• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.3
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• pp.317-324
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• 2020

Plastic wastes generated from domestic waste are separated by mixed discharge with foreign substances, and the cost of the separation and screening process increases, so recycling is relatively low. In this study, as a fundamental study for recycling mixed plastic wastes generated from domestic waste into concrete aggregates, changes in concrete properties according to the plastic waste types and the substitution rate were evaluated experimentally. The mixed plastic waste aggregate(MPWA) was found to have a lower density and a higher absorption rate compared to the coarse aggregate with good particle size distribution. On the other hand, the single plastic waste aggregate(SPWA) was composed of particles of uniform size, and both the density and the absorption rate were lower than that of the fin e aggregate. It was found that the MPWA substitution concrete did not cause a material separation phenomenon due to a relatively good particle size distribution even with the largest amount of plastic waste substitution, and the amount of air flow increased little. The compressive strength and flexural strength of the PWA substitution concrete decreased as the amount of substitution of the PWA increased due to the low strength of the PWA, the suppression of the cement hydration reaction due to hydrophobicity, and the low adhesion between the PWA and the cement paste. It was found that the degree of deterioration in compressive strength and flexural strength of concrete substituted with MPWA having good particle size distribution was relatively small.

• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.4
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• pp.114-119
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• 2003

The fermentative conversion of food wastes into probiotic feed was investigated by seeding of mixed inoculum of Lactobacillus acidophilus and Saccharomyces cerevisiae. After grinding finely, optimal fermentation conditions for aeration was investigated at $30^{\circ}C$, The viable cell count of lactic acid bacteria and yeast during fermentation were monitored by controlling aeration rate at each different aeration degree of 0v.v.m 0rpm, 0.25v.v.m 100rpm, 0.5v.v.m 200rpm, and 1v.v.m 500rpm respectively. The most active growth of the yeast was shown at 0.5v.v.m 200rpm as $4.5{\times}10^9CFU/m{\ell}$. By controlling aeration rate, the pH of the probiotics feed could be controlled between 4-5 for the enhancement of preservation characteristics and acceptability for cattle feeding.

• Resources Recycling
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• v.24 no.3
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• pp.34-43
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• 2015

Raw materials in steel industry decide on the productivity, quality and price competitiveness. Utilizing iron-containing by-products as raw materials for steel products can save the cost of cleaning up iron-containing by-products and solve environmental issues. Iron-containing by-products have a small particle size. If they are directly inserted in a steel making process, it cause a problem such as poor heat flow and scattering. To solve these problems and induce the additional reduction, study concern with iron ore-coal mixed briquette technique are conducted by many researchers. In this paper, method of making carbon composite briquette iron(CCBI) using iron-containing by-products was studied. The effect of composition of Fe-containing process wastes, reducing agent, flux and binder on formability of CCBI (carbon composite briquette iron) was measured.

• Journal of the Korean Wood Science and Technology
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• v.33 no.3 s.131
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• pp.79-88
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• 2005

This research studied the utilization of the bed log wastes as a papermaking grade pulp. Five different bed log samples from shiitake mushroom (Lentinus edodes (Berk.) Sing) cultivation were collected by the cultivating periods of 1 to 5 years. The wood chemical composition and the characteristics of kraft pulping of each sample were investigated. The results of chemical composition showed that the rate of carbohydrate (glucose and xylose) content in sapwood was decreased as the cultivation period was increased. In heartwood, there was no significant difference. The screening yield of non-cultivated bed log from kraft pulping was higher than that of cultivated one, but the reject of cultivated one, especially for 5 year-cultivated, was lower than non-cultivated bed log. The fiber length and width was continuously decreased as the cultivation period was increased. Therefore, the freeness of the pulp from the cultivated bed log was sharply decreased comparing to non-cultivated due to the fiber cutting and the increased fine content. The dry strengths were increased according to the increasing addition level of bed log kraft pulp to KOCC and non-cultivated wood pulp. From the overall results, the pulp from 5 years cultivated bed log can be reasonably used if it is mixed with long fiber pulp for advantages such as reducing beating time.

• Journal of the Korea Organic Resources Recycling Association
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• v.3 no.1
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• pp.13-20
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• 1995

The purpose of this study was to evaluate the potentials of food wastes as an animal feed. The food wastes from the Inha University and Hanyang University Hospitals were used for this fermentation study. As the additive, approximately 40~50% of dry bean curd dregs and sawdust was mixed for moisture adjustment, certain amount(l/300 of the total content) of inoculum was added into the 140L volume fermenter and fermented for 40~48 hours with the temperature of $46{\sim}52^{\circ}C$ maintained. Fermentation product with the dry bean curd dregs had the lower content of crude protein, crude ash, calcium and phosphorus than the commercial pig feed. Fermentation product with sawdust had the lower content in most components than the commercial pig feed except crude fiber content. Based upon these findings, it was considered that only the fermentation product with dry bean curd dregs as the additive could be used for the animal feed aid.

