32 results on '"Sung-Kyu Maeng"'
Search Results
2. Biomass formation and organic carbon migration potential of microplastics from a PET recycling plant: Implication of biostability
- Author
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Huyen Duong Thi, Sang Yeob Kim, Sang-Yeop Jung, Heejong Son, Seungdae Oh, and Sung Kyu Maeng
- Subjects
Environmental Engineering ,Health, Toxicology and Mutagenesis ,Environmental Chemistry ,Pollution ,Waste Management and Disposal - Published
- 2023
3. Impact of sonication on the algal organic matter characteristics of Anabaena circinalis, Microcystis aeruginosa, and Chlorella vulgaris
- Author
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Anh Tien Dang, Thi Huyen Duong, Ji-won Park, Sang-Yeob Kim, Jae Woo Lee, and Sung Kyu Maeng
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Process Chemistry and Technology ,Chemical Engineering (miscellaneous) ,Pollution ,Waste Management and Disposal - Published
- 2023
4. Biological detoxification of oxytetracycline using Achromobacter-immobilized bioremediation system
- Author
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Hiep T. Nguyen, Sharf Ilahi Siddiqui, Sung Kyu Maeng, and Seungdae Oh
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Process Chemistry and Technology ,Safety, Risk, Reliability and Quality ,Waste Management and Disposal ,Biotechnology - Published
- 2023
5. Effects of N-Acyl Homoserine Lactone on Immobilized Scenedesmus Quadricauda Bead Using Ca-Alginate
- Author
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Seon-Won Yoon, Jin Hyung Noh, Ji Won Park, Sang Yeob Kim, Yun Lee, Byeong Gyu Choi, and Sung Kyu Maeng
- Published
- 2022
6. Effects of N-acyl homoserine lactone on immobilized Scenedesmus quadricauda bead using Ca-alginate for wastewater treatment
- Author
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Seon-Won Yoon, Jin-Hyung Noh, Ji-Won Park, Sang-Yeob Kim, Yun Lee, Byeong-Gyu Choi, and Sung-Kyu Maeng
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Process Chemistry and Technology ,Safety, Risk, Reliability and Quality ,Waste Management and Disposal ,Biotechnology - Published
- 2022
7. Intermittent water supply impacts on distribution system biofilms and water quality
- Author
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Gonzalo Del Olmo, Stewart Husband, Sung Kyu Maeng, Víctor Soria-Carrasco, Isabel Douterelo, Joby Boxall, and Carolina Calero Preciado
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Environmental Engineering ,Microorganism ,0208 environmental biotechnology ,Water supply ,02 engineering and technology ,010501 environmental sciences ,01 natural sciences ,Distribution system ,Water Supply ,Water Quality ,Ecosystem ,Turbidity ,Waste Management and Disposal ,Biofilm growth ,0105 earth and related environmental sciences ,Water Science and Technology ,Civil and Structural Engineering ,business.industry ,Drinking Water ,Ecological Modeling ,Biofilm ,Pulp and paper industry ,Pollution ,020801 environmental engineering ,Biofilms ,Environmental science ,Water quality ,Water Microbiology ,business - Abstract
Intermittent water supplies (IWS) are routinely experienced by drinking water distribution systems around the world, either due to ongoing operational practices or due to one off interruptions. During IWS events changing conditions may impact the endemic biofilms leading to hydraulic mobilisation of organic and inorganic materials attached to pipes walls with a resulting degradation in water quality. To study the impact of IWS on the microbiological and physico-chemical characteristics of drinking water, an experimental full-scale chlorinated pipe facility was operated over 60 days under realistic hydraulic conditions to allow for biofilm growth and to investigate flow resumption behaviour post-IWS events of 6, 48 and 144 hours.\ud \ud \ud \ud Turbidity and metal concentrations showed significant responses to flow restarting, indicating biofilm changes, with events greater than 6 hours generating more turbidity responses and hence discolouration risk. The increase in pressure when the system was restarted showed a substantial increase in total cell counts, while the subsequent increases in flow led to elevated turbidity and metals concentrations. SUVA254 monitoring indicated that shorter times of non-water supply increased the risk of aromatic organic compounds and hence risk of disinfection-by-products formation. DNA sequencing indicated that increasing IWS times resulted in increased relative abundance of potential pathogenic microorganisms, such as Mycobacterium, Sphingomonas, and the fungi Penicillium and Cladosporium.\ud \ud \ud \ud Overall findings indicate that shorter IWS result in a higher proportion of aromatic organic compounds, which can potentially react with chlorine and increase risk of disinfection-by-products formation. However, by minimising IWS times, biofilm-associated impacts can be reduced, yet these are complex ecosystems and much remains to be understood about how microbial interactions can be managed to best ensure continued water safe supply.
- Published
- 2021
8. Effects of biochar addition on the fate of ciprofloxacin and its associated antibiotic tolerance in an activated sludge microbiome
- Author
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Seungdae Oh, Youngjun Kim, Donggeon Choi, Ji Won Park, Jin Hyung Noh, Sang-Yeop Chung, Sung Kyu Maeng, and Chang-Jun Cha
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Sewage ,Ciprofloxacin ,Charcoal ,Microbiota ,RNA, Ribosomal, 16S ,Health, Toxicology and Mutagenesis ,General Medicine ,Toxicology ,Pollution ,Anti-Bacterial Agents - Abstract
This study investigated the effects of adding biochar (BC) on the fate of ciprofloxacin (CIP) and its related antibiotic tolerance (AT) in activated sludge. Three activated sludge reactors were established with different types of BC, derived from apple, pear, and mulberry tree, respectively, and one reactor with no BC. All reactors were exposed to an environmentally relevant level of CIP that acted as a definitive selective pressure significantly promoting AT to four representative antibiotics (CIP, ampicillin, tetracycline, and polymyxin B) by up to two orders of magnitude. While CIP removal was negligible in the reactor without BC, the BC-dosed reactors effectively removed CIP (70-95% removals) through primarily adsorption by BC and biodegradation/biosorption by biomass. The AT in the BC-added reactors was suppressed by 10-99%, compared to that without BC. The BC addition played a key role in sequestering CIP, thereby decreasing the selective pressure that enabled the proactive prevention of AT increase. 16S rRNA gene sequencing analysis showed that the BC addition alleviated the CIP-mediated toxicity to community diversity and organisms related to phosphorous removal. Machine learning modeling with random forest and support vector models using AS microbiome data collectively pinpointed Achromobacter selected by CIP and strongly associated with the AT increase in activated sludge. The identification of Achromobacter as an important AT bacteria revealed by the machine learning modeling with multiple models was also validated with a linear Pearson's correlation analysis. Overall, our study highlighted Achromobacter as a potential useful sentinel for monitoring AT occurring in the environment and suggested BC as a promising additive in wastewater treatment to improve micropollutant removal, mitigate potential AT propagation, and maintain community diversity against toxic antibiotic loadings.
