<p>Cilj ovog rada bio je da se u laboratorijskim uslovima ispitaju efekti odabranih<br />unapredenih procesa oksidacije (Fenton proces, ozonizacija, TiO2-katalizovana ozonizacija,<br />perokson proces i TiO2-katalizovan perokson proces) i koagulacije na sadržaj i strukturu<br />prirodnih organskih materija u vodi, kao prekursora dezinfekcionih nusprodukata hlora.<br />Karaterizacija POM frakcionisanjem pre i nakon navedenih oksidacionih tretmana i<br />koagulacije izvr&scaron;ena je u cilju ispitivanja mehanizama oksidacije i uklanjanja POM, kao i<br />utvrdivanja promene reaktivnosti prekursorskog materijla DBP (trihalometana i halosircetnih<br />kiselina, kao najvi&scaron;e zastupljenih DBP, i haloacetonitrila, hlorpikrina i haloketona, kao<br />nedovoljno istraženih, visoko prioritetnih &bdquo;DBP u razvoju&ldquo;).<br />Analizom hemijskih karakteristika prirodnog matriksa utvrdeno je da voda sadrži<br />visoke koncentracije prirodnih organskih materija (DOC sirove iznosi 9,92&plusmn;0,87 mg/L) uz<br />dominaciju materija hidrofobnog karaktera (14% huminskih i 65% fulvinskih kiselina). U<br />slucaju sintetickog matriksa (sadržaj DOC 11,2&plusmn;0,37 mg/L) zastupljena je samo frakcija<br />huminske kiseline, te je iz tog razloga sinteticki matriks znatno hidrofobniji u odnosu na<br />prirodni. Veci stepen hidrofobnosti sintetickog matriksa u poredenju sa prirodnim matriksom,<br />rezultovao je i vecim sadržajem prekursora najzastupljenijih dezinfekcionih nusprodukata<br />hlora, THM i HAA. Vrednosti za PFTHM iznose 438&plusmn;88,2 &mu;g/L za prirodni matriks,<br />odnosno 3646&plusmn;41,3 &mu;g/L za sinteticki matriks, dok PFHAA prirodnog matriksa iznosi<br />339&plusmn;68,9 &mu;g/L, odnosno 559&plusmn;20,5 &mu;g/L za sinteticki matriks. Sadržaj HAN, CP i HK je<br />znatno niži u poredenju sa prekursorima THM i HAA. PFHAN iznosi 3,65 &mu;g/L za prirodni,<br />odn. 7,98 &mu;g/L za sinteticki matriks, dok prekursori CP nisu detektovani. Prekursori HK su<br />zastupljeni samo u strukturi POM prirodnog matriksa i PFHK iznosi 46,9&plusmn;5,08 &mu;g/L.<br />Hidrofoban materijal, kao dominantan u strukturi POM ispitivanih matriksa, je ujedno i<br />osnovni prekursorski materijal THM i HAA, dok su prekursori haloacetonitrila i haloketona u<br />navecoj meri zastupljeni u hidrofilnoj frakciji.<br />Ispitivanjem uticaja Fenton procesa na sadržaj POM, pri optimalnim reakcionim<br />uslovima (pH 5, reakciono vreme od 15 min. i brzina me&scaron;anja 30 o/min), postignuto je u<br />zavisnosti od primenjene doze Fe2+, molarnog odnosa Fe2+ i H2O2 i matriksa 80-95%<br />smanjenja saržaja DOC, 70-99% PFTHM, 37-92% PFHAA. Kao posledica uklanjanja POM<br />oksidaciojom i koagulacijom, zabeležene su blage fluktuacije u sadržaju prekursora HAN, CP<br />i HK.<br />Ispitivanjem uticaja ozonizacije u vodi pri razlicitim pH na sadržaj i strukturu POM<br />utvrdeno je da je ozonizacija u baznoj sredini efikasnija za uklanjanje POM u odnosu na<br />ozonizaciju u kiseloj sredini. Katalizovanje procesa ozonizacije primenom TiO2 u vodi<br />razlicitim pH unapreduje smanjenje sadržaja kako ukupnih organskih materija, tako i<br />specificnih prekursora DBP u poredenju sa ozonizacijom. Najefikasnije smanjenje sadržaja<br />POM postignuto je TiO2-O3 procesa u baznoj sredini primenom 3,0 mg O3/mg DOC i 1,0 mg<br />TiO2/L (30% DOC, 92-100% PFTHM, PFHAA, PFHAN i PFHK). TiO2-O3 proces pri svim<br />pH vrednostima produkuje manji sadržaj CP u odnosu na ozonizaciju. Veca efikasnost<br />primenjenih procesa u smanjenju sadržaja POM sintetickog matriksa u odnosu na prirodni<br />ukazuju da je frakcija huminske kiseline podložnija oksidacionom tretmanu u odnosu na<br />fulvinsku, kao dominantnu frakciju POM prirodnog matriksa. Kada je u pitanju mehanizam<br />oksidacije POM ispitivanih matriksa, primenom ozonizacije i TiO2-O3 procesa, pri svim pH<br />postignuta je potpuna oksidacija frakcije huminske kiseline do fulvinske kiseline i hidrofilnih<br />jedinjenja. U slucaju ozonizacije, sa povecanjem pH vrednosti sredine, usled povecane<br />produkcije hidroksil radikala iz ozona, povecao se i udeo odnosno sadržaj DOC u hidrofilnoj<br />frakciji ozonirane vode (86%-90%). Raspodela DOC nakon TiO2-O3 procesa pri svim pH<br />vrednostima je oko 70% i 50% u hidrofilnoj frakciji prirodnog i sintetickog matriksa, redom.