• Journal of Soil and Groundwater Environment
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• v.15 no.3
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• pp.15-26
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• 2010

The contaminated soils near abandoned mine area can threaten human's health and natural ecosystems through multiple pathways. Remediation of contaminated soil using physicochemical technologies are expensive and destructive of soil environments. On the other hand, environmentally friendly approach that maximize biological remediation, that is, phytoremediation, attracts attention as a low carbon green growth technology. This research is a field demonstration study, focused on the enhanced phytoremediation by bioaugmenting PGPR(Plant Growth Promoting Rhizobacteria)that is helpful on the growth of and heavy metal removal by Echinochloa frumentacea, at a Zn contaminated paddy soil near SamBo mine at Hwasung, Kyunggi. The results showed that the zinc removal by the plant with PSM(Phosphate Solubilizing Bacteria), a kind of PGPR, was three times higher than that by the control. The results are valuable as it is a result from the field-scale technology demonstration. The results also implies that application of PGPR can enhance heavy metal removal from contaminated soil in full scale phytoremediation using Echinochloa frumentacea.

• Journal of Periodontal and Implant Science
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• v.33 no.4
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• pp.651-671
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• 2003

The influence of calcium phosphate (Ca-P) coating on the bone response of titanium implants was investigated two types of titanium implants, i.e. as -machined ,as -machined with Ca-P coating, were prepared. The Ca-P coating produced by OCT Inc technique. These implants were inserted into the left and right femur of beagle dog, After implantation periods of 3 days, 1weeks, weeks, 4weeks, 8weeks, 12weeks. 24weeks, the bone-implant interface was evaluated histologically, histomorphometrically , and removal torque. Histological evaluation revealed no new bone formation around different implant materials after 2weeks of implantation. After 4 weeks, Ca-P coated implants showed a higher amount of bone contact than either of the non coated implants. After 12weeks, bone healing was almost completed. And implant were removed by reverse torque rotation with torque-measuring device. Mean torque values for 4weeks control were 2.375Kgf.cm and experimental were 2.725Kgf.cm. And mean torque values for 8weeks control were 1.25Kgf.cm and experimental were 1.0Kgf.cm On the basis of these findings, we concluded that deposition of a Ca-P coating on an implant has a beneficial effect on the bone response to this implant during the healing phase. Besides implant surface conditions the bone response is also determined by local implant site condition.

• Journal of Microbiology and Biotechnology
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• v.18 no.12
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• pp.1958-1965
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• 2008

A denitrifying polyphosphate-accumulating bacterium (YKP-9) was isolated from activated sludge of a 5-stage biological nutrient removal process with step feed system. This organism was a Gram-negative, coccus-shaped, facultative aerobic chemoorganotroph. It had a respiratory type of metabolism with oxygen, nitrate, and nitrite as terminal electron acceptors. The 16S rRNA gene sequence of strain YKP-9 was most similar to the 16S rRNA gene sequence of Paracoccus sp. OL18 (AY312056) (similarity level, 97%). Denitrifying polyphosphate accumulation by strain YKP-9 was examined under anaerobic-anoxic and anaerobic-oxic batch conditions. It was able to use external carbon sources for polyhydroxyalkanoates(PHA) synthesis and to release phosphate under anaerobic condition. It accumulated polyphosphate and grew a little on energy provided by external carbon sources under anoxic condition, but did neither accumulate polyphosphate nor grow in the absence of external carbon sources under anoxic condition. Cells with intracellular PHA cannot accumulate polyphosphate in the absence of external carbon sources under anoxic condition. Under oxic condition, it grew but could not accumulate polyphosphate with external carbon sources. Based on the results from this study, strain YKP-9 is a new-type denitrifying polyphosphate-accumulating bacterium that accumulates polyphosphate only under anoxic condition, with nitrate and nitrite as the electron acceptors in the presence of external carbon sources.