- Published
- 2022
9. Comparison of pre-oxidation between O3 and O3/H2O2 for subsequent managed aquifer recharge using laboratory-scale columns
- Author
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Se Hee Park, Seunghak Lee, Jaewon Choi, Hyun-Chul Kim, Jin Hyung Noh, and Sung Kyu Maeng
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Urban surface ,021110 strategic, defence & security studies ,Environmental Engineering ,Ozone ,Health, Toxicology and Mutagenesis ,0211 other engineering and technologies ,02 engineering and technology ,Groundwater recharge ,010501 environmental sciences ,Laboratory scale ,Contamination ,Pretreatment method ,01 natural sciences ,Pollution ,chemistry.chemical_compound ,Trihalomethane ,chemistry ,Environmental chemistry ,Dissolved organic carbon ,Environmental Chemistry ,Environmental science ,Waste Management and Disposal ,0105 earth and related environmental sciences - Abstract
A hybrid process of managed aquifer recharge with pre-oxidation was investigated as part of a multiple-barrier approach for safe water production. This study evaluated O3 and O3/H2O2 for the pre-oxidation of urban surface water prior to managed aquifer recharge (MAR) and compared their effectiveness with respect to trace organic contaminants (TrOCs), biostability, and trihalomethane formation potential. The combination of pre-oxidation and MAR was performed using long-term column studies, and the results confirmed the removal of 64 and 56% dissolved organic carbon by using O3 and O3/H2O2, respectively. MAR combined with O3 and O3/H2O2 achieved >50% removal of dissolved organic carbon with the first 5 days of residence time. O3 alone showed better performance in alleviating trihalomethane formation potential during chlorination compared to using O3/H2O2. The pre-oxidation of urban surface water was effective in attenuating selected TrOCs (35 - >99% removal), and subsequent MAR achieved >99% removal of selected TrOCs within the first 5 days, regardless of pretreatment methods examined in this study. The results of this study provide an understanding of the effects of O3 and O3/H2O2 as pre-oxidation processes on urban surface water prior to MAR, as well as the resulting impact on MAR.
- Published
- 2019
10. Reducing bacterial aerosol emissions from membrane bioreactors: The impact of SRT and the addition of PAC and calcium
- Author
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Sung Kyu Maeng, Soohoon Choi, Han Yong Kim, Jin Hyung Noh, and Hanna Choi
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Powdered activated carbon treatment ,Environmental Engineering ,chemistry.chemical_element ,Calcium ,Membrane bioreactor ,complex mixtures ,Bioreactors ,Bioreactor ,Waste Management and Disposal ,Water Science and Technology ,Civil and Structural Engineering ,Aerosols ,Sewage ,Chemistry ,Ecological Modeling ,Membranes, Artificial ,respiratory system ,Particulates ,Pollution ,Aerosol ,Charcoal ,Environmental chemistry ,Particle size ,Powders ,Aeration - Abstract
Bacterial aerosols resulting from membrane bioreactor (MBR) processes, which require excessive aeration in a confined space, are important to investigate because of their possible adverse effects on human health. This study investigated the influence of solid retention time (SRT) on bacterial aerosols from MBRs. Moreover, powdered activated carbon (PAC) and calcium were used to attenuate bacterial aerosol emissions from MBRs. The particulate matter (PM) emitted from the MBRs was reduced by 30.5 and 25.2% at SRTs of 20 and 80 d, respectively, compared to the level emitted at an SRT of 10 d. Total cell counts were similarly reduced at SRTs of 20 and 80 d. Longer SRTs also led to greater reductions in the particle size distribution of the sludge within 10 μm. Several factors in the MBR influenced the behavior of the bacterial aerosol emissions from the MBRs. This study showed that changes in viscosity and particle size induced by the SRT influenced the bacterial aerosol emissions in MBRs. Therefore, SRT was identified as an important design parameter affecting bacterial aerosol emissions in MBR processes. The amounts of particulate matter and bacterial aerosols were reduced in MBRs using PAC and calcium, both of which exerted an immediate effect on the bacterial aerosol emissions in MBRs by increasing the aerosol-particle size.
- Published
- 2019
11. Effects of hydraulic loading rate and organic load on the performance of a pilot-scale hybrid VF-HF constructed wetland in treating secondary effluent
- Author
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Yeonsung Jung, Seunghak Lee, Ji-Won Park, Woo Hyuck Bang, and Sung Kyu Maeng
- Subjects
Environmental Engineering ,Denitrification ,Health, Toxicology and Mutagenesis ,0208 environmental biotechnology ,chemistry.chemical_element ,Pilot Projects ,02 engineering and technology ,Wastewater ,010501 environmental sciences ,Waste Disposal, Fluid ,01 natural sciences ,Dissolved organic carbon ,Environmental Chemistry ,Organic matter ,Effluent ,Humic Substances ,0105 earth and related environmental sciences ,chemistry.chemical_classification ,Total organic carbon ,Suspended solids ,Public Health, Environmental and Occupational Health ,Proteins ,General Medicine ,General Chemistry ,Pollution ,020801 environmental engineering ,Biodegradation, Environmental ,chemistry ,Wetlands ,Environmental chemistry ,Constructed wetland ,Carbon - Abstract
This study evaluated the performance of a pilot-scale hybrid constructed wetland system for secondary effluent and investigated bulk organic matter characteristics. The hybrid constructed wetland consisted of a vertical-flow (VF) bed followed by a horizontal-flow (HF) bed. We also investigated the effects of hydraulic loading rates and influent organic load on the performance of the pilot-scale VF-HF hybrid constructed wetland. The results showed a high removal efficiency for suspended solids (>95%) and organic matter as determined by total organic carbon (>98.5%) and dissolved organic carbon (>70%), but no significant change in nitrogen removal was observed. The wetland treatment efficiency for suspended solids and organic matter showed a good buffer capacity even when hydraulic loading rates increased from 750 to 1500 L m−2 d−1 and 500–1000 L m−2 d−1 during the VF and HF stages, respectively. Moreover, there was no significant change in the performance when influent organic load increased eight-fold. Fluorescence excitation-emission matrix and liquid chromatography-organic carbon detection (LC-OCD) were used to investigate the dissolved organic matter characteristics in the hybrid VF-HF constructed wetland. Fluorescence excitation-emission matrix spectroscopy showed that both protein- and humic-like substances did not significantly change in the effluent when hydraulic loading rates and organic load increased by two- and eight-fold, respectively. Biopolymers determined using LC-OCD were effectively removed via the VF and HF stage wetlands, indicating the occurrence of biodegradation. Fluorescence excitation-emission matrix spectroscopy and LC-OCD provided the fate of dissolved organic matter characteristics in the hybrid VF-HF constructed wetland.
