• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.478-481
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• 2006

Energy is vital to global prosperity, yet dependence on fossil fuels as our primary energy source contributes to global climate change environmental degradation, and health problems. Hydrogen $(H_2)$ offers tremendous potential as a clean renewable energy currency. Hydrogen has the highest gravimetric energy density of any known fuel and is compatible with electrochemical and combustion processes for energy conversion without producing carbon-based emission that contribute to environmental pollution and climate change. Numerous methodologies have been developed for effective hydrogen production. Among them, the biological hydrogen production has gained attention, because hydrogen can be produced by cellular metabolismunder the presence of water and sunlight. The green alga Chlamydomonas reinhardtii is capable of sustained $H_2$ photoproduction when grown under sulfur deprived condition. Under sulfur deprived conditions, PSII and photosynthetic $O_2$ evolution are inactivated, resulting in shift from aerobic to anaerobic condition in the culture. After anaerobiosis, sulfur deprived algal cells induce a reversible hydrogenase and start to evolve $H_2$ gas in the light. According to above principle, we investigated the effect of induction parameters such as cell age, cell density. light intensity, and sulfate concentration under sulfur deprived condition We also developed continuous hydrogen production system by sulfate re-addition under sulfur deprived condition.

• Korean Journal of Organic Agriculture
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• v.25 no.4
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• pp.843-859
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• 2017

The JK-1 isolate which was the best producer of indole-3-acetic acid and carotenoid among the 388 strains isolated from 28 wetlands in Jeju, was identified to be Rhodopseudomonas palustirs belongs to a typical group of non sulfur purple bacteria based on 16S sRNA sequencing. This study investigated the effect of different cultural conditions of pH, temperature, agitation, light and aeration on growth, IAA and carotenoid production of photosynthetic bacterium JK-1 for optimization of IAA and carotenoid production. It was found that growth, IAA, carotenoid, and bacteriochlorophyll production with light (3,000~3,500 Lux) and agitation (100 rpm) showed better results than those with dark/static or dark/agitation (100 rpm) in anaerobic conditions. The optimal pH, temperature and agitation speed for cell growth were 7, $30^{\circ}C$, 150 rpm, for IAA production were 9, $30^{\circ}C$, 150rpm and for carotenoid production were 6, $25^{\circ}C$, 50 rpm, cultured for 72 h under anaerobic light, respectively. The growth and IAA production were high in aerobic culture compared with anaerocic culture, whereas carotenoid and bacteriochlorophyll content were decreased extremely in aerobic condition (0.5~1 vvm). Subsequently, the optimal culture conditions for JK-1 were selected with pH 7, $30^{\circ}C$ and 100 rpm under anaerobic light and the effect on plant growth was tested by pot assay. Inoculation of JK-1 with 3% (v/v) level caused increase in shoot and root dry weigh that varied from 20%~58% to 40%~28% in young radish in camparison to uninoculated treatment at 50 days of growth. The study suggests that the JK-1 isolate may serve as efficient biofertilizer inoculants to promote plant growth.

• Korean Journal of Food Science and Technology
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• v.30 no.6
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• pp.1321-1326
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• 1998

Extraction and storage conditions of oleoresin were studied from root portion of peeled garlic, an waste of garlic industry. Extraction with ethanol and methanol showed an high solid yields of $27{\sim}37%$ at the temperature range of $30{\sim}50^{\circ}C$. Two hours of extraction were found to be economic because of no significant increase in furthur extraction. Storage of the oleoresin under anaerobic condition such as vaccum or nitrogen resulted in a less changes in pH, total acidity, color and thiosulfinate content, than those changes under aerobic condition. Most of the thiosulfinate was decreased for all conditions after 14 days of storage at $25^{\circ}C$. Glucose and sucrose were increased and most of organic acids were decreased during storage under nitrogen condition. Addition of ascorbic acid and cysteine into oleoresin retained the garlic flavor, effectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.4
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• pp.508-517
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• 2020