• Journal of Mushroom
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• v.5 no.1
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• pp.43-49
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• 2007

Application of sludge wastes into the field may help soil fertility with physical, chemical and biological properties. Efficient use of sludge waste, however, requires an individual assessment of the waste products. A lot of experiment into the organic waste-treated soils has been done for decade. However, studies have not been carried out on the assessment of agricultural soil by Basidiomycota. This study was assessed the influence of sludge application on soil healthy in agricultural upland soils. The organic wastes selected for long-term application experiment in this study were municipal sewage sludge (MSS), industrial sewage sludge (ISS), leather processing sludge (LS), alcohol fermentation processing sludge (FS), and pig manure compost (PMC). To develop the soil healthy assesment method, soil samples were diluted by 20X with distilled water. After shaking at 200rpm for 30 minutes, the shaked sample was mixed on PDA(Potato Dextrose Agar). And sterilized at $121^{\circ}C$ for 20 minutes. Coriolus hirsutus (MKACC 50560) was inoculated on petri-dish including PDA mixed sample. After the media was incubated at $25^{\circ}C$ for five days, the mycelial growth of C. hirsutus was measured. When the mycelial growth on sample media was compared with growth on media contained PDA only, well grown media contained sample soil was assesed as healthy soil. The results suggest that the simple method by Coriolus hirsutus is a handy way to assess the healthy of waste sludge-applied upland soils.

• Journal of the Korean Ceramic Society
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• v.38 no.9
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• pp.839-845
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• 2001

In order to vitrify the Ion-Exchange Resin(IER), Dry Active Waste(DAW), and borate concentrate generated from the commercial nuclear facilities, the glass formulation study based on the their compositions was performed. Two glasses named as RG-1 and DG-1 were formulated as the candidate glasses for the vitrification of hte IER and DAW, respectively. A glass named as MG-1 was also formulated as a candidate glass for the vitrification of the mixed wastes containing the IER, DAW, and borate concentrate. The process parameters, product qualities, and economics were evaluated for the candidate glasses and confirmed experimentally for the some properties. The glass viscosity and electrical conductivity as the process parameters were in the desired ranges. the product qualities such as glass density, chemical durability, phase stability, etc. were satisfactory. In case of vitrifying the wastes using our developed glass formulation study, the volume reduction factors for the IER, DAW and mixed wastes were evaluated as 21, 89 and 75, respectively.

• Journal of Navigation and Port Research
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• v.33 no.1
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• pp.57-63
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• 2009

In order to effectively isolate the marine wastes with an effluent standard, the pretreatment process is required to isolate solid materials from the liquid-solid mixed wastes. The more effective the pretreatment becomes, the more processing capacity of posttreatment will be improved and process facilities will be downsized. In this paper, we suggested the vibrating reverse-slant screen, investigated the optimal vibration frequency and vibrator installation angle for the separation of the liquid solid mixed wastes. Several experiments for separation efficiency were conducted under the condition of various vibration frequency($35{\sim}60Hz$, 5Hz interval) and vibrator angle($0^{\circ}$, $30^{\circ}$, $45^{\circ}$, $90^{\circ}$) considering the crack of screen. The screen inclination angle is set up the gradient as $3^{\circ}{\sim}5^{\circ}$ through the preliminary experiments. Also, we made two types of screen(respectively rectangle and square screen). The separation device has shown the optimum efficiency at vibrator angle $0^{\circ}$ and vibration frequency 60Hz, and has no relation with the shape of screen. And the proposed technology is verified by comparing with quantity of suspended solids before and after filtration.

• Microbiology and Biotechnology Letters
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• v.6 no.2
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• pp.51-57
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• 1978

The study was made of the cultural condition and physiological characteristics of the symbiotic pair of microorganisms, Cellulomonas flavigena and the second organism. It also contains the results of a taxonomical study of the second organism. The results obtained wers summarized as follows : 1) Cell yield of the mixed culture, Cellulomonas and the second organism, was higher than that of each pure culture in CM-Cellulose medium. 2) The taxonomical characteristics of the second organism revealed that it probably belonged to the genus Sporocytophaga because it had a gliding motility and microcyst. 3) Optimum pH of the mixed culture was found to be in the vicinity of 7.2, and optimum temperature of the cell growth in the mixed culture was observed to be in the vicinity of 30$^{\circ}C$. 4) It was found that the majority of the population during growth in the mixed culture consisted of Cellulomonas flavigena. 5) Cellulomonas flavigena required thiamine and biotin as growth factors but Sporocytophaga sp. had no requirement of vitamins. 6) Gulucose was not found in detectable amounts in the medium of Cellulomonas flavigena but it was traced in the mixture by thin layer chromatography. 7) Sixteen amino acids were analyzed from the cell protein of Cellulomonas flavigena by amino acid autoanalyzer. The amount of the leucine, valine and arginine was very high.

• Journal of the Korean Chemical Society
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• v.21 no.4
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• pp.293-303
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• 1977

Cellulosic organic solid wastes such as bark and sawdust, and filter papers as a pure cellulose were pyrolyzed at $300^{\circ}C$ under nitrogen current and mixed current of nitrogen and air. Amounts of condensates collected in air, water, and dry ice-acetone cooling traps, noncondensable gases, and carbonized residues were surveyed. The components of volatile liquids condensed in dry ice-acetone trap were separated by means of gas chromatograph and identified by retention times and syringe reactions. Pyrolysis under nitrogen current produced 13.4∼29.6${\%}$ of tar, 0.01∼0.12${\%}$ of aqueous liquids, 0.24∼1.43${\%}$ of volatile liquids, 9.84∼42.41${\%}$ of noncondensable gases, and 44.0∼65.81${\%}$ of carbonized residues. Pyrolysis under mixed current decreased tar and condensable liquids, but increased noncondensable gases.Volatile liquids collected under nitrogen current separated into the same 19 components by Porapak Q column regardless of the materials and only difference among materials was relative amounts of components. Volatile liquids collected under mixed current separated into six components and mainly lower molecular weight compounds such as methanol and formaldehyde were produced. According to the retention times and syringe reactions, methanol, formaldehyde, acetone, acetaldehyde, acetic acid, and three other compounds presumably containing hydroxyl group in the molecular structure were identified out of 19 compounds.