https://scholar.korea.ac.kr/handle/2021.sw.korea/2742 2026-04-05T16:16:41Z https://scholar.korea.ac.kr/handle/2021.sw.korea/141852 Title: Insights into the minimization of excess sludge production in micro-aerobic reactors coupled with a membrane bioreactor: Characteristics of extracellular polymeric substances Authors: Cheng, Yu; Tian, Kun; Xie, Peng; Ren, Xianghao; Li, Ying; Kou, Yingying; Chon, Kangmin; Hwang, Moon-Hyun; Ko, Myung-Han Abstract: The production of excess sludge by the activated sludge system of wastewater treatment plants is a problem. In this study, the EPS characteristics on production and degradation were investigated in the real-scale food processing wastewater treatment system (i.e., a micro-aerobic reactor coupled with a membrane bioreactor (MAR-MBR)) with a treatment capacity of 150 t d(-1), which could cater for the low production of excess sludge (i.e., 9 t.a(-1); 76% moisture content). The total organic carbon concentrations in the different EPS fractions were in the following order: soluble EPS (S-EPS) < loosely bound EPS (LB-EPS) < tightly bound EPS (TB-EPS). Although the components (e.g., protein and humic acid-like substances) of each EPS fraction changed significantly throughout the MAR-MBR process owing to the low production of excess sludge, the degrees of change in S-EPS, LB-EPS, and TB-EPS were significantly different from the corresponding change in their relative molecular weights. Furthermore, the microbial community composition was beneficial for the release and degradation of EPS, and the regulation of gene functions via the MAR-MBR enhanced this process. 2022-04-01T00:00:00Z https://scholar.korea.ac.kr/handle/2021.sw.korea/141989 Title: Evaluation of strategic directions for supply and demand of green hydrogen in South Korea Authors: Chu, Kyoung Hoon; Lim, Jihun; Mang, Ji Sung; Hwang, Moon-Hyun Abstract: Currently, worldwide efforts are being made to replace fossil fuels with renewable energy to meet the goals of the Paris Agreement signed in 2015. Renewable energy, with solar and wind power as representative examples, focuses on hydrogen as a means of supplementing the intermittency in operation. Moreover, 17 advanced countries, including Australia and Europe, announced policies related to hydrogen, and Korea joined the ranks by announcing a roadmap to revitalize the hydrogen economy in 2019. As of 2020, the unit price of renewable energy in Korea is 0.1 $/kWh and 0.12 $/kWh for solar and wind power, respectively, which are more than five times higher than those of the world's best. The significant difference is due to the low utilization of power plants stemming from environmental factors. Consequently, securing the economic feasibility for the production of green hydrogen in Korea is difficult, and the evaluation of various policies is required to overcome these shortcomings. Currently, Korea's policy on renewable energy is focused on solar power, and despite the goal for a power generation of 57,483 GWh/year centered on offshore wind power by 2034, plans for utilization are lacking. By harnessing such energy, producing a percentage of the total green hydrogen required from the hydrogen economy roadmap can be realized, but securing economic feasibility may be difficult. Therefore, reinforcements in policies for the production of green hydrogen in Korea are required, and implementation of foreign policies for overseas cooperation in hydrogen production and import is necessary. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. 2022-01-08T00:00:00Z https://scholar.korea.ac.kr/handle/2021.sw.korea/141998 Title: High efficiency of simultaneous nitrification, denitrification, and organics removal in the real-scale treatment of high C/N ratio food-processing wastewater using micro-aerobic reactors Authors: Cheng, Yu; Li, Jiao-Yang; Ren, Xianghao; Li, Ying; Kou, Ying-Ying; Chon, Kangmin; Hwang, Moon-Hyun; Ko, Myung-Han Abstract: Micro-aerobic reactors (MARs) play an important role in simultaneous nitrification, denitrification, and organics removal but are affected by the C/N ratio. In this study, high C/N ratio food-processing wastewater was treated using two-step MARs. The average removal efficiencies of total nitrogen and chemical oxygen demand during the MAR process were 84.21% and 95.43%, respectively. The efficiency of simultaneous nitrification and denitrification was 88.87% and 17.26% in MAR-1 and MAR-2, respectively; simultaneously, organic matter was efficiently degraded. Protein-like materials were biodegraded preferentially, and the degree of change in fulvic-like substances was the greatest during the MAR processes. This was attributed to the spatial distribution of the dissolved oxygen concentration in a single MAR, which may influence the microbial community composition (e. g., that of Nitrospira) and the regulation of gene functions. 2022-01-01T00:00:00Z https://scholar.korea.ac.kr/handle/2021.sw.korea/135419 Title: Variation of free volume and thickness by high pressure applied on thin film composite reverse osmosis membrane Authors: Chu, Kyoung Hoon; Mang, Ji Sung; Lim, Jihun; Hong, Seungkwan; Hwang, Moon-Hyun Abstract: Analytical technologies for polymeric membranes, including positron annihilation lifetime spectroscopy (PALS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS), were employed to understand the origin and harmful effects of thin film composite (TFC) reverse osmosis (RO) membrane compaction. Although no variation in water flux exceeding 10% from the initial flux was observed under all compaction pressures, the hydraulic pressure induced by the high-pressure pump caused a rapid contraction of the free volume and thickness of the TFC RO membrane. In particular, due to the viscoelastic polymer properties of the active layer, a reduction of approximately 15% free volume and 48% thickness was observed at a compaction pressure of 60 bar. Consequently, the analytical procedures can provide a better understanding of membrane compaction during pressurized membrane processes and strategic development to reduce the harmful effects of membrane compaction. 2021-12-15T00:00:00Z