송상훈 Sang-hoon Song , 김란희 Ran-hui Kim , 이남훈 Nam-hoon Lee , 박진규 Jin-kyu Park

DOI:10.9786/kswm.2021.38.2.85

Abstract

This paper aims to review the aftercare completion criteria for closed landfills described in the literature. Our objectives are to characterize the waste stabilization phases and specific approaches to evaluate the completion of landfill aftercare and to review country-specific regulatory procedures and technical guidelines. The attainment of functional stability implies that a closed landfill does not pose a threat to human health and the environment in the absence of active aftercare control. The functional stability can be assessed according to three categories: (1) target values, (2) risk assessment, and (3) performance-based. Country-specific aftercare completion criteria should be developed with consideration of functional stability in Korea. Due to the limitations on the deposition of combustible materials in Korea, soil and groundwater impact by leachate emissions are more strictly monitored and controlled than landfill gas emissions. However, the maximum leachate head on a liner (as measured at the lowest point of the liner) for solid waste landfills is limited to 2.0m during the aftercare period in Korea. Thus, the leachate head needs to be eliminated at the time of aftercare completion.

Key Words

Landfill, Aftercare, Completion criteria, Organic stability, Functional stability

최태열 Tae-yeol Choi , 박민주 Min-ju Park , 김주환 Ju-hwan Kim , 이지헌 Ji-heon Lee , 이가희 Ga-hee Lee , 김학민 Hak-min Kim , 정대운 Dae-woon Jeong

DOI:10.9786/kswm.2021.38.2.97

Abstract

Heavy metal in paper sludge ash is removed by various acids, including ethylenediaminetetraacetic acid (EDTA), citric acid (CA), oxalic acid (OA), and hydrochloric acid (HCl). Among the various acids, the EDTA and OA show higher removal efficiencies for Pb, Cu, As, and Cd. In addition, the single, mixed, and sequence washing methods with EDTA and OA are compared to enhance the removal efficiencies of heavy metals. We found that the mixed washing method with EDTA and OA is the best at removing Pb, Cu, As, Hg, and Cd, achieving removal efficiencies of 49.19%, 31.29%, 28.42%, 10.00%, and 11.33%, respectively. We analyzed the elution concentrations of CN and Cl and the CaO content of the paper sludge ash to consider the possibility of recycling it. The elution concentrations of heavy metals, CN, and Cl satisfied the legal standards for paper sludge ash recycling.

Key Words

Heavy metal, Paper sludge ash, Washing method, Elution concentration, Legal standards for recycling

박윤수 Yoon Soo Park , 김용준 Yong-jun Kim , 오정근 Jung Keun Oh , 전태완 Tae-wan Jeon , 신선경 Sun-kyoung Shin , 엄남일 Nam-il Um

DOI:10.9786/kswm.2021.38.2.108

Abstract

At present, the amount of imported and exported waste is increasing every year. The most significant proportion of waste is coal ash, reaching 1,297,094 t/yr as of 2016. Coal ash imports have risen steadily since 2008, most of them coming from Japan., but the treatment cost of coal ash imported from Japan is much higher compared to that of domestic ones.n. In Korea, most of coal ash is used as alternative building materials and auxiliary fuels. Furtehrmore, the National Assembly and private organizations have raised questions about its environmental and human health hazards. This study first analyzed the current export-import status and materials flow of coal ash. Then, we performed a risk assessment for the imported coal ash and cement including imported coal ash. Finally, we proposed a management plan for coal ash according to continuous imports.

Key Words

Waste import and export, Coal ash, Cement

송연민 Yun Min Song , 조경상 Kyung Sang Cho

DOI:10.9786/kswm.2021.38.2.116

Abstract

The cake filtration theory in microfiltration was analyzed through experimental results. Micro-filtration of cupric solutions was performed with and without coagulation. The pore sizes of the filter media were 0.1 μm, 0.2 μm, and 0.45 μm. The average specific cake resistances were obtained under cross-flow filtration conditions by Ruth’s equation. The compressibility of the resultant cake was 1.19, verifying the micro-filtration mechanism. In addition, no significant improvement in permeate flow rates was identified with coagulants aluminum sulfate(alum), and polyaluminum chloride(PAC) compared to permeate flow rates without a coagulant.

