Application of material flow analysis for plastic waste management in the Republic of Korea.

The indiscriminate use of plastics and careless management of plastic waste have caused serious environmental challenges globally. The Republic of Korea (ROK) aims to address the issue by reducing plastic waste generation by up to 50%, and increasing recycling rate by up to 70%, by 2030. To determine the status and future directions for plastic waste management in the ROK, the present study undertook two tasks: (i) a material flow analysis of plastic waste material from industrial sectors to assess the current status of plastic waste recycling and treatment, (ii) an analysis of the material flow of plastic waste based on the "Waste Classification Code." According to the findings, 6.202 million metric tons of plastic waste were generated in 2018, out of which 69%, 25%, and 0.5% was recycled, incinerated, and landfilled, respectively. The recycling rate of synthetic resin waste, which accounts for 96% of synthetic waste polymers discharged in the industrial sector, was 69%, which is a very high rate. However, the closed-loop recycling rate was only 33%. Therefore, the system of management of synthetic resin waste discharge without classification of raw materials should be improved to increase the closed-loop recycling rate of synthetic waste polymers. Furthermore, to increase the closed-loop recycling rate, we suggest the subdivision of synthetic resin waste (51-03-01) in plastic waste classification to improve the discharge separation system, which has been mismanaged. Furthermore, we suggest the formulation of a new management strategy for plastic waste, in accordance with those of other hazardous substances, as regulated by the Waste Control Act.

Potential risk of exposure to heavy metals from co-processing of secondary wastes in the Republic of Korea.

The co-processing of secondary wastes during ordinary Portland cement (OPC) can result in high heavy metal concentrations in OPC products. However, earlier studies have not evaluated the concentrations of heavy metals (HMs) in OPC as a function of secondary input materials. Further, the health risk assessment (HRA) model has, thus far, has not been employed to assess the potential health risks associated with secondary raw materials and secondary fuels in OPC. Hence, to address these knowledge gaps, herein, monthly data for six HMs in the input materials and fuels from seven OPC manufacturers in the Republic of Korea were analyzed and modeled. Pb and Cu concentrations were found to be approximately 10-200 and 4-200 times higher than those of the other HMs, respectively. Furthermore, maximum Pb and Cu concentrations were 2-3 and 2-5 times higher than those reported in other countries, respectively. The quantity of input material had a significant influence on the observed patterns, and secondary raw materials, secondary additives, and secondary fuels were also determined to be important. Based on HRA assessment, although the risk levels were within permissible ranges, carcinogenic hazards attributable to Cr and Pb were not negligible. The results can aid in informed decision making and in implementing effective measures for managing risks associated with HMs in the OPC industry, thereby ameliorating threats to human health and environment.

Characterization of wastes from construction and demolition sector.

In Republic of Korea, construction and demolition (C&D) waste accounts for 49.9% of the total waste. In the present work, the mineralogical composition, the concentrations of 11 heavy metals, 19 PAH, and 7 polychlorinated biphenyl (PCB) congeners present in the 6 broad category (9 subcategories) of C&D hazardous waste were discussed along with their leaching characteristics. In concrete/mixed cement waste, the concentrations of As, Cr(6+), Hg, and Zn were in the range of 1.76-7.86, ND-1.63, 0.026-0.047, and 110.90-280.17 mg/kg, respectively. The asphalt waste sample A1 possessed relatively high concentrations of phenanthrene, fluoranthene, pyrene, benz(a)anthracene, benzo(a)pyrene, and indeno(1,2,3-cd)pyrene comparing to the other samples and it contains 0.08-0.1% of coal tar. Hazardous nature of the C&D wastes greatly depends on the source of the collection. Zn concentration was above 1000 mg/kg for road asphalt waste samples A4 and A5. Total PCB concentration were high in the soil waste sample S1 (130 µg/kg) as it was the excavated soil obtained from the premises of an oil station. Leaching of As, Ba, CN(-), and F(-) were observed in most of the C&D waste samples.

A study of the effect of testing for diversification of healthcare waste sterilization and crushing facilities.

