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Removal of Saxitoxin and Microcystin when present alone or simultaneously in drinking water plants with different PAC sourcesWALKE, DIVYANI 17 May 2023 (has links)
No description available.
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The Influence of Dissolved Organic Matter on the Fate of Polybrominated Diphenyl Ethers (PBDEs) in the EnvironmentWei-Haas, Maya Li 08 October 2015 (has links)
No description available.
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Iopamidol as a Precursor to DBP Formation in Drinking Water as a Function of Natural Matter and BromideAckerson, Nana Osei Bonsu January 2017 (has links)
No description available.
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Drinking water treatment sludge production and dewaterabilityфVerrelli, D. I. January 2008 (has links)
The provision of clean drinking water typically involves treatment processes to remove contaminants. The conventional process involves coagulation with hydrolysing metal salts, typically of aluminium (‘alum’) or trivalent iron (‘ferric’). Along with the product water this also produces a waste by-product, or sludge. The fact of increasing sludge production — due to higher levels of treatment and greater volume of water supply — conflicts with modern demands for environmental best practice, leading to higher financial costs. A further issue is the significant quantity of water that is held up in the sludge, and wasted. / One means of dealing with these problems is to dewater the sludge further. This reduces the volume of waste to be disposed of. The consistency is also improved (e.g. for the purpose of landfilling). And a significant amount of water can be recovered. The efficiency, and efficacy, of this process depends on the dewaterability of the sludge.In fact, good dewaterability is vital to the operation of conventional drinking water treatment plants (WTP’s). The usual process of separating the particulates, formed from a blend of contaminants and coagulated precipitate, relies on ‘clarification’ and ‘thickening’, which are essentially settling operations of solid–liquid separation.WTP operators — and researchers — do attempt to measure sludge dewaterability, but usually rely on empirical characterisation techniques that do not tell the full story and can even mislead. Understanding of the physical and chemical nature of the sludge is also surprisingly rudimentary, considering the long history of these processes. / The present work begins by reviewing the current state of knowledge on raw water and sludge composition, with special focus on solid aluminium and iron phases and on fractal aggregate structure. Next the theory of dewatering is examined, with the adopted phenomenological theory contrasted with empirical techniques and other theories.The foundation for subsequent analyses is laid by experimental work which establishes the solid phase density of WTP sludges. Additionally, alum sludges are found to contain pseudoböhmite, while 2-line ferrihydrite and goethite are identified in ferric sludges. / A key hypothesis is that dewaterability is partly determined by the treatment conditions. To investigate this, numerous WTP sludges were studied that had been generated under diverse conditions: some plant samples were obtained, and the remainder were generated in the laboratory (results were consistent). Dewaterability was characterised for each sludge in concentration ranges relevant to settling, centrifugation and filtration using models developed by LANDMAN and WHITE inter alia; it is expressed in terms of both equilibrium and kinetic parameters, py(φ) and R(φ) respectively.This work confirmed that dewaterability is significantly influenced by treatment conditions.The strongest correlations were observed when varying coagulation pH and coagulant dose. At high doses precipitated coagulant controls the sludge behaviour, and dewaterability is poor. Dewaterability deteriorates as pH is increased for high-dose alum sludges; other sludges are less sensitive to pH. These findings can be linked to the faster coagulation dynamics prevailing at high coagulant and alkali dose.Alum and ferric sludges in general had comparable dewaterabilities, and the characteristics of a magnesium sludge were similar too.Small effects on dewaterability were observed in response to variations in raw water organic content and shearing. Polymer flocculation and conditioning appeared mainly to affect dewaterability at low sludge concentrations. Ageing did not produce clear changes in dewaterability.Dense, compact particles are known to dewater better than ‘fluffy’ aggregates or flocs usually encountered in drinking water treatment. This explains the superior dewaterability of a sludge containing powdered activated carbon (PAC). Even greater improvements were observed following a cycle of sludge freezing and thawing for a wide range of WTP sludges. / Further aspects considered in the present work include deviations from simplifying assumptions that are usually made. Specifically: investigation of long-time dewatering behaviour, wall effects, non-isotropic stresses, and reversibility of dewatering (or ‘elasticity’).Several other results and conclusions, of both theoretical and experimental nature, are presented on topics of subsidiary or peripheral interest that are nonetheless important for establishing a reliable basis for research in this area. / This work has proposed links between industrial drinking water coagulation conditions, sludge dewaterability from settling to filtration, and the microstructure of the aggregates making up that sludge. This information can be used when considering the operation or design of a WTP in order to optimise sludge dewaterability, within the constraints of producing drinking water of acceptable quality.
