박상우 Sang-woo Park , 장성호 Seong-ho Jang

DOI:10.9786/kswm.2015.32.6.529

Abstract

Results of reviews on bio-gas production and policy trends in the European Union (EU) are as follows. In the EU, Germany leads in bio-gas production with 29 TWh of energy produced through energy crops as of 2013. This could be achieved through renewable energy laws and increases in feed in tariff (FIT) schemes in Germany. In the EU, bio-gas has been verified to play an important role and contribute to greenhouse gas reduction. However, it is necessary to provide a measure to improve sustainability criteria and decrease the consumer's share of expenses. If bio-gas is produced using organic wastes instead of energy crops, this problem can be solved. If the bio-gas production policies in the EU are applied in South Korea, bio-gas market will be promoted and greenhouse gas emission can be reduced in the future.

Key Words

Organic waste, Biogas, Policy trends, Energy recovery

김재경 Jae-kyung Kim , 이승희 Seung-whee Rhee

DOI:10.9786/kswm.2015.32.6.540

Abstract

Carbonization using chicken manure was used to obtain an energy source. In order to estimate the reaction rate at the optimal conditions for chicken manure in carbonization process it is estimated the reaction kinetics for the process. The carbonization process for chicken manure was optimized at carbonization temperature 300℃ to 400℃ in 20minutes. From the examination of conversion characteristics of chicken manure, carbonization reaction can be described by the 1st order kinetic reaction. Frequency factor(A) of reaction rate for chicken manure was evaluated to be 0.55 × 10-² min^-1 and the activation energy was estimated to be 3,815.0 kcal/kmol. As increased carbonization temperature from 250℃ to 400℃, reaction rate constant of chicken in the 1st order kinetic reaction is also increased from 0.0604 min^-1 to 0.1383 min^-1. In this study, carbonization degree of chicken manure in carbonization process was estimated by kinetic reaction deduction. The result of kinetic reaction in carbonization of chicken manure was evaluated to be 1st order kinetic reaction.

Key Words

Chicken manure, Carbonization, Kinetic reactions, Conversion, Activated energy

한성국 Seong Kuk Han , 정희숙 Hee Suk Jung , 송형운 Hyoung Woon Song , 안대현 Dae Hyun Ahn

DOI:10.9786/kswm.2015.32.6.547

Abstract

Recently, it is increase in the processing of organic waste using anaerobic digestion. Therefore, the studies on the processing method for increasing the anaerobic digestion waste water. Among them, purification treatment and liquid fertilizer have been issues. But, efficiency of the ways is very insufficient. While increasing the anaerobic digestion process, increasing study for the treatment of anaerobic digestion waste water. In this study, It was evaluate the characteristic of liquid fertilizer of anaerobic digestion waste water as affected by aeration rate and solid-liquid separation. Also, we review liquid fertilizer degree using maturity assessment indicators of liquid fertilizer by national institute of animal science. As a result, insertion of air(3.5 L/min) sample after solid-liquid separation appeared was the highest. pH and color was difficult to understanding correlation with liquid fertilizer among maturity assessment indicators(seed germination, ammonia(NH3), hydrogen sulfide(H₂S), electrical conductivity(EC), pH, color, etc).

Key Words

Anaerobic Digestion Waste Water, Solid-liquid Separation, Liquid Organic Fertilizer, Aeration, Germination Index

