• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.2
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• pp.189-194
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• 2005

The food wastes recycling system should be constructed before 2005 in the city area. In order to manufacture the good compost, salt remaining rate should be minimized. We studied the effective method of minimizing salt ratio by diluting with low water ratio. We got the salt remaining ratio less than 0.3% by effective fragmentation method, and we applied the IR heating in order to make good compost.

• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.2
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• pp.66-73
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• 2003

To investigate the availability of solidified wastes as resource, wastewater sludge, waste gypsum and fly ash were mixed and the results with various mixing ratios are as follows. Compressive strength turned out to be increasing as the amount of waste gypsum increases, keeps longer curing inhibition, and higher forming Pressure under the conditions of waste gypsum/sludge ratio 0.31-0.45, and 0.9kg cement as 15% and 1.2kg cement as 20% of total amount. Solidified agent under the fly ash/sludge ratio 0.45, 0.6, compressive strength seemed to be higher than standard one which means solidified wastes with these conditions could be applicable in real life. These results inform that concentrations of the leachate $Cr^{+6}$, Cu, Zn, Cd, Pb solidified matrix, containing low concentration of heavy metal, were cured with/without enough time it still will cause adverse effect on nature environment and application of heavy metal sequester must be needed to reuse industrial wastes from incineration plant solidified matrix. Total cost price, when considering manufacturing capability of the facilities for resourcerizing as 18,000ton was presented 678,664,000 won, as it were, manufacturing cost price was 37,704 won per ton. The results as above has shown that it's possible to use the mixture of waste gypsum/sludge, fly ash/sludge, cement, additions, and solidification matter as substitute of materials like brick, block, interlocking which has proper compressive strength of KS L 5201 and KS F 4004.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.1
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• pp.97-102
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• 2000

This study was carried out to investigate the effects of operating temperatures on decomposition and physicho-chemical properties of household food wastes in a fermentation dryer, which was manufactured by Samwoo Co. Ltd. The household food wastes of 100 kg can be put and dried in this dryer at once. The experiments were performed at each temperature of $35^{\circ}C$, $45^{\circ}C$, $55^{\circ}C$ and $70^{\circ}C$ for two days respectively. The samples taken at the fixed time were dried at $105^{\circ}C$ and analyzed to find the decomposition rate and the concentration of each substance. The results obtained were as follows: The decomposition rate at 35 and $70^{\circ}C$ was the highest and showed the similar tendency during the experimental period. The higher the operating temperature was, the faster the water content of the composting material reduced. pH value increased at the operating temperature of 55 and $70^{\circ}C$ and was higher than at the other operating temperatures. Nitrogen content did not show any tendency during the experimental period. $P_2O_5$ and CaO content increased during the experimental period but MgO, $K_2O$ and NaCl were not accumulated. Cu content based on dry matter was in the range of ND~100.4 mg/kg and Cd, Pb and Cr were not detected.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.212-212
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• 2006

Polyurethane wastes can be depolymerized with glycols and/or amines. The depolymerization products may be recycled for the preparation of various polyurethanes. Caprolactam was employed to depolymerize Spandex fibers and the depolymerization products were evaluated as raw materials for the preparation of polyurethane elastomers. The depolymerization products were homogeneous and could be used to prepare polyurethane elastomers acceptable for various applications as binders.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.2
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• pp.140-145
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• 2000

This study was performed to investigate whether the earthworm cast could be reused as bulking agent in the whole processing of the food wastes using the earthworm. In addition, the growth conditions of microorganism lived upon earthworm lasts was investigated. Because the raw food wastes used in this experiment had low pH, and high moisture and organic matter contents, it was unsuitable to use as direct feeds to earthworm. However, when the food wastes were mixed with some earthworm cast, the mixtures were suitable to the feed condition and the growth environment of the earthworm. Therefore, it shows the possibility that the earthworm cast be reused as bulking agent for food wastes. In the microbiological investigation on earthworm cast, the bacteria showed most high density among the microbial species. And the microbial density showed higher under the mid-temperature than under high-temperature, and higher under the anaerobic than the aerobic condition. The drying methods of earthworm cast for the moisture adjusting, has no effect on microorganism growth whether natural or artificial drying. And the activity of enzyme presented more highly before the drying than after the drying.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.3
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• pp.326-332
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• 2011

