신가영 Kayoung Shin , 이성유 Seong You Lee , 황용우 Yong Woo Hwang , 강홍윤 Hong-yoon Kang , 권택관 Tack-kwan Kweon

DOI:10.9786/kswm.2023.40.2.93

Abstract

In this study, economic and environmental effects were analyzed by linking material flow cost accounting (MFCA) and life cycle assessment (LCA) methodologies to the process of recycling palladium in a plated spent catalyst solution. Based on an MFCA analysis of recycling 1 kg of palladium, the results indicated that the positive product cost accounted for 82%, whereas 18% was the negative product cost due to material loss, resulting in a total of approximately KRW 139 million. The cost by mass factor indicated that the material cost, including the expenses for catalysts and chemicals, was the highest (57%), followed by the system cost, such as labor and maintenance costs (32%), and the waste management cost (10%). In addition, greenhouse gas (GHG) emissions of 1.97E+03 kgCO₂eq were estimated as output cost by using the emission permit in the Korean emission trading system (K-ETS) market, which is equivalent to KRW 50,922. Although this additional output cost on waste management cost was insignificant when 1 kg of Palladium was recycled, this effect would be significant in the future when the amount of recycling increases. Additionally, if the output cost of GHG emissions is applied to the controlled entities under the K-ETS, the effect on waste management costs will be significant.

Key Words

Material flow cost accounting (MFCA), Life cycle assessment (LCA), Palladium recycling, Material flow analysis (MFA), Emission trading system (ETS)

정대웅 Daewoong Jung , 박철우 Chulwoo Park , 장은석 Eun Suk Jang

DOI:10.9786/kswm.2023.40.2.106

Abstract

In this study, a numerical study was conducted on the flow characteristics of a cyclone separator for the disposal of medical waste. To analyze the composition of medical waste, samples were collected from medical facilities. Then, particle size analysis was conducted after the shredding process. A performance evaluation of the cyclone separator when collecting fine particles generated from five types of medical waste was also conducted. The flow characteristics generated inside the cyclone separator were analyzed, and the maximum tangential and axial velocities were 11.3 and 6.5 m/s, respectively. Depending on the diaper, ringer string, syringe, gauze, and cotton particles, more than 90% could be collected from particles sized over 148.2, 148, 25.3, 29.2, and 34.8 μm, respectively.

Key Words

Medical waste, Cyclone separator, Particle behavior, Flow characteristics, Computational Fluid Dynamics (CFD)

장진만 Jinman Chang , 이남훈 Namhoon Lee , 윤석표 Seok-pyo Yoon , 최종식 Jongsik Choi , 허경태 Gyongtae Hur , 이재영 Jai-young Lee

DOI:10.9786/kswm.2023.40.2.115

Abstract

With the increasing amount of waste, the lack of landfill facilities has become the issues. However, it is difficult to construct new landfill facilities due to the “not in my back yard” (NIMBY) phenomenon. The abandoned quarry is a mountainous area damaged by mining. In abandoned quarry areas, there is a high possibility of disasters (such as landslides) and environmental problems (such as illegal waste dumping). In this study, cases of abandoned quarries being used as landfill facilities are investigated and the associated legal system is analyzed, with the aim of improving the utilization of abandoned quarry sites as landfill facility sites. As a result of reviewing the regulations, it was determined that the restoration exemption institution (the most crucial system for using abandoned quarries as landfill facilities) should improve its effectiveness. Therefore, to solve this problem, it is essential to clarify the direction of management at the start of quarries.

Key Words

Quarry, Waste treatment, Landfill, Landfill site

서동천 Dong-cheon Seo , 강철호 Chul-ho Kang , 김용진 Yong-jin Kim

DOI:10.9786/kswm.2023.40.2.124

Abstract

In this study, the characteristics of beach litter on five islands in the western area of the South Sea of the Korean Peninsula were evaluated. This coastal area has the largest scale of aquaculture in Korea, the largest number of islands, and is heavily influenced by marine debris flowing from upstream. The mean abundance of macrolitter (25 ~ 300 mm) was 76.7 ± 108.8 items/m, which was generally larger than domestic and foreign research results. Plastics and expanded polystyrene (EPS) respectively exhibited high ratios of 91.2% and 58.9% on average, while EPS fragments and fibertype plastics ropes for fishery accounted for the largest share. Mesolitter (5 ~ 25 mm) averaged 7.1 ± 4.8 items/m, which was a very low proportion among beach litter by size. The results also revealed that marine litter on island beaches is greatly affected by natural factors (such as wind and ocean currents) in addition to the size and items of aquaculture in the nearby sea and the fishing gear used. Statistically significant results were also obtained by examining the abundance and quantity of beach litter in the 4 randomly selected survey sections (from a total of 20) with a length of 5 m. Moreover, the possibility of inferring the weight from the abundance of beach litter was confirmed by the correlation between the abundance and quantity.

