박상우 Sang-woo Park

DOI:10.9786/kswm.2017.34.2.107

Abstract

Response measures to the resource circulation society and the new climate plan must be prepared by the central government in conjunction with local governments. The future directions of such measures can be established by investigating and evaluating trends in waste disposal currently in use by various cities and provinces. Against this backdrop, the current status of municipal waste generation and disposal in 16 Korean cities and provinces was examined. Although the percentage of waste recycled has increased, the rate of increase is declining. The percentage of waste disposed of in landfills has declined over time, but some landfills have already reached their limits. The amount of waste incinerated has grown more than the amounts recycled or disposed of in landfills. It will soon be necessary to develop measures that further increase the percentage of waste disposed of via incineration and improve the recovery of incineration-related energy. All cities and provinces should strive to improve the operating performance of their incineration facilities while reducing operating costs.

Key Words

Local government, Waste disposal, Municipal waste, Resource circulation society

권영현 Young-hyun Kwon , 손준익 Jun-ik Son , 신선경 Sun-kyoung Shin , 김기헌 Ki-heon Kim

DOI:10.9786/kswm.2017.34.2.117

Abstract

The paper industry requires continuous automation of processes ranging from injection of raw materials to initial paper processes and final processing. Thus, it is a capital- and equipment-intensive industry that requires large investments in facilities and consumes significant amounts of energy for production. Since the concept of a 'Waste Minimization and Sustainable Resource Circulation Society' is key waste management policy, the effective use of waste has been emphasized. To this end, there is significant research on energy conversion in waste incineration plants. Domestically, there is a desire to review and improve sustainable technology development systems in order to maximize thermal energy recovery in waste incineration plants. Therefore, this study compared the energy recovery rate calculation methods currently used in eight paper industry incineration plants. The lower heating value and energy recovery & use rate calculation methods were applied in accordance with the “waste resource energy recovery & use calculation method” located in Paragraph 2 of Article 3 in the Enforcement Decree of the “Wastes Control Act” of 2015. Calculations made using the current method (on the basis of output) showed an average energy recovery rate of 78.6% (75.5 ~ 82.8%), whereas the waste resource energy recovery & use rate calculation method (based on volume used) produced an energy recovery rate of 53.3% (42.5 ~ 74.8%).

Key Words

Incineration heat, Energy recovery, Lower heating value, Paper industry

강준구 Jun-gu Kang , 손준익 Jun-ik Son , 민지수 Ji-su Min , 권준화 Jun-hwa Kwon , 권영현 Young-hyun Kwon , 유하녕 Ha-nyoung Yoo , 고영재 Young-jae Ko , 장미정 Mi-jeong Jang , 전태완 Tae-wan Jeon , 신선경 Sun-kyoung Shin

DOI:10.9786/kswm.2017.34.2.125

Abstract

Recently, domestic waste policy has focused on resource circulation. In accordance with Article 3, Paragraph 2 of the “Enforcement Rules of Wastes Control Act”, which is targeted at waste incineration facilities, we established and announced methods for calculating the recovery and utilization rates of incineration-sourced heat in 2015. The lower heating value is important to energy recovery and utilization rate calculations. Hence, the lower heating values of the waste incineration facilities were estimated using the thermal method from KS B 6205. Heat loss decreases the heat recovery efficiency, and should be measured and evaluated. The surface temperatures of the incinerator and boiler are required to determine heat loss. Presently, the contact point temperature method is used to measure the surface temperature. It is difficult to apply this method to the average surface temperature of an incineration facility. In this study, 20 Korean waste incineration facilities were selected for heat loss estimates based on waste incineration temperature, incinerator type, and incineration capacity. Infrared thermal cameras were used to measure the surface temperatures of the waste incineration facilities.

Key Words

Infrared camera, Heat loss, Waste incineration plant, Waste energy, Energy recovery

심명화 Myunghwa Shim , 이경호 Kyeong Ho Lee , 류돈식 Don Sik Ryu , 김윤희 Yoon Hee Kim

DOI:10.9786/kswm.2017.34.2.132

Abstract

Because methane-producing bacteria (MPB) and sulfate-reducing bacteria (SRB) compete for anaerobic utilization of organic matter, the methane generation potential (Lo) decreases logarithmically with the decrease in the COD/SO4 ratio. The Lo correction coefficient equals the Lo at a particular COD/SO₄ ratio divided by the maximum Lo. An Lo correction coefficient was derived each year based on the COD/SO₄ ratios of waste added to the landfill. The methane generation potential was multiplied by the Lo correction coefficient in order to correct the LFG (landfill gas) generation calculation. At the second Sudokwon landfill site (2000 ~ present), the COD/SO₄ ratio decreased from 11.6 in 2000 to 4.8 in 2014. Thus, the Lo correction coefficient decreased from 0.89 in 2000 to 0.42 in 2014. The LFG 2008-2014 production correction was calculated using the model equation (Scholl canyon), and was almost the same (91 ~ 113%) as the quantity measured, including LFG that was collected, flared, or allowed to diffuse through the landfill. The methane oxidation correction factor, calculated from the concentrations of nitrogen and oxygen within the landfill gas, was between 0.92 and 1 for the first landfill site and between 0.96 and 1 for the second landfill site. Air ingress into the landfill had a negligible effect on gas generation.

