박영수 Young-su Park , 임용택 Yong-taek Lim , 박수남 Soo-nam Park , 구재회 Jae-hoi Gu , 민광기 Kwang-gi Min

DOI:10.9786/kswm.2019.36.6.495

Abstract

The purpose of this study is to use data mining methods to assess effective operation methods by developing prediction models for gas composition, an indicator of the effectiveness of waste gasification. We have examined an algorithm that can predict the correlation between gasifier temperature and syngas composition. We found that H2 concentrations are highly negatively correlated with the temperature of the drying zone and pyrolysis zone in the gasifier. However, CO concentrations were not correlated with the gasifier temperature. Results of analyses using PLS, MLR, PCR, and SVR, indicated that SVR showed the highest prediction accuracy result at 86.5%.

Key Words

Data mining, Prediction model, Syngas composition, Exploratory study, Waste gasification system

정두희 Doo-hee Jung , 김산 San Kim , 김진수 Jin-su Kim

DOI:10.9786/kswm.2019.36.6.507

Abstract

The purpose of this study was to evaluate the removal efficiency of organic matter, nitrogen, and phosphorus through the biofiltration process using oyster shells as the main carriers, which are byproducts of aquaculture and photosynthetic bacteria and are useful micro-organisms in small-scale sewage treatment. Pilot test results of the biofiltration process proposed in this study are similar to those of controls using suspended growth in the T-I region, which is the average load of organic matter removal efficiency according to load and water temperature variation. By contrast, the removal efficiency of nitrogen and phosphorus was improved regardless of changes in temperature. Particularly, in the T-Ⅱ region, which is constantly under low load, the removal efficiencies of organic matter (+10.8%), nitrogen (+10.9%), and phosphorus (+23.4%) under low water temperatures were relatively high compared to controls.

Key Words

Biofiltration, Photosynthetic bacteria, Oyster shells, Carrier

박영철 Young-cheol Bak , 최주홍 Joo-hong Choi

DOI:10.9786/kswm.2019.36.6.517

Abstract

Waste oyster shell as catalysts for transesterification of soybean oil was investigated to produce the bio-diesel oil. The experimental conditions included molar ratios of the methanol to oil (6:1, 9:1, 12:1 and 15:1), the concentration of catalyst used (5, 10, 15, and 20wt%), the reaction temperatures (50, 60 and 70℃), and calcination temperature of oyster shell (800, 900 and 1,000℃). The experimental results showed that the conversion of soybean oil increased with the methanol mixing ratio and with the reaction temperature. The conversion was increased with the concentration of catalyst, but slightly decreased over 20wt.%. A 12:1 molar ratio of methanol to oil, addition of 15% oyster shell catalyst, 900℃ calcination temperature of oyster shell, and 60℃ reaction temperature gave the best results. The Fatty Acid Methyl Ester (FAME) conversion exceeded 94% at 1 h.

Key Words

Oyster shell, Catalyst, Bio-diesel, Soybean oil, Transesterification

이성현 Sunghyoun Lee , 정광화 Gwanghwa Jeong , 이동준 Dongjun Lee , 이동현 Donghyeon Lee , 곽정훈 Junghoon Kwag

DOI:10.9786/kswm.2019.36.6.524

Abstract

Swine manure has been recognized as an organic source of composting material, and much research has been conducted for its efficient utilization and treatment. This study was carried out to analyze the changes in fertilizer composition, heavy metals, and fiber content during composting by mixing pig manure with sawdust. The test was set as a simple sedimentation type composting and a ventilation sedimentation type composting. In EXP1 and EXP2, 100 L and 150 L of air were blown for each cubic meter of composting material. The composting fermentation period was set at four weeks. The fermentation temperature during the composting process increased from 67℃ to 75℃ between 1 and 2 days. It was judged that this was due to the rapid increase in the abundance of thermophilic bacteria. The contents of the fertilizer during the composting period were found to be largely changed in EXP1 and EXP2 but not in the REF. Cadmium, mercury, and lead were not detected in throughout the test. The coefficient of variation in copper content in the REF, EXP1, and EXP2 was 0.033, 0.058, and 0.071, and the coefficient of variation in zinc content was 0.025, 0.041, and 0.079. Copper and zinc contents did not change significantly during the composting period. After fermentation, the heavy metal content of the compost was less than the value determined by the composting organic fertilizer standard. The variation patterns in NDF, ADF, and cellulose contents were similar to one another during the composting period. The change in fiber content was larger in EXP1 and EXP2 than in the REF.