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Toxicité environnementale et écotoxicité de nanotubes de carbone chez des diatomées benthiques : de la cellule au biofilm / Environmental toxicity and ecotoxicity of carbon nanotubes in benthic diatoms : from cell to biofilmVerneuil, Laurent 09 January 2015 (has links)
Différents effets de nanotubes de carbone (NTC) sur des diatomées benthiques ont été évalués via des approches microscopiques et biochimiques. Il a été montré que la structure du frustule, paroi silicifiée propre aux diatomées, est déterminante sur l'entrée ou non des NTC dans les cellules. Une internalisation des NTC dans la cellule a conduit à des effets génotoxiques et tératogènes. L'interaction des NTC avec les substances polymériques extracellulaires (SPE) produites par les diatomées a aussi été évaluée. Les SPE ont favorisé l'agglomération des NTC entre eux, ainsi que leur isolement physico-chimique vis-à-vis des diatomées. Une réponse des diatomées à la présence des NTC par la surproduction de SPE explique partiellement le retard de croissance observé. De plus, Des interactions entre SPE et NTC, majoritairement hydrophobes, ont été révélées. Ces interactions ont permis de réduire considérablement les effets des NTC sur les diatomées au cours du temps. / Various effects of carbon nanotubes (CNTs) on benthic diatoms were assessed via microscopic and biochemical approaches. It has been shown that the structure of the specific to diatoms silicified frustule has a key role in the entry or not of CNTs into the cells. Moreover, Internalization of CNTs in the cell led to genotoxic and teratogenic effects. The interaction of the CNTs with the extracellular polymeric substances (EPS) produced by diatoms was also evaluated. EPS favored agglomeration of CNTs between them as well as their physico-chemical isolation for diatoms. A response of diatoms in the presence of CNTs by the overproduction of EPS partially explains the observed growth retardation. In addition, interactions between the EPS and CNTs, mainly hydrophobic, have been revealed. These interactions significantly reduced the effects of CNTs in diatoms over time.
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Uticaj oksidacionih procesa na bazi ozona, vodonik-peroksida i UV zračenja na sadržaj i reaktivnost prirodnih organskih materija u vodi / The influence of oxidation processes based on ozone, hydrogen peroxide and UV irradiation on the content and reactivity of natural organic matter in waterPetronijević Mirjana 28 August 2019 (has links)
<p>Cilj istraživanja u okviru ove doktorske disertacije je utvrđivanje efekata različitih<br />oksidacionih procesa na bazi ozona, vodonik-peroksida i UV zračenja na sadržaj i reaktivnost prirodnih organskih materija (POM) u različitim vodenim matriksima. Ispitivanja su sprovedena na a) podzemnoj vodi sa teritorije Kikinde i Temerina (prirodni matriks) i b) sintetičkom vodenom matriksu (rastvoru komercijalno dostupne huminske kiseline), koji se među sobom razlikuju po sastavu i strukturi prisutne POM i sadržaju bromida. Za oksidacioni proces (ozonizacija, UV fotoliza, oksidacija sa H<sub> 2</sub>O<sub>2</sub>, kombinovani O <sub>3 </sub>/UV proces i kombinovani H <sub>2</sub>O<sub>2</sub><br />/UV proces) pojedinačno ispitan je uticaj različitih doza oksidanata i reakcionih uslova.Posebna pažnja posvećena je ispitivanju uticaja navedenih tretmana na<br />formiranje neorganskog bromata, kao i uticaja na sadržaj prekursora dezinfekcionih nusproizvoda nakon hlorisanja (THM, HAA, HAN, HK i CP).