박상우 Sang-woo Park

DOI:10.9786/kswm.2021.38.1.1

Abstract

Japan's current circular economy policy originates from the "Policy guidelines for economic revitalization and desirable society" of 1999. Led by the Prime Minister at the time, the guidelines of this policy set the economic target of Japan for the year 2010 and suggested that the economy should be in harmony with the environment, which aligns with the concept of a circular economy. In this respect, Japan was clearly ahead of the EU, as the European Commission did not introduce a circular economy package until 2015. Furthermore, after the Japanese Prime Minister announced the adoption of the policy, the legislation for a circular economy society was enacted and revised to support that policy. One of the most distinct legislations is the Framework Act on Resource Circulation. In the implementation of relevant laws, both the Ministry of the Environment and the Ministry of Economy, Trade, and Industry supervise the policies and systems to establish a circular economy. Notably, these policies and systems have not only been based on the notion that recycling is a way to dispose of waste, but are also a way to achieve substantial resource reuse. The concept of a circular economy is not a matter of choice; it must also be established in the Korean economy to overcome the climate crisis and promote sustainable development. Korea’s waste policy should promote the harmonization of the environment and economy. Therefore, it is necessary to establish a system whereby the Ministry of Environment and the Ministry of Trade, Industry, and Energy can cooperate.

Key Words

Waste policy, Circular economy, SDGs, Climate crisis

송연민 Yun Min Song , 석종혁 Jong Hyuk Seok

DOI:10.9786/kswm.2021.38.1.12

Abstract

The purpose of this study is to figure out the waste production and characteristics of Incheon Metropolitan City (IMC) for a sustainable cyclic economy and waste reduction, and thus propose a policy direction for recyclable resources as high value-added wastes. In 2017 in IMC, the production and emission unit of domestic (domestic and business) wastes were 2,290 tons/day and 0.76 kg/cap.-day, respectively. Comparing the recycling of domestic wastes in 2017 vs. in 2012, papers (18.8%→36.0%) and plastics (19.9%→11.6) increased, while glass bottles (13.8%→10.0%) and synthetic resins (19.9%→17.3%) decreased. At the time of this study, the number of industry sectors in IMC were 6,308 in the metal processing field, 955 in wood processing, and 1,091 in clothing and textile, for the production and utilization of up-cyclable waste materials. Based on the research data, supply and demand forecasting in related industries is required for the establishment of stable and high value-added recyclable materials. Subsequently, it is necessary for the recycling markets to revitalize the establishment of pretreatment facilities for upcyclable materials, material classification and development, and material banks.

Key Words

Sustainable cyclic economy, Waste reduction, High value-added recyclable materials, Incheon Metropolitan City, IMC

최정우 Jeong Woo Choi , 윤성열 Seong Yeol Yun , 조우리 Woori Cho , 김장영 Jang Yeong Kim , 김수향 Su Hyang Kim , 이재영 Jai-young Lee

DOI:10.9786/kswm.2021.38.1.20

Abstract

Hydrothermal Liquefaction (HTL) was applied to convert plastic into oil resources. Polyethylene, Polystyrene, Polypropylene, which are the most commonly used and discharged of various types of plastics, respectively, in the ratio of 1:9 to water and oil under optimal conditions (PE=240℃-40min, PS=270℃-60min, PP=240℃-60min) Was extracted. Then they evaluated their potential for use as liquid fuel. The characteristics of the liquid fuel changed according to the HTL reaction temperature and time. Therefore, it is believed that HTL can be used to convert plastic into oil resources.