Key Words

Landfill gas, COD/SO₄, Methane generation potential, Air ingress

박세용 Seyong Park , 오두영 Dooyoung Oh , 정철진 Cheoljin Cheong , 장은석 Eunsuk Jang , 송형운 Hyoungwoon Song

DOI:10.9786/kswm.2017.34.2.140

Abstract

This study was conducted to evaluate the effects of physical characteristics. Twelve specific odorous compounds and various sources of bacteria were tested via treatment of food waste using an ultra-thermophilic aerobic composting process. Food waste was mixed with seed material and operated for 47 days. During composting, the temperature was maintained at 80-90℃. The variations in O₂, CO₂ and NH₃ production suggested typical microorganism-driven organic decomposition patterns. After composting, the concentrations of 12 specific odorous compounds other than ammonia did not exceed the allowable exhaust limits for odor. After composting, thermophiles represented 50% of all bacteria. After composting, the percentage of thermophile bacterial increased by 15%. Therefore, both stable composting operation and economic benefit can be expected when an ultra-thermophilic composting process is applied to food waste.

Key Words

Food waste, Ultra thermophilic aerobic composting process, Physical characteristics, Specific odorous compounds, Thermophile bacteria

윤철우 Cheol-woo Yoon , 엄남일 Nam-il Um , 김우일 Woo-il Kim , 강영렬 Young-yeul Kang , 정다위 David Chung , 김기헌 Ki Heon Kim , 신선경 Sun-kyoung Shin

DOI:10.9786/kswm.2017.34.2.148

Abstract

The purpose of this study was to determine the feasibility of using waste stone and waste stone sludge, generated by stone grinding operations, as substitutes for natural resources. In addition, the possibility of expanding the scope of safe recycling was confirmed via an environmental assessment. This assessment was carried out by measuring particle size distributions and physical and chemical characteristics, as well as via dissolution and content tests. Waste stones and powdered waste stone sludge generated from the I-, K-, and R-quarries located in the Geochang area were selected and sampled. The pH was weakly alkaline (7.74 - 9.7), and the water content ranged from 21.29% to 32.57%. Only the Iquarry sample exceeded the 30% water content limit. The Waste Control Act regulates the use of filler materials such as bottom restoration and lowland materials in the quarry to less than 30%. Leaching tests conducted using I-, K-, and R-quarry samples were analyzed. The samples did not exceed the controlled waste criteria for hazardous substances defined by the Waste Management Act. The limits for Pb, Cr, As, Hg, Cd, and Cr⁶⁺ are 3 mg/L, 3 mg/L, 1.5 mg/L, 0.005 mg/L, 0.3 mg/L, and 1.5 mg/L, respectively. Based on the results of content tests, only Cu (252 mg/Kg) exceeded the 1 area standard (150 mg/kg) for troublesome soil contamination defined in the Enforcement Regulations of the Soil Environment Conservation Act. Based on this environmental assessment, current policies allow expansion of recycling.

Key Words

Waste stone, Stone grinding operation, Heavy metals, Recycling

김종빈 Jong Bin Kim , 이재영 Jai-young Lee

DOI:10.9786/kswm.2017.34.2.159

Abstract

Contaminated water from abandoned mines, non-sanitary landfills, and tunnel excavation flows into rivers via groundwater. These sources of contamination contain significant heavy metals and are discharged without treatment. As contaminated water flows into the river, water quality decreases. Furthermore, water that flows into rivers also contaminates the soil. This causes problems for both the environment and society. However, it is difficult to place water treatment plants at each source of contamination because of problems related to economics, site security, etc. The author has selected permeable reactive barriers (PRBs) to solve these problems. The aim of this study is to develop eco-friendly technology for reuse of waste. In this study, three reacting media were used. The first reacting medium was zero-valent iron (ZVI). ZVI can be used as a PRB and is effective at removing heavy metals. The second medium was steel-making slag. It is suitable for removal of heavy metals because its components include lime and iron oxide. The final reacting medium was bark. The bark is the outer layer of a tree, and consists of dead tree trunk tissue. The chemical structure of bark includes carboxyl and hydroxyl moieties that combine well with heavy metals. In this study, the materials to be removed were heavy metals including arsenic, cadmium, copper, lead, zinc, and nickel. The experiment was carried out for two months using two pilot scale PRBs. ZVI and steel-making slag were placed on the front of the two pilot scale PRBs under the same conditions. Activated carbon and bark were placed on the end of each device. After two months, the experiment showed efficient removal of arsenic and lead. It is possible to reduce the generation of waste by removing heavy metals with waste materials like bark.