<br />Analiza hemijskih parametara sintetičkog matriksa (5,44±0,30 mg C/l; 0,255±0,015 cm<sup> -1</sup> ; 4,68±0,41 lm<sup> -1</sup> mg <sup>-1 </sup>) pokazuje da u njemu preovladavaju huminnske materije visoke hidrofobnosti. Visok sadržaj POM pretežno hidrofobnog karaktera je zabeležen i u vodi iz Kikinde (5,170,72 mg C/l; 0,2010,001 cm <span id="cke_bm_192S" style="display: none;"> </span><span id="cke_bm_190S" style="display: none;"> </span><sup>-1</sup><span id="cke_bm_192E" style="display: none;"> </span><span id="cke_bm_190E" style="display: none;"> </span> ; 3,88±0,70 lm<span id="cke_bm_193S" style="display: none;"> </span><sup> -1</sup><span id="cke_bm_193E" style="display: none;"> </span> mg<sup> -1</sup> ), dok je sadrža<span id="cke_bm_194E" style="display: none;"> </span>j POM u sirovoj vodi iz Temerina (2,060,38 mg C/l; 0,0500,001 cm<span id="cke_bm_203S" style="display: none;"> </span><span id="cke_bm_201S" style="display: none;"> </span><sup> -1</sup><span id="cke_bm_203E" style="display: none;"> </span><span id="cke_bm_201E" style="display: none;"> </span> ; 2,43±0,21 lm <span id="cke_bm_204S" style="display: none;"> </span><sup>-1</sup><span id="cke_bm_204E" style="display: none;"> </span> mg <sup>-1</sup><span id="cke_bm_205E" style="display: none;"> </span><span id="cke_bm_202E" style="display: none;"> </span><span id="cke_bm_191E" style="display: none;"> </span><br />) značajno niži i preovladavaju POM hidrofilnog karaktera. Veći stepen hidrofobnosti sintetičkog matriksa u poređenju sa prirodnim matriksima, rezultovao je i većom reaktivnosti organske materije sa hlorom, što se može zaključiti na<br />osnovu visokih vrednosti PFDBP nakon hlorisanja. Vrednost PFTHM u sintetičkom matriksu iznosi 544±85,9 µg/l, dok je PFTHM u kikindskoj i temerinskoj sirovoj vodi znatno niži (279±32,3 i 180±44,0 µg/l, respektivno). Vrednost PFHAA u sintetičkom matriksu iznosi 484±77,5 µg/l, dok je PFHAA u kikindskoj 244±11,1 µg/l i u temerinskoj vodi 165±32,5 µg/l. Sadržaj HK (8,05±3,63 µg/l sintetički matriks; 14,91,38 µg/l Kikinda; 7,400,25 µg/l Temerin) je znatno niži u poređenju sa prekursorima THM i HAA, dok prekursori HAN i hlorpikrina nisu detektovani u sirovoj vodi. Nusproizvodi koji se dominantno formiraju u svim ispitivanim vodenim matriksima su hlorovani THM i HAA, dok se bromovani DBPformiraju u znatno nižim koncentracijama. Zastupljenost bromovanih DBP u temerinskoj vodi<br />je znatno veći u poređenju sa vodom iz Kikinde, kao rezultat prisustva veće koncentracije bromida u sirovoj vodi (0,05±0,01 mg Br -/l Temerin; 0,03±0,01 mg Br<br />-/l Kikinda). Ispitivanjem uticaja oksidacionih procesa (UV fotolize, ozonizacije, oksidacije vodonik-peroksidom) na sadržaj i reaktivnost POM u ispitivanim vodenim matriksima utvrđeno je da tretman vode UV zračenjem i vodonik-peroksidom, kada se primenjuju kao samostalan tretman, ne pokazuju značajnu efikasnost u smanjenju sadržaja POM.Tretman vode ozonom se pokazao kao veoma efikasan u uklanjanju POM i u smanjenju sadržaja prekursora DBP kod svih ispitivanih vodenih matriksa, kao rezultat smanjenja reaktivnosti POM ka formiranju ovih DBP. Smanjenje sadržaja POM u vodi tokom tretmana raste sa povećanjem primenjene doze ozona, pri čemu se najbolji rezultati postižu pri najvećoj primenjenoj dozi od 3,0 mg O 3/mg DOC (do 32% DOC, 92% UV254 sintetički matriks; do 17% DOC, 76% UV 254 Kikinda; do 15% DOC i 66% UV254 Temerin). U sintetičkom matriksu najveće smanjenje PFTHM (za 76%) i PFHAA (za 80%) u odnosu na sadržaj u sirovoj vodi se postiže pri dozi od 1,0 mg O<sub>3 </sub>/mg DOC. Najveće smanjenje PFTHM (za 38%)<br />i PFHAA (za 42%) u vodi iz Kikinde postiže se pri dozi od 3,0 mg O <sub>3 </sub>/mg DOC. U vodi iz Temerina najveće smanjenje PFTHM (za 27%) je pri dozi od 3,0 mg O <sub>3</sub> /mg DOC, dok