Key Words

Island beach litter, Aquaculture area, Marine debris, Macroplastics, Mesoplastics

전경원 Kyung-won Jeon , 곽승현 Seung Hyun Kwak , 장원준 Won-jun Jang

DOI:10.9786/kswm.2023.40.2.135

Abstract

In this study, the collection system for recycling waste was investigated to increase the recycling rate of domestic waste in Gyeongsangnam-do. The typical methods for collecting domestic waste are door-to-door and regional base collections. The characteristics of these methods and the cases of regional base collection in other municipal governments (such as Jeju, Seoul, and Daegu) were also identified. In Gyeongsangnam-do, regional base collection facilities were installed and operated at farming and fishing villages. The exterior and detailed operation procedure of the regional base collection was varied by the sub-municipal government in Gyeongsangnam-do. Most regional base collection facilities operated well, although some had problems (such as illegal dumping of large amounts of waste and insufficient collections) that require more systematic management. In addition, a survey was conducted with the residents in Gyeongsangnam-do and public officials to confirm their perceptions related to the discharge and collection methods of domestic waste.

Key Words

Domestic waste, Recycling waste, Regional base collection, Perception survey

김관용 Gwanyong Kim , 정득준 Deukjun Jeong , 이상철 Sangchul Lee

DOI:10.9786/kswm.2023.40.2.143

Abstract

This study is related to the manufacture of recycled outsoles, whose friction with the contact surface is improved through an amorphous pattern method, in which butyl rubber, which is entirely imported, is replaced with general rubber and leather solid waste. This study also investigated the change in the cross-linking properties and mechanical properties of the outsole according to the contents of the leather trimming waste. In addition, a mixture study of the general rubbers (NR and BR) was conducted to the enhance the abrasion resistance of the outsole to improve its functionality.

Key Words

Leather soild waste, Rubber out-sole, Recycle shoes

강장현 Jang-hyun Kang , 이선주 Sun-ju Lee , 장수한 Su-han Jang , 강영렬 Young-yeul Kang , 윤영삼 Young-sam Yoon , 유흥민 Heung-min Yoo

DOI:10.9786/kswm.2023.40.2.151

Abstract

The hazardous wastes generated in process industries cause numerous incidents that can damage the human body and environment. This study aimed to investigate hazardous characteristics (HC) and expand the current industrial classification for the HC of waste. To this end, the leaching toxicity, substances in contact with water, emission of flammable gases, flammable, corrosive, oxidizing, pyrophoric, and explosive characteristics of industrial wastes were evaluated. For the analysis, 85 samples were collected from 60 industries and 6 types of wastes (acid waste, alkali waste catalysts, adsorbents, absorbents, and spent batteries). The results confirmed that the samples exhibited the following characteristics: leaching toxicity (8 samples), flammable (16 samples), corrosive (23 samples), explosive (3 samples), and pyrophoric (3 samples) characteristics. However, oxidizing characteristics, substances in contact with water, and emission of flammable gases were not observed. Additionally, the leaching ratios of metals based on elements and industries were evaluated using leaching tests, and the relationship between the leaching concentration and metal contents was determined using normality tests. The leaching ratios of arsenic was statistically significant with an adequate p-value (= 0.746), and the leaching ratios of metals for the publishing industry was statistically significant with an adequate p-value (= 0.154). The results revealed that 34 new industries generated waste with HC. The results of this study can provide quantitative information on the HC for safe waste disposal and recycling.