<br />Frakcija koja se dominantno formira nakon navedenih oksidacionih tretmana je hidrofilna nekisela<br />frakcija. Frakcionisanjem POM nakon oksidacionih tretmana je utvrdeno da su<br />prekursori THM i HAA kako hidrofobne aromaticne strukture, tako i hidrofilna polarna<br />jedinjenja, dok je najreaktivniji prekursorski materijal HAN, CP i HK sadržan u hidrofilnoj<br />frakciji POM.<br />Uvodenjem H2O2 u proces ozonizacije (O3/H2O2 i iO2-O3/H2O2) u slabo baznoj<br />sredini (pH 7-7,5) postignut je jo&scaron; veci stepen oksidacije POM i povecanje udela hidrofilnih<br />struktura (oko 88%) ispitivanih matriksa u odnosu na ozonizaciju i iO2-O3 (oko 70%),<br />primenom 3,0 mg O3/mg DOC; O3:H2O2=1:1 i 1,0 mg iO2/L. Povecanje sadržaja prekursora<br />THM i HAA samo u slucaju prirodnog amtriksa posledica je povecanja reaktivnosti frakcije<br />fulvinske kiseline nakon O3/H2O2 i iO2-O3/H2O2 procesa, u kojoj su ujedno i prekursori HK<br />najzastupljeniji. Najveci sadržaj azotnih DBP (HAN i CP) sadrži hidrofilna frakcija POM.<br />Ispitivanjem kombinovanih procesa ozonizacije i TiO2-O3 i koagulacije utvrdeno je da<br />oksidacioni tretmani imaju pozitivne efekte u uklanjaju POM koagulacijom. Maksimalna<br />efikasnost smanjenja sadržaja DOC od 32% postignuto je primenom 3,0 mg O3/mg DOC i<br />200 mg FeCl3/L, dok su ne&scaron;to niže doze ozona pogodne za uklanjanje prekursora DBP (80-<br />89% PFTHM, PFHAA, PFHAN i PFHK, primenom 0,7-1,0 mg O3/mg DOC i 200 mg<br />FeCl3/L). Prekursori CP koji se formiraju ozonizacijom zaostaju u vodi nakon koagulacije.<br />Rezultati dobijeni tokom istraživanja ukazuju da se primenom razlicitih oksidacionih i<br />unapredenih oksidacionih procesa može smanjiti sadržaj POM i prekursora DBP do<br />odredenog stepena. Kao najefikasniji u uklanjaju kako ukupnih organskih materija, tako i<br />specificih prekursora DBP se pokazao Fenton proces. Kada su u pitanju unapredeni procesi<br />oksidacije zasnovani na primeni ozona, uvodenje katalizatora ili H2O2 kao oksidanta u proces<br />ozonizacije, kao i odabir optimalne pH vrednosti procesa može unaprediti oksidabilnost<br />organskih molekula. Pri tom, poznavanje mehanizama oksidacije POM iz razlicitih izvora<br />primenom ozona i/ili hidroksil radikala, kao i mehanizma uklanjanja POM koagulacijom<br />može se primeniti za odabir i optimizovanje odgovarajuceg procesa u tretmanu vode za pice,<br />a u zavisnosti od kvaliteta sirove vode.</p> / <p>The aim of this work was to examine under laboratory conditions the effects of<br />certain advanced oxidation processes (Fenton process, ozonation, TiO2-catalyzed ozonation,&nbsp;peroxone process and TiO2-catalyzed peroxone process) and coagulation on the content,&nbsp;structure and role of natural organic matter in water as the precursors of chlorine disinfection&nbsp;byproducts. The NOM was characterized by fractionation before and after these oxidation&nbsp;treatments and coagulation, in order to investigate NOM oxidation mechanisms and identify&nbsp;the changes in the reactivity of DBP precursor material (trihalomethanes and haloacetic acids,&nbsp;as the most abundant DBP, and haloacetonitriles, chloropicrin and haloketones, as underresearched,&nbsp;high priority &ldquo;emerging DBP&rdquo;).