This study aimed to determine the minimum period of aeration treatment of co-digestate to develop it as liquid fertilizer and the chemical changes that occur in the aerobic liquefying process. The co-digestates were divided into three types depending on their additives: swine slurry anaerobic digestate (SS AD), swine slurry 70% + cow slurry 30% anaerobic digestate (SS + CS AD), and swine slurry 70% + apple pomace 30% anaerobic digestate (SS + AP AD). The pH of all co-digestates increased rapidly after 3 days of aerobic treatment, but had slightly decreased in SS AD after 9 days and in SS + CS AD and SS + AP AD after 15 days. All co-digestates showed a strongly reduced pH between 27 and 36 days of aeration treatment. SS AD had lower pH value, dissolved oxygen (DO), NH₄-N, and NO₃-N content under aerobic conditions than other co-digestates. To assess the fully decomposed liquid fertilizer, a germination test was performed on the undiluted and diluted co-digestate using the liquid fertilizer germination index (LFGI) method. The relative germination ratio, relative root elongation, and germination index of SS AD were higher than those of the others. When the LFGI method was used for the germination test, all co-digestates showed an appropriate germination index of 70 after 60 days of aeration treatment. Thus, we suggest that the minimum period of aeration treatment for co-digestates might be 60 days to develop the fully decomposed liquid fertilizer.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.3
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• pp.323-329
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• 2005

In this paper, performance of a hybrid sequential aerobic-anaerobic natural system was investigated. Continuous aerobic and anoxic conditions were created by alternatively placing waste stabilization pond (WSP) and wale. hyacinth pond (WHP). Two pilot-scale treatment lines were built and operated; The first consists of WSP integrated with WHP and the second of WSP connected with Dark Pond(DP), namely control system ponds which were used to examine the effects of water hyacinth on nitrification and de-nitrification. The overall performance in nitrogen was 86% reduction in WSP-WHP and 36% in WSP-control pond system. Nitrogen was mostly removed by nitrification and de-nitrification which simultaneously occurred in the same water hyacinth ponds. For the de-nitrification, benthic layer was found out to be adequate support as a carbon source. In addition, WSP-WHP system was very effective in reducing phosphorus. Overall P removal efficiency in WSP-WHP is 81%, while it is only 16% in WSP-control. difference in phosphorus reduction between those two systems is thought to be caused by the plants and probably their roots producing extra-cellular materials, but these aspects need to be further studied.

• Journal of Korean Society on Water Environment
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• v.25 no.2
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• pp.227-234
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• 2009

In this research, a retrofitting process, which consists of a pretreatment system (coagulation) for dye wastewater combined with a biological nutrient system (MLE process using media), for a sewage treatment plant that has to treat dye wastewater efficiently with domestic wastewater were developed and a pilot plant was operated for verifying adoptability and performance of the developed advanced process for dye wastewater. From the results of the pilot plant operation, BOD 52.9%, $COD_{Cr}$ 55.9%, and color 71.3% were removed in pretreatment of coagulation process and the biodegradability of dye wastewater was improved to $0.32{\sim}0.59BOD/COD_{Cr}$ of the coagulated wastewater from $0.29{\sim}0.43BOD/COD_{Cr}$ of the raw dye wastewater. The final effluent concentrations were BOD of 8 mg/L, $COD_{Cr}$ of 43 mg/L, $COD_{Mn}$ of 18 mg/L, T-N of 8 mg/L, and T-P of 1.3 mg/L, respectively. Color was removed from 1655 to 468 unit by coagulation and then to 123 unit by MLE process. The HPLC analysis of aromatic amines in wastewater showed that decolorization was achieved by cometabolism while aromatic amines were produced by cleavage of azo bonds under anaerobic conditions and these products were removed in an aerobic tank subsequently. Nitrification rates of attached and suspended microorganisms were evaluated comparatively and the acclimating conditions of bacteria on media were validated by the scanning electron microscope.

• Safety and Health at Work
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• v.11 no.1
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• pp.109-117
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• 2020

Background: Ammonia and hydrogen sulfide are harmful gases generated during aerobic/anaerobic bacterial decomposition of livestock manure. We evaluated ammonia and hydrogen sulfide concentrations generated from workplaces at livestock farms and determined environmental factors influencing the gas concentrations. Methods: Five commercial swine farms and five poultry farms were selected for monitoring. Real-time monitors were used to measure the ammonia and hydrogen sulfide concentrations and environmental conditions during the manure-handling processes. Monitoring was conducted in the manure storage facility and composting facility. Information on the farm conditions was also collected through interview and walk-through survey. Results: The ammonia concentrations were significantly higher at the swine composting facilities (9.5-43.2 ppm) than at other manure-handling facilities at the swine and poultry farms, and high concentrations of hydrogen sulfide were identified during the manure agitation and mixing process at the swine manure storage facilities (6.9-19.5 ppm). At the poultry manure-handling facilities, the ammonia concentration was higher during the manure-handling processes (2.6-57.9 ppm), and very low hydrogen sulfide concentrations (0-3.4 ppm) were detected. The air temperature and relative humidity, volume of the facility, duration of manure storage, and the number of animals influenced the gas concentrations. Conclusion: A high level of hazardous gases was generated during manure handling, and some levels increased up to risk levels that can threaten workers' health and safety. Some of the farm operational factors were also found to influence the gas levels. By controlling and improving these factors, it would be possible to protect workers' safety and health from occupational risks.

