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Kim I.S.,Gwangju Institute of Science and Technology | Lee J.,Wonju Regional Environmental Office | Kima S.J.,Gwangju Institute of Science and Technology | Yu H.W.,University of Arizona | Jang A.,Sungkyunkwan University
Environmental technology | Year: 2014

The change in bacterial community structure induced by bacterial competition and succession was investigated during seawater reverse osmosis (SWRO) in order to elucidate a possible link between the bacterial consortium on SWRO membranes and biofouling. To date, there has been no definitive characterization of the microbial diversity in SWRO in terms of distinguishing time-dependent changes in the richness or abundance of bacterial species. For bacterial succession within biofilms on the membrane surface, SWRO using a cross-flow filtration membrane test unit was operated for 5 and 100h, respectively. As results of the pyrosequencing analysis, bacterial communities differed considerably among seawater and the 5 and 100 h samples. From a total of 33,876 pyrosequences (using a 95% sequence similarity), there were less than 1% of shared species, confirming the influence of the operational time factor and lack of similarity of these communities. During SWRO operation, the abundance of Pseudomonas stutzeri BBSPN3 (GU594474) belonging to gamma-Proteobacteria suggest that biofouling of SWRO membrane might be driven by the dominant influence of a specific species. In addition, among the bacterial competition of five bacterial species (Pseudomonas aeruginosa, Bacillus sp., Rhodobacter sp., Flavobacterium sp., and Mycobacterium sp.) competing for bacterial colonization on the SWRO membrane surfaces, it was exhibited that Bacillus sp. was the most dominant. The dominant influences ofPseudomonas sp. and Bacillus sp. on biofouling during actual SWRO is decisive depending on higher removal efficiency of the seawater pretreatment.

Kim K.,National Water Research Institute | Park M.,National Water Research Institute | Min J.-H.,National Water Research Institute | Ryu I.,Wonju Regional Environmental Office | And 2 more authors.
Journal of Hydrology | Year: 2014

A simulation framework of algal bloom in a river channel with data assimilation (DA) was developed by employing two numerical models coupled to simulate a watershed and the embedded river channel. The Hydrological Simulation Program-Fortran (HSPF) model simulates flow discharge and water quality from the subwatersheds and the Environmental Fluid Dynamics Code (EFDC) model takes the subwatershed model outputs at the watershed-river confluence points as boundary forcing to simulate river hydrodynamics and water quality. The ensemble Kalman filter (EnKF) was used for assimilation of water quality variables in the framework, linking uncertainty of model simulation and observation. The simulation uncertainty of the HSPF was quantified at the confluence points as simple stochastic error models developed by comparing the model simulation and the observation. The error models reflect uncertainty of both hydrologic and water quality simulation, including uncertainty associated with point and non-point pollution sources in the watershed. The outputs of the HSPF at the confluence points were perturbed with the error models before used in the following ensemble simulation of the EFDC for the main river. DA was conducted with weekly chlorophyll- a data observed along the river to update chlorophyll- a concentrations of the EFDC model grids. The results showed that the model performance was improved by the assimilation: the root mean square error (RMSE) and the mean continuous probability rank score (CPRS) significantly decreased compared to the open-loop simulation. The updated spatial distribution of chlorophyll- a concentration along the river channel was in reasonable agreement with the observation. Although only chlorophyll- a data was involved in the assimilation, phosphate was selected among other water quality variables for update in order to evaluate the effect of chlorophyll- a assimilation on those variables. It turned out that the phosphate simulation was not much improved by the chlorophyll- a data, which was due to weak correlation between the two variables in the model ensemble. Lastly, chlorophyll-a simulation uncertainty in the river attributed to the simulation uncertainty of each variable in the watershed was evaluated. For that, two additional simulations were made, with perturbation only to flow and phosphate respectively at the confluence points. The spread of chlorophyll- a ensemble of each case became significantly narrower than the original case, indicating that the difference is attributed to the uncertainty of the other unperturbed variables. © 2014 Elsevier B.V.

Ahn M.-C.,Wonju Regional Environmental Office | Yi S.-M.,Seoul National University | Holsen T.M.,Clarkson University | Han Y.-J.,Kangwon National University
Journal of Environmental Monitoring | Year: 2011

The characteristics of Hg wet deposition were investigated in a rural area of Korea from August 2006 to July 2008. The volume weighted mean (VWM) Hg(T) concentration and cumulative Hg(T) flux were 8.8 ng L -1 and 9.4 μg m -2 per year, respectively. The VWM Hg(T) concentration varied seasonally, similar to the seasonal pattern in atmospheric Hg(p) concentration. The enhancement of both VWM Hg(T) and atmospheric Hg(p) concentrations in spring and winter was likely caused by the long-range transport of Hg from China. Monthly VWM Hg(T) and atmospheric Hg(p) concentrations were well correlated (R 2 = 0.36); however, there was no correlation between VWM Hg(T) and RGM (reactive gaseous mercury) concentrations, suggesting that Hg(p) was responsible for the majority of the Hg in wet deposition at this site. The VWM Hg(T) concentration in snow was statistically higher than in rain. In addition, the atmospheric Hg(p) concentration appeared to be elevated for snow events as well. This suggests that both elevated Hg(p) concentrations and the enhanced scavenging efficiency of snow for Hg(p) were responsible for the elevated VWM Hg(T) concentrations measured during snow events. © 2011 The Royal Society of Chemistry.