This study conducted sterilization testing under different conditions using different strains for sterilization and crushing, the intermediate healthcare waste treatment phase, and proposed strategies for diversifying corresponding facilities in addition to promoting their installation. Five indicator microorganisms were selected to test the sterilization efficiency of steam, microwave, and chemical methods. Steam sterilization testing was conducted in accordance with legal and technological standards, microwave testing was carried out according to the legal standard, and chemical sterilization employed three typical compounds. Steam and microwave sterilization achieved 99.9999 % inactivation rates for all five strains under both conditions used; whereas under the chemical sterilization analyses, sodium hypochlorite (1000 ppm) failed to meet the inactivation requirement of the fungal strain Candida albicans, requiring further investigation. Based on these findings, this study presents strategies for diversifying sterilization·crushing facilities and promoting their installation.

Applicability assessment of a plasma melting technology for a fly ash recycling system in the Republic of Korea.

ABSTRACTThe Ministry of Environment of Korea has proposed a ban on landfill disposal of municipal solid waste (MSW) from 2026. Thus, it is inferred that the amount of incineration ash will increase drastically. Against this backdrop, this study assessed the applicability of a plasma melting process to fly ash. Fly ash was collected from 14 incineration facilities to analyze its basic properties and perform melting experiments. Furthermore, scanning electron microscope (SEM) analysis and economic feasibility assessment were conducted. The molten fly ash slag exhibited a pH value of 9.9, and the ignition loss of fly ash was found to range from 14.5 to 25.7 wt.%. None of seven toxic elements (arsenic (As), cadmium (Cd), cyanide (CN), mercury (Hg), hexavalent chromium (Cr(VI)), copper, and lead (Pb)) was detected from the molten slag. In addition, 99.3 wt.% of chloride ion (Cl-), 97.9 wt.% of fluoride ion (F-), and 98.1 wt.% of sulphate ion (SO42-) were removed. The contents in the molten slag were found to be 0.19, 7.8, 27.8, 33.1, and 38 mg/kg for Cd, Pb, zinc, nickel, and F, respectively, and none of CN, Hg, and As was detected, thereby meeting the criteria for soil pollution. All of the environmental standards were met, and SEM analysis confirmed stable quality with high density and no surface pore. In the economic feasibility assessment, a profit of approximately 152.4 $/ton was also estimated compared to landfill disposal.

An improved strategy for effectively managing the transboundary movement of waste based on the basel convention: A case study in South Korea.

Despite the efforts made to minimize the illegal trafficking of hazardous waste and prevent environmental pollution worldwide in accordance with the 1989 Basel Convention (BC), the illegal transboundary movement of waste and associated environmental pollution are ongoing. This study proposes a three-stage theoretical approach to effectively managing this waste. In stage one, the Convention, including its 2019 revisions, stipulates six primary requirements: clear declaration, hazardous waste, onsite inspection, responsibility, transport management, and final disposal after import. In stage two, the export and import management system is divided into four facets: customs preprocessing, customs processing, follow-up, and law. The challenges are presented of how to align the waste disposal with the Basel Convention's main requirements. Stage three presents a discussion of the effectiveness of the countermeasures derived in stage two for disposing of waste both within individual nations and internationally. Then, the theoretical approach was applied to analyzing South Korea Ministry of Environment's Act on the Transboundary Movement of Hazardous Waste and Their Disposal (revised in 2017). The strategy was demonstrated to be an improvement, and these study results can be foundational data to newly establish laws or revise existing acts on transboundary movement of waste (TMW) in each country.

A Study on Safety Management Plan for Recycling of Medium-Contact Wastes via Ecotoxicity Assessment.

In South Korea, hazardous characteristics of wastes to be recycled are managed through the "Environmental Impact Assessment of Recycling" system. The ecotoxicity of medium-contact recyclable wastes, that is, those in contact with soil, groundwater, surface water, etc., is managed according to this system and is determined based on whether or not they exceed an ecotoxicity value (TU) of 2.0. The ecotoxicity of wastes is tested and determined by using pretreated eluate samples according to the Official Wastes Test Standard and applying the Official Water Pollution Process Test Standard. However, no ecotoxicity management limits are stipulated for medium-contact recycling using wastes in numerous other countries. This study aims to evaluate applicability and safety of the ecotoxicity test for wastes used in medium-contact recycling and establish an efficient management plan for hazardous characteristic wastes. Target wastes for the survey were selected based on the Wastes Control Act in South Korea. Nine types of waste were selected, which are representative types of wastes to which ecotoxicity is applied. In order to secure the representativeness of the target samples, a total of 45 samples were collected by selecting 5 cases each of the 9 waste types in consideration of the type of industry and amount of waste generated. Limit exceedance was calculated for each category of hazardous substances (leaching, total content), pH, and ecotoxicity of a total of 45 samples, and was found to increase in the order of leaching 2.22% < pH 9.09% < content 31.11% < ecotoxicity 37.21%. This indicates that the limit exceedance was maximum in the ecotoxicity category. Therefore, the application of ecotoxicity limit is efficient for identifying and comprehensively managing the environmental impacts of various types of hazardous substances contained in wastes from the perspective of comprehensive toxicity.