• Journal of Periodontal and Implant Science
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• v.40 no.6
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• pp.257-264
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• 2010

Purpose: Connective tissue reattachment to periodontally damaged root surfaces is one of the most important goals of periodontal therapy. The aim of this study was to develop a root conditioning agent that can demineralize and detoxify the infected root surface. Methods: Dentin slices obtained from human teeth were treated with a novel root planing agent for 2 minutes and then washed with phosphate-buffered saline. Smear layer removal and type I collagen exposure were observed by scanning electron microscopy (SEM) and type I collagen immunostaining, respectively. Cell attachment and lipopolysaccharides (LPS) removal demonstrated the efficiency of the root conditioning agent. Results: SEM revealed that the smear layer was entirely removed and the dentinal tubules were opened by the experimental gel. Type I collagen was exposed on the surfaces of the dentin slices treated by the experimental gel, which were compared with dentin treated with other root planing agents. Dentin slices treated with the experimental gel showed the highest number of attached fibroblasts and flattened cell morphology. The agar diffusion assay demonstrated that the experimental gel also has effective antimicrobial activity. Escherichia coli LPS were effectively removed from well plates by the experimental gel. Conclusions: These results demonstrated that this experimental gel is a useful tool for root conditioning of infected root surfaces and can also be applied for detoxification of ailing implant surface threads.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.22 no.1
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• pp.1-17
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• 2017

This study was conducted to investigate the nutrient distribution and controlling factors in small stream estuaries. The seasonal variations of nutrient concentration (nitrate, ammonium and phosphate) were observed from 2010 to 2012 in the three streams located in Dang-hang (closed estuary: Go-seong, open estuary: Gu-man and Ma-am). The nutrient concentrations in Go-seong were significantly higher than other estuaries, because Go-seong is relatively large and has large nutrient load from the watershed. The dyke located at the estuary, also, caused the high nutrient concentration by reducing the dilution and increasing residence time. In all three streams, nitrate concentration was high at upstream and decreased toward the downstream, because high load of nutrient input were located at upstream. Dilution and biogeochemical removal toward the downstream also caused the trends. Especially, denitrification, a typical nitrogen removing process showed clear tendency of gradual decreasing from upstream to downstream. However, Ammonium and phosphate concentrations were high at upstream and decreased toward the downstream only when the nutrient loads from the rivers were high. Nutrient concentrations were low in summer and high in winter. Freshwater discharge in summer caused a decrease of the residence time and increase of the transport of nutrients to downstream and reduced the nutrient concentrations in the estuary. Nutrient removal by the biological production during high temperature periods also affected the low nutrient concentrations. Small stream estuaries showed distinct nutrient dynamics. It is necessary to understand these characteristics in order to properly manage the small stream estuary.

• KSBB Journal
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• v.18 no.3
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• pp.211-216
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• 2003

The removal yield of dissolved organic matter in drinking water by biological activated carbon (BAC) process was investigated. The tested processes wer raw water-AC process (BAC1), raw water-ozonation-BAC process (BAC2), and raw water-ozonation-coagulation/sedimentation-BAC process (BAC3). The amounts of organic matter was measured as dissolved organic carbon (DOC), ulta-violet radiation at 254 nm wavelength ($UV_{254}$), total nitrogen (T-N), ammonia nitrogen (NH_3$-N), and total phosphate (T-P). As a results, 30.7% DOC was removed by BAC2 process, which showed higher removal efficiency than BAC1 or BAC3 processes. The removal yield of $UV_{254}$ in BAC1, BAC2, and BAC3 processes were observed as 45.3%, 44.6%, 58.4%, respectively. And the removal yield of ammonia nitrogen were 66%, 81%, 29% in each BAC processes. The optimal empty bed contact time (EBCT) of BAC processes was estimated as 10 minute. This study has shown that BAC process combined with ozone treatment was efficient for removing dissolved organic matter in water.