&nbsp;Through analysis of the chemical characteristics of the natural matrix, it was found&nbsp;that the water contains high concentrations of natural organic matter (raw water DOC was&nbsp;9.92 &plusmn; 0.87 mg/L) dominated by substances with a hydrophobic character (14% humic and&nbsp;65% fulvic acids). The synthetic matrix studied (DOC content of 11.2 &plusmn; 0.37 mg/L)&nbsp;contained only the humic acid fraction, and was therefore significantly more hydrophobic&nbsp;compared to the natural one. The greater degree of hydrophobicity in the synthetic matrix&nbsp;relative to the natural matrix resulted in a higher content of precursors of the most frequent&nbsp;chlorine disinfection byproducts, THM and HAA. The THMFP of the natural matrix was&nbsp;438&plusmn;88.2 mg/L, compared to 3646&plusmn;41.3 mg/L for the synthetic matrix, while the HAAFP of&nbsp;the natural matrix was 339&plusmn;68.9 mg/L, compared to 559&plusmn;20.5 mg/L for the synthetic matrix.&nbsp;The contents of HAN, CP, and HK precursors were much lower than the THM and HAA&nbsp;precursors. HANFP were 3.65 mg/L for natural, and 7.98 mg/L for the synthetic matrix,&nbsp;whilst CP precursors were not detected. HK precursors were present only in the structure of&nbsp;the natural NOM matrix, with a HKFP of 46.9&plusmn;5.08 mg/L. Hydrophobic material, as the&nbsp;dominant structure in the investigated NOM matrix, is the basic precursor material of THM&nbsp;and HAA, while the precursors of haloacetonitriles and haloketones are represented mostly in&nbsp;the hydrophilic fraction.<span style="font-size: 12px;">Whilst examining the influence of the Fenton process on the NOM content, under&nbsp;</span><span style="font-size: 12px;">optimal reaction conditions (pH 5, reaction time of 15 min and stirring speed of 30 rpm),&nbsp;</span><span style="font-size: 12px;">depending upon the applied dose of Fe2+, the molar ratio of Fe2+ and H2O2, and the matrix,&nbsp;</span><span style="font-size: 12px;">reductions in the DOC content of 80-95%, in the THMFP of 70-99%, and in the HAAFP of&nbsp;</span><span style="font-size: 12px;">37-92%, were achieved. As a result of removing NOM by oxidation and coagulation, mild&nbsp;</span><span style="font-size: 12px;">fluctuations in the contents of HAN, CP and HK precursors were recorded.&nbsp;</span><span style="font-size: 12px;">The investigation into the effects of ozonation at different pH levels on the content&nbsp;</span><span style="font-size: 12px;">and structure of NOM has shown that ozonation under alkaline conditions is more effective at&nbsp;</span><span style="font-size: 12px;">removing NOM than ozonation under acidic conditions. Catalyzing the ozonation process&nbsp;</span><span style="font-size: 12px;">using TiO2 in water with different pH promotes the reduction of both total organic matter and&nbsp;</span><span style="font-size: 12px;">specific DBP precursors in comparison with ozonation alone. The most effective NOM&nbsp;</span><span style="font-size: 12px;">reduction was achieved using the TiO2-O3 process in alkaline conditions using 3.0 mg O3/mg&nbsp;</span><span style="font-size: 12px;">DOC and 1.0 mg TiO2/L (30% DOC, 92-100% THMFP, HAAFP, HANFP and HKFP). The&nbsp;</span><span style="font-size: 12px;">TiO2-O3 process produces lower amounts of CP at all pH values, relative to ozonation. The&nbsp;</span><span style="font-size: 12px;">applied processes showed increased efficacy in reducing the NOM content of the synthetic&nbsp;</span><span style="font-size: 12px;">matrix compared with the natural matrix, which shows that the humic acids fraction is more&nbsp;</span><span style="font-size: 12px;">susceptible to oxidation treatments than the fulvic acids which are the dominant faction of the&nbsp;</span><span style="font-size: 12px;">natural NOM matrix. Regarding the NOM oxidation mechanism in the investigated matrices,&nbsp;</span><span style="font-size: 12px;">using ozonation and the TiO2-O3 process, complete oxidation of the humic acid fraction to&nbsp;</span><span style="font-size: 12px;">fulvic acids and hydrophilic compounds was achieved at all pH levels. In the case of&nbsp;</span><span style="font-size: 12px;">ozonation, increasing the pH in the matrix lead to an increase in hydroxyl radicals production&nbsp;</span><span style="font-size: 12px;">from ozone, and the proportion or content of DOC in the hydrophilic fraction of ozonated&nbsp;</span><span