Key Words

Hydrothermal liquefaction, Plastic, Liquid fuel

임성빈 Seong-been Im , 이윤희 Yunhee Lee , 어성욱 Seong-wook Oa

DOI:10.9786/kswm.2021.38.1.26

Abstract

In this study, a nitrogen enrichment apparatus was designed as a way to recover nitrogen resources from livestock manure. The properties of the nitrogen concentrates were analyzed by varying operating parameters and conditions. The nitrogen enrichment apparatus was decompressed and heated based on the fundamental principle of conversion of dissolved ammonium ions into ammonia depending on the temperature. Converted to a gas, ammonia was recovered as nitrogen concentrates by an indirect cooling system. Samples were used in three types: raw livestock manure, solid-liquid separated wastewater, and dewatered effluent after thermohydrolysis. When operating based on a pressure of 0.3 bar, the solids concentration of the samples and the amount of livestock manure input were correlated with the operating time, final temperature, and recovery amount. The results were as follows: the lower the solids concentration and the higher the amount of input, the greater the amount of recovery was possible. When 60 L of livestock manure were added, a maximum of 35 L was recovered. In the case of a 40 L input, up to 19 L were recovered. The average concentration of the recovered nitrogen concentrate was 13,385 mg/L based on T-N, and was concentrated to a maximum of 18,915 mg/ L. As the nitrogen concentrate recovered, the concentration of the nitrogen decreased, and when large amounts were recovered, up to 93.6% of the nitrogen content in the livestock manure was recovered.

Key Words

Nitrogen recovery, Nitrogen enrichment, Nitrogen concentration condensate, Organic matter, Livestock recycling

정상철 Sang-chul Jung , 전미진 Mi-jin Jeon , 권기욱 Ki-wook Kwon , 전용우 Yong-woo Jeon

DOI:10.9786/kswm.2021.38.1.36

Abstract

In this work, the performance of biogas separation that uses an asymmetric hollow fiber membrane module was investigated. Several experiments were conducted by varying parameters such as feed flow rate, stage-cut, and membrane module configuration, to obtain a high methane concentration above 95.0%. A mathematical model, based on mass balances for the separation modules, was compared with the experimental data. The finite difference method was applied to calculate the membrane biogas separation behaviors. The proposed single-stage module can easily be extended to the multi-stage module. Furthermore, the validity of the model calculation was examined, indicating close agreement between the calculation results and experimental data. This study presents an appropriate methodology and mathematical modeling for the analysis of the separation performance of hollow fiber membrane with an asymmetric structure. Using the proposed model, the calculated results were in good agreement with the experimental data.

Key Words

Asymmetric hollow-fiber membrane, Biogas separation, Gas separation model

손세구 Se Gu Son , 이우근 Woo-keun Lee , 김영도 Young Do Kim , 김경남 Kyung Nam Kim

DOI:10.9786/kswm.2021.38.1.47

Abstract

Industrial waste and by-products such as blast furnace slag, coal fly ash, and mine tailing have been discharged and improperly managed, leading to secondary environmental contamination. However, these wastes can be used as construction materials through geopolymer techniques. Geopolymer paste and concrete samples were prepared using tungsten mine tailing and blast furnace slag as the raw materials in this research. Compressive strength was measured to evaluate the characteristics of the samples. Additionally, XRD and SEM analyses were performed. A higher compressive strength of the geopolymer paste was obtained by reducing the content of the tungsten mine tailing: 125.4 MPa for 40 wt.% of the mine tailing. Furthermore, the compressive strengths for the prepared concrete samples (GMR-5NA, GMR- 5FA, and GMR-5RA) were 54.3 MPa, 58.1 MPa, and 32.9 MPa after 28 days, respectively. According to the XRD analysis for the prepared paste and prepared concrete, the geopolymer structure was identfied. Therefore, tungsten mine tailing can be used as alternative cement material.

Key Words

Geopolymer binder, Mine tailing, Aluminosilicate gel, Geopolymer paste, Geopolymer concrete

이우근 Woo-keun Lee , 심정민 Jung-min Shim

DOI:10.9786/kswm.2021.38.1.57

Abstract

Heavy metal leaching from waste, such as waste limestone (WL), poses a significant secondary environmental problem. It is necessary to develop methods to detoxify these hazardous pollutants and effectively recycle them as resources. In this work, factors for enhancing insulating properties with the use of waste as resources have been studied. Waste, such as WL, melting slag (MS), and aluminum dross were used as raw materials to prepare insulating brick using the geopolymer technique. Sufficient amounts of Si and Al in raw materials were also required to prepare the insulating brick. Therefore, MS was used to supplement the proportion of Si and Al in order to form the geopolymer. The effects of the addition of aluminum dross and the molar ratio of alkali activator on the insulating properties were discussed. Additionally, the compressive strength and the apparent porosity of the prepared bricks were analyzed. The optimal properties of the brick material were obtained at a mixing ratio of WL to MS of 9.5 : 0.5 and 3 wt. % Al dross. Under these conditions, thermal conductivity, compressive strength, and volume-specific gravity were 0.27W/m·K, 2.58MPa, and 0.76, respectively. According to the regression analysis of the thermal conductivity and apparent porosity, a strong negative correlation between the two factors was obtained.

