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Removal of disinfection by-products from contaminated water using a synthetic goethite catalyst via catalytic ozonation and a biofiltration system.

Wang YH, Chen KC - Int J Environ Res Public Health (2014)

Bottom Line: Ozone can rapidly react with aromatic compounds and oxidize organic compounds, resulting in a decrease in the fluorescence intensity of dissolved organic matter (DOM).Catalytic ozonation has a higher removal efficiency for dissolved organic carbon and higher ultraviolet absorbance at 254 nm compared to those of ozonation without a catalyst.The use of catalytic ozonation and subsequent biofiltration leads to a lower DBP formation potential during chlorination compared to that obtained using ozonation and catalytic ozonation alone.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Science and Engineering, National Pingtung University of Science and Technology, Neipu, Pingtung County 912, Taiwan. P9831002@mail.npust.edu.tw.

ABSTRACT
The effects of synthetic goethite (α-FeOOH) used as the catalyst in catalytic ozonation for the degradation of disinfection by-product (DBP) precursors are investigated. A biofiltration column applied following the catalytic ozonation process is used to evaluate the efficiency of removing DBP precursors via biotreatment. Ozone can rapidly react with aromatic compounds and oxidize organic compounds, resulting in a decrease in the fluorescence intensity of dissolved organic matter (DOM). In addition, catalytic ozonation can break down large organic molecules, which causes a blue shift in the emission-excitation matrix spectra. Water treated with catalytic ozonation is composed of low-molecular structures, including soluble microbial products (SMPs) and other aromatic proteins (APs). The DOM in SMPs and APs is removed by subsequent biofiltration. Catalytic ozonation has a higher removal efficiency for dissolved organic carbon and higher ultraviolet absorbance at 254 nm compared to those of ozonation without a catalyst. The use of catalytic ozonation and subsequent biofiltration leads to a lower DBP formation potential during chlorination compared to that obtained using ozonation and catalytic ozonation alone. Regarding DBP species during chlorination, the bromine incorporation factor (BIF) of trihalomethanes and haloacetic acids increases with increasing catalyst dosage in catalytic ozonation. Moreover, the highest BIF is obtained for catalytic ozonation and subsequent biofiltration.

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Changes in the Pi,n of the DOM samples after catalytic ozonation and catalytic ozonation/biofiltration (RW: raw water; O3, ozonation; ozone concentration: 2.5 mg·L−1; gas flow: 50 mL·min−1;).
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ijerph-11-09325-f004: Changes in the Pi,n of the DOM samples after catalytic ozonation and catalytic ozonation/biofiltration (RW: raw water; O3, ozonation; ozone concentration: 2.5 mg·L−1; gas flow: 50 mL·min−1;).

Mentions: Furthermore, the fluorescence regional integration (FRI) technique developed by Chen et al. [23], which calculates the integration of the volume beneath each EEM region, was used to evaluate the quantity of each DOC fraction. The percent fluorescence response (Pi,n) for each EEM region was calculated based on the FRI technique. The results are shown in Figure 4. Pi,n represents the composition of DOM and its distribution in the five excitation-emission regions. As shown in Figure 4a, the three main compositions of DOM in the raw water were Region IV (33.8%), Region II (26.1%) and Region III (19.0%). The percentage of the low-molecular structures (the sum of Regions I and II) in the water treated with catalytic ozonation increased with increases in the catalyst dosage, becoming the main composition of the DOM. Figure 4b shows the Pi,n of water treated with biofiltration following either ozonation or catalytic ozonation. It can be seen that the percentage of simple APs (Region I) and SMPs (Region II) decreased compared to that for ozonation or catalytic ozonation alone (Figure 4a). This implies that these substances can be preferentially removed by biofiltration due to their high biodegradability [10]. The percentage of low-molecular structures (sum of Regions I and II) also decreased with increases in the catalyst dosage for dosages of 0 to 1.5 g·L−1. This result indicates that the α-FeOOH catalyst in catalytic ozonation can promote the formation of BDOC, which can be degraded by the subsequent biofiltration.