- Published
- 2019
12. Fluorescence descriptors for algal organic matter and microalgae disintegration during ultrasonication
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Waris Khan, Ji Won Park, and Sung Kyu Maeng
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Process Chemistry and Technology ,Safety, Risk, Reliability and Quality ,Waste Management and Disposal ,Biotechnology - Published
- 2022
13. Treatment of highly saline RO concentrate using Scenedesmus quadricauda for enhanced removal of refractory organic matter
- Author
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Sungpyo Kim, Wook Jin Choi, Sung Kyu Maeng, Waris Khan, Ji-Won Park, Hee Sung Yang, Hyun-Chul Kim, Ihnsup Han, Kyung Guen Song, and Hyoungmin Woo
- Subjects
chemistry.chemical_classification ,Mechanical Engineering ,General Chemical Engineering ,0208 environmental biotechnology ,Aqueous two-phase system ,02 engineering and technology ,General Chemistry ,010501 environmental sciences ,Biodegradation ,01 natural sciences ,Decomposition ,020801 environmental engineering ,chemistry.chemical_compound ,chemistry ,Wastewater ,Environmental chemistry ,Dissolved organic carbon ,General Materials Science ,Organic matter ,Hydrogen peroxide ,Reverse osmosis ,0105 earth and related environmental sciences ,Water Science and Technology - Abstract
This study achieves a better understanding how Scenedesmus quadricauda microalgae participate in the phycoremediation of a reverse osmosis (RO) concentrate at a high salinity (8000 mg Cl− L− 1). Algal treatment of the RO concentrate under continuous illumination resulted in a notable increase in the biodegradability of dissolved organic matter, subsequent removal of biodegradable fractions, and simultaneous removal of nutrients (N and P). This is the first time that S. quadricauda is shown to induce the degradation of polymeric organic matter in the RO concentrate, which is typically refractory to microbial decomposition. In this study, the mechanisms for algae-induced degradation were investigated by measuring the hydrogen peroxide (H2O2) released out of algal cells and dispersed in the aqueous phase. The algae-induced biodegradation process has an advantage over typical electrochemical oxidation technologies in that photo-sensitive living organisms are capable of self-repair, reproduction, and nutrient uptake. Our results indicate that the use of algae-induced oxidation is highly feasible as a safe, inexpensive technology to pre-treat non- or slowly-biodegradable organic matter in wastewater prior to downstream biological processing.
- Published
- 2018
14. Characterization and assessment of organic carbon migration and biomass formation potential of polymeric pipes using modified BioMig
- Author
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Sung Kyu Maeng, Jin Hyung Noh, Thi Huyen Duong, and Ji-Won Park
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Total organic carbon ,Process Chemistry and Technology ,Biomass ,02 engineering and technology ,010501 environmental sciences ,Contamination ,engineering.material ,Polyethylene ,021001 nanoscience & nanotechnology ,Pulp and paper industry ,01 natural sciences ,Pollution ,Characterization (materials science) ,Current (stream) ,chemistry.chemical_compound ,Coating ,chemistry ,engineering ,Chemical Engineering (miscellaneous) ,Environmental science ,Leachate ,0210 nano-technology ,Waste Management and Disposal ,0105 earth and related environmental sciences - Abstract
To evaluate and approve the materials that can be in contact with drinking water with respect to biological contamination, organic carbon migration and biomass formation potential assays are widely employed. In previous studies, to conduct the assays, the entire material was exposed to the test water by submerging the material into glass jars. However, these are not realistic conditions since the water contact only the inner surface of the pipe in the distribution system, which may be different from the outer surface with respect to the coating layers. Furthermore, the extra components such as the glass jar containers and stainless steel holders might be the sources of organic carbon contamination. These two factors may result in imprecise conclusions. Here, we introduced a minor but essential modification to the BioMig test, which is the most current test on the migration potential and biomass formation potential. In this modified BioMig method, the outer surface and cutting edges, which are not in contact with water in practical water distribution systems, would not be exposed to the test water. Moreover, the assimilable organic carbon formation potential via chlorination in the leachates was observed and recommended as an additional test in the migration potential assay. The modified test results demonstrated that polyethylene (PE) material is the most unfavorable material, notably when used in chlorinated drinking water. This proposed test provided an alternative approach to the decision-makers with respect to evaluating the pipe material characteristics.
- Published
- 2021
15. Dissolved organic matter characteristics and removal of trace organic contaminants in a multi-soil-layering system
- Author
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Jin Hyung Noh, Kyung Guen Song, Se-Yeon Won, Sung Kyu Maeng, and Ji-Won Park
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Chemistry ,Process Chemistry and Technology ,Sand filter ,Slag ,02 engineering and technology ,Fractionation ,010501 environmental sciences ,Contamination ,021001 nanoscience & nanotechnology ,01 natural sciences ,Pollution ,Wastewater ,visual_art ,Environmental chemistry ,Dissolved organic carbon ,visual_art.visual_art_medium ,Chemical Engineering (miscellaneous) ,Water treatment ,0210 nano-technology ,Zeolite ,Waste Management and Disposal ,0105 earth and related environmental sciences - Abstract
This study investigated the role of soil mixture blocks (SMBs) in the removal of trace organic contaminants and the changes in dissolved organic matter characteristics in a laboratory-scale multi-soil-layering (MSL) system. The experimental setup included three soil-based water treatment systems, namely MSL, MSL without SMBs (zeolite/slag), and a sand filter. The effect of SMBs in the removal of dissolved organic matter in MSL was not significant, but the use of zeolite/slag in MSL enhanced the removal of humic substances and building blocks. Through membrane fractionation, the size distribution of dissolved organic matter in the MSL system was not changed, and the majority of the dissolved organic matter is below 1 kDa. Ten pharmaceutically active compounds and three endocrine-disrupting compounds were used to investigate the removal of selected trace organic contaminants in the MSL system, zeolite/slag, and sand filter. The attenuation of pentoxifylline, caffeine, 17α-ethinylestradiol, estrone, and 17β-estradiol in the MSL system was similar to that for zeolite/slag, and the removal efficiency was greater than 80%. However, pentoxifylline, caffeine, 17α-ethinylestradiol, estrone, and 17β-estradiol exhibited relatively low removal efficiencies in the sand filter compared to those in the MSL system and zeolite/slag. Results from this study provide insight into the removal of selected trace organic contaminants in MSL system, which could be considered as one of the series of barriers to remove trace organic contaminants in wastewater.
