• The Korean Journal of Pesticide Science
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• v.6 no.4
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• pp.309-319
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• 2002

Soil adsorption study was carried out to define the mobility of pesticides or to evaluate leaching potential in soils. Five pesticides including ethoprophos, procymidone, iprobenfos, isoprothiolane, and butachlor were subjected to optimized adsorption experiment protocol for three types of cultivation soils. Freundlich adsorption coefficients (K) were ranged $0.35{\sim}0.95$ for ethoprophos, $0.98{\sim}2.2$ for iprobenfos, $1.2{\sim}4.3$ for procymidone, $1.5{\sim}3.5$ for isoprothiolane and $7.9{\sim}19$ for butachlor in three soils. Based on Koc values, ethoprophos was classified as mobile, iprobenfos, isoprothiolane and procymidone as moderately mobile and butachlor as slightly mobile. Two evaluation methods, Groundwater Ubiquity Score (GUS) index and standard indices of soil-chemical adsorption and biodegradation, were used for the estimation of pesticide leaching potential. Leachability of isoprothiolane and iprobenfos were evaluated as moderate, ethoprophos as a little potential, while butachlor and procymidone showed very low leaching potential. The leaching potential of pesticides was essentially determined on the basis of intrinsic properties of the pesticides and environmental properties. Among the soil properties, organic matter gave a great influence on the leachability of soils. Therefore, leachabilities of pesticides were expected less in loam with relatively higher organic matter than clay loam with lower organic matter.

• The Korean Journal of Pesticide Science
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• v.20 no.3
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• pp.203-210
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• 2016

Polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants, found in the many environments. PCBs exerts various toxicological effects, including endocrine-disrupting activity. Most researches with these toxicants performed with soil matrix with mixtures of congeners, namely Aroclor, while the biological activities have been tested with animals. However, studies with pure congeners are limited. In this study, 5 congeners were synthesized and their fates (bioaccumulation, degradation, kinetics) were studied in carrot-soil system. The soil half-lives of biphenyl, PCB-1, PCB-3, PCB-77, and PCB-126 were 20.2, 16.0, 11.6, 46.5, 198.0 days, respectively. In general, the longer half-lives were observed with the higher hydrophoicity of PCBs. Times, required for maxium accumulation of PCBs in carrot (Tmax) were 10-20 days for most congeners and the concentrations were 0.4-2.6 mg/kg. The concentrations of PCBs in carrot were kept as constant after Tmax, except PCB-126. The concentration ratio between carrot and soil after 90 days of treatment were 1.7, 8.1, 1.9, 1.8, and 5.9 for biphenyl, PCB-1, PCB-3, PCB-77, and PCB-126. Because of the increase of biomass, the total residual amount of PCBs in carrots however, increased till the end of experiment. The portions of PCB-126 in carrot were 1.1% of the soil residues at 90 days after planting.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.64-71
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• 2018

The purpose of this study is to investigate the characteristics of the substrate of dairy wastewater through aerobic biodegradation and to use the results as the basic data for the efficient treatment of dairy wastewater. The SCODcr of the part of the matter that consisted of readily biodegradable organics (Ss) was 84.2%, which is higher than those of seafood processing wastewater (75.8~77.9%) and pigpen wastewater (58.2%). The proportion of non-biodegradable organics (SI) ranged from 5.6% to 6.4%, and the proportion of inert organics (SIi) generated by microbial metabolism ranged from 3.6 to 3.7%. The content coefficient (YI) of the non-biodegradable dissolved organic matter was in the range of 0.092 to 0.099, and the generation coefficient (Yp) of the inert substance produced by the microbial metabolism was in the range of 0.039 to 0.040. The analysis results of the organic component coefficient showed that approximately 91.0% of the dissolved organic matter of the dairy wastewater was biodegradable, and approximately 92.5% of the dissolved organic matter was the Ss component. Furthermore, the proportion of biodegradable organic matter in the total organic matter (TCODcr) was 89.3%. The proportions of non-biodegradable organics (SI) and non-biodegradable suspended organics (XI) were 3.0% and 7.7%, respectively, which are lower than those in similar wastewater. This means that the milk processing wastewater has a high aerobic biodegradability.