se za smnjenje PFHAA (za 54%) najbolje pokazala doza od 1,0 mg O<br />3 /mg DOC. Sadržaj prekursora HK i HAN (temerinska voda) je veoma nizak nakon tretmana. Tretman vode ozonom vodi ka formiranju DBP sa više supstituisanih atoma broma, dok u vodama sa srednjim sadržajem bromida (50 µg Br -/l) dovodi do formiranja bromata. Kombinacijom ozonizacije sa UV zračenjem se značajno može pospešiti efiksnost uklanjanja POM postignuta primenom samostalne ozonizacije. Najveće smanjenje sadržaja POM u sintetičkom matriksu (za 85% DOC, 98% UV254 i 87% SUVA), u vodi iz Kikinde (za<br />23% DOC, 83% UV 254, 77% SUVA), i vodi iz Temerina (za 15% DOC, 80% UV<br />254 i 75% SUVA), u odnosu na vrednosti u netretiranoj vodi postignuto je pri najvećoj primenjenoj dozi od 3,0 mg O<sub> 3</sub> /mg DOC i 6000 mJ/cm 2 . Efikasnost procesa raste u vodama u kojima preovladavaju POM veće hidrofobnosti. MeĎutim, iako se O<sub> 3</sub> /UV procesom postiže visok stepen smanjenja PFTHM u sintetičkom matriksu se najbolje pokazao tretman ozonom (1,0 mg O3/mg DOC), dok se najveće smanjenje PFHAA (82%) postiže pri dozi ozona od 1,0 mg O<sub>3/</sub>mg DOC i UV zračenja od 6000 mJ/cm <sup>2 .</sup> U vodi iz Kikinde se PFTHM smanjuje za 50% pri dozi od 3,0 mg O <sub>3</sub>/mg DOC i 6000 mJ/cm 2 , dok se u slučaju uklanjanja prekursora<br />HAA ozonizacija pokazala kao superiorniji proces. U vodi iz Temerina se u pogledu uklanjanja prekursora THM i HAA ozonizacija pokazala kao optimalan proces. Visok alkalitet prirodnih voda inhibira radikalski mehanizam u toku AOP i favorizuje oksidaciju POM molekulskim ozonom. Prekursori HK se formiraju u veoma niskim koncentracijama i njihov sadržaj ne varira značajno tokom tretmana. U prirodnim matriksima tokom AOP pri dozi ozona od 3,0 mg O<sub>3</sub> /mg DOC dolazi do formiranja HAN, međutim, nije uočen jasan trend sa povećanjem doze UV zračenja. Tretman doprinosi formiranju bromovanih vrsta THM, dok se tokom AOP pri najvećoj dozi ozona od 3,0 mg O<sub>3</sub> /mg DOC formiraju bromovani HAN.<br />Najveće smanjenje sadržaja POM primenom kombinacije oksidacije sa H <sub>2</sub>O<sub>2</sub><br />i UV zračenja u sintetičkom matriksu (za do 17% DOC, 70% UV 254 ), u vodi iz Kikinde (za do 22% DOC, 53% UV<sub>254</sub>), i vodi iz Temerina (za do 7% DOC, 68% UV<br /><sub>254 </sub>), u odnosu na vrednosti u sirovoj vodi, se postižu pri dozi H <sub>2</sub>O<sub>2</sub> i UV zračenja od 3,0 mg H<sub>2</sub>O<sub>2</sub>/mg DOC i 6000 mJ/cm <sup>2</sup> .<br />Najveće smanjenje PFTHM od 54% u sintetičkom matriksu se postiže pri dozi od 0 mg H<sub>2</sub>O<sub>2</sub>/mg DOC i 6000 mJ/cm <sup>2</sup> , dok se smanjenje PFHAA (za 35%) postiže primenom doze vodonik-peroksida i UV zračenja od 1,0 mg H <sub>2</sub>O<sub>2</sub> /mg DOC i 3000 mJ/cm <sup>2</sup> . U vodi izKikinde H<sub>2</sub>O<sub>2</sub> /UV proces ne utiče značajno na sadržaj prekursora THM, dok se najveće smanjenje PFHAA (za 35%) postiže pri dozi od 3,0 mg H<sub> <span id="cke_bm_235S" style="display: none;"> </span>2<span id="cke_bm_235E" style="display: none;"> </span></sub>O<sub>2</sub>/mg DOC i 600 mJ/cm <sup>2</sup> .H<span id="cke_bm_184S" style="display: none;"> </span><sub>2</sub><span id="cke_bm_184E" style="display: none;"> </span>O<sub>2</sub><span id="cke_bm_185E" style="display: none;"> </span>/UV proces dovodi do smanjenja PFTHM u Temerinskoj vodi za 74% pri dozi od 3,0 mg H<sub>2</sub>O<sub>2</sub>/mg DOC i 600 mJ/c<span id="cke_bm_236E" style="display: none;"> </span>m <sup>2</sup> , dok primenjeni tretman ne pokazuje značajan uticaj na<br />PFHAA. Prekursori HK su detektovani u sintetičkom matriksu i temerinskoj vodi u niskim koncentracijama. U