• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.10a
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• pp.153-153
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• 2003

In Korea, the number of municipal and hazardous waste incinerators have been increasing since the 1980s. In addition, municipal waste incinerators (MWI) are almost always located in residential areas. Therefore, the human health risk caused by dioxin has become a growing public concern in Korea. In this report, we describe the results of study in which serum levels of PCDDs/PCDFs in a group of workers at the MWI were compared to those in a comparison group of community residents who had never worked at the MWI.

• Bulletin of the Korean Chemical Society
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• v.23 no.6
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• pp.817-824
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• 2002

Granular activated carbon(GAC) is highly effective in removing organic compounds which are resistant to biological disintegration in wastewater treatment. However, GAC has reached its full adsorptive capacity, GAC needs to be regenerated before it can be used for a further adsorption cycle. Countercurrent oxidative reaction (COR) technique has been developed and evaluated for the regeneration of spent GAC. Various parameters such as flame temperature, the loss of carbon, destruction and removal efficiency (DRE) of organic compounds, surface area, surface structure, adsorptive capacity, etc. were examined to determine the performance of COR. The results of these tests showed that adosorptive capacity of regenerated GAC was completely recovered, the loss of carbon was controllable, flame temperature was high enough to insure complete destruction and removal $(\geq99.9999%)$ of specific organics of interest, polychlorinated biphenyls (PCBs), that are thermally stable, and on formation of toxic byproducts such as polychlorinated dibenzo-p-dioxins (PCDDs) or polychlorinated dibenzofurans (PCDFs) were detected during the regeneration process. The COR technique is environmentally benign, easy to use and less copital intensive than other available regeneration technologies.

• Bulletin of the Korean Chemical Society
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• v.18 no.8
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• pp.814-818
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• 1997

The chemical waste treatment, APEG (alkali/polyethylene glycol) process has been shown to be effective for the dechlorination of PCBs in transformer oil. Considerable amount of PCBs, however, still remains in the waste exceeding the 25-50 ppm limit set by regulatory agency. A new thermal regeneration technology has been developed in our laboratory for disposal of hazardous organic wastes. Due to the limited oxidation of carbon surface through the reverse movement of flame front to oxidant flow, this technology was termed counterflow oxidative system (COS). Specially, the oxidant flow in the COS process is a principal parameter which determines the optimum conditions regarding acceptable removal and destruction efficiency of adsorbed organic wastes at minimal carbon loss. The COS process, under optimum conditions, was found to be very effective and the removal and destruction efficiency of 99.99% or better was obtained for residual PCBs in the waste while bulk (≥90%) of carbon was recovered. Any toxic formation of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzo furans (PCDFs) were not detected in the regenerated carbon and impinger traps. The results of surface area measurement showed that the adsorptive property of regenerated carbon is mostly reclaimed during the COS process.

• Journal of the Korean Applied Science and Technology
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• v.34 no.2
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• pp.327-337
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• 2017

A continuous low temperature ($510^{\circ}C{\sim}530^{\circ}C$) pyrolysis experiment in a pilot-scale of 85.3 kg/hr was carried out by the mixed feedstock of half dried digested sewage sludge and waste plastics. As a result, the amount of pyrolysis gas generated was maximum 68.3% of input dry mass and scored $40.9MJ/Nm^3$ of lower heating value (LHV), and the percentage of air inflow caused by continuous pyrolysis was 19.6%. The oil was produced 4.2% of the input dry mass, and the LHV was 32.5 MJ/kg. The sulfur and chlorine contents, which could cause corrosion of the facility, were found to be 0.2% or more respectively. The carbide generated was 27.5% of the input dry mass which shows LHV of 10.2 MJ/kg, and did not fall under designated waste from the elution test. The concentration of carbon monoxide, sulfur oxides and hydrogen cyanide of emitted flu gas from pyrolysis gas combustion was especially high, and dioxin (PCDDs/DFs) was within the legal standards as $0.034ng-TEQ/Sm^3$. Among the 47 water pollutant contents of waste water generated from dry flue gas condensation, several contents such as total nitrogen, n-H extract and cyanide showed high concentration. Therefore, the merge treatment in the sewage treatment plants after pre-treatment could be considered.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.2
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• pp.214-219
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• 2007

66 micropollutants analyses in 9 wastewater treatment plants(WWTPs) along Nak-dong river were implemented to identify the concentrations and removal efficiencies before and after treatment processes. As a result of study, the concentration levels discharged from WWTP effluents to water system were below the water quality criteria and the levels of other studies. The removal efficiencies were 84.6%(DAF/CCR) and 81.6%(AC) for 1,4-dioxane. Phenol, Clphs and PAHs were removed 94.6%, 66.4% and 80.6% respectively by the activated sludge(AS) process. The removal efficiencies of Clbzs were 45.3% for the activated sludge(AS) process and 60.6% for the activated carbon(AC) process. However, other processes besides AS and AC, the removal efficiencies of Clbzs were very low(<20%). The sand filtration(SF) process that could remove particle matters showed the best efficiency for PCDDs / Fs removal$(\geq99%)$. However, in case of relatively low PCDDs/Fs concentration level in influent, the removal efficiency was not so high$(\leq50%)$.

