• Journal of Microbiology and Biotechnology
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• v.26 no.3
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• pp.540-548
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• 2016

Microbially induced calcium carbonate precipitation (CCP) is a long-standing but re-emerging environmental engineering process for production of self-healing concrete, bioremediation, and long-term storage of CO₂. CCP-capable bacteria, two Bacillus strains (JH3 and JH7) and one Sporosarcina strain (HYO08), were isolated from two samples of concrete and characterized phylogenetically. Calcium carbonate crystals precipitated by the three strains were morphologically distinct according to field emission scanning electron microscopy. Energy dispersive X-ray spectrometry mapping confirmed biomineralization via extracellular calcium carbonate production. The three strains differed in their physiological characteristics: growth at alkali pH and high NaCl concentrations, and urease activity. Sporosarcina sp. HYO08 and Bacillus sp. JH7 were more alkali- and halotolerant, respectively. Analysis of the community from the same concrete samples using barcoded pyrosequencing revealed that the relative abundance of Bacillus and Sporosarcina species was low, which indicated low culturability of other dominant bacteria. This study suggests that calcium carbonate crystals with different properties can be produced by various CCP-capable strains, and other novel isolates await discovery.

• Journal of Environmental Science International
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• v.31 no.12
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• pp.1051-1059
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• 2022

This study investigated microbial communities and their diversity in a full-scale mesophilic anaerobic digester treating sewage sludge. Influent sewage sludge and anaerobic digester samples collected from a wastewater treatment plant in Busan were analyzed using high-throughput sequencing. It was found that the microbial community structure and diversity in the anaerobic digester could be affected by inoculation effect with influent sewage sludge. Nevertheless, distinct microbial communities were identified as the dominant microbial communities in the anaerobic digester. Twelve genera were identified as abundant bacterial communities, which included several groups of syntrophic bacteria communities, such as Candidatus Cloacimonas, Cloacimonadaceae W5, Smithella, which are (potential) syntrophic-propionate-oxidizing bacteria and Mesotoga and Thermovigra, which are (potential) syntrophic-acetate-oxidizing bacteria. Lentimicrobium, the most abundant genus in the anaerobic digester, may contribute to the decomposition of carbohydrates and the production of volatile fatty acids during the anaerobic digestion of sewage sludge. Of the methanogens identified, Methanollinea, Candidatus Methanofastidiosum, Methanospirillum, and Methanoculleus were the dominant hydrogenotrophic methanogens, and Methanosaeta was the dominant aceticlastic methanogens. The findings may be used as a reference for developing microbial indicators to evaluate the process stability and process efficiency of the anaerobic digestion of sewage sludge.

• Asian Journal of Atmospheric Environment
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• v.3 no.1
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• pp.19-26
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• 2009

The environmental Kuznets curve hypothesis assumes an inverted U-shaped relationship between environmental damage and income, and such curves have been used to study how economic growth affects the environment. In this study, we analyzed data for gross domestic product (GDP) per capita and for sulfur emissions in the industrialized countries of the United Kingdom, United States of America, and Japan, as well as data for the developing country of China, to determine the relationship between emissions and income in these countries. Attempts by these countries' governments to incorporate environmental policy considerations into the income-environment relationship were also examined. The potential role of the environmental Kuznets curve as a policy tool was investigated. We determined that, at least in the case of sulfur emissions, policies and institutions significantly reduced environmental degradation in the industrialized countries studied. Furthermore, the environmental Kuznets curve can reliably predict the future relationship between environmental impact and GDP for developing countries.

• Environmental Engineering Research
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• v.10 no.4
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• pp.191-198
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• 2005

A novel technology for the removal of nitrogen from wastewater, an autotrophic denitrification process with sulfur particles, has been developed. A respirometer was employed to monitor the nitrogen gas produced in the reactor, while 4',6-diamidino-2-phenylindole staining was employed to investigate the biomass distribution in terms of cell number according to the reactor height. From the respirometric monitoring, the denitrification reaction was defined as a first order reaction. The reactor was divided into 7 sections and biomass was analyzed in each section where cell number was ranged from $4.8\;{\times}\;10^6\;to\;8.7\;{\times}\;10^7$ cells/g dry weight of sulfur. Cells placed mostly in the lower layer ( < 10 cm of height). A function for biomass distribution was obtained with non-linear regression. Then a mathematical model has been developed by combining a plug-flow model with the biomass distribution function. The model could make a vertical profile of the up-flow packed-bed reactor resulting in a reasonable comparison with measured nitrate concentration with 5% of error range.