Key Words

Insulting property, Melting slag, Waste Limestone, Geopolymer, Al dross

김남균 Nam-kyun Kim , 오재성 Jea-sung Oh , 김경문 Kyoung-mun Kim , 최병일 Byung-il Choi , 유석 Seok Yoo

DOI:10.9786/kswm.2021.38.1.64

Abstract

In modern society, polyurethane foam is widely used owing to its excellent mechanical and physical properties. At the same time, polyurethane foam waste disposal has become a social problem. Current recycling systems have low added value as well as sustainability and economic limitations Therefore, the development and commercialization of high valueadded products recycling the waste is pivotal. This study, we presented a method for upcycling polyurethane foam waste into flame-retardant . In addition, the utility of the process was analyzed by conducting experiments on basic physical properties and fire safety, by examining fire safety through tests and fire simulations.

Key Words

Wasted polyurethane foam, Upcycling, Basic physical properties, Flame retardant performance

최희철 Hee-chul Choi , 이재영 Jai-young Lee , 윤이준 Yi-joon Yoon , 이병용 Byung-young Lee , 최상일 Sang-il Choi

DOI:10.9786/kswm.2021.38.1.70

Abstract

This study applied a stabilization method to treat contaminated soil. First, the stabilization efficiency and the proper mixing ratio were derived by mixing the stabilizer (KSPA) and contaminated soil. Subsequently, to improve the limitations of the stabilizer, waste resources (eggshell, pig bone, and steel slag) were incorporated to evaluate the stabilization efficiency. The modified stabilizer showed a significant reduction in the amount of heavy metal leaching when compared with other leaching yields (raw materials (contaminated soil) and applying the KSPA only). After 28 days of mixing the waste resources with KSPA, lead and chromium, excluding arsenic, showed up to 100% stability, confirming improved stabilization efficiency in complex contaminated soil.

Key Words

Waste resources, Heavy metals, Contaminated soil, Stabilization, Solidification

황재오 Je-o Hwang , 김종서 Jong-seo Kim , 이동호 Dong-ho Rie

DOI:10.9786/kswm.2021.38.1.78

Abstract

This study aims to quantitatively analyze the environmental hazards (heavy metals and microorganisms) found in the working environment of waste recycling sorting facilities and to study the effects of conveyor cleaning. Analyses of samples taken, from before cleaning and after cleaning, of three conveyors at two recyclable material screening sites were performed between February and June. The hazardous substances measured in this study were 14 heavy metals (Fe, Cu, Mn, Pb, Zn, Ni, Cd, Cr, Al, As, Co, Sn, Si, and Mo) and the biological agents were bacteria and fungi. As a result of cleaning the conveyor, the analyses revealed that Cd, Sn, Co, and Mo heavy metals were no longer detected. The average values of the heavy metals by element were: Cu 3.1(±1.3) μg/cm², Fe 40.1(±2.6) μg/cm², Pb 3.2(±1.7) μg/cm², Mn 3.7(±0.8) μg/cm², Ni 0.6(±0.3) μg/cm², Zn 9.2(±2.6) μg/cm², As 0.7(±0.4) μg/cm², Al 8.8(±1.3) μg/cm², and Si 7.7(±3.5) μg/cm2. Results of the microbial analyses detected a total of 11 bacteria, while Pseudomonas spp. and Bacillus spp. were commonly detected. No fungi were detected. Results after physically cleaning the conveyor showed that the heavy metals removal rate was more than 99%, while microorganisms were not detected. Based on the results of this study, recycling facilities involves workers’ exposure to heavy metals and germs. To prevent the risks, regular physical equipment cleaning and personal hygiene are required.

Key Words

Waste recycling sorting, Conveyor cleaning, Domestic waste, Occupational hygiene