Key Words

Micro-filtration, Cake filtration theory, Average specific cake resistance

이일석 Il-seuk Lee , 곽인호 In-ho Kwak , 조현정 Hyun-jung Jo

DOI:10.9786/kswm.2021.38.2.122

Abstract

Developed countries, including EU countries, have been promoting national-level research and policies for sustainable development since 2010. These countries regard efficient management of resources as a critical theme of future national competitiveness. In this study, we investigated the policies and indicators that are being promoted for efficient resource management, re-established the concept of resource efficiency management, and proposed indicators for efficient resource management in Korea. In addition, we suggested management possibilities for the indicators and the direction for systematic management of these through the calculation of the indicators.

Key Words

Resource efficiency, Resource productivity, Resource circularity, Resource environmental impact, Resource management indicators

박동규 Dong Kyoo Park , 조성수 Sung-su Cho , 민홍 Hong Min , 류상오 Sang Oh Ryu , 김병환 Byung Hwan Kim

DOI:10.9786/kswm.2021.38.2.134

Abstract

The purpose of this study is to evaluate the applicability of low-cost industrial lime hydrate to the desulfurization process of iron ore sintering gas and to derive optimal operating conditions. Sulfur dioxide removal by lime hydrate was investigated using simulated iron ore sintering gases. The kinetic parameters of sulfation were determined based on the global reaction mechanism. The results show that sulfur removal efficiency decreases with increasing reaction temperature and gas hourly space velocity. The time to maintain 70% efficiency decreases from 15 minutes to 11 minutes and 7 minutes. Due to its mathematical simplicity, a first-order reaction model was applied. The model fit the lime hydrate sulfation reaction well, producing an apparent activation energy of 10.8 kJ/mol and a pre-exponential factor of 1.64 s^-1. The desulfurization efficiency of lime hydrate is approximately 65% the efficiency of sodium bicarbonate. As a result, lime hydrate has the potential to replace more expensive sodium-based reactants.

Key Words

Iron ore sintering, Flue gas, Desulfurization, Lime hydrate, Sodium bicarbonate

이두길 Doo Gil Lee , 박성용 Seong Yong Park , 이상조 Sang Jo Lee , 정재우 Jae Woo Chung

DOI:10.9786/kswm.2021.38.2.144

Abstract

This study aimed to assess the eco-friendliness and constructability of buildings that use recycled aggregates. Specifically, this study adopted the revised certification criteria for new residential buildings (for detached houses) under the Green Building Certification Standards. These standards were applied to evaluate the eco-friendliness and constructability of three public restrooms that use 100% recycled aggregates compared to those with general aggregates only. The results showed that both the public restrooms with recycled aggregates and the general public restrooms recorded high scores in the ‘constructability-indoor environment’ and ‘constructability-maintenance’ categories. However, the indices related to ‘eco-friendliness-energy and environmental pollution,’ plus ‘eco-friendliness-materials,’ and ‘ecofriendliness- ecology’ were only high for public restrooms with recycled aggregates. A low score was also achieved in both groups with respect to the ‘eco-friendliness-water circulation’ index. These results imply that the workability of the public toilets using recycled aggregate is estimated to be high in construction sites. Therefore, it is necessary to prepare detailed guidelines for recycled aggregates to be implemented in the construction sites in the near future.

Key Words

Recycled concrete, Recycled aggregate, Restroom construction, Eco-friendliness, Constructability

지승민 Seungmin Ji , 장용철 Yong-chul Jang , 김홍경 Hongkyoung Kim , 이가인 Gain Lee , 이소라 Sora Yi

