Uticaj oksidacionih procesa na bazi ozona, vodonik-peroksida i UV zračenja na sadržaj i reaktivnost prirodnih organskih materija u vodi

Abstract

Cilj istraživanja u okviru ove doktorske disertacije je utvrđivanje efekata različitih 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 2O2, kombinovani O 3 /UV proces i kombinovani H 2O2 /UV proces) pojedinačno ispitan je uticaj različitih doza oksidanata i reakcionih uslova.Posebna pažnja posvećena je ispitivanju uticaja navedenih tretmana na formiranje neorganskog bromata, kao i uticaja na sadržaj prekursora dezinfekcionih nusproizvoda nakon hlorisanja (THM, HAA, HAN, HK i CP). Analiza hemijskih parametara sintetičkog matriksa (5,44±0,30 mg C/l; 0,255±0,015 cm -1 ; 4,68±0,41 lm -1 mg -1 ) 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 -1 ; 3,88±0,70 lm -1 mg -1 ), dok je sadrža j POM u sirovoj vodi iz Temerina (2,060,38 mg C/l; 0,0500,001 cm -1 ; 2,43±0,21 lm -1 mg -1 ) 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 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 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 -/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 O3 /mg DOC. Najveće smanjenje PFTHM (za 38%) i PFHAA (za 42%) u vodi iz Kikinde postiže se pri dozi od 3,0 mg O 3 /mg DOC. U vodi iz Temerina najveće smanjenje PFTHM (za 27%) je pri dozi od 3,0 mg O 3 /mg DOC, dok se za smnjenje PFHAA (za 54%) najbolje pokazala doza od 1,0 mg O 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 23% DOC, 83% UV 254, 77% SUVA), i vodi iz Temerina (za 15% DOC, 80% UV 254 i 75% SUVA), u odnosu na vrednosti u netretiranoj vodi postignuto je pri najvećoj primenjenoj dozi od 3,0 mg O 3 /mg DOC i 6000 mJ/cm 2 . Efikasnost procesa raste u vodama u kojima preovladavaju POM veće hidrofobnosti. MeĎutim, iako se O 3 /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 O3/mg DOC i UV zračenja od 6000 mJ/cm 2 . U vodi iz Kikinde se PFTHM smanjuje za 50% pri dozi od 3,0 mg O 3/mg DOC i 6000 mJ/cm 2 , dok se u slučaju uklanjanja prekursora 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 O3 /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 O3 /mg DOC formiraju bromovani HAN. Najveće smanjenje sadržaja POM primenom kombinacije oksidacije sa H 2O2 i UV zračenja u sintetičkom matriksu (za do 17% DOC, 70% UV 254 ), u vodi iz Kikinde (za do 22% DOC, 53% UV254), i vodi iz Temerina (za do 7% DOC, 68% UV 254 ), u odnosu na vrednosti u sirovoj vodi, se postižu pri dozi H 2O2 i UV zračenja od 3,0 mg H2O2/mg DOC i 6000 mJ/cm 2 . Najveće smanjenje PFTHM od 54% u sintetičkom matriksu se postiže pri dozi od 0 mg H2O2/mg DOC i 6000 mJ/cm 2 , dok se smanjenje PFHAA (za 35%) postiže primenom doze vodonik-peroksida i UV zračenja od 1,0 mg H 2O2 /mg DOC i 3000 mJ/cm 2 . U vodi izKikinde H2O2 /UV proces ne utiče značajno na sadržaj prekursora THM, dok se najveće smanjenje PFHAA (za 35%) postiže pri dozi od 3,0 mg H 2 O2/mg DOC i 600 mJ/cm 2 .H 2 O2 /UV proces dovodi do smanjenja PFTHM u Temerinskoj vodi za 74% pri dozi od 3,0 mg H2O2/mg DOC i 600 mJ/c m 2 , dok primenjeni tretman ne pokazuje značajan uticaj na 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 H2O2 /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 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 O3 /mg DOC se pokazao kao optimalan proces.

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. 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.