• Journal of the Korean earth science society
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• v.43 no.2
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• pp.303-311
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• 2022

Gadolinium, commonly used as a contrast agent for magnetic resonance imaging (MRI), is discharged into aquatic environments without removal after treatment in wastewater treatment plants (WWTPs) because of its high stability. In this study, we collected water samples from Suyeong WWTP, Busan, to investigate the dissolved rare earth element (REE) removal capacity of each wastewater treatment process and to evaluate the discharge of anthropogenic Gd (Gd_anth) from effluents. As wastewater passed through each stage of treatment, the concentrations of light REEs (La-Eu) decreased, whereas those of heavy REEs (Tb-Lu) were relatively consistent. Negative Sm anomalies (<1) were observed in several samples, indicating that Sm can be removed by adsorption onto particles or phosphate during the biological removal process. Positive Gd anomalies (149±50, n=9) were observed in all samples. The ratios of Gd_anth concentrations to measured Gd concentrations in all wastewater treatment processes were higher than 97%. This indicates that Gd_anth was discharged to the Suyeong River without removal during the wastewater treatment process. Considering the daily treatment capacity in each process, the total flux of Gd_anth was estimated to be 259 mmol/day. Our results suggest that mid- and/or long-term monitoring of Gd is needed because Gd_anth is continuously discharged into Suyeong Bay through WWTPs.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.4
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• pp.334-340
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• 1997

It was proven that rice straw can serve can serve as a good support medium for trickling filter with livestock wastewater treatment. The efficiency of removal of removal of environmentally undesirable components from the wastewater by the straw medium was no less inferior to other commonly used support materials. The treated straw was also proven to be a source of abundant plant nutrients. The growth of orchard grass was enhanced greatly by the application of large quantity of the support medium. A maximum yield of dry matter was obtained at the rate of 40 ton/ha. Inorganic NPK elements as background fertilizers were highly recommended for better development in an early stage of growth. The nutritional status of the soil was very much improved by the addition of the medium in terms of exchangeable cations(K, Ca, Mg and Na), available phosphate, and organic matter contents. Nutrient uptake by orchard grass such as N, P and cations was enhanced by rice straw medium treatment and that was proportional to the levels of treatment.

• Applied Biological Chemistry
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• v.41 no.6
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• pp.465-470
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• 1998

For the need of bio-degradable flocculant in stage of wastewater treatment, some cultural conditions of bioflocculant production were optimized with Aeromonas hydrophila KH-54. About 260 strains of type culture and bacteria isolated from marsh, pond, activated sludge, etc were examined for their ability to flocculate kaolin particles and swine wastewater. Among them, KH-54 showed the highest flocculating activity and was identified as Aeromonas hydrophila according to the cultural, morphological and physiological properties. The maximum production of the flocculant secreted by Aeromonas hydrophila KH-54 was observed in culture medium containing 2.0% mannitol, 0.05% ammonium chloride, 0.02% potassium phosphate dibasic, 0.01% $MgSO_4{\cdot}7H_2O$ and 0.05% yeast extract at initial pH 7.0 when cultured on rotary shaker controlled at $25^{\circ}C$ and 150 rpm. Under the optimized condition, the flocculating ability reached to 770 units/ml of kaolin flocculating activity and 81% of NTU removal efficiency against swine wastewater after 4 days cultivation. The bioflocculant was also effective on various organic wastewaters other than swine wastewater, showing NTU removal rate ranging from 92% to 34%.

• Journal of Korea Soil Environment Society
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• v.4 no.1
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• pp.97-108
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• 1999

Reduction 2, 4, 6-trinitrotoluene by zero valent iron was studied in a batch reactor under anoxic conditions. Results showed that the removal of trinitrotoluene (TNT)followed a pseudo-first order reaction and the rate was linearly dependent on the available reactive surfau area of the zero valent iron surface area, resulting a rate constant of 0.0981min$^{1}m$$^{-2}m$. High concentrations of the final product, presumably triaminotoluene which needs to be treated by other means, accumulated in the solution. However , little amount of TAT was extracted from the metal surface by using acetonitrile or phosphate buffered water (pH 7.0). Other common major intermediate in biological TNT degradation, a group of aminodinitrotoluenes, was not detected in the solution. Therefore, it is postulated that the reduction of nitro group by $Fe^0$ occurs simultaneously in all three positions and a TNT reduction model by zero valent iron was suggested.