temerinskoj vodi nakon AOP pri dozi vodonik-peroksida od 3,0 mg H<sub>2</sub>O<sub>2</sub> /mg DOC dolazi do formiranja HAN i hlorpikrina. Primenjeni tretman vodi ka formiranju bromovanih DBP. Svi rezultati dobijeni u toku istraživanja ukazuju na neophodnost optimizacije procesa u tretmanu ispitivanih vodenih matriksa i određivanja optimalnog procesa uzimajući u obzir<br />karakteristika sirove vode i efikasnost koja se želi postići.Kombinacijom dva i više konvencionalnih tretmana i optimizacijom reakcionih uslova može se postići visoka efikasnost uklanjanja POM, kao i ciljano uklanjanje prekursorskog materijala odabranih DBP, međutim tretman vode ozonom pri dozi od 1,0 mg O<sub>3</sub><br />/mg DOC se pokazao kao optimalan proces.</p> / <p>The aim of the research of this PhD thesis was to determine the effects of various oxidation processes based on ozone, hydrogen peroxide and UV irradiation on the content and reactivity of natural organic matter (NOM) in different water matrices. The tests were carried out on a) groundwater from the territory of Kikinda and Temerin (natural matrix) and b) synthetic aqueous matrix (solution of commercially available humic acid), which differ in the composition and structure of NOM present and the content of bromide. For the oxidation process (ozonation, UV photolysis, oxidation with H 2O2 , combined O 3 /UV process and combined H 2O2 /UV process), the influence of different doses of oxidants and reaction conditions was examined individually. Particular attention was paid to the influence of the above treatment on the formation of inorganic bromate, as well as the effect on the content of precursors of disinfectant by-products after chlorination (THM, HAA, HAN, HK and CP).Analysis of the chemical parameters of the synthetic matrix (5.44±0.30 mg C/L; 0.255±0.015 cm -1 ; 4.68±0.41 lm -1 mg -1 ) shows that the high-hydrophobic humic compounds predominate in this water. Also, high NOM content of predominantly hydrophobic character was recorded in Kikinda water (5.170.72 mg C/L; 0.2010.001 cm -1 ; 3.88±0.70 lm -1 mg -1 ), while NOM content in raw water from Temerin (2.060.38 mg C/L; 0.0500.001 cm -1 ; 2.43±0.21 lm -1 mg -1 ) significantly lower and predominate NOM of hydrophilic character. A higher degree of hydrophobicity of the synthetic matrix in comparison with natural matrices, resulted in higher reactivity of organic matter with chlorine, which can be concluded on the basis of high PFDBP values after chlorination. The PFTHM value in the synthetic matrix was 544±85.9 µg/L, while the PFTHM in the raw waters from Kikinda and Temerin was significantly lower (279±32.3 and 180±44.0 µg/L, respectively). The PFHAA value in the synthetic matrix was 484±77.5 µg/L, while PFHAA in the Kikinda water was 223 244±11.1 µg/L and in the Temerin water was 165±32.5 µg/L. The content of precursors of HK (8.05±3.63 µg/L synthetic matrix; 14.91.38 µg/L Kikinda; 7.400.25 µg/L Temerin) was significantly lower compared to precursors of THMs and HAAs, while precursors of HANs and chloropicrin were not detected in raw water. The by- products that were predominantly formed in all the tested water matrices were chlorinated THMs and HAAs, while the brominated DBPs were formed at substantially lower concentrations. The presence of brominated DBPs in Temerine water were significantly higher compared to Kikinda water as a result of the presence of higher bromide content in raw water (0.05±0.01 mg Br -/L Temerin; 0.03±0.01 mg Br -/L Kikinda). By examining the influence of oxidation processes (UV photolysis, ozonation,hydrogen peroxide oxidation) on the content and reactivity of NOM in the tested water matrix, it was found that the