Applications of UV/H2O2, UV/persulfate, and UV/persulfate/Cu2+ for the elimination of reverse osmosis concentrate generated from municipal wastewater reclamation treatment plant: Toxicity, transformation products, and disinfection byproducts.

Reverse osmosis concentrate (ROC) resulting from treatment of municipal wastewater reclamation involves high concentrations of recalcitrant pollutants. This study evaluated the toxicity of an ROC containing harmful biocides during representative UV synergistic oxidation processes (SOPs) (e.g., UV/hydrogen peroxide (H2O2), UV/persulfate (PS), and UV/PS/Cu2+). Treated ROC exhibited up to 1.3-2.3 times higher toxicity than the parent compounds such as dodecyl trimethyl ammonium chloride (DTAC) and dodecyl dimethyl benzyl ammonium chloride (DDBAC). Based on the intermediates identification, the major toxic intermediates were screened through silico assessment using the quantitative Ecological Structure-Activity Relationship (ECOSAR) tool. The transformation products (TPs) of hydroxylation and ketonization were the major formed reactions from the UV/PS/Cu2+. Also, some cytotoxic TPs were accumulated during the UV/H2O2 and UV/PS oxidations, where the carbonaceous-disinfection byproducts were more than the nitrogenous-disinfection byproducts. In the presence of chloride and bromide, chlorate and bromate could be formed during the UV-SOP; they were influenced by the different water matrix in comparison with the different ROC. Also, the formation of the total organic halogen species (TOX) was found to follow this order: UV/PS/Cu2+ < UV/H2O2 < UV/PS. In this study, the predicted cytotoxicity using the correlation between the TOX and the cytotoxicity was more acceptable than that of the cytotoxicity index method. Further, the R-square of the correlation between the TOX and the cytotoxicity for the UV/H2O2 and UV/PS was 0.82 and 0.79, respectively. The predicted cytotoxicity using the TOX correlation method in the ROC could also be used to monitor and prevent the application of different oxidations in municipal wastewater reclamation treatment plants.

Assessment of quality test methods for solid recovered fuel in South Korea.

Management of solid recovered fuel (SRF) in South Korea is unique from most other countries in that it is based on a single standard. All SRFs are distributed at the same price irrespective of their performance, resulting in utilization problems and a low degree of acceptance among consumers. Moreover, the difficulty of temperature maintenance during transportation, excessive ash content, and the use of inappropriate microwave acid digestion methods pose challenges to SRF reliability. To address these issues, we compared the relevant management statuses in South Korea with those of the international community and reviewed the effects of the transportation temperature, ash content, and microwave acid digestion technique. The moisture, ash, sulfur, and chlorine contents as well as the lower heating values (LHVs) of all the samples from South Korea were found to be below the standard [international] thresholds, and they were barely influenced by the transportation temperature. In addition, 5 g samples were found to be more appropriate for ash content analysis than the 20 g samples used in South Korea, with the former producing smaller standard deviations. The optimal microwave acid digestion conditions were also determined to be a reaction time with nitric acid of >10 min, temperature of 180 °C, and microwave power of 600 W. The results of this study highlight the need for revising the SRF test methods used in South Korea, to boost the market and enhance quality reliability.

Characteristics of PCDDs/PCDFs in stack gas from medical waste incinerators.