The authors examined the effects of operating parameters on the $H_2$ production by dark fermentation of the wastewater generated from food waste recycling facilities, in short "food waste wastewater (FWW)". Central composite design based response surface methodology was applied to analyze the effect of initial pH (5.5-8.5) and substrate concentration (2-20 g Carbo. COD/L) on $H_2$ production. The experiment was conducted under mesophilic ($35^{\circ}C$) condition and a heat-treated ($90^{\circ}C$ for 20min)anaerobic digester sludge was used as a seeding source. Although there was a little difference in carbohydrate removal, $H_2$ yield was largely affected by the experimental conditions, from 0.38 to 1.77 mol $H_2$/mol $hexose_{added}$. By applying regression analysis, $H_2$ yield was well fitted based on the coded value to a second order polynomial equation (p = 0.0243): Y = $1.78-0.17X_1+0.30X_2+0.37X_1X_2-0.29X_1{^2}-0.35X_2{^2}$, where $X_1$, $X_2$, and Y are pH, substrate concentration (g Carbo. COD/L), and hydrogen yield (mol $H_2$/mol $hexose_{added}$), respectively. The 2-D response surface clearly showed a high inter-dependency between initial pH and substrate concentration, and the role of these two factors was to control the pH during fermentation. According to the statistical optimization, the optimum condition of initial pH and substrate concentration were 7.0 and 13.4 g Carbo. COD/L, respectively, under which predicted $H_2$ yield was 1.84 mol $H_2$/mol $hexose_{added}$. Microbial analysis using 16S rRNA PCR-DGGE showed that $Clostridium$ sp. such as $Clostridium$ $perfringens$, $Clostridium$ $sticklandii$, and $Clostridium$ $bifermentans$ were main $H_2$-producers.

• Proceedings of the KAIS Fall Conference
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• 2007.11a
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• pp.400-402
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• 2007

본 논문은 쓰레기 소각로에서 발생하는 폐열을 활용하여 유기성 폐기물의 재활용하는 방안을 제시한다. 파쇄된 유기성 폐기물을 증류 건조시켜 건조된 고형물과 응축수로 분리하여 응축수는 액비나 탈취제로 활용하고 고형물은 단미사료로 활용하는 완벽한 재활용시스템이다. 탈리액의 해양투기가 금지될 경우 탈리액을 획기적으로 줄이는 대안이라 여겨진다.

• Proceedings of the KAIS Fall Conference
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• 2007.05a
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• pp.294-296
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• 2007

본 논문은 고온 고압 수증기를 활용한 유기성 폐기물의 가수분해현상과 이를 이용한 퇴비 등의 재활용 방안을 제시한다. 사료화의 경우는 3.27 기압 $135^{circ}C$ 전후의 포화수증기로 교반처리하여 영양소 파괴를 줄이고 멸균 및 가수분해가 일어나게 하여 소화가 잘되는 사료를 만들 수 있고, 퇴비화의 경우는 16기압. $200^{circ}C$ 전후의 포화수증기로 교반처리하여 가수분해, 산가수분해, 열분해 및 탄화가 일어나도록 하여 목초액과 활성탄을 함유한 보온성, 보비성 및 통기성이 양호한 퇴비를 만든다. 응축수는 액비로 사용가능하므로 완전 재활용이 가능하다.

• Proceedings of the KAIS Fall Conference
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• 2007.05a
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• pp.297-298
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• 2007

본 논문은 가열된 폐식용유를 이용하여 음식물류폐기물에 포함된 수분을 증발시키고 고형성분을 익혀 사료, 퇴비 및 연료화 할 수 있는 장치를 소개한다. $200^{\circ}C$의 폐식용유에서 l분 이내에 완전 건조 처리되며 멸균을 시킬 수 있어 효과적이다. 열원은 소각로 열을 재활용할 경우 경제적이다. 탈리액의 해양투기가 금지될 경우 탈리액을 획기적으로 줄이는 대안이라 여겨진다.

• Resources Recycling
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• v.25 no.2
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• pp.17-24
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• 2016

This study aims at evaluating environmental impacts on recycling process of used small household appliances. The recycling process mainly consists of manual dismantling, crushing and various sorting processes to effectively recover valuable resources and to minimize environmental impact. In this study, life-cycle assessment (LCA) methodology is applied to analyze major environmental parameters such as GWP, ADP, POCP, EP, etc. One of the major impact categories on the weight basis in the recycling process is global warming (GWP) 57.1%, next to ADP 35.4% and POCP 4.8%, respectively. As a result of environmental impact on recovery of valuable resources/ton, the GWP of plastics for ABS is highest (33.7%) compared to ferrous metals (9.4%). The effects of environmental and economical benefit are also analyzed to compare with the amount of virgin materials to be recycled by recycled materials. In addition, recycled materials are also more economical in comparison to virgin materials due to the environmental avoiding effect by recycling. In conclusion, the key environmental issues related to the recycling of e-wastes are analyzed and therefore, the effective recycling process will contribute to mitigate global warming potential in the near future.