• Journal of Microbiology and Biotechnology
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• v.26 no.8
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• pp.1452-1456
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• 2016

Overexpression of the genes encoding phosphoeneolpyruvate carboxykinase (pckA) and NAD-dependent malic enzyme (maeA) facilitates higher intracellular ATP and NAD(P)H concentrations, respectively, under aerobic conditions in Escherichia coli. To verify a hypothesis that higher intracellular energy reserves might contribute to H₂ fermentation, wild-type E. coli strains overexpressing pckA and maeA were cultured under anaerobic conditions in a glucose minimal medium. Overexpression of pckA and maeA enabled E. coli to produce 3-times and 4-times greater H₂ (193 and 284 nmol, respectively) than the wild type (66 nmol H₂). The pckA and maeA genes were further overexpressed in a hydrogenase-3-enhanced E. coli strain. The hydrogenase-3-enhanced strain (W3110+fhlA) produced 322 nmol H₂, whereas the ATP-enhanced strain (W3110+fhlA+pckA) produced 50% increased H₂ (443 nmol). Total H₂ in the NAD(P)H-enhanced strain (W3110+fhlA+maeA) was similar to that in the control strain at 319 nmol H₂. Possible explanations for the contribution of the increased cellular energy reserves to the enhanced hydrogen fermentation observed are discussed based on the viewpoint of metabolic engineering strategy.

• Journal of Environmental Science International
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• v.28 no.10
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• pp.851-861
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• 2019

In this study, we performed a sediment elution experiment to evaluate water quality in terms of phosphorus, as influenced by the dissolved oxygen consumed by sediments. Three separate model column treatments, namely, raw, calcined, and sonicated oyster shell powders, were used in this experiment. Essential phosphorus fractions were examined to verify their roles in nutrient release from sediment based on correlation analyses. When treated with calcined or sonicated oyster shell powder, the sediment-water interface became "less anaerobic," thereby producing conditions conducive to partial oxidation and activities of aerobic bacteria. Sediment Oxygen Demand (SOD) was found to be closely correlated with the growth of algae, which confirmed an intermittent input of organic biomass at the sediment surface. SOD was positively correlated with exchangeable and loosely adsorbed phosphorus and organic phosphorus, owing to the accumulation of unbound algal biomass-derived phosphates in sediment, whereas it was negatively correlated with ferric iron-bound phosphorus or calcium fluorapatite-bound phosphorus, which were present in the form of "insoluble" complexes, thereby facilitating the free migration of sulfate-reducing bacteria or limiting the release from complexes, depending on applied local conditions. PCR-denaturing gradient gel electrophoresis revealed that iron-reducing bacteria were the dominant species in control and non-calcined oyster shell columns, whereas certain sulfur-oxidizing bacteria were identified in the column treated with calcined oyster powder.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.6
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• pp.535-550
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• 2018

Total organic carbon (TOC) will replace chemical oxygen demand ($COD_{Mn}$) as an effluent water quality standard in public sewage treatment works (PSTWs) from 2021 in Korea. To ensure effective control of TOC in the effluent, investigation was carried out into TOC levels and sewage treatment operation factors in five target PSTWs using anaerobic-anoxic-aerobic ($A_2O$) processes, media, membrane, and sequencing batch reactor (SBR) technologies. TOC removal efficiencies appeared to be 93-96% on average. As a fraction of TOC, biodegradable dissolved organic carbon (BDOC) was reduced from 64% in the influent to 9% in the effluent in these PSTWs. During the investigation, biological treatment processes were applied flexibly for operation factors such as HRT, SRT, MLSS, F/M ratios and BOD volume loads, based on the influent characteristics and design conditions. As a result, we suggest efficient operating conditions in PSTWs by evaluating relationships between TOC removal and operation factors.