Toxic polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in 45 stack gas samples were measured from 19 medical waste incinerators in South Korea using high-resolution gas chromatography equipped with a high-resolution mass spectrometer. The average concentrations of the sum of 17 toxic PCDD/PCDF congeners emitted from the medical waste incinerators ranged from 0.153 to 101.9 ng/Sm3. Based on the World Health Organization toxic equivalency factor, they ranged from 0.007 to 5.437 ng-TEQ/Sm3. The congener patterns of PCDDs/PCDFs were described using principal component analysis and presented four patterns. In the evaluation of annual average total TEQ concentrations, outlying stack gas samples were excluded. In this study, the number of chlorine substitutions was evaluated as an important factor in congener patterns. Coefficient of determination values were employed for evaluation of correlation between PCDDs and PCDFs. 1,2,3,4,6,7,8-HpCDF was measured as the most emitted congener, while 2,3,4,7,8-PeCDF was the greatest TEQ contributor.

Emission of polybrominated diphenyl ethers (PBDEs) in use of electric/electronic equipment and recycling of e-waste in Korea.

The emission rates of polybrominated diphenyl ethers (PBDEs) from electric/electronic products during their use and disposal were estimated. E-wastes, including televisions and refrigerators, gathered at recycling centers were also analyzed to estimate their emissions. The average concentrations of PBDEs in TV rear covers produced before and after the year 2000 were 145,027 mg/kg and 14,049 mg/kg, respectively. The PBDEs concentration in TV front covers was lower than the concentration in TV rear covers. The concentration in the components of the refrigerator samples ranged from ND to 445 mg/kg. We estimated the atmospheric emissions of PBDEs based on the concentrations. The annual emissions from TV rear covers produced before 2000 were calculated to be approximately 162.1 kg and after 2000, the annual emissions were 18.7 kg. Refrigerators showed the lowest annual emissions of PBDEs (0.7 kg). The atmospheric concentrations were also measured to calculate emissions generated during the recycling process. The highest concentration was 16.86 ng/m(3) emitted from the TV sets during the dismantling process. The concentrations of PBDEs generated in the plastic processing field ranged from 2.05 to 5.43 ng/m(3) depending on the products, and ambient air in open-air yards showed concentrations in the range of 0.32 to 5.55 ng/m(3). Emission factors for the recycling process were calculated using the observed concentrations. The estimated emissions according to the emission factors ranged from 0.3×10(-1) to 90.3 kg/year for open-air yards and from 0.1×10(-1) to 292.7 kg/year for the dismantling and crushing processes of TV set, depending on the production year.

1H-NMR-based profiling of organic components in leachate from animal carcasses disposal site with time.

Leachate, generated by the decomposition of animal carcasses, presents many environmental, sanitary, and food safety hazards. However, research on the characteristics of leachate is lacking. In this study, we performed biochemical profiling of leachate from two animal species (pig and cattle) in two soil types (sandy loam and sandy soil) using (1)H-NMR-based profiling, followed by multivariate data analysis. The leachate was collected from a well-controlled artificial burial site over a 31-week period. Principal components analysis (PCA) of the NMR data showed similar patterns between species and soil types. Organic components, including organic acids and phenols, predominated, and their levels increased with time. The methylamine level in leachate from pig carcasses 18 weeks following burial was significantly higher than that from cattle carcasses; leachate from cattle carcasses in sandy soil 1 week after burial contained unique components (specifically ethanol, formate, alanine, N-methylation, and taurine), in contrast with those from sandy loam soil. This study suggests that a NMR-based profiling approach is useful to characterize the organic components in leachate from animal carcasses over time.

Hazardous waste characterization among various thermal processes in South Korea: a comparative analysis.

Ministry of Environment, Republic of Korea (South Korea) is in progress of converting its current hazardous waste classification system to harmonize it with the international standard and to set-up the regulatory standards for toxic substances present in the hazardous waste. In the present work, the concentrations along with the trend of 13 heavy metals, F(-), CN(-) and 19 PAH present in the hazardous waste generated among various thermal processes (11 processes) in South Korea were analyzed along with their leaching characteristics. In all thermal processes, the median concentrations of Cu (3.58-209,000 mg/kg), Ni (BDL-1560 mg/kg), Pb (7.22-5132.25mg/kg) and Zn (83.02-31419 mg/kg) were comparatively higher than the other heavy metals. Iron & Steel thermal process showed the highest median value of the heavy metals Cd (14.76 mg/kg), Cr (166.15 mg/kg) and Hg (2.38 mg/kg). Low molecular weight PAH (BDL-37.59 mg/kg) was predominant in sludge & filter cake samples present in most of the thermal processes. Comparatively flue gas dust present in most of the thermal processing units resulted in the higher leaching of the heavy metals.