• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.4019-4023
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• 2014

This study examined the effectiveness of ultrasound on enhancing the dewaterability and volume reduction of bio solids from a waste treatment plant. The test specimen was obtained from a storage tank immediately before the dewatering process at a local treatment plant. The test conditions included the energy levels of ultrasonic waves and treatment time. The tests were undertaken using three types of different treatment processors (7 liter, 1 ton, 7 ton container). The capillary suction time (CST) and the viscosity of sludge, which is one of the influencing factors for dewaterbility, were obtained under various test conditions. The results showed that ultrasound increases the CST of the raw specimens, whereas a significant reduction (20 % of the maximum value) of CST occurred in the sample with ultrasound and flocculent. The decrease in viscosity reached 40 % of the maximum value. A centrifugal test was performed to examine the characteristics of the sludge settlement. The settling rate and time required to reach the final values were both enhanced by the ultrasonic energy. An ultrasonic treatment is potentially useful tool for reducing the amount of released sludge. To examine the possible use of field application, the real scale sonic processor was designed and operated. The results were similar (50 % of the maximum value) to those of laboratory experiments.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.3
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• pp.154-159
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• 2006

It is essential to understand the decomposition characteristics for developing the optimum anaerobic digestion system of organic wastes. In this study, BMP (Biochemical Methane Potential) test using serum bottle was conducted to evaluate the anaerobic degradability of fish offal. 3 different groups of fish offal including waste from mackerel and hairtail handling except viscera and fish viscera were chosen for the substrates. Grinded fish offal was transferred anaerobically to serum bottle in amounts of 50 ml, 100 ml and 150 ml, respectively. BMP test was carried out in triplicate. Cumulative methane production and methane production rate depending on incubation time were evaluated. These results varied depending on substrate characteristics. The average values of ultimate methane yield ranged between $420ml{\cdot}CH_4/g{\cdot}VS$ and $490ml{\cdot}CH_4/g{\cdot}VS$, and the methane production and degradation rate of viscera were higher than those of other parts of fish offal. According to the analysis of elemental composition, average C/N ratio of fish offal used in this study was 5.2. Theoretical ultimate methane yield calculated from elemental composition was $522ml{\cdot}CH_4/g{\cdot}VS$. Biodegradability was calculated as 0.847.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.6
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• pp.581-585
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• 1986

A growth experiment of the Israeli strain of common carp (Cyprinus carpio) under varying dissolved oxygen levels in the recirculating water system was conducted at the Fish Culture Experiment Station of the National Fisheries University of Pusan from August 28, 1985 to September 17, 1985. Five tanks with a capacity of $5m^3$ of water each were used under the same condition of water parameters except for dissolved oxygen levels which were designed to maintain at 2.0, 2.5, 3.0, 3.5 and 4.0 mg/l ranges. The weight of fish in the beginning was about 300g and each tank was stocked with 200kg of fish. DO level of 3.5mg/l was found to be the best level with a feed coefficient of 1.57 and a daily growth rate of $1.411\%$ whereas 4.mg/l showed a slightly decreased performance of 1.63 and $1.365\%$ respectively. The amounts of feed consumed in 3.5 and 4.0mg/l DO levels were almost the same. Below 3.0mg/l DO levels the growth rate markedly decreased. Furthermore, in 2.0 and 2.5 mg/l groups, the fish did not accept feed vigorously and after feeding the fish usually concentrated around the inflow point showing oxygen deficiency response, The experiment indicates that the DO range of 3.5 to 4.0mg/l is the optimum level for the best growth at $27.5^{\circ}C$. DO concentration above these levels is considered a waste of energy resulting in uneconomical performance, and on the other hand, below these levels, the carp certainly shows a poor growth performance.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.1
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• pp.1-7
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• 2014

This paper aims to explain the safety assessment and remediation mechanism of Granulated Coal Ash (GCA) as a material for the remediation of coastal sediments and to evaluate the improvement of the sediment in Kaita Bay, where GCA was applied. The concentrations of heavy metal contained in GCA and the dissolved amounts of heavy metal from GCA satisfied the criteria for soil and water pollution in Japan. The mechanisms on the remediation of coastal sediments using GCA is summarized as follows; (1) removal of phosphate and hydrogen sulfide (2) neutralization of acidic sediment (3) oxidation of reductive sediment (4) increase of water permeability (5) increase of soil strength (6) material for a base of seagrass. From the results obtained from the field experiment carried out in Kaita Bay, it was clarified that GCA is a promizing material for remediation of coastal sediment. This remediation technology can contribute to promote waste reduction in society and to decrease cost of coastal sediment remediation by applying GCA in other polluted coastal areas.

