Browsing by Author "Chao, Shu-Ju"

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Characteristics of low and high SUVA precursors: Relationships among molecular weight, fluorescence, and chemical composition with DBP formation
(2020-07-20)
Hua, Lap-Cuong
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Chao, Shu-Ju
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Huang, Kochin
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Huang, Chihpin
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環境工程研究所
Disinfection by-products (DBPs) formed upon water treatment is an emerging issue worldwide. While monitoring of DBP precursors can easily be achieved for high specific UV absorbance (SUVA) organic (>6 L/mg.m), low and extremely low SUVA precursors (<2 L/mg.m) are difficult to monitor or even to predict their DBP formation behaviour. This study investigated the relationships among NOM characteristics, such as molecular weight (MW), fluorescence, and chemical composition, with DBP formation resulting from the chlorination of relatively high and low SUVA precursors. High SUVA precursors were formed by C-rich substances (82-85% of total mass) corresponding with high C/N and C/O (>100 and >5, respectively). Such precursors exhibited the fluorescence of long-wavelength humic-like signal and occurred at a high MW range (>30 kDa). By contrast, low SUVA precursors were either N-rich and/or O-rich substances, associated with much lower carbon content (40-70%). Low SUVA, N-rich precursors particularly also occurred at a high MW region (>100 kDa) and produced a strong protein-like fluorescence signal. When SUVA values of O-rich precursors were extremely low (<1 L/mg.m) they were accompanyied by short-wavelength humic-like fluorescence. During DBP tests, high SUVA produced only high yields of carbonaceous DBPs (e.g trichloromethane, haloacetic acids, haloketones), whereas low SUVA Nrich precursors yielded high levels of both C and NDBPs (e.g. haloacetonenitrile, chloropicrin). By contrast, extremely low SUVA precursors produced significantly lowlevels of both C and NDBPs (total <30 mu g/mgC). Furthermore, 19 of 20 regression models of DBP formation using log-transformed MW gave R-2 = 0.50-0.97. The strong regressions and correlations of NOM characteristics with DBPs in this study provide a better understanding of the influence of precursors characteristics on DBP monitoring, especially for low SUVA NOM. (C) 2020 Elsevier B.V. All rights reserved.
Effects of C/N ratio on nitrate removal and floc morphology of autohydrogenotrophic bacteria in a nitrate-containing wastewater treatment process
(2018-07-01)
Tran Ngoc Phu Nguyen
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Chao, Shu-Ju
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Chen, Pei-Chung
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Huang, Chihpin
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環境工程研究所
The effects of C/N ratio of a nitrate-containing wastewater on nitrate removal performed by autohydrogenotrophic bacteria as well as on the morphological parameters of floc such as floc morphology, floc number distribution, mean particle size (MPS), aspect ratio and transparency were examined in this study. The results showed that the nitrate reduction rate increased with increasing C/N ratio from 0.5 to 10 and that the nitrogen removal of up to 95% was found at the C/N ratios of higher than 5 (between 0.5-10). Besides, high C/N ratio values reflected a corresponding high nitrite accumulation after 12-hr operation, and a fast decreasing rate of nitrite in the rest of operational time. The final pH values increased with the C/N ratio increasing from 0.5 to 2.5, but decreased with the C/N ratio increasing from 2.5 to 10. There were no significant changes in floc morphology with the MPSs ranging from 35 to 40 mu m. Small and medium-sized flocs were dominant in the sludge suspension, and the number of flocs increased with the increasing C/N ratios. Furthermore, the highest apparent frequency of 10% was observed at aspect ratios of 0.5 and 0.6, while the transparency of flocs changed from 0.1 to 0.7. (C) 2017 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.
Fluorescent and molecular weight dependence of THM and HAA formation from intracellular algogenic organic matter (IOM)
(2019-01-01)
Hua, Lap-Cuong
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Chao, Shu-Ju
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Huang, Chihpin
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環境工程研究所
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Institute of Environmental Engineering
This study (i) examined the formation of two major carbonaceous disinfection by-products (C-DBPs), trihalomethanes (THMs) and haloacetic acids (HAAs), during the chlorination of intracellular algogenic organic matter (IOM) extracted from two commonly blooming algae M. aerugittosa (MA) and Chlorella sp. (CH), and (ii) investigated the roles and relationships of fluorescent and molecular weight (MW) properties on/with IOM-derived THMs and HAAs. The extracted IOM samples were separated into different MW fractions by centrifugal devices with membrane support with MW cut-offs of 100, 30, 10, 3, and 1 kDa. We observed an overall reduction of C-DBPs with a decrease of IOM-MW from >100 kDa to <1 kDa. Of six fractionated IOM, a large fraction (>100 kDa) contributed the largest amount to the MW distribution of IOM, accounting for 33 and 42% of the total dissolved organic carbon (DOC) of MA and CH, respectively. It also had the highest-yielding potential to produce significant levels of THMs and HAM, and total C-DBPs over other small MW fractions. Although small MW fractions (>10 kDa) contributed around 50% of the total DOC, they made an insignificant contribution (>20%) to the THMs, HAM, and overall C-DBPs. Furthermore, the decrease of IOM MW caused a shift from the domination of HAA formation to THM formation, especially when MW was <10 kDa. By canonical correspondent analysis, the relationship of IOM-derived THMs and HAAs with IOM properties was examined. In particular, large fractions of IOM, exhibiting aromatic protein- (AP) and soluble microbial product- (SMP) like fluorescence, are favorable for the formation of HAAs, whereas small MW fractions of IOM with HA- and FA-like fluorescence preferentially tends to form THMs. Our findings evidently show the strong dependence of IOM-derived THMs and HAAs on the fluorescent and MW properties. Therefore, the characterization of MW and fluorescent properties can provide the advantages in the control of algae-derived DBPs upon the chlorination of eutrophic water. (C) 2018 Elsevier Ltd. All rights reserved.
