The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Kangwoo Cho - One of the best experts on this subject based on the ideXlab platform.
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A submerged membrane bioreactor under unprecedentedly short hydraulic retention time enabled by non-woven fabric pre-filtration and electrochemical membrane cleaning
Journal of Membrane Science, 2019Co-Authors: Chong Min Chung, Kazuo Yamamoto, Kangwoo ChoAbstract:Abstract This study reports that electrochemical oxidation (EO) coupled with non-woven fabric (NWF) filter synergistically mitigated fouling in a submerged membrane bioreactor (MBR) under hydraulic retention time (HRT) of 1 h. Our NWF-EO-MBR was equipped with NWF prefilter cage surrounding microfiltration (MF) membrane with IrO2 anodes in vicinity. Continuous operation showed a retarded increase of transmembrane pressure at intermittent current density (5 mA cm−2) to prolong operation duration by 40% under constant flux (13.75 L m−2 h−1). Primary separation of bio-flocs by NWF not only reduced physically removable fouling on MF, but also allowed augmented concentration of electrolytic free chlorine (FC) near 4.0 mgCl2 L−1 inside the NWF cage. The FC degraded dissolved foulants to reduce physically irremovable hydraulic resistance of MF. A limited nitrification under the short HRT was assisted by electrochemical Breakpoint Chlorination, resulting 72% total nitrogen removal efficiency on average. Terminal restriction fragment length polymorphism fingerprinting indicated that the microbial community in mixed liquor was less influenced by FC than that in bio-cake on MF. The energy consumption of EO was approximated to 28 Wh per m3 of permeate.
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Sequential Combination of Electro-Fenton and Electrochemical Chlorination Processes for the Treatment of Anaerobically-Digested Food Wastewater.
Environmental science & technology, 2017Co-Authors: Yong Uk Shin, Ha Young Yoo, Seonghun Kim, Kyung Mi Chung, Yong Gyun Park, Kwang Hyun Hwang, Seok Won Hong, Hyunwoong Park, Kangwoo Cho, Jaesang LeeAbstract:A two-stage sequential electro-Fenton (E-Fenton) oxidation followed by electrochemical Chlorination (EC) was demonstrated to concomitantly treat high concentrations of organic carbon and ammonium nitrogen (NH4+–N) in real anaerobically digested food wastewater (ADFW). The anodic Fenton process caused the rapid mineralization of phenol as a model substrate through the production of hydroxyl radical as the main oxidant. The electrochemical oxidation of NH4+ by a dimensionally stable anode (DSA) resulted in temporal concentration profiles of combined and free chlorine species that were analogous to those during the conventional Breakpoint Chlorination of NH4+. Together with the minimal production of nitrate, this confirmed that the conversion of NH4+ to nitrogen gas was electrochemically achievable. The monitoring of treatment performance with varying key parameters (e.g., current density, H2O2 feeding rate, pH, NaCl loading, and DSA type) led to the optimization of two component systems. The comparative eva...
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Sequential Combination of Electro-Fenton and Electrochemical Chlorination Processes for the Treatment of Anaerobically-Digested Food Wastewater
2017Co-Authors: Yong Uk Shin, Ha Young Yoo, Seonghun Kim, Kyung Mi Chung, Yong Gyun Park, Kwang Hyun Hwang, Seok Won Hong, Hyunwoong Park, Kangwoo Cho, Jaesang LeeAbstract:A two-stage sequential electro-Fenton (E-Fenton) oxidation followed by electrochemical Chlorination (EC) was demonstrated to concomitantly treat high concentrations of organic carbon and ammonium nitrogen (NH4+–N) in real anaerobically digested food wastewater (ADFW). The anodic Fenton process caused the rapid mineralization of phenol as a model substrate through the production of hydroxyl radical as the main oxidant. The electrochemical oxidation of NH4+ by a dimensionally stable anode (DSA) resulted in temporal concentration profiles of combined and free chlorine species that were analogous to those during the conventional Breakpoint Chlorination of NH4+. Together with the minimal production of nitrate, this confirmed that the conversion of NH4+ to nitrogen gas was electrochemically achievable. The monitoring of treatment performance with varying key parameters (e.g., current density, H2O2 feeding rate, pH, NaCl loading, and DSA type) led to the optimization of two component systems. The comparative evaluation of two sequentially combined systems (i.e., the E-Fenton–EC system versus the EC–E-Fenton system) using the mixture of phenol and NH4+ under the predetermined optimal conditions suggested the superiority of the E-Fenton–EC system in terms of treatment efficiency and energy consumption. Finally, the sequential E-Fenton–EC process effectively mineralized organic carbon and decomposed NH4+–N in the real ADFW without external supply of NaCl
Chong Min Chung - One of the best experts on this subject based on the ideXlab platform.