Key Words

Composting, Fertilizer ingredient contents, Fiber contents, Heavy metal contents, Swine manure

이상철 Sang-chul Lee , 김관용 Gwan-yong Kim , 정득준 Deuk-jun Jung

DOI:10.9786/kswm.2019.36.6.534

Abstract

Industrial compressed gaskets are used to connect the ends of pipes with flanges, and to fit the flanges to the joint surfaces to maintain the airtightness of the flanges. Gaskets are widely used for sealing in all industrial fields, such as the petrochemical industry, power plants, the shipbuilding and marine industry, and marine plants. Gaskets can be either metal or non-metallic. Non-metallic gaskets are made in the form of a plate using materials such as rubber, asbestos, non-asbestos fibers, and paper. Non-metallic gaskets are flexible so are generally used to make products that do not require tightening forces. In this study, fiber waste obtained as a by-product of the manufacturing process were selected, recovered, pulverized, and dried. This was then mixed with a binder to prepare a gasket sheet. The binder used in this study was NBR (acrylonitrile-butadiene rubber).

Key Words

Fiber waste, Gasket, Compression sheet, Recycle process

김도용 Do-yong Kim , 정철진 Cheol-jin Jeong , 장은석 Eun-suk Jang , 김대기 Daegi Kim

DOI:10.9786/kswm.2019.36.6.543

Abstract

The coastal waste consisted primarily of fishing nets, ropes, plastic bottles, wood, buoys, Styrofoam, and incombustible materials such as glass, cans, and shells. Combustible matter accounted for the greatest proportion of the waste (85%), with a high calorific value of 9,130 ~ 10,140 kcal/kg for the plastics and 4,297 kcal/kg for the wood. Coastal waste can thus be a useful energy source as solid refuse fuel. However, the high salt content of coastal waste limits its use as a fuel. Thus, the salt removal characteristics of a physical treatment method were investigated in this research. The salt removal efficiency was 43 ~ 85% for plastics (e.g., fishing nets, rope, PET bottles) and 5.9 ~ 21.2% for wood (e.g., wooded plates and bamboo), which were the major contributors to coastal waste. These results indicate that physical treatment using a vibration separator can effectively remove the salts adsorbed onto the surface of coastal waste.

Key Words

Coastal waste, Salt removal, Physical treatment, Fuel property

윤철우 Cheol-woo Yoon , 엄남일 Nam-il Um , 전태완 Tea-wan Jeon , 신선경 Sun-kyoung Shin

DOI:10.9786/kswm.2019.36.6.549

Abstract

In this study, an environmental hazardous impact assessment for the ladle furnace slag generated in the steelmaking process was conducted. The purpose of this study was to examine the possibility of expanding the recycling opportunities for ladle furnace slag. First, the physical and chemical properties were reviewed, and it was found that CaO accounted for more than 50% of the slag. Therefore, it was deemed necessary to assess the health hazards associated with the recycling of the slag. Because CaO is highly alkaline, inhalation and eye contact are a concern for workers during the manufacturing, storage, and transportation of the accelerator product. To avoid this, workers should wear personal safety gear and prevent damage. Applying an environmental hazardous impact assessment for non-media contact, no item exceeded the standards for heavy metal content in cement replacement material following recycling. Because the content criteria are defined for only five elements (As, Cd, Cu, Pb, and Hg), it is believed that using ladle furnace slag as a cement substitute will not contravene the Waste Control Act. The results for fluoride were close to the criteria for the warren level of soil contentment prescribed under the Soil Environment Conservation Act. Therefore, the environmental impact of using ladle furnace slag as an alternative material for accelerator products was considered to be minimal. However, it is necessary to ensure safety via continuous environmental monitoring when it is used in accelerator products. After conducting an environmental hazardous impact assessment for media contact, it was deemed necessary to review the aging process of ladle furnace slag. The slag may be used for recycling after aging in accordance with the “Guidelines for the Recycling of Steel Slag and Coal Ash for Emission Operators.”