- Published
- 2021
16. Effects of powdered activated carbon and calcium on trihalomethane toxicity of zebrafish embryos and larvae in hybrid membrane bioreactors
- Author
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Jin Hyung Noh, Sungpyo Kim, Sung Kyu Maeng, Ji-Won Park, and Soohoon Choi
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Powdered activated carbon treatment ,animal structures ,Environmental Engineering ,Health, Toxicology and Mutagenesis ,0211 other engineering and technologies ,chemistry.chemical_element ,02 engineering and technology ,010501 environmental sciences ,Calcium ,Membrane bioreactor ,01 natural sciences ,chemistry.chemical_compound ,Bioreactors ,Bioreactor ,Animals ,Environmental Chemistry ,Waste Management and Disposal ,Zebrafish ,0105 earth and related environmental sciences ,021110 strategic, defence & security studies ,biology ,fungi ,biology.organism_classification ,Pollution ,Trihalomethane ,Membrane ,chemistry ,Charcoal ,Larva ,embryonic structures ,Toxicity ,Biophysics ,Powders ,Trihalomethanes - Abstract
This study investigated the effect of powdered activated carbon and calcium on trihalomethane toxicity in zebrafish embryos and larvae in hybrid membrane bioreactors. Two hybrid membrane bioreactors were configured with the addition of powdered activated carbon or calcium to reduce the trihalomethane formation potential. Trihalomethane formation decreased by approximately 37.2% and 30.3% in membrane bioreactor-powdered activated carbon and membrane bioreactor-calcium, respectively. Additionally, the toxic effect of trihalomethane formation was examined on zebrafish embryos and larvae. About 35% of the embryos exposed to trihalomethanes (800 ppb) showed signs of deformation, with the majority displaying coagulation within 24 h after exposure. Color preference tests, which were conducted to identify any abnormal activities of the embryos, showed an increase in preference from short to longer wavelengths upon exposure to high levels of trihalomethanes. This may indicate damage to the optical organs in zebrafish when exposed to trihalomethanes. Behavioral analysis showed reduced mobility of zebrafish larvae under different trihalomethane concentrations, indicating a decrease in the average activity time with an increasing trihalomethane concentration. The membrane bioreactor effluents were toxic to zebrafish embryos and larvae in the presence of high trihalomethane concentrations. To understand the mechanism behind trihalomethane toxicity, further studies are needed.
- Published
- 2021
17. Seasonally related effects on natural organic matter characteristics from source to tap in Korea
- Author
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Hyun-Chul Kim, Sung Kyu Maeng, Ilhwan Choi, and S.H. So
- Subjects
Environmental Engineering ,0208 environmental biotechnology ,chemistry.chemical_element ,02 engineering and technology ,010501 environmental sciences ,01 natural sciences ,Natural organic matter ,Water Purification ,law.invention ,law ,Republic of Korea ,Dissolved organic carbon ,Chlorine ,Environmental Chemistry ,Biological activated carbon ,Waste Management and Disposal ,Filtration ,0105 earth and related environmental sciences ,Total organic carbon ,Chemistry ,Drinking Water ,Sedimentation ,Pollution ,Carbon ,020801 environmental engineering ,Charcoal ,Environmental chemistry ,Water treatment ,Seasons - Abstract
In this study, natural organic matter (NOM) characteristics were investigated over three years of monthly monitoring to determine the effect of seasonal variations on NOM levels from source to tap. Liquid chromatography with organic carbon detection (LC-OCD) was used to determine NOM characteristics and the level of reduction of biodegradable dissolved organic carbon (BDOC). The average dissolved organic matter concentration in the source water (Lake Paldang, Korea) was not significantly different between summer and winter. However, the distribution of NOM components, such as biopolymers, building blocks, low molecular weight (MW) neutrals and acids, identified by LC-OCD, varied seasonally. While high MW NOM was preferentially removed by coagulation/sedimentation/rapid sand filtration (CSR), no seasonal effects were observed on the removal of high MW NOM. CSR and biological activated carbon (BAC) filtration showed a better efficiency of BDOC removal in winter and summer, respectively. High concentrations of chlorine used in the treatment plants in summer resulted in 10% higher DOC concentrations during disinfection. Overall NOM removal efficiencies from source to tap were 45% and 35% for summer and winter, respectively. Principal component analysis also indicated that seasonal variations (principal component 1) showed the strongest positive correlation with the overall performance of water treatment. The long-term monitoring of drinking water treatment processes showed that seasonal variations were important factors affecting NOM characteristics during water treatment.
- Published
- 2017
18. Influences of NOM composition and bacteriological characteristics on biological stability in a full-scale drinking water treatment plant
- Author
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Sungpyo Kim, Anne S. Meyer, Ji-Won Park, Sung Kyu Maeng, and Hyun-Chul Kim
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Environmental Engineering ,Ozone ,Halogenation ,Health, Toxicology and Mutagenesis ,0208 environmental biotechnology ,02 engineering and technology ,010501 environmental sciences ,engineering.material ,Bacterial growth ,01 natural sciences ,Water Purification ,chemistry.chemical_compound ,Biopolymers ,Dissolved organic carbon ,Escherichia coli ,Environmental Chemistry ,Organic matter ,Organic Chemicals ,Humic Substances ,0105 earth and related environmental sciences ,chemistry.chemical_classification ,Total organic carbon ,biology ,Drinking Water ,Public Health, Environmental and Occupational Health ,General Medicine ,General Chemistry ,biology.organism_classification ,Pollution ,Carbon ,020801 environmental engineering ,chemistry ,Environmental chemistry ,engineering ,Water treatment ,Biopolymer ,Hydrophobic and Hydrophilic Interactions ,Filtration ,Bacteria - Abstract
The influences of natural organic matter (NOM) and bacteriological characteristics on the biological stability of water were investigated in a full-scale drinking water treatment plant. We found that prechlorination decreased the hydrophobicity of the organic matter and significantly increased the high-molecular-weight (MW) dissolved organic matter, such as biopolymers and humic substances. High-MW organic matter and structurally complex compounds are known to be relatively slowly biodegradable; however, because of the prechlorination step, the indigenous bacteria could readily utilise these fractions as assimilable organic carbon. Sequential coagulation and sedimentation resulted in the substantial removal of biopolymer (74%), humic substance (33%), bacterial cells (79%), and assimilable organic carbon (67%). Rapid sand and granular activated carbon filtration induced an increase in the low-nucleic-acid content bacteria; however, these bacteria were biologically less active in relation to enzymatic activity and ATP. The granular activated carbon step was essential to securing biological stability (the ability to prevent bacterial growth) by removing the residual assimilable organic carbon that had formed during the ozone treatment. The growth potential of Escherichia coli and indigenous bacteria were found to differ in respect to NOM characteristics. In comparison with E. coli, the indigenous bacteria utilised a broader range of NOM as a carbon source. Principal component analysis demonstrated that the measured biological stability of water could differ, depending on the NOM characteristics, as well as on the bacterial inoculum selected for the analysis.
