• Resources Recycling
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• v.32 no.1
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• pp.3-12
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• 2023

Bauxite residues represent industrial wastes that have been accumulating over the past 120 years since the beginning of the alumina industry. They are typically classified as harmful substances owing to their strong alkalinity and salinity characteristics. These residues, with quantities steadily increasing by more than 150 million tons annually worldwide, are recycled into various industrial materials using dealkalization processing. This study investigates the generation process of alkaline substances in bauxite smelting and the recent techniques adopted for controlling their alkalinity. The properties of bauxite residues are known to vary depending on the raw mining and digestion methods. Thus, the dealkalization process must be selected considering the type of alkaline material, local environment, and infrastructure.

• Resources Recycling
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• v.8 no.3
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• pp.18-25
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• 1999

The study on the electrosorption of cobalt ions onto a porous activated carbon fiber (ACF) was performed to treat radioactive liquid wastes resulting from chemical or electrochemical decontamination and to regenerate the spent carbon electrode, Cyclic voltammetry was investigated on a rotating-disk electrode (RDE) to determine the region of potentials within which only double-layer charging should occur. The application of an electric potential increased the sorption of the cobalt ions. The adsorbed cobalt Ions could be released into the solution by reversing the appling potential, showing the reversibility of the process.

• Resources Recycling
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• v.11 no.3
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• pp.37-45
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• 2002

Triboelectrostatic Separation procese is a technology that different particles charged after contact and rubbing different materials are separated in an electric field. At this time, charged polarity of different materials depends on their own work function. Therefore this study discovers work functions of various plastics and determines charging characteristics for the specific optimum operation condition. The experiment is conducted with two sample sets composed of various different plastics. Each sample is charged by contact and rubbing different materials. Surface charge of charged particles is measured by Faraday Cage. The specific work function of an each plastic is driven by measured charging amount and charged particles are separated in a certain electric field ($\pm$20 kV). At last, the relationship between charging amount and separation efficiency is induced by the separation experiment.

• Journal of the Korea Organic Resources Recycling Association
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• v.19 no.2
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• pp.28-32
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• 2011

This paper introduces about the study on the construction of zero energy villages in Korea using waste and biomass, and explains how to analyze the quantity of various resources from agriculture, livestock industry, forestry, and food waste with a village as a unit. Finally, three different scenarios for the construction of zero energy villages were suggested, based on the presumed amount of energy per each town.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.3
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• pp.39-46
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• 2018

Two domestic earthworm populations used in vermicomposting in different lacalities were collected. The one was from Hongcheon (Kangwon province) and the other was from Youngdong (Chungcheong province). Reproductive capacities and the degree of reproductive isolation of two population were investigated. CO I gene sequences were also compared. There was no difference in their reproductive capacities. And there was no reproductive isolation between two populations. Two populations were identified as Eisenia andrei or Eisenia fetida by CO I gene biomarkers. Phylogenetic tree formulated by CO I gene sequence strongly suggested that two populations were just the same species.

• Resources Recycling
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• v.29 no.1
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• pp.35-42
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• 2020

Even asbestos-containing waste (ACW) are highly harmful to humans, it continues being produced due to the massive disposal of asbestos-containing products. A development of asbestos detoxification and recycling technologies is required. Heat treatment using microwave is the most efficient method for ACW detoxification. However, microwave heat treatment method has the limitation that asbestos does not absorb microwave at room temperature. That is why, in this study, ACW was detoxified by microwave heat treatment adding the ACW between SiC plates, which are inorganic heating elements that absorb microwaves at room temperature. In order to improove the heat transfer, ACW was crushed and pulverized and then heated using microwave. Microwave heat treatment temperature and time variables were adjusted to investigate the detoxification properties according to heat treatment conditions. After heat treatment, treated ACW was analyzed for detoxification properties through crystal structure and microstructure analysis using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Microwave heat treatment method using SiC plate can be heated up to the target temperature within a short time. Finally, complete asbestos detoxification was confirmed from the crystal structure and the microstructure when the microwave heat treatment was performed at 1,200℃ for at over 60 minutes and at 1,300℃ for at over 10 minutes.

• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.1
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• pp.101-101
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• 2003

본 연구는 남은 음식물을 유산균을 이용하여 발효 사료화 하기 위해 실시하였다. 발효를 촉진시키기 위한 균주로는 Lactobacillus acidophilus를 사용하였고 최적의 발효조건을 갖는 공기 주입량을 알아보기 위해 시료의 발효 조건을 각각 달리 하였다. 시료는 교반하지 않고 공기주입 또한 없는 혐기적 조건의 것과 50rpm의 속도로 교반하면서 0.25v.v.m의 공기를 주입한군, 70rpm의 속도로 교반하면서 0.5v.v.m의 공기를 주입한 군으로 나누었다. 시료는 모두 $37^{\circ}C$로 유지하면서 48시간 발효 시키며 12시간 단위로 시료를 채취하였다. p.H와 유기산함량, 환원당함량과 유산균수를 측정하여 남은 음식물을 발효시키기 위한 최적의 공기 주입량을 알아보았다. 실험결과 50rpm 0.25v.v.m에서 가장 낮은 p.H를 보여주었고 유기산 함량과 환원당 함량은 70rpm 0.5v.v.m에서 가장 높은 함량을 보였다. 유산균은 50rpm 0.25v.v.m에서 가장 많은 증식되었음을 보여주어 적절한 공기의 주입이 남은 음식물의 발효를 촉진하는 것으로 보여진다.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.248-252
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• 2012

To evaluate the possibility of water plant wastes in composting for agricultural recycling, Phragmites communis (PHRCO), Typha orientalis (TYHOR) and Zizania latifolia (ZIZLA) were used as a compost materials. In composting basin, cumulative oxygen consumptions of the compost used by water plant wastes were rapidly increased at the early stage and slightly decreased in around 15 days. Cumulative oxygen consumptions under different water plant wastes were higher in the order of TYHOR > ZIZLA > PHRCO. Temperature changes during composting process were rapidly increased at the early stage and then slowly decreased to $30{\sim}40^{\circ}C$. The maximum temperatures were higher in the order of ZIZLA ($72.2^{\circ}C$ at 11 days after starting composting) > TYHOR ($70.2^{\circ}C$ at 10 days after starting composting) > PHRCO ($66.5^{\circ}C$ at 7 days after starting composting). Oxygen consumptions at maximum temperature were higher in the order of TYHOR ($12,485mg\;O_2\;kg^{-1}$) > ZIZLA ($12,400mg\;O_2\;kg^{-1}$) > PHRCO ($9,340mg\;O_2\;kg^{-1}$). Organic matter contents, moisture contents and OM/N rates in the compost ranged 39.5~44.8%, 29.6~35.6% and 27.9~32.9, respectively. Considering that water plant waste can supply some of the nutrient requirements of crops and is a valuable fertilizer.

• Resources Recycling
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• v.22 no.3
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• pp.73-80
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• 2013

Metal prices are rapidly rising due to increasing demand of metals and limited available resources according to the industrial requirement. As a result, securing a stable supply of these metal resources has been recognized as a core element of national competitiveness and sustained economic growth. In the case of magnesium and its alloys which are entirely depending on import, low-grade magnesium scraps from end-of-life vehicles and 3C(Camera, Computer, Communication) parts and magnesium wastes such as sludge and dross generated during melting process are hardly recycled. Accordingly, the development and commercialization of recycling technology of low-grade magnesium scrap is desperately needed to improve efficiency of resource circulation and to establish the required proprietary of resource metal supply and demand. In this study, papers and patents on recycling technologies of waste magnesium were analyzed. The range of search was limited in the open patents of USA (US), European Union (EP), Japan (JP), Korea (KR) and SCI journals from 1974 to 2012. Patents and journals were collected using key-words searching and filtered by filtering criteria. The trends of the patents and journals was analyzed by the years, countries, companies, and technologies.

• Resources Recycling
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• v.25 no.3
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• pp.29-36
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• 2016

The characteristics analysis and pH neutralization test were carried out to use of slurry generated from recycling processes of construction wastes. D (5.0) of raw sludge was $42.4{\mu}m$ and over 60 % of sludge distribute under 45 um (-325 mesh). Muscovite and carbonate minerals were main minerals of fine particles, and the portion of carbonate minerals increased as particle size decreased. Although the more heavy metals were observed in the finer particle size, the contents was found to be less than Korean contaminated soil regulation (area 2). The effects of flocculants addition for accelerating solid-liquid separation were negligible because the slurry already contains excess of coagulant added in the waste concrete recycling process. It was difficult to neutralize the sludge supernatant due to high pH (about 12) by adding acids, but the introduction of $CO_2$ decreased the pH to 8.5, The precipitate recovered during $CO_2$ introduction was determined to be $CaCO_3$ with XRD, and it indicates that high pure $CaCO_3$ could be obtained during the process.