• Microbiology and Biotechnology Letters
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• v.39 no.2
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• pp.161-167
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• 2011

We previously showed that five strains belonging to Pseudomonas could remove TPH (Total Petroleum Hydrocarbons) efficiently when they are applied to TPH-contaminated soil. We optimized the bioremediation condition using different hydrocarbons and nutrients conditions to improve the efficiency. We setup lab-scale column bioreactor to monitor TPH and diesel removal efficiency. When we applied five Pseudomonas sp. mixtures to 25,000 $mg{\cdot}kg^{-1}$ TPH-contaminated soil (diesel 10,000 $mg{\cdot}kg^{-1}$, kerosene 10,000 $mg{\cdot}kg^{-1}$, gasoline 5,000 $mg{\cdot}kg^{-1}$) with the optimum condition, 76.3% of TPH removal efficiency was shown for 25 days. Meanwhile, in the application of five Pseudomonas sp. mixtures to 20,000 $mg{\cdot}kg^{-1}$ diesel-contaminated soil with the optimum condition, 99.2% of diesel removal efficiency was shown for 40 days. In the application to lab-scale bioreactor with five high efficiency bacteria, 88.5% of TPH removal efficiency was shown for 45 days. Based on the results from this study, we confirmed that this mixed Pseudomonas sp. consortium might improve the bioremediation of TPH in contaminated soil, the efficacy can be controlled by improving the nutrients. We also confirmed that the nutrients and oxygen for biodegradation of TPH could contribute on the management and control of applications of these strains for the study of bioremediation of TPH-contaminated soil.

• Polymer(Korea)
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• v.36 no.3
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• pp.326-331
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• 2012

In this study, expanded poly(tetrafluoro ethylene) (ePTFE) graft was modified to be used as a hemodialysis vascular access. Biodegradable poly(D,L-lactide-$co$-glycolide) (PLGA) was coated onto the inner surface of ePTFE graft with paclitaxel, which is often used as an anti-cancer agent and for reducing neointimal hyperplasia. Surface characterization before and after PLGA coating was carried out by SEM and ATR-FTIR. Porous sturcture of ePTFE was maintained after coating of PLGA solution. The amounts of coated PLGA and paclitaxel determined by ATR-FTIR and HPLC were 1.96 and 0.263 mg/$cm^2$, respectively. Young's modulus was decreased and tensile strength was increased by PLGA coating. Released paclitaxel as a function of incubation time was monitored by HPLC. Approximately 35% of coated paclitaxel was released steadily for 4 weeks with the biodegradation of PLGA. From these results, it is expected that the effect of paclitaxel on reducing neointimal hyperplasia and stenosis is maintained for a long time.

• Polymer(Korea)
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• v.33 no.5
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• pp.469-476
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• 2009

In this study, biodegradable superporous hydrogels(SPHs) with fast swelling and superabsorbent properties were prepared using biodegradable crosslinkers and their physicochemical properties were characterized. A biodegradable crosslinker (PLA-PEG-PLA DA) was synthesized by a ring opening polymerization of D,L-lactide (LA) using hydrophilic poly(ethylene glycol) as a macroinitiator, followed by diacrylation of the end groups for the introduction of polymerizable vinyl groups. Various kinds of hydrogels with different chemical compositions were prepared and characterized in terms of swelling ratio, swelling kinetics, and biodegradation properties. The synthetic results were confirmed by $^1H$-NMR, FT-IR and GPC measurements, and the porous structures of the prepared SPHs and their porosities were identified by a scanning electron microscope and mercury porosimetry, respectively. The physicochemical properties of SPHs could be controlled by varying their chemical compositions and their cytotoxicity were found to be very low by MTT assay.

• Journal of the Korea Organic Resources Recycling Association
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• v.10 no.1
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• pp.109-119
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• 2002

This study is to estimate that food waste bags with biodegradable plastic are really decomposed by microorganism in composting with food waste and to examinate how biodegradable plastic affects composting. 6 kinds of 30%, 4 kinds of 100% and 2 kinds of none biodegradable plastics were used in d1is study. In 30% biodegradable plastics the highest Degradation rare is 6% in meso-condition and 10% in thermal-condition. Srain at auto break decreased to 150% in meso-condition and 120% in thermal-condition. Stress at max load were also reduced to $180kgf/cm^2$ in mesocondition and $200kgf/cm^2$ in thermal-condition. Usually, LLDPE decreased larger than HDPE in physical characreristics but HDPE is higher in degradation rate. 1n stain at auto break and stress ar max load 100% biodegradable plastic declined to 230% and to $380kgf/cm^2$ in meso-condition and to 440% and to $400/cm^2$ in thermal-condition respectively. 100% biodegradable plastics showed higher biodegradation and decomposition then 30%. They appeared clearly through SEM observation. As a result, it was not appropriate to use 30% biodegradable plastics as food waste bag because they were not decomposed perfectly. It is possible to use 100% biodegradable plastic as it but cost is too high. So development of technique is needed.