- Published
- 2016
19. Effects of phosphate and hydrogen peroxide on the performance of a biological activated carbon filter for enhanced biofiltration
- Author
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Jin Hyung Noh, Song Hee Yoo, Heejong Son, Katherine E. Fish, Sung Kyu Maeng, and Isabel Douterelo
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Environmental Engineering ,Health, Toxicology and Mutagenesis ,0211 other engineering and technologies ,02 engineering and technology ,010501 environmental sciences ,01 natural sciences ,Phosphates ,chemistry.chemical_compound ,Biopolymers ,Dissolved organic carbon ,Environmental Chemistry ,Polyvinyl Chloride ,Hydrogen peroxide ,Waste Management and Disposal ,Effluent ,0105 earth and related environmental sciences ,021110 strategic, defence & security studies ,Biofilm ,Hydrogen Peroxide ,Stainless Steel ,Phosphate ,Pulp and paper industry ,Pollution ,Filter (aquarium) ,Trihalomethane ,chemistry ,Biofilms ,Charcoal ,Biofilter ,Filtration ,Water Pollutants, Chemical ,Trihalomethanes - Abstract
Biofilm formation on biofilters can influence their hydraulic performance, thereby leading to head loss and an increase in energy use and costs for water utilities. The effects of a range of factors, including hydrogen peroxide and phosphate, on the performance of biological activated carbon (BAC) and biofilm formation were investigated using laboratory-scale columns. Head loss, total carbohydrates, and proteins were reduced in the nutrient-enhanced, oxidant-enhanced, and nutrient + oxidant-enhanced BAC filters. However, there were no changes in the removal of dissolved organic matter, trihalomethane formation potential, or selected trace organic contaminants. The biofilm formation on polyvinyl chloride and stainless steel coupons using the laboratory biofilm reactor system was lower when the effluent from a nutrient-enhanced column was used, which indicated that there was less biofilm formation in the distribution systems. This may have been because the effluent from the nutrient-enhanced column was more biologically stable. Therefore, enhanced biofiltration could be used not only to reduce head loss in biofilters, but also to delay biofilm formation in distribution systems.
- Published
- 2020
20. Inhibition of total oxygen uptake by silica nanoparticles in activated sludge
- Author
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Jinwoo Cho, Changwon Suh, Mark Sibag, Kwan Hyung Lee, Byeong-Gyu Choi, Jae Woo Lee, and Sung Kyu Maeng
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Environmental Engineering ,Health, Toxicology and Mutagenesis ,Membrane lipids ,chemistry.chemical_element ,Waste Disposal, Fluid ,Oxygen ,chemistry.chemical_compound ,Bioreactors ,Microscopy, Electron, Transmission ,Respiration ,Environmental Chemistry ,Waste Management and Disposal ,Fatty acid methyl ester ,Principal Component Analysis ,Bacteria ,Sewage ,Fatty Acids ,Biological activity ,Silicon Dioxide ,Pollution ,Activated sludge ,Biochemistry ,chemistry ,Toxicity ,Nanoparticles ,Composition (visual arts) - Abstract
Nanoparticle toxicity to biological activities in activated sludge is largely unknown. Among the widely used nanoparticles, silica nanoparticles (SNP) have a limited number of studies associated with inhibition to the activated sludge process (ASP). We demonstrated SNP inhibition of activated sludge respiration through oxygen uptake rate (OUR) measurement. Based on the percentage inhibition of total oxygen consumption (IT), we observed that smaller SNPs (12 nm, IT = 33 ± 3%; 151 nm, IT = 23 ± 2%) were stronger inhibitors than larger SNPs (442 and 683 nm, IT = 5 ± 1%). Transmission electron micrographs showed that some of the SNPs were adsorbed on and/or apparently embedded somewhere in the microbial cell membrane. Whether SNPs are directly associated with the inhibition of total oxygen uptake warrants further studies. However, it is clear that SNPs statistically significantly altered the composition of microbial membrane lipids, which was more clearly described by principal component analysis and weighted Euclidian distance (PCA-ED) of the fatty acid methyl ester (FAME) data. This study suggests that SNPs potentially affect the biological activity in activated sludge through the inhibition of total oxygen uptake.
- Published
- 2015
21. Factors affecting crystallization of copper sulfide in fed-batch fluidized bed reactor
- Author
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Seong Taek Yun, Eunhoo Jeong, Jaeshik Chung, Seok Won Hong, Jae Woo Choi, and Sung Kyu Maeng
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chemistry.chemical_classification ,Sulfide ,Inorganic chemistry ,Metals and Alloys ,Sulfidation ,Industrial and Manufacturing Engineering ,Sodium sulfide ,law.invention ,Crystallinity ,Copper sulfide ,chemistry.chemical_compound ,Chemical engineering ,chemistry ,law ,Fluidized bed ,Materials Chemistry ,Partial oxidation ,Crystallization - Abstract
This work has assessed factors affecting crystallization of copper sulfide (CuS) under batch conditions and in fed-batch fluidized bed reactor (FBR) using calcium-coated sands as a seed material. Compared with using sodium sulfide nonahydrate as a sulfidation reagent, larger CuS crystals were produced from sodium sulfide pentahydrate, most likely because of the lower surface charge. Due to the partial oxidation of sulfide in the pentahydrate form, the optimum molar ratio of Cu2 + to S2 − was found to be 1:2, higher than the theoretical ratio. Crystal growth and aggregation were further increased by using calcium ion as a cross-linker among the CuS fines ( 95% of the initial Cu2 + (100 mg Cu2 +/L) was successfully transformed to CuS crystals within 120 min. The size and crystallinity of the star-shaped CuS crystals were confirmed by FEG–SEM and XRD analyses, respectively. Principal component analysis indicated that the resting height and the seed type were the primary parameters affecting CuS crystallization in the fed-batch FBR.
- Published
- 2015
22. Electrospun nanofibrous PVDF–PMMA MF membrane in laboratory and pilot-scale study treating wastewater from Seoul Zoo
- Author
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Sung Kyu Maeng, Jin-Hyung Noh, Sang Hyup Lee, Hyun-Chul Kim, Byeong Gyu Choi, and Kyung Guen Song
- Subjects
Materials science ,Mechanical Engineering ,General Chemical Engineering ,Microfiltration ,General Chemistry ,Membrane bioreactor ,Polyvinylidene fluoride ,Electrospinning ,Contact angle ,chemistry.chemical_compound ,Membrane ,chemistry ,Wastewater ,Chemical engineering ,Polymer chemistry ,General Materials Science ,Effluent ,Water Science and Technology - Abstract
Polyvinylidene fluoride (PVDF) blended with polymethyl methacrylate (PMMA) was electrospun into nanofibrous membranes, which had a mean pore size of 0.45 μm. The pure water permeability of the prepared membrane was higher compared to previous reports in which conventional cast membranes with equivalent mean pore size and contact angle were characterized for the purposes of domestic and industrial uses. Microscopic diagnoses were also conducted to characterize the physical and morphological natures of the nanofibrous membrane, which revealed that the prepared membrane was much smoother than conventional cast membranes. The increase in resistance to filtration was negligible up to 16 days without membrane cleaning for filtration of the secondary effluent; however this was not the case when the membranes were used for bioreactors. Suspended solids in the secondary effluent were completely removed, and a 48% removal of chemical oxygen demand was also achieved. Pilot-scale testing of the electrospun nanofibrous PVDF–PMMA membrane was also conducted on secondary effluent from the Seoul Zoo wastewater treatment plant (12 m 3 d − 1 ). Our results revealed that the nanofibrous membrane has the potential to become a mainstream application in post-treatment of secondary effluent, which could lead us to explore the use of nanofibrous membranes for diverse applications.
