorem: trihalometany, chlorofenole i chloraminy. Testy określające mutagenność wody do picia jednoznacznie zdyskwalifikowały chlorowanie wstępne jako bezpieczny dla człowieka sposób uzdatniania. Chlor powinien być zastąpiony innymi utleniaczami, takimi jak ozon czy dwutlenek chloru. Wody silnie zanieczyszczone powinny być uprzednio poddane koagulacji, filtracji i sorpcji na węglu aktywnym i dopiero potem dezynfekowane. Podstawą systemu kontroli jest ustalenie norm oraz rozwój metod analitycznych pozwalających na wykrycie wszystkich możliwych zanieczyszczeń.

EN

As a source of drinking water, both underground and surface waters may be used. However, they must be treated before the use for consumption purposes. Excessive amount of Fe, Mn, NH3 and NO3 must be removed from underground waters. In surface waters the most dangerous for health are compounds, which are formed during upgrading and disinfection processes with chlorine: trihalomethane, chlorofenols and chloramine. Preliminary chlorination was discredited without any doubts as a safe treatment method by muthagenic investigations. Chlorine should be substituted with other oxidants such as ozone or chlorine dioxide. Strongly contaminated waters should be coagulated, filtered and sorbed on activated carbon before disinfectation. Establishment of normative and analytic methods allowing to detect alt possible pollutants is a base of control system.