UV irradiation and treatment by hydrogen peroxide, when used as an independent treatment, did not show significant efficacy in reducing the NOM content. Water treatment by ozone proved to be very effective in eliminating NOM and reducing the content of DBP precursors in all tested water matrices, as a result of the reduction of NOM reactivity to the formation of these DBPs. Reduction of NOM content in water during treatment increased with increasing the applied dose of ozone, with the best results achieved at the highest dosage of 3.0 mg O 3/mg DOC (up to 32% DOC, 92% UV 254 synthetic matrix, up to 17% DOC, 76% UV 254 Kikinda, up to 15% DOC and 66% UV254 Temerin). In the synthetic matrix the highest reduction in PFTHM (76%) and PFHAA (by 80%) compared to raw water content was achieved at a dosage of 1.0 mg O 3/mg DOC. The highest reduction in PFTHM (38%) and PFHAA (42%) in Kikinda water was achieved at a dose of 3.0 mg O3 /mg DOC. In Temerin water, the highest reduction in PFTHM (27%) was at a dose of 3.0 mg O 3/mg DOC, while the dose of 1.0 mg O3 /mg DOC was best shown for removing PFHAA (by 54%). The content of the precursors of HKs and HANs (Temerin water) was very low after treatment. Water treatment by ozone led to the formation of DBPs with more substituted bromine atoms, while in waters with a mean bromide content (50 μg Br -/L) led to bromate formation.Combination of ozonation with UV irradiation can greatly accelerate the effectiveness of NOM removal achieved by the use of ozonation alone. The highest reduction in NOM content in the synthetic matrix (by 85% DOC, 98% UV 254 and 87% SUVA), in Kikinda water (by 23% DOC, 83% UV 254 , 77% SUVA) and water from Temerin (by 15% DOC, 80% UV 254 and 75% SUVA), compared to the values in raw water, was achieved at the highest dose of 3.0 mg O 3 /mg DOC and 6000 mJ/cm 2 . The efficiency of the process was growing in the waters where NOM predominates of hydrophobicity. Although the O 3 /UV process achieved a high degree of reduction in PFTHM in the synthetic matrix the ozonation (1.0 mg O3 /mg DOC) was proved as more efficient, while the highest reduction in PFHAA (82%) was achieved at a ozone dose of 1.0 mg O 3/mg DOC and UV irradiation of 6000 mJ/cm 2 . In the water from Temerin, in case to removal of precursors of THM and HAA, ozonation was proved to be an optimal process. High alkalinity of natural waters inhibits the radical mechanism during AOP and favors NOM oxidation with molecular ozone. HKs precursors were formed at very low concentrations and their content did not vary significantly during the treatment. In natural matrices during the AOP at a ozone dose of 3.0 mg O3 /mgDOC, HANs were formed, however, there was no clear trend with increasing UV irradiation. The treatment contributed to the formation of brominated THM species, while during the AOPs, brominated HANs were formed at the maximum dose of ozone of 3.0 mg O3/mg DOC. 224 The largest decrease in NOM content by the combination of oxidation with H2O2 and UV irradiation in the synthetic matrix (for up to 17% DOC, 70% UV 254 ), in Kikinda water (up to 22% DOC, 53% UV 254), and water from Temerin (7% DOC, 68% UV 254 ), compared to the values in raw water, were obtained at a dose of H 2O2 and UV irradiation of 3.0 mg O3 /mg DOC and 6000 mJ/cm 2 . The highest PFTHM reduction of 54% in the synthetic matrix was achieved at a dosage of 1.0 mg H2O2/mg DOC and 6000 mJ/cm 2 , while a decrease in PFHAA (35%) was achieved using a dose of hydrogen peroxide and UV irradiation of 1.0 mg H2O2/mg DOC and 3000 mJ/cm 2 . In the water from Kikinda, the H2O2 /UV process did not significantly affect on the THM precursors content, while the