A comparative study of the effects of ozonation and TiO2-catalyzed ozonation on the selected chlorine disinfection by-product precursor content and structure

Molnar, Jelena; Agbaba, Jasmina; Dalmacija, Božo; Klašnja, Mile; Dalmacija, Milena; Kragulj, Marijana

doi:10.1016/j.scitotenv.2012.03.020

Cited by 74 publications

(48 citation statements)

References 36 publications

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“…The formation potentials of HAN4 were reduced by 53% in the presence of t-BuOH while in presence of H 2 O 2 , the reduction was 29% lower. The results shown here were consistent with the findings of Molnar et al (2012b) who showed that • OH reactions generated from TiO 2 -catalyzed ozonation resulted in an increase in hydrophilic NOM fractions, which are known to contain HAN precursors. In terms of THAMs, which can be formed from hydrolysis of HANs (Glezer et al 1999) or from other HAN-independent reactions (Huang et al 2012), addition of t-BuOH tends to improve reduction of THAM formation potentials relative to ozonation without t-BuOH.…”

Section: Effect Of Ozonation Conditions On Formation Of Known Dbpssupporting

confidence: 92%

Reducing disinfection byproduct formation potential using ozonation and biological drinking water treatment

Vera¹,

Andrew²

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The occurrence of natural organic matter (NOM) in source waters presents a concern in water treatment plants due to formation of toxic disinfection byproducts (DBPs). In this doctoral thesis, the fate of NOM during ozonation, biofiltration, and chlorination was investigated to identify important aspects in these processes that can be manipulated for better DBP control. Specifically, this thesis studied (1) reaction mechanisms of ozone with dissolved organic nitrogen (DON), an important fraction of NOM that forms nitrogenous DBPs, (2) role of ozone and• OH-mediated attack on NOM and DBP formation during chlorination, and (3) impact of ozonation on biodegradability of DBP precursors.The reaction of ozone with DON (Chapter 4) was observed to produce various transformation products including nitrate (NO 3 -) and ammonium (NH 4 + residual after 24 h = 1 -2 mg/L) as follows: THM4 (37%), HAA8 (44%), CH (107%), HK2 (97%), HAN4 (33%), trichloroacetamide (TCAM, 43%), and AOX (27%), but a decrease in concentrations of THNM2 (43%). Coupling ozonation with biofiltration prior to chlorination effectively lowered the formation potentials of all DBPs including CH, HK2, and THNM2, all of which increased after ozonation. The dynamics of DBP formation potentials during BAC filtration at different EBCTs followed first-order reaction kinetics. Minimum steady-state concentrations were attained at an EBCT of 10 -20 min, depending on the DBP species. The rate of reduction in DBP formation potentials varied among individual species before reaching their minimum concentrations. CH, HK2, and THNM2 had the highest rate constants of between 0.5 and 0.6 min -1 followed by HAN4 (0.4 min -1 ), THM4 (0.3 min -1 ), HAA8 (0.2 min -1 ), and AOX (0.1 min -1 ). Relative to concentrations after ozonation, the reduction in formation potential for most DBPs (e.g., at 15 min EBCT) was less than 50% but was higher than 70% for CH, HK2, and THNM2. The formation of bromine-containing DBPs increased with increasing EBCT likely due to an increase in Br -/DOC ratio.-iv- Dr. Wolfgang Gernjak co-advised me during my PhD candidature and played an integral part in all the chapters of this thesis. He was involved in the initial conceptual thinking, to developing research ideas, identifying appropriate experimental design, and interpreting research data. He also provided critical reviews in all the manuscripts. Declaration by authorDr. Maria José Farré, who was my principal advisor in 2013, is recognized for sharing her expertise in disinfection byproduct research (i.e., from laboratory techniques, instrumentation, and theory). Our regular exchange of viewpoints were essential in the conception of research ideas and approaches related to DBPs. She was also highly involved in the writing and review of manuscripts.Prof. Urs von Gunten, who is a world-leading expert in application of ozone for water treatment, was my host professor during my research visit at École Polytechnique Fédérale de Lausanne (EPFL)where I performed the bulk of the experiments repor...

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Section: Effect Of Ozonation Conditions On Formation Of Known Dbpssupporting

confidence: 92%

Reducing disinfection byproduct formation potential using ozonation and biological drinking water treatment

Vera¹,

Andrew²

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“…O pH tem valores entre 6,9 e 7,8, e a temperatura varia entre 29 ºC e 35ºC durante o período em estudo (Tabela 3 e 4). De acordo com Molnar et al, (2012), a temperatura é um fator que influencia quase todos os processos físi-cos, químicos e biológicos da água. As descargas indiscriminadas de detergentes nas águas naturais levam a prejuízos de ordem esté-tica, provocados pela formação de espuma.…”

Section: Análise Dos Parâmetros Físico-químicos E Microbiológicosunclassified

Avaliação genotóxica e mutagênica de amostras de efluentes tratados por lagoas de estabilização em Teresina-Piauí

Costa¹,

Monteiro²,

Batista³

2018

RDAE

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“…Serbian workers Molnar et al (2012) examined the catalytic effect of titanium dioxide (TiO2, 80/20 anatase/rutile ratio) on the ozonation outcome of waters (groundwater from the Central Banat Province of Vojvodina, a water rich in mostly of hydrophobic character NOM) and on the formation of the THMs and HANs after subsequent chlorination operation. TiO2-catalyzed process reduced significantly the content of total NOM (up to 18% DOC) compared to ozonation alone (up to 6% DOC), and improved THM precursor content removal (FP reaching 80%).…”

Section: Pretreatmentmentioning

confidence: 99%

New Trends in Disinfection By-Products Formation upon Water Treatment

Boucherit¹,

Moulay²,

Ghernaout³

et al. 2015

CHEM

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This review paper deals with the formation of disinfection by-products (DBPs). Water basin remains a wonderful chemical reactor that allows the occurrence of intricate secondary disinfection chemical reactions, forming several hundreds of DBPs at the same time with microorganisms killing. The kinetics of DBPs formation is tightly dependent on water physicochemical characteristics such as temperature, hydrophobic/hydrophilic fractions in natural organic matter (NOM), pH, and pretreatment. Reducing DBPs levels in drinking water is not a relevant measure as the newly-developed analytical techniques and the health-related research reveal that the tolerable DBPs' levels must be further decreased and would be detected at ng L-1 instead of μg L-1 scale. Furthermore, because of the fact that man is being exposed to DBPs concentrations in drinking water in his lifetime, there will be a cumulative effect of these toxic chemical products even at their more reduced concentrations. Hence, the removal of these chemical products is sought for and is considered a real challenge and the main objective of water treatment technology for mankind survival.

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A comparative study of the effects of ozonation and TiO2-catalyzed ozonation on the selected chlorine disinfection by-product precursor content and structure

Cited by 74 publications

References 36 publications

Reducing disinfection byproduct formation potential using ozonation and biological drinking water treatment

Reducing disinfection byproduct formation potential using ozonation and biological drinking water treatment

Avaliação genotóxica e mutagênica de amostras de efluentes tratados por lagoas de estabilização em Teresina-Piauí

New Trends in Disinfection By-Products Formation upon Water Treatment

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