Key Words

Leaching toxicity, Hazardous characteristics, Industry classification, Waste

석종혁 Jong Hyuk Seok , 송연민 Yun Min Song

DOI:10.9786/kswm.2023.40.2.162

Abstract

In this study, an alternative material recycling method for wastepaper that was not reused as paper was proposed. First, the cellulose in wastepaper was hydrolyzed, saccharified, and retrieved mainly as acetic acid. Thereafter, the availability of the hypothesis was examined using pure cellulose (Sigmacell 20, SC20), after which waste paper (1 : 1 mass ratio of newspaper and toilet paper, WP) was used as the sole substrate in a batch reactor and a continuous reactor. In the batch experiment, the concentration of the acetic acid produced when SC20 was used as the substrate was proportional to the substrate concentration in the tested range, and the maximum concentrations of acetic acid at substrate concentrations of 15, 20, 25 g/L were 3,000, 3864, and 4,146 mg/L, respectively. At a substrate concentration of 25 g/L, acetic acid and ethanol reached their maximum concentrations three and four days after the experiment, respectively, and was accompanied by the production of other organic acids, such as propionic acid. The production of acetic acid using WP was approximately 91% with SC20, but both substrates exhibited a similar tendency. In the continuous experiment conducted for approximately 1 month, during the first stage (1 ~ 12 days), the concentrations of acetic acid and total organic acids reached 1,900 and 2,150 mg/L, respectively, at a HRT of 2 days and SC20 concentration of 10 g/L. After the first stage, when WP was used as the substrate instead of SC20, the maximum concentrations of total organic acids during the second (13 ~ 23 day, 13 gWP/L) and third stages (24 ~ 32 days, 26 gWP/L) were 1,299 and 1,736 mg/L respectively. In addition, no inhibition of the substrates and products was observed under the experimental conditions.

Key Words

Wastepaper, Material recycling, Acetic acids, Biological conversion

상병찬 Byoungchan Sang , 이승정 Seungjeong Lee , 이재희 Jaehee Lee , 이도연 Doyeon Lee , 엄태인 Taein Ohm

DOI:10.9786/kswm.2023.40.2.172

Abstract

This study analyzed the physicochemical properties and combustion characteristics of dried food waste and agricultural by-products to evaluate the feasibility of biowaste as a solid fuel product. The drying performance of food waste was confirmed by using a closed steam recirculation dryer and an automatic shutdown control system equipped with a moisture intensity sensor. Elementary analysis, proximate analysis, calorific value analysis, and TGA analysis were conducted on 4 types of food waste samples including coffee grounds and 3 types of agricultural by-product samples. When the automatic shutdown control system was applied, the drying performance and drying efficiency were improved by 10.7% and 10.6%, respectively, and it was possible to obtain the effect of reducing the drying time and energy consumed for drying. The moisture content of the dried food waste and agricultural by-product was 0.5 ~ 9.14wt.%, and the ash content of them was 3.3 ~ 12.5wt.%, which satisfied the quality standards of Bio-SRF. The low calorific value of dried food waste was 4,000 ~ 4,710 kcal/kg, and the low calorific value of agricultural by-products was 3,250 ~ 3,770 kcal/kg. Dried food waste and agricultural by-products meet the Bio-SRF standards and have a high low calorific value. Therefore, it is judged that if the drying technology applied with the automatic shutdown control system is used for solid fuel manufacturing, it can contribute to vitalizing the domestic SRF market.

Key Words

Drying process, Bio-waste, Solid refuse fuel, Combustion

최상민 Sang-min Choi , 민병대 Byung-dae Min , 유동우 Dong-woo Yoo , 권성구 Sung-ku Kwon

DOI:10.9786/kswm.2023.40.2.183

Abstract

Circulating fluidized bed boilers use a bed material such as natural sand for uniform heat distribution. However, the alkali content of biomass fuel can decrease the melting point of natural sand, leading to clinker formation inside the boiler. To address this issue, we sought to evaluate the applicability of bottom ash (BA) from a coal-fired power plant as an alternative to natural sand (JU) by comparing and analyzing their characteristics under the same conditions. The molar ratio of Al₂O₃ in BA and K₂CO₃ in the reagent was mixed and ground to achieve ratios of 1 : 1 and 1 : 2, and the plasticity temperatures were set to 700℃, 800℃, 900℃, and 1000℃. Solubility tests and X-ray diffraction analyses were conducted and our findings indicated that the initial deformation temperature occurred at 700℃ - 800℃ for JU-2 and at 900℃ for JU-1. As the temperature increased, the amorphous phase of JU increased, whereas the amorphous phase of BA decreased. Furthermore, the crystalline phases of microcline and gelenite decreased as the temperature increased, whereas those of leucite and wollastonite increased.

Key Words

CFB boiler, Bed material, Bottom ash, K₂CO₃, Alkaline conditions