• Journal of Environmental Science International
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• v.24 no.11
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• pp.1343-1362
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• 2015

As a result of analysis based on the observed data for BOD, COD and TOC in order to manage non-biodegradable organics in the Geumho River, COD/BOD ratio was analyzed as the occupying predominance proportion. In this study, the classification(changes in water quality measurement : increase, equal, decrease) and measurement of BOD and COD were analyzed for trends over the past 10 years from 2005 to 2014 in the Geumho River. The Geumho River is expected to need non-biodegradable organics management because BOD was found to be reduced 61.1% and COD was found to be increased 50%. As a result of the analysis of land use, the Geumho-A is a unit watershed area of $921.13km^2$, which is the most common area that is occupied by forests. The Geumho-B is a unit watershed area of $436.8km^2$, which is the area that is highest occupied by agriculture and grass of 24.84%. The Geumho-C is a unit watershed area of $704.56km^2$ accounted for 40.29% of the entire watershed, which is the area that is occupied by urban of 15.12%. Load of non-biodegradable organics, which is not easy biodegradable according to the discharge, appeared to be increased because flow coefficient of COD and TOC at the Geumho-B were estimated larger than 1 value. The management of non-point sources of agricultural land is required because the Geumho-B watershed area occupied by the high proportion of agriculture and field. In this segment it showed to increase the organics that biodegradation is difficult because the ratio of BOD and TOC was decreased rapidly from GR7 to GR8. Thus, countermeasures will be required for this.

• Journal of Periodontal and Implant Science
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• v.25 no.3
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• pp.603-613
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• 1995

The purpose of this investigation was to evaluate on the biodegradability, biocompatibility and tissue regenerative capacity of synthetic bioabsorbable membranes in beagle dogs. For animal study, 9 adult beagle dogs were used to examination, on the surgical implantation of membranes and histological analysis. In each animal, the 3rd and 4th premolars of the both sides of the mandible were selected as test teeth. Two types of bioresorbable membranes including "Guidor membrane", "S-membranes" were used to examining for biological activity, and also Gore-tex membranes was used for positive control. Surgically created defects were made in 2 premolars of both sides of the mandible at $3{\times}4mm^2$ in size and tested membranes were implanted in the defected area. A plaque control regimen was instituted with daily tooth brushing with a 0.1% chlorhexidine digluconate during experimental periods. All the experimental animals were sacrificed after 2, 4, and 8 weeks from surgery and undecalcified slides were prepared using the "sawing and grinding" technique described by Donath and Breuner". In biodegradability, all the membranes were started their biodegradation from two weeks after implantation and gradually demolished of their frame morphology from eight weeks. However, demolition of membranes in 8 weeks after implantation was highest in Guidor membranes and followed by S-membranes. Biocompatibilityof two kinds of biodegradable membranes including Guidor and S-mambrane were shown to be well tolerated to the surrounding tissue, and were minimal accumulation of inflammatory cell infiltration around the implanted membranes to compare with Gore-tex membrane. Regeneration of defected alveolar bone was initiated from two weeks of membrane implantation and new bone formation was gradually increased from that time. However, pattern of new bone formation on the defected areas of two kinds of biodegrable membranes was almost similar and quite competitive comparing with Gore-tex membrane. These results implicate that bioresorbable membranes should be highly useful tool for guided tissue regeneration of periodontal defects.

• Journal of Periodontal and Implant Science
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• v.33 no.2
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• pp.301-310
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• 2003

The purpose of this study is to evaluate the biocompatibility and the biorsorbability of several types of calcium polyphosphate made through change of manufacturing process for 12 month. To solve limitation of calcium phosphate, we developed a new ceramic, Calcium Polyphosphate(CPP), and report the biologic response to CPP in extraction sites of beagle dog. Porous CPP blocks were prepared by condensation of anhydrous $Ca(H_2PO_4)_2$ to form non-crystalline $Ca(PO_3)_2$ and then milled to produce CPP powder. CPP powder, CPP block, and CPP granules added with $Na_2O$ were implanted in extraction sockets and histologic observation were performed at 12 months later. Like 3 months results, histologic observation at 12 months revealed that CPP matrix were mingled with and directly apposed to new bone without any adverse tissue reaction, CPP powder show direct bony contact, but new bone formation and fibrous tissue encapsulation showed in CPP block. 10% $Na_2O$ CPP granules show more inflammatory cells infiltration around graft materials compared at 3 month, but 15% $Na_2O$ CPP granules show less. This result revealed that regardless of addition of $Na_2O$, CPP had a high affinity for bone and had been resorbed slowly. From this results, it was suggested that CPP is promising ceramic as a bone substitute and addition of $Na_2O$ help biodegradation but optimal concentration of $Na_2O$ and other additive component to increase degradation rate should be determined in further study.