Removal of disinfection by-products from contaminated water using a synthetic goethite catalyst via catalytic ozonation and a biofiltration system.

Wang YH, Chen KC - Int J Environ Res Public Health (2014)

Changes in the Pi,n of the DOM samples after catalytic ozonation and catalytic ozonation/biofiltration (RW: raw water; O3, ozonation; ozone concentration: 2.5 mg·L−1; gas flow: 50 mL·min−1;).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4199022&req=5

ijerph-11-09325-f004: Changes in the Pi,n of the DOM samples after catalytic ozonation and catalytic ozonation/biofiltration (RW: raw water; O3, ozonation; ozone concentration: 2.5 mg·L−1; gas flow: 50 mL·min−1;).
Mentions: Furthermore, the fluorescence regional integration (FRI) technique developed by Chen et al. [23], which calculates the integration of the volume beneath each EEM region, was used to evaluate the quantity of each DOC fraction. The percent fluorescence response (Pi,n) for each EEM region was calculated based on the FRI technique. The results are shown in Figure 4. Pi,n represents the composition of DOM and its distribution in the five excitation-emission regions. As shown in Figure 4a, the three main compositions of DOM in the raw water were Region IV (33.8%), Region II (26.1%) and Region III (19.0%). The percentage of the low-molecular structures (the sum of Regions I and II) in the water treated with catalytic ozonation increased with increases in the catalyst dosage, becoming the main composition of the DOM. Figure 4b shows the Pi,n of water treated with biofiltration following either ozonation or catalytic ozonation. It can be seen that the percentage of simple APs (Region I) and SMPs (Region II) decreased compared to that for ozonation or catalytic ozonation alone (Figure 4a). This implies that these substances can be preferentially removed by biofiltration due to their high biodegradability [10]. The percentage of low-molecular structures (sum of Regions I and II) also decreased with increases in the catalyst dosage for dosages of 0 to 1.5 g·L−1. This result indicates that the α-FeOOH catalyst in catalytic ozonation can promote the formation of BDOC, which can be degraded by the subsequent biofiltration.

Bottom Line: Ozone can rapidly react with aromatic compounds and oxidize organic compounds, resulting in a decrease in the fluorescence intensity of dissolved organic matter (DOM).Catalytic ozonation has a higher removal efficiency for dissolved organic carbon and higher ultraviolet absorbance at 254 nm compared to those of ozonation without a catalyst.The use of catalytic ozonation and subsequent biofiltration leads to a lower DBP formation potential during chlorination compared to that obtained using ozonation and catalytic ozonation alone.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Science and Engineering, National Pingtung University of Science and Technology, Neipu, Pingtung County 912, Taiwan. P9831002@mail.npust.edu.tw.

ABSTRACT
The effects of synthetic goethite (α-FeOOH) used as the catalyst in catalytic ozonation for the degradation of disinfection by-product (DBP) precursors are investigated. A biofiltration column applied following the catalytic ozonation process is used to evaluate the efficiency of removing DBP precursors via biotreatment. Ozone can rapidly react with aromatic compounds and oxidize organic compounds, resulting in a decrease in the fluorescence intensity of dissolved organic matter (DOM). In addition, catalytic ozonation can break down large organic molecules, which causes a blue shift in the emission-excitation matrix spectra. Water treated with catalytic ozonation is composed of low-molecular structures, including soluble microbial products (SMPs) and other aromatic proteins (APs). The DOM in SMPs and APs is removed by subsequent biofiltration. Catalytic ozonation has a higher removal efficiency for dissolved organic carbon and higher ultraviolet absorbance at 254 nm compared to those of ozonation without a catalyst. The use of catalytic ozonation and subsequent biofiltration leads to a lower DBP formation potential during chlorination compared to that obtained using ozonation and catalytic ozonation alone. Regarding DBP species during chlorination, the bromine incorporation factor (BIF) of trihalomethanes and haloacetic acids increases with increasing catalyst dosage in catalytic ozonation. Moreover, the highest BIF is obtained for catalytic ozonation and subsequent biofiltration.

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