Key Words

PRB (Permeable Reactive Barrier), ZVI (Zero-Valent Iron), Steel-making slag, Barks

박성빈 Sungbin Park , 윤균덕 Kyoonduk Yoon , 이우찬 Woochan Lee

DOI:10.9786/kswm.2017.34.2.168

Abstract

In this study, we investigated variations in particle size distribution in the process flow from a fluff-SRF manufacturing process in Y city via particle size analysis of waste. About 110 kg of MSW was analyzed in accordance with the process flows for the analysis of the particle size distribution by separating from 300 mm to 10 mm. The first tranche of waste was crushed with a primary crusher such that 100% of particles were smaller than 200 mm. A secondary crusher was used to ensure that 90% of particles were smaller than 10 mm. The crushing function and disintegration effect resulted in waste that contained 30% particles smaller than 10 mm. The primary multistage bulk selection process separated the first non-combustibles from waste passed by the secondary crusher. It produced 19.24% non-combustibles. Secondary multistage bulk selection discharges the final set of non-combustibles from the first non-combustibles after recovering any remaining combustibles. The combustible recovery ratio was 28.24%, and the final non-combustible discharge ratio was about 71.76%. The regular and high-speed disintegrators exhibited 85% and 97% efficiency in producing waste smaller than then 50 mm, respectively. This is thought to improve the yield and quality of SRF in the context of a reasonable management plan via characteristic analysis of residues from the disintegration process.

Key Words

MSW (municipal solid waste), Size distribution, SRF (solid refuse fuel)

백승기 Seung-ki Back , 정법묵 Bup-mook Joung , 이은송 Eun-song Lee , 성진호 Jin-ho Sung , 이선재 Seon-jea Lee , 박용준 Young-joon Park , 서용칠 Yong-chil Seo

DOI:10.9786/kswm.2017.34.2.180

Abstract

This study investigates leaching and thermal treatment characteristics of mercury in waste phosphor powder from UV lamp for industrial use. Waste phosphor powder contaminated with mercury compounds requires proper treatment for final disposal. A sequential extraction procedure was conducted in order to estimate the stability of mercury compounds in waste phosphor powder. The fraction of mercury compounds leached in initial steps by ion-exchangeable and low acidic solutions was 62%, which would be unstable. Finally 36% of mercury compounds was left as a strongly stable form before last step of acid digestion by aqua regia. Mercury was decomposed rapidly during initial period in thermal treatment. However, the decomposition rate reached in steady later. Correlation of mercury content in residues with concentration of leaching extract was attempted in order to set a thermal treatment condition. When mercury content in residue of phosphor powder could be lowed up to about 13 mg-Hg/kg by thermally with satisfying the Korean leaching standard limit of 0.005 mg-Hg/L.

Key Words

Mercury, UV lamp, Phosphor powder, Thermal treatment, Leaching test

이호경 Ho-kyung Lee , 공효명 Hyo-myeong Gong , 백승민 Seung-min Baek , 김우석 Woo-suk Kim , 곽윤근 Yoon-keun Kwak

DOI:10.9786/kswm.2017.34.2.188

Abstract

This study is an experimental program developed to estimate the effect of size on the shear performance of reinforced concrete (RC) beams with stirrups made from recycled coarse aggregates (RCA). The test was conducted on eight RC beams with shear reinforcement, and the main variables were section size and RCA replacement ratio (R_r = 0% or 30%). The tension reinforcement ratio (ρ = 0.012), shear span-to-depth ratio (a/d = 1.5), and width-to-depth ratio (h/b = 1.5) were fixed. Empirical test results, theoretical results, and code calculations were compared for each specimen. The results demonstrated that the empirical test results of each sample compared favorably with the theoretical calculations within a sufficient safety margin (1.32-2.61). Also, a comparison between RCA-RC beams with R_r = 30% and RC beams containing natural coarse aggregates (NCAs) showed that the two beams exhibited similar load-displacement curves and shear strengths. Consequently, RCA-RC beams made using a RCA replacement ratio of up to 30% do not cause safety or serviceability problems.