style="font-size: 12px;">water (86%-90%) increased. The distribution of DOC after the TiO2-O3 process at all pH&nbsp;</span><span style="font-size: 12px;">values was about 70% and 50% in the hydrophilic fraction of the natural and synthetic&nbsp;</span><span style="font-size: 12px;">matrices, respectively. The dominant fraction formed after the oxidation treatments was the&nbsp;</span><span style="font-size: 12px;">hydrophilic non-acid fraction. By NOM fractionation after the oxidation treatments, it was&nbsp;</span><span style="font-size: 12px;">shown that the THM and HAA precursors are hydrophobic aromatic structures and&nbsp;</span><span style="font-size: 12px;">hydrophilic polar compounds, whilst the most reactive precursor materials for HAN, CP and&nbsp;</span><span style="font-size: 12px;">HC are contained in the hydrophilic NOM fraction.&nbsp;</span><span style="font-size: 12px;">Introducing H2O2 into the ozonation process (O3/H2O2 and iO2-O3/H2O2) in weak&nbsp;</span><span style="font-size: 12px;">basic conditions (pH 7 to 7.5) enhances further the degree of NOM oxidation and increases&nbsp;</span><span style="font-size: 12px;">the proportion of hydrophilic structures (88%) in the examined matrices in comparison to&nbsp;</span><span style="font-size: 12px;">ozonation and iO2-O3 (about 70%), using 3.0 mg O3/mg DOC; O3:H2O2=1:1 and 1.0 mg&nbsp;</span><span style="font-size: 12px;">iO2/L. An increase in the THM and HAA precursor contents occurred in the case of the&nbsp;</span><span style="font-size: 12px;">natural matrix as a result of the increased reactivity of the fulvic acid fraction after the&nbsp;</span><span style="font-size: 12px;">O3/H2O2 and iO2-O3/H2O2 processes, and HK precursors were also present. The highest&nbsp;</span><span style="font-size: 12px;">content of nitrogen DBP (HAN and CP) was found in the hydrophilic NOM fraction.&nbsp;</span><span style="font-size: 12px;">By examination of the combined processes of ozonation, TiO2-O3 and coagulation, it was&nbsp;</span><span style="font-size: 12px;">shown that oxidative treatments have a positive effect on NOM removal by coagulation. A&nbsp;</span><span style="font-size: 12px;">maximum efficacy in reducing DOC by 32% was achieved with 3.0 mg O3/mg DOC and&nbsp;</span><span style="font-size: 12px;">200 mg FeCl3/L, whereas slightly lower ozone doses are suitable for the removal of DBP&nbsp;</span><span style="font-size: 12px;">precursors (80-89% THMFP, HAAFP, HANFP and HKFP, using 0.7-1.0 mg O3/mg DOC&nbsp;</span><span style="font-size: 12px;">and 200 mg FeCl3/L). CP precursors which are formed during ozonation remain in the water&nbsp;</span><span style="font-size: 12px;">after coagulation.&nbsp;</span><span style="font-size: 12px;">The results obtained during this investigation show that the application of different oxidation&nbsp;</span><span style="font-size: 12px;">and enhanced oxidation processes can reduce the contents of NOM and DBP precursors to&nbsp;</span><span style="font-size: 12px;">some degree. The most effective process at removing both total organic matter and specific&nbsp;</span><span style="font-size: 12px;">DBP precursors proved to be the Fenton process. With respect to enhanced oxidation&nbsp;</span><span style="font-size: 12px;">processes based upon the use of ozone, by introducing catalysts or H2O2 as an oxidant in the&nbsp;</span><span style="font-size: 12px;">ozonation process and by selecting the optimum pH for the process, the oxidizability of&nbsp;</span><span style="font-size: 12px;">organic molecules can be improved. In addition, knowledge of the NOM oxidation&nbsp;</span><span style="font-size: 12px;">mechanisms from different sources using ozone and / or hydroxyl radicals, as well as the&nbsp;</span><span style="font-size: 12px;">mechanism of NOM removal by coagulation, can be used to select and optimize the most&nbsp;</span><span style="font-size: 12px;">appropriate process in drinking water treatment, depending upon the quality of the raw water.</span></p>