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A submerged membrane bioreactor under unprecedentedly short hydraulic retention time enabled by non-woven fabric pre-filtration and electrochemical membrane cleaning
Journal of Membrane Science, 2019Co-Authors: Chong Min Chung, Kazuo Yamamoto, Kangwoo ChoAbstract:Abstract This study reports that electrochemical oxidation (EO) coupled with non-woven fabric (NWF) filter synergistically mitigated fouling in a submerged membrane bioreactor (MBR) under hydraulic retention time (HRT) of 1 h. Our NWF-EO-MBR was equipped with NWF prefilter cage surrounding microfiltration (MF) membrane with IrO2 anodes in vicinity. Continuous operation showed a retarded increase of transmembrane pressure at intermittent current density (5 mA cm−2) to prolong operation duration by 40% under constant flux (13.75 L m−2 h−1). Primary separation of bio-flocs by NWF not only reduced physically removable fouling on MF, but also allowed augmented concentration of electrolytic free chlorine (FC) near 4.0 mgCl2 L−1 inside the NWF cage. The FC degraded dissolved foulants to reduce physically irremovable hydraulic resistance of MF. A limited nitrification under the short HRT was assisted by electrochemical Breakpoint Chlorination, resulting 72% total nitrogen removal efficiency on average. Terminal restriction fragment length polymorphism fingerprinting indicated that the microbial community in mixed liquor was less influenced by FC than that in bio-cake on MF. The energy consumption of EO was approximated to 28 Wh per m3 of permeate.
Márta Vargha - One of the best experts on this subject based on the ideXlab platform.
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Formation of Chlorination by-products in drinking water treatment plants using Breakpoint Chlorination
Microchemical Journal, 2019Co-Authors: Dávid Stefán, Norbert Erdélyi, Bálint Izsák, Gyula Záray, Márta VarghaAbstract:Abstract In drinking water treatment plants generally Chlorination is applied for disinfection using Cl 2 , ClO 2 , or NaOCl reagents. In Hungary due to the relatively high ammonium ion concentration of source water originating from deep aquifiers, not only the disinfection but simultaneously the ammonium ion removal is also a crucial task to prevent the nitrite formation. For this purposes the Breakpoint Chlorination is used which needs approximately 10 times more chlorine than the disinfection resulting in enhanced formation of organic and inorganic by-products. Chlorination by-product formation was investigated in twelve drinking water treatment plants applying Breakpoint Chlorination. Trihalomethanes were detected in the highest concentration (14.7 μg/L to 143 μg/L), followed by haloacetic acids and haloacetonitriles. In 50% of the investigated water treatment plants, the concentration of trihalomethanes in finished water exceeded the Hungarian parametric value, but it was the same range as in water supplies using chlorine for disinfection. The concentration of trihalomethanes, haloacetic acids, haloacetonitriles and adsorbable organic halides in finished water was found to correlate with residual free chlorine ( r > 0.5) and raw water temperature ( r > 0.48). At high bromide concentration (c Br- > 0.2 mg/L) of the raw water the proportion of brominated by-products (trihalomethanes and haloacetic acids) increased up to 50%. Chlorate concentration was particularly high at drinking water treatment plants using hypochlorite (0.66–2.0 mg/L). By-products are mostly generated at Breakpoint Chlorination, but their additional formation within the water distribution system is also significant, especially where the concentration of free chlorine is high and the residence time is long. Elimination (potentially biodegradation) of haloacetic acids and haloacetonitriles was observed at several sampling sites. The efficiency of the granulated activated carbon filters in removing adsorbable organic halides, trihalomethanes and haloacetic acids amounted generally under 25%.