• Environmental Analysis Health and Toxicology
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• v.17 no.4
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• pp.285-298
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• 2002

In Korea, no CRA (comparative risk analysis) studies have been undertaken, nor have their methodologies of such studies been established. Therefore, the objectives of this study were to establish the framework of CRA consisting of health risk, economic risk and perceived risk, and to estimate and compare these risks among the three environmental problems of air pollution, indoor air pollution and drinking water contamination, which are themselves subject to the eight sub -problems of hazardous air pollutants (HAPs), regulated pollutants (representative as PM 10) and dioxins (PCDDs/PCDFs) in air pollution, indoor air pollutants (IAPs) and radon in indoor air pollution, and drinking water pollutants (DWPs), disinfection by -products (DBPs) and radionuclides in drinking water contamination in Seoul, Korea. After which, the priorities of these problems were set by individual and integrated risk. From the results, the rankings of both health risk and economical risk were in the following order: radon, PM10, IAPs, HAPs, DWPs, dioxins, DBPs, and radionuclides among the eight sub problems. On the contrary, the ranking of perceived risk was in the following order: HAPs, dioxins, radionuclides, PM10, DWPs, IAPs, Radon and then DBPs among the eight sub-problems.

• Journal of Environmental Science International
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• v.18 no.7
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• pp.709-714
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• 2009

Catalytic activities of $V_2O_5/TiO_2$ catalyst were investigated under reaction conditions such as reaction temperature, catalyst size, inlet concentration and space velocity. A 1,2-dichlorobenzene(1,2-DCB) concentrations were measured in front and after of the heated $V_2O_5/TiO_2$ catalyst bed, and conversion efficiency of 1,2-DCB was determined from it's concentration difference. The conversion of 1,2-DCB using a pellet type catalyst in the bench-scale reactor was lower than that with the powder type used in the micro flow-scale reactor. However, when the pellet size was halved, the conversion was similar to that with the powder type catalyst. The highest conversion was shown with an inlet concentration of 100 ppmv, but when the concentration was higher or lower than 100 ppmv, the conversion was found to decrease. Complete conversion was obtained when the GHSV was maintained at below 10,000 $h^{-1}$, even at the relatively low temperature of $250^{\circ}C$. Water vapor inhibited the conversion of 1,2-DCB, which was suspected to be due to the competitive adsorption between the reactant and water for active sites.

• Journal of Environmental Health Sciences
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• v.26 no.3
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• pp.11-17
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• 2000

There are among the most relevant toxic emissions from incinerators such as polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dioxin-like polychlorinated biphenyls (PCBs). Induction of cytochrome P4501A1 catalyzed 7-ethoxyresorufin O-deethylase(EROD) activity in mammalian cell culture(EROD bioassay) is thought to be a selective and sensitive parameter used for the quantification of dioxin-like components. In this study, the toxic emissions from several school waste incinerators were evaluated by determination of CYPIA catalytic activity and cytotoxicity using cell culture microbioassay. The incinerator residue and soil samples were collected from the schools located in Kyunggi province from April to June 1999. The samples were extracted in a Soxhlet apparatus using toluene for 20 hours. In order to clean-up, concentrated crude extracts were applied to basic alumina column. The EROD activities of extracts in the H4IIE cells were from 1.91$\pm$0.32 ng-TEQ/g to 24.54$\pm$3.48 ng-TEQ/g of biochemical-TEQ value. In soil samples, CYP1A catalytic activity was 0.09~0.64 ng-TEQ/g. EROD bioassay, seems to be a useful short-term bioassay when information about the biological response of complex environmental samples is needed. Although further study is needed, these results indicate that the potent toxic emissions are produced from school waste semi-incinerators.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.6
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• pp.599-605
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• 2005

The characteristics of PCDD/Fs were studied when accumulating on 1 to 4 year old pine needles that were used as passive samplers of atmospheric POPs. The rate of concentration increase was linear in lower(tetra- through hexa-) chlorinated PCDD/Fs, but higher (hepta- and octa-) chlorinated homologue concentrations did not increase with needle age. The lower were in gas phase and the higher in particles. Photodegradation rates of PCDDs on pine needles were similar to PCDFs, higher chlorinated PCDD/Fs tend to photolyze quickly. Therefore it is recommended that the younger needles should be collected to avoid errors from the depositional accumulation rates and photodegradation, and that, when comparing local concentrations of PCDD/Fs, needles of same age should be collected to reduce the errors.

• Journal of the Korean Chemical Society
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• v.43 no.3
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• pp.286-293
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• 1999

A comnprehensive process which combines chemical with thermal treatment by controlled counterflow oxidation has been developed for disposal of PCBs in transformer oil. PCBs which not completely removed by chemical treatment, after being filtered with appropriate adsorbent during the oil circulations, was thermally treated. Destruction efficiencies of better than 99.99% was obtained, with no measurable formation of PCDDs (polychlorinated dibenzo-p-dioxins) or PCDFs (polychlorinated dibenzofurans). The combination also permits high recovery of oil and inorganic supports from scrap power transformers. The process is environmentally benign, easy to use and less capital intensive than other available technologies.