highest reduction in PFHAA (35%) was achieved at a dose of 3.0 mg H2O2/mg DOC and 600 mJ/cm 2 . The H 2O2 /UV process led to a decrease in PFTHM in the Temerin water by 74% at a dose of 3.0 mg 2O2 /mg DOC and 600 mJ/cm 2 , whereas the treatment applied had no significant effect on PFHAA. HKs precursors were detected in synthetic matrix and the Temerin water at low concentrations. In the water after the AOP at a dose of 3.0 mg H 2O2 /mg DOC of hydrogen peroxide, HANs and chloropicrin were formed. The applied treatment led to the formation of brominated DBPs.<br />All the results obtained during the research indicate the necessity of optimization the process in the treatment of the examined water matrices and determination of the optimal process taking into account the characteristics of raw water and the efficiency to be achieved. By combining two or more conventional treatments and optimizing the reaction conditions, high NOM removal efficiency can be achieved, as well as removal of the targeted precursor material of the selected DBPs, but the treatment of ozone water at a dose of 1.0 mg O3 /mg DOC was proved to be an optimal process.</p>
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In Situ and Ex Situ Study of Nanoparticles Stability and Transformation in Simulated Aquatic Natural Media / Situ och Ex Situ studie av Nanopartiklars Stabilitet och Transformation i Simulerade Akvatiska MiljöerNguyen, Dinh, Samuelsson, Jonathan, Grönvall, Vilma January 2022 (has links)
Nanopartiklar är partiklar med storlekar i området 1 till 100 nm, och som uppvisar nanospecifika egenskaper. Egenskaperna kan variera helt mellan olika typer av nanopartiklar, även bland partiklarna och deras respektive material i bulk format på grund av deras unika storlekar, former och strukturer. I denna studie har vi analyserat storlekarna och den kolloidal stabiliteten på tre nanopartiklar, Co, Y2O3, CeO2 i färskvatten och färskvatten med naturligt organiskt material med hjälp av sonifikation, NTA, AAS och ICP analys. Nanopartiklarna lät vara utsatta i lösningarna i upp till six timmar, där analys med hand av NTA skedde efter den nollte, första och sjätte timmen. Partiklarna uppvisade olika egenskaper, och alla tre partiklar varierade i storlek under experimentet. Kobalt hade tendensen att minska i storlek i bägge lösningar, medan storlekarna på yttrium- och cerium oxid tenderade att variera. För att främja vår förståelse av nanopartiklar, behövs fler studier för att få en full förståelse för de unika egenskaperna hos dessa partiklar. / Nanoparticles are particles with sizes in the range of 1 to 100 nm, which also have nanospecific properties. Their properties vary wildly between different types of nanoparticles, even among nanoparticles and their respective particles in bulk format heeding to their highly individual shapes, sizes and structures. In this study we analyzed the sizes and colloidal stability of three different nanoparticles, Co, Y2O3 and CeO2 in freshwater and freshwater with natural organic matter solutions using sonication, NTA-, AAS-, and ICP analysis. The nanoparticles were exposed to the solutions for up to six hours, with analysis being performed at the zero, first and sixth hour. The particles indeed showed different properties, as all three particles varied in size throughout the experiment. Cobalt had the tendency to decrease in size as time progressed in both solutions, while the mean size of yttrium- and cerium oxide varied. To further our understanding of nanoparticles, more studies need to be performed to properly understand the individual properties of these nanoparticles.
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