Choi D.,B K Company Ltd | Yu S.,Chosun University | Baek S.H.,Korea Institute of Science and Technology | Kang Y.-H.,Wonju Regional Environmental Office | And 2 more authors.
Biotechnology and Bioprocess Engineering | Year: 2016

In the present study, we synthesized 65 dichlorobenzylamine derivatives and investigated their algicidal activity against harmful red tides. The 3,4-dichlorobenzylamine derivatives showed relatively high activity against Cochlodinium polykrikoides, Heterosigma akashiwo, Chattonella marina, and Heterocapsa circularisquama, and the synthesized compounds 27, 28, 33, 34, 35, and 36 showed the highest algicidal activity after 24 h at 0.1 ~ 1.0 μM LC50 against the four harmful algae species. To verify the safety of the compounds, acute ecotoxicology tests using the water flea (Daphnia magna) and zebrafish (Danio rerio) were conducted, and the tests confirmed that compounds 33 and 34 were not harmful because the target organisms showed high survival rates at 15 μM. The results indicate that compounds 33 and 34 are suitable substances for use in controlling harmful algae species. © 2016, The Korean Society for Biotechnology and Bioengineering and Springer-Verlag Berlin Heidelberg.

Tsukada M.,Shinshu University | Khan Md.M.R.,University of Manitoba | Inoue E.,Shinshu University | Kimura G.,Shinshu University | And 3 more authors.
International Journal of Biological Macromolecules | Year: 2010

To study the properties and structure of aquatic silk, nest-spinning hydropsychid caddisfly (Stenopsyche marmorata) larva were collected from a Japanese river and the silk glands were removed from the larva by dissecting and dried on the glass plate at room temperature. The silk fibers were obtained by removing fibrous materials, which the aquatic insects spun at the bottom of glass container and the microstructure and physical properties of aquatic silk protein fibres and their solid silk protein gland were evaluated. Silk fiber produced by the caddisfly larvae is composed of two filament embedded in a layer of glue. The results of Fourier transform infrared spectroscopy and X-ray diffraction measurements suggested the existence of binary structure containing random coil conformation and additional minor β-molecular structure. Differential scanning calorimetry results are characterized by two broad endothermic transitions, at 230 °C and 320 °C, which corresponds to the decomposition of silk glue and silk fiber from caddis fly, respectively. The storage modulus (E′) remained almost unchanged and nearly constant at above 60 °C until about 214 °C, where it began to show a sharp drop. A prominent relaxation peak appeared in the imaginary part of the modulus (loss peak at 230 °C), in response to the strong motional transitions exhibited by the silk fiber at this temperature. There was significant difference of tensile strength of single solid silk protein gland in dry and wet state. The results obtained are quite promising as a basis for possible future biotechnological and adhesive applications of aquatic silk. © 2009 Elsevier B.V. All rights reserved.

Joo J.-H.,Hanyang University | Kang Y.-H.,Wonju Regional Environmental Office | Park B.S.,Hanyang University | Park C.-S.,Hanyang University | And 2 more authors.
Journal of Applied Phycology | Year: 2015

Although many algicidal substances have been developed, their field application remains a serious challenge due to their high toxicity in the ecosystem and also due to economic reasons. Therefore, we evaluated the claim that naphthoquinone (NQ) derivatives can be used for the efficient mitigation of natural Stephanodiscus hantzschii blooms in freshwater. We tested a total of 23 algicidal NQ compounds to select the best based on the algicidal activity of S. hantzschii species. Among them, NQ 4–6 showed the highest algicidal activities (96 % at ≥0.2 μM). We conducted an acute toxicity assessment of the new algicide and found that NQ 4–6 had advanced solubility and lower toxicity, as represented by the survival rates of Selenastrum capricornutum, Daphnia magna, and Danio rerio, which are interconnected components of the freshwater ecosystem. None of these organisms seemed to be affected by the highest NQ concentration (2 μM), indicating a lack of significant toxic effects. These results indicate that the NQ 4–6 compound is promising for use as a selective control agent for S. hantzschii that does not cause negative side effects in the freshwater ecosystem. To evaluate the possibility of field application of NQ 4–6, we first performed microcosm tests. In the microcosm tests (60 L), S. hantzschii was completely eliminated 10 days after inoculation with the NQ 4–6 compound (0.2 μM). In the microcosm experiments, the dynamics of the biotic (except the phytoplankton) and abiotic factors showed similar trends in the control and treatment groups. Therefore, the NQ 4–6 compound has potential as an alternative algicidal substance to effectively mitigate natural S. hantzschii blooms. © 2015 Springer Science+Business Media Dordrecht

Kim S.-J.,Gwangju Institute of Science and Technology | Lee J.,Wonju Regional Environmental Office | Yu H.-W.,University of Arizona | Kim I.S.,Gwangju Institute of Science and Technology
Desalination and Water Treatment | Year: 2013

Aquaporin biomimetic membrane can only transfer water molecules in and out of the membrane while preventing the passage of other smaller ions and solutes. AquaporinZ (AqpZ), widely spread in Escherichia coli cell membrane, has shown higher water permeability than conventional membranes. Application of those exceptional properties as water purification membrane material is promising. The objective of this study was to assess protein expression conditions for AqpZ mass production. Recombinant AqpZ was successfully synthesized and identified via sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and western blot analysis. The highest level of expression of his-tagged AqpZ (12.2 mg/L) was achieved using E. coli BL21(DE3) host strain by the addition of 0.1 mM isopropyl-b-D-thiogalactoside and 5 h postinduction time. Subsequently, solubilization and purification of his-tagged AqpZ were carried out. © 2013 Copyright Balaban Desalination Publications.

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