Ching-hua Huang - One of the best experts on this subject based on the ideXlab platform.
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N-nitrosodimethylamine (NDMA) formation potential of amine-based water treatment polymers: Effects of in situ chloramination, Breakpoint Chlorination, and pre-oxidation.
Journal of hazardous materials, 2014Co-Authors: Sang Hyuck Park, Lokesh P. Padhye, Pei Wang, Min Cho, Jae-hong Kim, Ching-hua HuangAbstract:Recent studies show that cationic amine-based water treatment polymers may be important precursors that contribute to formation of the probable human carcinogen N-nitrosodimethylamine (NDMA) during water treatment and disinfection. To better understand how water treatment parameters affect NDMA formation from the polymers, the effects of in situ chloramination, Breakpoint Chlorination, and pre-oxidation on the NDMA formation from the polymers were investigated. NDMA formation potential (NDMA-FP) as well as dimethylamine (DMA) residual concentration were measured from poly(epichlorohydrin dimethylamine) (polyamine) and poly(diallyldimethylammonium chloride) (polyDADMAC) solutions upon reactions with oxidants including free chlorine, chlorine dioxide, ozone, and monochloramine under different treatment conditions. The results supported that dichloramine (NHCl2) formation was the critical factor affecting NDMA formation from the polymers during in situ chloramination. The highest NDMA formation from the polymers occurred near the Breakpoint of Chlorination. Polymer chain breakdown and transformation of the released DMA and other intermediates were important factors affecting NDMA formation from the polymers in pre-oxidation followed by post-chloramination. Pre-oxidation generally reduced NDMA-FP of the polymers; however, the treatments involving pre-ozonation increased polyDADMAC's NDMA-FP and DMA release. The strategies for reducing NDMA formation from the polymers may include the avoidance of the conditions favorable to NHCl2 formation and the avoidance of polymer exposure to strong oxidants such as ozone.
Kazuo Yamamoto - One of the best experts on this subject based on the ideXlab platform.
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A submerged membrane bioreactor under unprecedentedly short hydraulic retention time enabled by non-woven fabric pre-filtration and electrochemical membrane cleaning
Journal of Membrane Science, 2019Co-Authors: Chong Min Chung, Kazuo Yamamoto, Kangwoo ChoAbstract:Abstract This study reports that electrochemical oxidation (EO) coupled with non-woven fabric (NWF) filter synergistically mitigated fouling in a submerged membrane bioreactor (MBR) under hydraulic retention time (HRT) of 1 h. Our NWF-EO-MBR was equipped with NWF prefilter cage surrounding microfiltration (MF) membrane with IrO2 anodes in vicinity. Continuous operation showed a retarded increase of transmembrane pressure at intermittent current density (5 mA cm−2) to prolong operation duration by 40% under constant flux (13.75 L m−2 h−1). Primary separation of bio-flocs by NWF not only reduced physically removable fouling on MF, but also allowed augmented concentration of electrolytic free chlorine (FC) near 4.0 mgCl2 L−1 inside the NWF cage. The FC degraded dissolved foulants to reduce physically irremovable hydraulic resistance of MF. A limited nitrification under the short HRT was assisted by electrochemical Breakpoint Chlorination, resulting 72% total nitrogen removal efficiency on average. Terminal restriction fragment length polymorphism fingerprinting indicated that the microbial community in mixed liquor was less influenced by FC than that in bio-cake on MF. The energy consumption of EO was approximated to 28 Wh per m3 of permeate.