- Published
- 2014
23. Ozonation of piggery wastewater for enhanced removal of contaminants by S. quadricauda and the impact on organic characteristics
- Author
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Sung Kyu Maeng, Han-soo Kim, Hyun-Chul Kim, Hyung Joo Kim, Wook Jin Choi, and Kyung Guen Song
- Subjects
Environmental Engineering ,Environmental remediation ,Sus scrofa ,Bioengineering ,Wastewater ,Waste Disposal, Fluid ,Ozone ,Microalgae ,Animals ,Animal Husbandry ,Organic Chemicals ,Waste Management and Disposal ,Effluent ,Waste management ,Renewable Energy, Sustainability and the Environment ,Chemistry ,General Medicine ,Contamination ,Pulp and paper industry ,Molecular Weight ,Anaerobic digestion ,Waste treatment ,Biodegradation, Environmental ,Spectrometry, Fluorescence ,Sewage treatment ,Water treatment ,Water Pollutants, Chemical - Abstract
The feasibility of using ozonation pretreatment was investigated for a better performance of post microalgae-based wastewater remediation when treating piggery effluent which was anaerobically digested and subsequently micro-filtered. Ozonation pretreatment at a dose of 1.1 mg-O 3 mg-C −1 or higher significantly improved the transmittance of light illumination through the mixed liquor by decolorizing the piggery effluent as culture media, which resulted in increasing both the productivity of algal biomass and the associated removal of inorganic nutrients from the effluent. Ozonation also converted refractory organic constituents in the piggery effluent to a large number of biodegradable fractions via both partial-mineralization and low-molecularization. These fractions were facilely removed through biological assimilation during the mixotrophic cultivation of a microalga S. quadricauda . The results revealed that ozonation could be one of the most promising strategies for the pretreatment of highly-colored piggery effluent prior to algae-based wastewater treatment.
- Published
- 2014
24. Increasing hydrophobicity of poly(propylene) fibers by coating reduced graphene oxide and their application as depth filter media
- Author
-
Jae Hyun Jung, Kyung Guen Song, Eunhyea Chung, Subramaniyan Ramasundaram, Sang Hyup Lee, Sung Kyu Maeng, and Seok Won Hong
- Subjects
Materials science ,Scanning electron microscope ,Graphene ,General Chemistry ,engineering.material ,Superhydrophobic coating ,law.invention ,Contact angle ,Synthetic fiber ,Coating ,law ,Depth filter ,engineering ,General Materials Science ,Fiber ,Composite material - Abstract
The effect of increasing the hydrophobicity of poly(propylene) (PP) fibers, the most frequently used synthetic filter materials, on depth filtration performance was investigated. Reduced graphene oxide (RGO) was employed to fabricate highly hydrophobic surfaces by a dip-coating method. The anchoring of RGO on the surface of the PP fibers was confirmed by the appearance of signals corresponding to RGO in Raman and X-ray photoelectron spectra. In addition, scanning electron microscopy images revealed the presence of wrinkled and folded RGO sheets on the PP fibers. The water contact angle increased from 108° to 125° after the first RGO coating, and it was saturated at about 135°. Using kaolin as model hydrophilic particles, the depth filters with RGO-coated PP fibers showed a superior performance in terms of water flux and trans-filter pressure in comparison with those with the pristine and hydrophilic PP fibers prepared by coating functionalized GO. More importantly, particle detachment was enhanced by the hydrophobic coating during backwashing. This can be ascribed to the weakened attractive force between the RGO-coated fiber surfaces and kaolin particles due to the increase of hydrophobicity. This approach provides an effective means of enhancing the performance of synthetic fiber-based depth filters.
- Published
- 2014
25. Hybridization of natural systems with advanced treatment processes for organic micropollutant removals: New concepts in multi-barrier treatment
- Author
-
Sairam Sudhakaran, Sung Kyu Maeng, and Gary L. Amy
- Subjects
Osmosis ,Environmental Engineering ,Halogenation ,Sedimentation (water treatment) ,Health, Toxicology and Mutagenesis ,Context (language use) ,Water Purification ,Membrane technology ,law.invention ,Adsorption ,law ,Environmental Chemistry ,Organic Chemicals ,Reverse osmosis ,Filtration ,Waste management ,Chemistry ,Drinking Water ,Advanced oxidation process ,Public Health, Environmental and Occupational Health ,General Medicine ,General Chemistry ,Pollution ,Charcoal ,Nanofiltration ,Oxidation-Reduction ,Water Pollutants, Chemical - Abstract
Organic micropollutants (OMPs) represent a major constraint in drinking water supply. In the past, emphasis has been on individual treatment processes comprising conventional treatment (coagulation, sedimentation, and filtration) followed by advanced treatment processes (adsorption, ion-exchange, oxidation, and membrane separation). With the depletion of water resources and high demand for power and chemical usage, efforts need to be made to judiciously use advanced treatment processes. There is a new interest in multiple barriers with synergies in which two coupled processes can function as a hybrid process. Within the context of this paper, the hybrid processes include a natural treatment process coupled with an advanced process. Pilot/full-scale studies have shown efficient removal of OMPs by these hybrid processes. With this hybridization, the usage of resources such as power and chemicals can be reduced. In this study, coupling/hybridization of aquifer recharge and recovery (ARR) with oxidation (O3), advanced oxidation process which involves OH radicals (AOP), nanofiltration (NF), reverse osmosis (RO) and granular activated carbon (GAC) adsorption for OMP removal was studied. O3 or AOP as a pre-treatment and GAC, NF, RO, or UV/chlorination as a post-treatment to ARR was studied. NF can be replaced by RO for removal of OMPs since studies have shown similar performance of NF to RO for removal of many OMPs, thereby reducing costs and providing a more sustainable approach.