Probing algogenic organic matter (AOM) by size-exclusion chromatography to predict AOM-derived disinfection by-product formation
(2018-12-15)
Hua, Lap-Cuong
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Lin, Jr-Lin
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Chao, Shu-Ju
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Huang, Chihpin
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環境工程研究所
High-performance size exclusion chromatography (HPSEC) coupled with peak-fitting technique was used to probe molecular weight (MW) properties of algogenic organic matter (AOM). The qualitative and quantitative MW information derived was used to predict AOM-derived disinfection by-product (DBP) formation. We resolved overlapping HPSEC chromatograms of all AOM samples into six major peaks with R-2 > 0.996. This study gave significant insight into the HPSEC profiles of AOM, in which resolved peaks A and B (biopolymers) and peak C (humic substances) showed a strong correlation with the formation of carbonaceous-DBPs (C-DBPs). This likely resulted from the abundance of aromatic structures and conjugated C=C double bonds in their chemical nature. Our results also indicated the importance of algal cells, including intra-cellular and cell-bound organic matter, over extra-cellular organic matter as precursors to C-DBP formation. The application of the information extracted from HPSEC profiles associated with the fluorescent components of AOM showed great improvements in the predictability of THMs, HAAs, and C-DBPs with R-2 > 0.7 and p < 0.05. The outcome of this study will significantly benefit effective control of AOM-derived DBP formation by the chlorination of eutrophic waters. (C) 2018 Elsevier B.V. All rights reserved.
Teratogenic responses of zebrafish embryos to decabromodiphenyl ether (BDE-209) in the presence of nano-SiO2 particles
(2017-07-01)
Chao, Shu-Ju
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Huang, Chin Pao
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Chen, Pei-Chung
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Huang, Chihpin
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環境工程研究所
This study investigated the influence of nano-SiO2 particles (nSiO(2)) on the teratogenic responses of zebrafish embryos to decabromodiphenyl ether (BDE-209). Zebrafish embryos were exposed to BDE-209 in the absence and presence of nSiO(2) for 96 h post fertilization (hpf). Results showed that formation of nSiO(2)-BDE-209 associates promoted both extracellular and intracellular uptake of BDE-209 by zebrafish embryos, thereby increasing the bioconcentration of BDE-209 on the chorion surface and the embryos. Results also showed embryos delay hatching temporarily when co-exposure to BDE-209 and nSiO(2) at 60 hpf. Furthermore, there was heartbeat decline (28.3 beats/10s) and increase in irregular heartbeat (45.8%) in zebrafish larvae at 96 hpf, compared to the sole exposure to BDE-209 (32.7 beats/10s and 0%). Malformation in terms of spinal curvature (SC), pericardial edema (PE) and yolk sac edema (YSE) were observed on zebrafish larvae at 33.9, 23.4, and 18%, respectively. Overall, abnormal development of zebrafish was apparent when co-exposure to BDE-209 and nSiO(2). All relevant evidence considered, nSiO(2) could facilitate the transport of BDE-209 towards zebrafish embryos and negatively impact the development of zebrafish. (C) 2017 Elsevier Ltd. All rights reserved.
Uptake of BDE-209 on zebrafish embryos as affected by SiO2 nanoparticles
(2018-08-01)
Chao, Shu-Ju
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Huang, C. P.
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Chen, Pei-Chung
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Chang, Shih-Hsien
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Huang, Chihpin
It was hypothesized that interactions between emerging contaminants such as decabromodiphenyl ether (BDE-209) and nanoparticles (NPs) such as nano-SiO2 (nSiO(2)), can affect contaminant transport in the aquatic environment and its ecotoxicity. This study assessed the influence of nSiO(2) on the uptake of BDE-209 by zebrafish embryo. The distribution of BDE-209 and nSiO(2) on the external chorion and the internal embryo mass (i.e., dechorionated embryo) was measured. For single exposure of nSiO(2) to zebrafish embryo, separately, results showed that nSiO(2) accumulation on the chorion surface was higher than that in the dechorionated embryo. The nSiO(2) accumulation on the chorion surface was 129-200 mg-nSiO(2)/gchorion at 48 h post fertilization, hpf, of exposure time, whereas the equilibrium adsorption of nSiO(2) on the dechorionated embryo was ca. 0.42-0.54 mg-nSiO(2)/g-embryo at 6 hpf. Results showed that the formation of nSiO(2)-BDE-209 associates promoted both extracellular and intracellular uptake of BDE-209 by zebrafish embryo, thereby increasing the bioconcentration of BDE-209 on the chorion surface and in embryo. The results also revealed that the accumulation of BDE-209 on the chorion was remarkably greater than that on the dechorionated embryo at 48 hpf. The uptake of BDE-209 was 17.2 +/- 0.45 mg/g-chorion (or 86 ng-BDE-209/chorionated embryo) and 0.37 +/- 0.01 mg/g-embryo (or 18.6 ng-BDE-209/dechorionated embryo), respectively, when co-exposure of zebrafish embryos to BDE-209 and nSiO(2). Results from the SEM and EDS analysis revealed that nSiO(2) already passed through the chorion and adhered to the embryo surface/mass. (C) 2018 Elsevier Ltd. All rights reserved.