• Journal of Korean Society on Water Environment
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• v.18 no.2
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• pp.151-157
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• 2002

Landfill leachate is one of highly contaminated and heterogeneous wastewater. The leachate from initial landfill can be treated by anaerobic process because it contains biodegradable matters, particularly, volatile fatty acids (VFAs). However, the anaerobic treatment of leachate is generally required longer hydraulic retention time (HRT) than aerobic process and another treatment process to satisfy effluent concentration. Therefore the modification of conventional anaerobic treatment is needed. Two phase anaerobic membrane process (TPAMP) is an integrated membrane process to be able to separate anaerobic metabolism into two phase which are acidogenesis and methanogenesis for improvement of anaerobic treatment efficiency. In this study, the efficiency of TPAMP and conventional anaerobic treatment were compared in terms of HRT, effluent SCOD, VFAs Membrane used in TPAMP was the UF of capillary type with the surface area of $0.048m^2$. The average effluent SCOD of conventional anaerobic treatment was 1352 mg/L and the removal was 96 % at HRT 60 days, while in TPAMP, 927 mg/L and 98% at HRT 30 days.

• Environmental Analysis Health and Toxicology
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• v.23 no.1
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• pp.47-51
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• 2008

The toxicity of environmental pollutants was measured between a image of the surface topography in HeLa cells using atomic force microscopy for the possibility of toxic effect measurement and environmental monitoring. A image of the surface topography by AFM were estimated as toxic endpoints. The surface topography by AFM was observed a change of the cell surface in the environmental pollutants, but the standard of the measurement requires for the dose-effect degree. The overall results indicate that the possibility of measurement using AFM were confirmed a dose-effect degree related toxic effects, but it requres correlation between more various biomarker and AFM's measurements if the possibility of the toxic effect measurement was established.

• Structural Engineering and Mechanics
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• v.75 no.6
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• pp.723-736
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• 2020

In this paper, acoustic emission (AE) and pattern recognition are utilized to identify the AE signal signatures caused by propagation of stress corrosion cracking (SCC) in a 304 stainless steel plate. The surface of the plate is under almost uniform tensile stress at a notch. A corrosive environment is provided by exposing the notch to a solution of 1% Potassium Tetrathionate by weight. The Global b-value indicated an occurrence of the first visible crack and damage stages during the SCC. Furthermore, a method based on linear regression has been developed for damage identification using AE data.

• Journal of Microbiology and Biotechnology
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• v.24 no.2
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• pp.270-279
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• 2014

Microbial community shifts, associated with performance data, were investigated in an anaerobic batch digester treating high-solid food waste under mesophilic conditions using, a combination of molecular techniques and chemical analysis methods. The batch process was successfully operated with an organic removal efficiency of 44.5% associated with a biogas yield of 0.82 L/g $VS_{removal}$. Microbial community structures were examined by denaturing gel gradient electrophoresis. Clostridium and Symbiobacterium organisms were suggested to be mainly responsible for the organic matter catabolism in hydrolysis and acidogenesis reactions. The dynamics of archaeal and methanogenic populations were monitored using real-time PCR targeting 16S rRNA genes. Methanosarcina was the predominant methanogen, suggesting that the methanogenesis took place mainly via an aceticlastic pathway. Hydrogenotrophic methanogens were also supported in high-solid anaerobic digestion of food waste through syntrophism with syntrophic bacterium. Microbial community shifts showed good agreement with the performance parameters in anaerobic digestion, implying the possibility of diagnosing a high-solid anaerobic digestion process by monitoring microbial community shifts. On the other hand, the batch results could be relevant to the start-up period of a continuous system and could also provide useful information to set up a continuous operation.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.196-203
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• 2013

Environmental problems like global warming have now become important issues that should be considered in all industries, including construction. In South Korea, many studies have been conducted to achieve the government's goals of reduction in environmental impacts. However, the research on buildings has only focused on CO₂ emission as a research target despite the fact that other environmental impacts resulting from ozone depletion and acidification should also be considered, in addition to global warming. In this regard, this study attempted to propose assessment criteria and methods to evaluate the environmental performance of the structures from various aspects. The environmental impact category can be divided into global impacts, regional impacts, and local impacts. First, global impacts include global warming, ozone layer depletion, and abiotic resource depletion, while regional impacts include acidification, eutrophication, and photochemical oxidation. In addition, noise and vibration occurring in the building construction phase are defined as local impacts. The evaluation methods on the eight environmental impacts will be proposed after analyzing existing studies, and the methods representing each environmental load as monetary value will be presented. The methods presented in this study will present benefits that can be obtained through green buildings with a clear quantitative assessment on structures. Ultimately, it is expected that if the effects of green buildings are clearly presented through the findings of this study, the greening of structures will be actively expanded.

• Environmental Engineering Research
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• v.14 no.3
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• pp.153-157
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• 2009

Arsenic at abandoned mine sites has adversely affected human health in Korea. In this study, the feasibility of using cationic surfactant-modified activated carbon (MAC) to remove As(V) was evaluated in terms of adsorption kinetics, adsorption isotherms, and column experiments. The adsorption of As(V) onto MAC was satisfactorily simulated by the pseudo-second-order kinetics model and Langmuir isotherm model. In column experiments, the breakthrough point of AC was 28 bed volumes (BV), while that of MAC increased to 300 BV. The modification of AC using cationic surfactant increased the sorption rate and sorption capacity with regard to As(V). As a result, MAC is a promising adsorbent for treating As(V) in aqueous streams.