- Published
- 2013
26. Influences of solid retention time, nitrification and microbial activity on the attenuation of pharmaceuticals and estrogens in membrane bioreactors
- Author
-
Sung Kyu Maeng, Kyu Tae Lee, Kyung Guen Song, and Byeong Gyu Choi
- Subjects
Ketoprofen ,Time Factors ,Environmental Engineering ,Estrone ,Fluorescence ,chemistry.chemical_compound ,Adenosine Triphosphate ,Bioreactors ,medicine ,Gemfibrozil ,Organic Chemicals ,Waste Management and Disposal ,Water Science and Technology ,Civil and Structural Engineering ,Fenoprofen ,Bezafibrate ,Chromatography ,Bacteria ,Ecological Modeling ,Clofibric acid ,Estrogens ,Membranes, Artificial ,Nitrification ,Pollution ,Carbon ,Biodegradation, Environmental ,Pharmaceutical Preparations ,Solubility ,chemistry ,Sodium azide ,Water Pollutants, Chemical ,medicine.drug - Abstract
This study investigated the influences of solid retention time (SRT), nitrification, and microbial activity on the attenuation of pharmaceuticals and estrogens and the total estrogenic activity, using identical bench-scale membrane bioreactors. Phenacetine, acetaminophen, pentoxifylline, caffeine, bezafibrate, ibuprofen, fenoprofen, 17β-estradiol, and estrone were effectively attenuated even at short SRT (8 d). However, the attenuation efficiencies of gemfibrozil, ketoprofen, clofibric acid, and 17α-ethinylestradiol were dependent upon SRTs (20 and 80 d). Some acidic pharmaceuticals (gemfibrozil, diclofenac, bezafibrate, and ketoprofen) and 17α-ethinylestradiol were partially degraded by nitrification. Relatively high removal efficiencies were observed for 17β-estradiol and estrone (natural estrogens) compared to 17α-ethinylestradiol (synthetic estrogen) when nitrification was inhibited. Most of selected pharmaceuticals were not significantly attenuated under presumably abiotic conditions by adding sodium azide except phenacetine, acetaminophen, and caffeine. In this study, carbamazepine was found to be recalcitrant to biological wastewater treatment using membrane bioreactors regardless of the change of SRTs and microbial activity.
- Published
- 2013
27. Correlation between effluent organic matter characteristics and membrane fouling in a membrane bioreactor using advanced organic matter characterization tools
- Author
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Byeong Gyu Choi, Kyung Guen Song, Sung Kyu Maeng, and Jinwoo Cho
- Subjects
chemistry.chemical_classification ,Chromatography ,Fouling ,Chemistry ,Mechanical Engineering ,General Chemical Engineering ,Membrane fouling ,General Chemistry ,Biodegradation ,Membrane bioreactor ,Membrane ,Extracellular polymeric substance ,Environmental chemistry ,Bioreactor ,General Materials Science ,Organic matter ,Water Science and Technology - Abstract
Three identical bench-scale membrane bioreactors (MBRs) were operated to investigate the formation of effluent organic matter (EfOM) via biodegradation at different solid retention times (8, 20 and 80 days). The characteristics of organic matter in supernatants, bound extracellular polymeric substances (EPS), soluble microbial products (SMP) and effluents changed at different solid retention times (SRTs). EfOM characteristics affecting membrane fouling with respect to total hydraulic resistances and specific cake resistances were investigated using advanced organic characterization tools. EfOM characteristics determined by size exclusion chromatography with organic carbon detection, fluorescence excitation–emission matrix spectroscopy and polarity rapid assessment method were compared with the membrane fouling. In this study, a database collected from three identical bench-scale MBRs operated at different SRTs for 12 months is analyzed to investigate the intercorrelations (either positive or negative) between EfOM characteristics and membrane fouling using principal component analysis (PCA). Principal component-1 embodied the characteristics of EfOM (i.e., aliphatic biopolymers vs. aromatic humic substances), and explained 59% of the data variability. This study provides useful data on EfOM characteristics with membrane fouling, and a multivariate statistical analysis (PCA) can be used to depict the intercorrelations between EfOM characteristics and SRTs in MBRs.
- Published
- 2013
28. Effects of effluent organic matter characteristics on the removal of bulk organic matter and selected pharmaceutically active compounds during managed aquifer recharge: Column study
- Author
-
Aleksandra Magic-Knezev, Sung Kyu Maeng, Saroj K. Sharma, Chol D.T. Abel, Kyung Guen Song, and Gary L. Amy
- Subjects
chemistry.chemical_classification ,Total organic carbon ,Chemistry ,Waste Disposal, Fluid ,Anoxic waters ,Water Purification ,Wastewater ,Environmental chemistry ,Dissolved organic carbon ,Environmental Chemistry ,Sewage treatment ,Organic matter ,Groundwater ,Oxidation-Reduction ,Effluent ,Water Pollutants, Chemical ,Water Science and Technology ,Waste disposal - Abstract
Soil column experiments were conducted to investigate the effects of effluent organic matter (EfOM) characteristics on the removal of bulk organic matter (OM) and pharmaceutically active compounds (PhACs) during managed aquifer recharge (MAR) treatment processes. The fate of bulk OM and PhACs during an MAR is important to assess post-treatment requirements. Biodegradable OM from EfOM, originating from biological wastewater treatment, was effectively removed during soil passage. Based on a fluorescence excitation-emission matrix (F-EEM) analysis of wastewater effluent-dominated (WWE-dom) surface water (SW), protein-like substances, i.e., biopolymers, were removed more favorably than fluorescent humic-like substances under oxic compared to anoxic conditions. However, there was no preferential removal of biopolymers or humic substances, determined as dissolved organic carbon (DOC) observed via liquid chromatography with online organic carbon detection (LC-OCD) analysis. Most of the selected PhACs exhibited removal efficiencies of greater than 90% in both SW and WWE-dom SW. However, the removal efficiencies of bezafibrate, diclofenac and gemfibrozil were relatively low in WWE-dom SW, which contained more biodegradable OM than did SW (copiotrophic metabolism). Based on this study, low biodegradable fractions such as humic substances in MR may have enhanced the degradation of diclofenac, gemfibrozil and bezafibrate by inducing an oligotrophic microbial community via long term starvation. Both carbamazepine and clofibric acid showed persistent behaviors and were not influenced by EfOM.
- Published
- 2012
29. Role of biodegradation in the removal of pharmaceutically active compounds with different bulk organic matter characteristics through managed aquifer recharge: Batch and column studies
- Author
-
Saroj K. Sharma, Sung Kyu Maeng, Chol D.T. Abel, Gary L. Amy, and Aleksandra Magic-Knezev
- Subjects
Octanol ,chemistry.chemical_classification ,Biocide ,Environmental Engineering ,Hydraulic retention time ,Chemistry ,Ecological Modeling ,Sorption ,Biodegradation ,Pollution ,law.invention ,Partition coefficient ,chemistry.chemical_compound ,Biodegradation, Environmental ,Pharmaceutical Preparations ,law ,Environmental chemistry ,Spectrophotometry, Ultraviolet ,Organic matter ,Waste Management and Disposal ,Water Pollutants, Chemical ,Filtration ,Water Science and Technology ,Civil and Structural Engineering - Abstract
Natural water treatment systems such as bank filtration have been recognized as providing effective barriers in the multi-barrier approach for attenuation of organic micropollutants for safe drinking water supply. In this study, the role of biodegradation in the removal of selected pharmaceutically active compounds (PhACs) during soil passage was investigated. Batch studies were conducted to investigate the removal of 13 selected PhACs from different water sources with respect to different sources of biodegradable organic matter. Neutral PhACs (phenacetine, paracetamol, and caffeine) and acidic PhACs (ibuprofen, fenoprofen, bezafibrate, and naproxen) were removed with efficiencies greater than 88% from different organic matter water matrices during batch studies (hydraulic retention time (HRT): 60 days). Column experiments were then performed to differentiate between biodegradation and sorption with regard to the removal of selected PhACs. In column studies, removal efficiencies of acidic PhACs (e.g., analgesics) decreased under conditions of limited biodegradable carbon. The removal efficiencies of acidic PhACs were found to be less than 21% under abiotic conditions. These observations were attributed to sorption under abiotic conditions established by a biocide (20 mM sodium azide), which suppresses microbial activity/biodegradation. However, under biotic conditions, the removal efficiencies of these acidic PhACs were found to be greater than 59%. This is mainly attributed to biodegradation. Moreover, the average removal efficiencies of hydrophilic (polar) neutral PhACs (paracetamol, pentoxifylline, and caffeine) with low octanol/water partition coefficients (log Kow less than 1) were low (11%) under abiotic conditions. However, under biotic conditions, removal efficiencies of the neutral PhACs were greater than 98%. In contrast, carbamazepine persisted and was not easily removed under either biotic or abiotic conditions. This study indicates that biodegradation represents an important mechanism for the removal of PhACs during soil passage.