Key Words

Recycling, Environmental hazardous impact assessment, Ladle furnace slag, Steelmaking, Hazardous waste

이세현 Sea-hyun Lee

DOI:10.9786/kswm.2019.36.6.560

Abstract

The amount of aggregate used in concrete is very low. The reason for avoiding the use of the recycled aggregate is quality, stability, and problems in the cement paste and the foreign matter content attached to the recycled aggregate. Therefore, in this study, we investigated the physical properties of the rotor hammer before and after passing through the manufacturing process of the rotary impact and multistage wind pressure treatment methods to stabilize the quality of circulating fine aggregate. After passing through the rotor hammer and multistage wind pressure treatment devices, the density increased more than 3.3%. The absorption rate decreased to 16.7% on average after passage. In addition, the particle shape judging result rate, the amount lost in the 0.08 mm sieve amount test, the amount of clay lump, and the safety and the particle size distribution were excellent after passing through the rotor hammer and multi-stage wind pressure-treating apparatus. Organic matter was reduced to 65.9% and the average amount of inorganic impurities decreased to 12.8% after the passage. The material can be applied as recycled fine aggregate for concrete satisfying KS F 2527 standard.

Key Words

Rotor hammer, Rotor impact, Recycled fine aggregate, Density, Percentage of absorption

정법묵 Bup-mook Jeong , 김동주 Dong-ju Kim , 박동규 Dong-kyu Park , 박영수 Young-su Park

DOI:10.9786/kswm.2019.36.6.567

Abstract

Basic oxide, such as SiO₂ and A_l2O₃, which are the main components of ash, are generally known as materials with high melting temperatures. One characteristic of these components is that the melting temperature is lowered by the formation of a eutectic compound under constant mass ratio conditions. In this study, combustion melting technology was applied to reduce the volume of sludge and to minimize its potential to cause harm. Analyses of the basic properties of the sludge and ash were performed to assess the melting and heavy metal emission characteristics of the sludge. An XRF analysis was performed to calculate the basicity of the sludge waste. The ratio of basicity (CaO/SiO₂) was calculated using the XRF analysis results. We used one kind of sewage sludge and two kinds of waste water sludge. The basicity was 0.642 for sewage, 0.193 for dyeing, and 4.132 for wastewater sludge. The basicity was controlled by adding CaO or SiO₂. The experiment was carried out at a constant temperature, and the pouring index was calculated by measuring the melting length according to the basicity.

Key Words

Melting, Sewage sludge, Fluidity, Basicity, Incineration

윤상혁 Sang Hyuck Yoon , 김상헌 Sang-heon Kim , 이세현 Sea-hyun Lee

DOI:10.9786/kswm.2019.36.6.576

Abstract

The modified CBR of the road construction recycled aggregate produced from the rotor impact and the bottom-up blower increased to 8.0% on average after passing, and the compaction performance was improved. The abrasion loss and sand equivalent were superior to those measured before passing through the rotary impact and the bottom-up type blower. The material satisfied recycled aggregate quality standards and could be used as recycled aggregate for road construction. Organic foreign matter content decreased to 67.5% after passing, and inorganic matter content decreased to 24.2% after passing. In addition, it is more effective to remove organic foreign matter than inorganic matter, which can be applied to recycled aggregate for road construction satisfying KS F 2574 standard. The recycled aggregate for road construction after passing through the rotor impact and the bottom-up type fan was satisfactory in both the plastic index and the liquid limit, and it seems to have resistance to bearing capacity and external force.

Key Words

Vertical, Spreader, Impact, Recycled aggregate for road construction, Modified CBR, Foreign material