• Journal of the Korean Society of Safety
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• v.27 no.2
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• pp.49-56
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• 2012

If cement can be manufactured with industrial byproducts such as granulated blast furnace slag, phosphogypsum, and waste lime instead of clinker, there would be many advantages, including maximum use of these industrial byproducts for high value-added resources, conservation of natural resources and energy by omitting the use of clinker, minimized environmental pollution problems caused by CO2 discharge, and reduction of the production cost. By this reason, in this study, mechanical behavior tests of non-burnt cement concrete were performed, and elasticity modulus and stress-strain relationship of non-burnt cement concrete were proposed. 6 test members were manufactured and tested according to reinforcement ratio and concrete compressive strength. By the test results, there was no difference between ordinary concrete and non-burnt cement concrete of flexural behavior. In order to verify the proposed non-burnt cement concrete model, nonlinear analytical model was derived by using strain compatibility method. By the results of comparison between test results, ordinary concrete model and proposed model, The proposed model well predicted the flexural behavior of non-burnt cement concrete.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.3
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• pp.172-177
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• 2014

Low pressure air flotation (LAF) pilot plant for sludge thickening was installed in Chung Nam N.S. municipal waste water treatment plant to verify its application possibility. Effects of operating conditions such as coagulant dosages and microbubble water ratio on thickening of the mixed sludge were examined. Microbubbles which were generated in the chamber of $1.5kgf/cm^2$ by high speed collision method with foaming agent were used to float sludge. Solid loading of $30kg/m^2/hr$, solid contents in thickened sludge of 60,300 mg/L and SS removal efficiency of 99% were obtained through long period operating LAF in conditions of mixed sludge concentration of 14,400 mg/L, coagulant dosage of 27.6 mg/L, foaming agent addition of 4.0 mg/L and microbubble water injection ratio of 9.7%.

• Journal of the Korea Institute of Building Construction
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• v.12 no.1
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• pp.115-121
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• 2012

If cement could be manufactured with industrial byproducts such as granulated blast furnace slag, phosphogypsum, and waste lime rather than clinker, there would be many advantages, including the maximization of the use of these industrial byproducts for high value-added resources, the conservation of natural resources and energy by omitting the use of clinker, the minimization of environmental pollution problems caused by $CO_2$ discharge, and the reduction of the production cost. For this reason, in this study, mechanical behavior tests of non-sintered cement concrete were performed, and elasticity modulus and stress-strain relationship of non-sintered cement concrete were proposed. Nine test members were manufactured and tested according to reinforcement ratio and concrete compressive strength. According to the test results, there was no difference between general cement concrete and non-sintered cement concrete in terms of flexure and shear behavior.

• Journal of the Korea Organic Resources Recycling Association
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• v.13 no.1
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• pp.115-123
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• 2005

In this study, life cycle assessment(LCA) technique was employed to evaluate the environmental impact of material recycling of polyethylene terephthalate(PET) bottle. Life cycle inventory was established based on the data collected from recycling companies in Korea. Simapro 5.0 LCA software and Eco-indicator 95 index were used for the analysis. The biggest impact by the material recycling of PET bottle on the environmental category was the global warming. It is because melting and production of the recycled PET product consume a significant amount of electricity and energy. In the environmental pollution discharge, $CO_2$ emission was the highest, followed by NOx. This is probably due to the use of diesel and gasoline in the consumption of electricity and transportation. All the environmental impact showed (-) value except the ozone layer depletion, which means that the material recycling of PET bottle is environmentally fair. The use of recycled PET product greatly reduced the environmental impact.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.3
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• pp.20-25
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• 2012

As a kind of distributed energy system, the co-generation system based Diesel engine using after-treatment device was devised for its environmental friendly and economic qualities. It is utilized in that the electric power is produced by the generator connected to the Diesel engine, and waste heat is recovered from both the exhaust gases and the engine itself by the finned tube and shell & tube heat exchangers. An after-treatment device composed ceramic heater and DOC(Diesel Oxidation Catalyst) is installed at the engine outlet in order to completely reignite the unburned fuel from the Diesel engine. In this study, mutual relation of each experimental condition was derived through minimum number of experiment using Taguchi Design and ANOVA recently used in the various fields. It is found that the total efficiency (thermal efficiency plus electric power generation efficiency) of this system reaches maximum 94.4% which is approximately higher than that of the typical diesel engine exhaust heat recovery system.

• Journal of Adhesion and Interface
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• v.6 no.2
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• pp.6-12
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• 2005

The plasma generally, ionized gas state, is the 4th material state composed the universe. Generating the plasma artificially has been studied by spending energy and it has a lot of applications in human's life. There are several merits to modify the surface of polymer using plasma. Above all, plasma maintains the property of polymer because of it changes the property of surface only. Also, it doesn't use a organic solvent and it is the environment friendship because of there are no waste under processing. Furthemore, in case of high-pressure plasma, it is possible that automated-processing continuously. In this study, we tried the reforming of surface to rise the adhesive strength between the material of polymer, experimented the rising of adhesive strength through a experiment of peel strength by virtue of processing time and using gas, confirmed the change of polymer's surface through measuring the surface contact angle analyzer and scanning electron microscopy (SEM).