Key Words

Recycled coarse aggregate(RCA), Construction waste, RCA Replacement ratio, Shear strength, Size effect

한성국 Seong Kuk Han , 장은석 Eun Suk Jang , 박세용 Se Yong Park , 양승규 Seong Kyu Yang , 이기쁨 Gi Bbum Lee , 김호 Ho Kim , 윤수경 Sue Kyung Yun

DOI:10.9786/kswm.2017.34.2.199

Abstract

Recently, production of sewage and wastewater sludge have increased sharply with the population density and related industrial activity. As a result, studies of sludge treatment and reduction have been conducted and a pre-treatment method that uses thermal hydrolysis has emerged as a solution to this problem. To address problems with the thermal hydrolysis pre-treatment process, the deaeration and nitrogen recovery processes have been set up together, thus generating factors that inhibit dewaterability. In this study, the effect of pre-treatment, deaerated sludge on dewaterability-inhibiting factors (pH, temperature, aeration rate) was evaluated and alternative solutions were prepared. First, the dewaterability improvement effect increased rapidly at 190℃ or higher when thermal hydrolysis pre-treatment was applied. Then, 1 L of thermal hydrolysis pre-treatment reactants at 190℃ were injected into 1, 5, and 10 L/min air flows at 50℃, but no significant difference in capillary suction time (CST) or time to filter (TTF) was found. The dewaterability improved when the temperatures of the pre-treatment reactants varied between 30, 50, and 70℃ under aeration at 5 L/min. However, when the pH was increased to 7, 9, or 11 at 5 L/min and 50℃, the dewaterability worsened by at least 10 times relative to the hydrolysis pre-treatment reactants. The zeta potential decreased from -30 mV to -50 mV as the pH increased. Thus, the stabilities and dispersities of the reactants increased due to the repulsive force of the particles. This was confirmed to be the cause of poor dewaterability. A coagulant can be used to solve to this problem, or the deaeration process can be placed after solid-liquid separation and the heat of thermal hydrolysis can be extracted via heat exchanger.

Key Words

CST (Capillary Suction Time), TTF (Time to Filter), Zeta potential, Dewaterability, Thermal hydrolysis

이규빈 Gyu-bin Lee , 박영훈 Young-hoon Park , 최영환 Young-whan Choi , 손병구 Beung-gu Son , 김준엽 Jooh-yup Kim , 강남준 Nam-jun Kang , 강점순 Jum-soon Kang

DOI:10.9786/kswm.2017.34.2.205

Abstract

The current study was performed to investigate the effect of recycling coir substrates on the growth, fruit yield, and quality of strawberry plants. Analysis of physical properties revealed that the pH of a fresh coir substrate was 5.04 while those of substrates reused for one and two years were 5.20 and 5.33, respectively. The electrical conductivity (EC) of a new substrate was as high as 4.58 dS·m^-1. This can cause salt stress after transplanting. The EC tended to decrease as the substrate was recycled, and the EC of a two-year recycled substrate was 1.48 dS·m^-1. The fresh substrate had lower nitrogen and calcium concentrations, but higher phosphate, potassium, and sodium concentrations than the recycled coir substrate. The coir substrates recycled for one or two years maintained better chemical properties for plant growth than the fresh substrate. Strawberry growth varied depending on the number of years that the coir substrate was recycled. In general, strawberries grown in substrates that had been reused for two years did better than those grown in substrates that had been reused once or were fresh. Ninety days after transplanting, a plant grown in a substrate that had been reused for two years contained 25 leaves, which was 3.6 more than with a fresh substrate. In addition, the plants grown in a substrate that had been reused for two years exhibited larger leaf areas than those grown in other substrates. Coir substrates that had been reused for one year increased the number and area of leaves, but not as much as the substrate that had been reused for two years. One- and two-year reused coir substrates increased the weight of strawberries produced relative to the unused substrate, but the difference was not statistically significant. The plants grown in two-year reused substrates were longer and wider, as well. Also, the number of fruits per plant was higher when substrates were reused. Specifically, the number of fruits per plant was 28.7 with a two-year reused substrate, but only 22.2 with a fresh substrate. The fruit color indices (as represented by their Hunter L, a, b values) were not considerably affected by recycling of the coir substrate. The Hunter L value, which indicates the brightness of the fruit, did not change significantly when the substrate was recycled. Neither Hunter a (red) nor b (yellow) values were changed by recycling. In addition, there were no significant changes in the hardnesses, acidities, or soluble solid-acid ratios of fruits grown in recycled substrates. Thus, it is thought that recycling the coir substrate does not affect measures of fruit quality such as color, hardness, and sugar content. Overall, reuse of coir substrates from hydroponic culture as high-bed strawberry growth substrates would solve the problems of new substrate costs and the disposal of substrates that had been used once.

Key Words

Coir, Recycling, Strawberry