- Published
- 2011
30. Proposing nanofiltration as acceptable barrier for organic contaminants in water reuse
- Author
-
Sung Kyu Maeng, Victor Yangali-Quintanilla, Gary Amy, Maria D. Kennedy, and Takahiro Fujioka
- Subjects
Waste management ,Environmental science ,Filtration and Separation ,General Materials Science ,Sewage treatment ,Nanofiltration ,Physical and Theoretical Chemistry ,Contamination ,Reuse ,Biodegradation ,Reverse osmosis ,Biochemistry - Abstract
For water reuse applications, “tight” nanofiltration (NF) membranes (of polyamide) as an alternative to reverse osmosis (RO) can be an effective barrier against pharmaceuticals, pesticides, endocrine disruptors and other organic contaminants. The use of RO in existing water reuse facilities is addressed and questioned, taking into consideration that tight NF can be a more cost-effective and efficient technology to target the problem of organic contaminants. It was concluded that tight NF is an acceptable barrier for organic contaminants because its removal performance approaches that of RO, and because of reduced operation and maintenance (OM for 1,4-dioxane, source control or implementation of treatment processes in wastewater treatment plants will be an option; for NDMA, a good strategy is to limit its formation during wastewater treatment, but there is evidence that biodegradation of NDMA can be achieved during ARR.
- Published
- 2010
31. Organic micropollutant removal from wastewater effluent-impacted drinking water sources during bank filtration and artificial recharge
- Author
-
Sung Kyu Maeng, Emmanuel Ameda, Gesche Grützmacher, Gary L. Amy, and Saroj K. Sharma
- Subjects
Environmental Engineering ,Databases, Factual ,Fresh Water ,Water Purification ,Water Supply ,Dissolved organic carbon ,Organic Chemicals ,Waste Management and Disposal ,Water Science and Technology ,Civil and Structural Engineering ,Total organic carbon ,geography ,geography.geographical_feature_category ,Chemistry ,Ecological Modeling ,Environmental engineering ,Groundwater recharge ,Pollution ,Anoxic waters ,Carbon ,Berlin ,Wastewater ,Oxidation-Reduction ,Surface water ,Filtration ,Water Pollutants, Chemical ,Groundwater ,Water well - Abstract
Natural treatment systems such as bank filtration (BF) and artificial recharge (via an infiltration basin) are a robust barrier for many organic micropollutants (OMPs) and may represent a low-cost alternative compared to advanced drinking water treatment systems. This study analyzes a comprehensive database of OMPs at BF and artificial recharge (AR) sites located near Lake Tegel in Berlin (Germany). The focus of the study was on the derivation of correlations between the removal efficiencies of OMPs and key factors influencing the performance of BF and AR. At the BF site, shallow monitoring wells located close to the Lake Tegel source exhibited oxic conditions followed by prolonged anoxic conditions in deep monitoring wells and a production well. At the AR site, oxic conditions prevailed from the recharge pond along monitoring wells to the production well. Long residence times of up to 4.5 months at the BF site reduced the temperature variation during soil passage between summer and winter. The temperature variations were greater at the AR site as a consequence of shorter residence times. Deep monitoring wells and the production well located at the BF site were under the influence of ambient groundwater and old bank filtrate (up to several years of age). Thus, it is important to account for mixing with native groundwater and other sources (e.g., old bank filtrate) when estimating the performance of BF with respect to removal of OMPs. Principal component analysis (PCA) was used to investigate correlations between OMP removals and hydrogeochemical conditions with spatial and temporal parameters (e.g., well distance, residence time and depth) from both sites. Principal component-1 (PC1) embodied redox conditions (oxidation-reduction potential and dissolved oxygen), and principal component-2 (PC2) embodied degradation potential (e.g., total organic carbon and dissolved organic carbon) with the calcium carbonate dissolution potential (Ca(2+) and HCO(3)(-)) for the BF site. These two PCs explained a total variance of 55% at the BF site. At the AR site, PCA revealed redox conditions (PC1) and degradation potential with temperature (PC2) as principal components, which explained a total variance of 56%.
- Published
- 2010
32. Fate and effect of silver on the anaerobic digestion process
- Author
-
Sung Kyu Maeng and Spyros G. Pavlostathis
- Subjects
Thiosulfate ,Acidogenesis ,Environmental Engineering ,Waste management ,Methanogenesis ,Ecological Modeling ,Silver sulfide ,Pollution ,Silver nitrate ,chemistry.chemical_compound ,Anaerobic digestion ,Activated sludge ,chemistry ,Waste Management and Disposal ,Sludge ,Water Science and Technology ,Civil and Structural Engineering ,Nuclear chemistry - Abstract
Laboratory assays were conducted to assess the anaerobic biodegradability of a silver-bearing, waste activated sludge as well as the effect of silver compounds on the anaerobic digestion process. All assays were performed at 35°C in the dark. The ultimate biodegradability of a silver-bearing waste activated sludge (5.0 g silver/kg sludge dry solids) was 61% as compared to 59% for the control (i.e., silver-free) sludge. The rate and extent of methane production was similar for both sludge samples. Addition of either silver nitrate or silver sulfide to methanogenic, mixed cultures up to an equivalent concentration of 100 mg Ag/l did not affect the rate and extent of methane production. Silver thiosulfate when tested at an equivalent concentration of 100 mg Ag/l (and 1000 mg S/l), resulted in accumulation of ca. 28 mM of fatty acids (mainly acetate), 90% inhibition of methanogenesis and 39% inhibition of acidogenesis. However, when using silver-free, thiosulfate-amended controls, it was concluded that the observed inhibition in the silver thiosulfate-amended cultures was not attributed to the silver but rather to the excess thiosulfate (used as an alternative electron acceptor resulting in the production of soluble sulfide at inhibitory levels). Computer simulations under typical anaerobic digestion conditions using the geochemical equilibrium speciation program MINTEQA2 resulted in extremely low concentrations (
- Published
- 2000
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