DOI:10.9786/kswm.2021.38.2.153

Abstract

This study examined resource efficiency based on resource productivity and resource circularity between 2000 and 2018 in Korea. Various indicators were used to determine whether economic growth and material consumption were decoupled in the period. Korea is a country with limited land area and a high population density. Therefore, the decoupling of economic growth from raw material use in Korea is vital for relieving pressure on the environment and achieving sustainable development. This study found that the resource productivity between 2000 and 2018 increased 60%, indicating relative decoupling between economic growth and material use was observed. However, the resource productivity (2.54 million USD/1000 ton) in 2017 was relatively low compared with those from the OECD G7 countries (average of 3.6 million USD/1000 ton). Resource circularity increased 2.5 times between 2000 and 2018, while landfilling decreased to 38%. Resource recycling, one of the critical components for resource efficiency, enabled significant savings of raw materials for manufacturing and production in industries. Waste minimization and prevention is still a challenging task due to the ever-increasing waste generation over time. Several indicators for resource productivity and circularity can be used for national targets of resource efficiency towards a circular economy in Korea. More detailed methodology and calculations for the indicators with official and reliable data are still needed to eliminate the uncertainty of material flows in temporal and spatial boundaries.

Key Words

Resource productivity, Resource circularity, MFA, Decoupling, DMC

이종수 Jong-soo Lee , 김도완 Do-wan Kim , 이재호 Jae-ho Lee , 배재근 Chae-gun Phae

DOI:10.9786/kswm.2021.38.2.165

Abstract

Among plastic packaging materials, colorless pet bottles have high added value as recyclable resources. Still, most of them are currently recycled as medium and low-grade materials due to the mixing of other items and foreign substances in the discharge stage. The Ministry of Environment implemented a pilot project to separate and discharge only colorless PET bottles from the existing recycling system to increase the recycling quality of colorless bottles. To analyze the results of the pilot project, step-by-step monitoring was carried out. This study analyzed the performance and expected effects of separate discharge for colorless pet bottles according to population indicators, economic indicators, and environmental indicators. As a result of this analysis, problems, such as not removing labels and reducing discharge, were identified. It was deemed necessary to take measures to address these problems by implementing public relations for residents and introducing separate discharge assistants. In the screening phase, the quality level of colorless pet bottle compressed products increased due to decreased imports of residues and non-target materials at the pilot project. In the recycling phase, we expected higher prices for colorless pet bottles and increased recycling quality. However, the effect of recycling companies’ separate process lines was insignificant due to the low reliability of pet bottle selection. If these problems are resolved, economic benefits from increased material recycling through high-quality raw material recycling and higher unit prices are expected.

Key Words

Colorless PET, Recycling, Separate discharge, Operational performance

김장영 Jang Yeong Kim , 조우리 Woori Cho , 이재영 Jai-young Lee

DOI:10.9786/kswm.2021.38.2.176

Abstract

In this study, biochar was created from coffee wastes with a high moisture content by applying a hydrothermal carbonization (HTC) method. Environmental problems during the treatment and optimal conditions were derived based on the adsorption performance of biochar. In addition, we compared biochar and activated biochar to evaluate their potential as adsorbents for VOCs by chemical activation using KOH to activate micro-secessions of biochar. The highest yield was obtained at 260 ℃ for 1 h and the iodine adsorption performance at approximately 687.11 mg/L. Therefore, the HTC optimal reaction conditions using coffee wastes increased its potential for use as an adsorbent. KOH was used as a chemical activator to activate the biochar under optimal generative conditions. A second batch test was conducted and analyzed for yield and iodine adsorption performance. The second batch test showed that the optimal activation temperature was about 700℃, the optimal mixing ratio of biochar and KOH was 1 : 0.5, and the optimal activation time was 1 h for 1,105.33 mg/g iodine adsorption performance. Toluene adsorption experiments were conducted to evaluate the VOC adsorption potential of coffee wastes, biochar, activated biochar, and GAC (Granular Activated Charcoal, Untreated). As a result, activated biochar, which was adsorbed at 240 minutes, was considered a more efficient adsorbent than coffee wastes, biochar, and GAC. Therefore, this study conducted an adsorbent evaluation of activated biochar produced from the HTC process. The resultant biochar showed higher efficiency in a shorter period and was sufficient to be used as an adsorbent.

Key Words

Hydrothermal carbonization, HTC, Coffee waste, Biochar, Activated carbon, Toluene