김대봉 Dae-bong Kim , 이효익 Hyo-ik Lee

DOI:10.9786/kswm.2015.32.6.553

Abstract

The purpose of this study is to analyse whether the capability assesment index to perform services as well as credit ratings for the governmental procurement bidding influence earnings management behaviour using discretionary accruals and real earnings management in the construction waste disposal industry. For this study, out of the 530 population(interim disposal service companies for construction waste) across the country, the final sample of 144 companies is selected for an analysis period of six years, starting from 2008 to 2013. The modified Jones model (1995) is used to measure earnings management and the Kothari et al. model (2005) reflecting return on total assets (ROA) is also applied to produce the discretionary accruals. In addition, earnings management through real activities is measured by the model developed by Roychowdhury (2006) and the method developed by Cohen et al. (2008) is adopted to calculate the measurement of integration of real earnings management. Overall, our empirical results of the analysis show that the capability assessment index to perform services as well as credit ratings significantly influence earnings management behaviour in the construction waste disposal industry. First, the managers of companies having higher assessment index report increased profits through adjusting both discretionary accruals and real earings management. Second, the managers of speculative enterprises which rank lower credit ratings use higher income-increasing discretionary accruals. These research findings imply that the regulatory authorities should properly consider the earnings management behavior of the construction waste disposal service industry in setting the qualification standards for the governmental procurement bidding. The usefulness of this study results can be highlighted by alerting the industry managers that improper earnings management practices not only decrease the successful bidding chances of the companies involved but also deteriorate long-term firm values in the market.

Key Words

Discretionary accruals management, Real earnings management, Credit ratings, Capability assessment to perform services, Construction waste disposal industry bidding

변민우 Min-woo Byeon , 안종화 Johng-hwa Ahn

DOI:10.9786/kswm.2015.32.6.566

Abstract

This study aimed to determine adhered mortar content of recycled aggregate (RA) using microwave irradiation (700 W) and mixed solution of hydrochloric acid (HCl) and hydrogen peroxide (H₂O₂). The optimum condition was first to soak RA in tap water for 30 min and then RA was soaked in mixed solution of 30% HCl and 15% H₂O₂ (HCl : H₂O₂= 1 : 2) for 70-90 min after 15-min microwave irradiation. The mortar of RA in the condition was completely removed within 2.3 hrs. Reaction rate (k) with the condition was -0.6408 hr^-1, which was about 190 times faster than that with HCl only (k = -0.0034 hr^-1).

Key Words

Adhered mortar, Microwave heating, Recycled aggregate, Acid treatment, Hydrogen peroxide

윤영식 Young-sik Yoon , 민재홍 Jae-hong Min , 김동주 Dong-ju Kim , 박영수 Yeong-su Park , 구재회 Jae-hoi Gu , 민지홍 Ji-hong Min , 김기현 Ki-hyun Kim , 이상훈 Sang-hoon Lee

DOI:10.9786/kswm.2015.32.6.574

Abstract

This research performed the effects of the air ratio to produce the syngas from the fixed-bed gasifier for municipal solid waste. At the inside of reactor, temperature depends on amount of the oxidant to classify four distinct process, combustion, reduction (gasification), pyrolysis and dry zone. As decreasing the air flow rate, the particulate matters had a tendency to decrease, proportionally. In this system, the producer gas needs the clean-up process over 98% efficiency for connecting the internal combustion engine to generate electric power. At the test 1 and 2, while the air ratio decreased, the LHV of syngas and CGE were increased. however, at the test 3, because the oxidizer had injected more less than demanded, these showed a decreasing tendency.

Key Words

MSW, Gasification, Tar, Particulate, Air ratio

이희성 Hee-sung Lee , 정미정 Mi-jeong Jeong , 전태완 Tae-wan Jeon , 김용준 Yong-jun Kim , 연진모 Jin-mo Yeon , 조윤아 Yoon-a Cho , 조나현 Na-hyeon Cho , 신선경 Sun-kyoung Shin , 안도요시토 Yoshito Andou

DOI:10.9786/kswm.2015.32.6.583

Abstract

The innovation in this study is the complexation of Erianthus fibers (Erianthus arudinaceus) with compatibilizer in PP by extrusion, to produce a material with an improvement in mechanical properties. The aim is to provide a generalpurpose material from biomass that does not compete with food as an alternate material from the petroleum base. Erianthus is a cellulose resource crop which is a source of bio fuel, is inedible, highly productive and promising energy resource, there has been little report on its use as a material. It also is a cellulose resource crop with a high productivity as a fiber reinforcement material with low environmental load. Development of Erianthus fiber reinforced polypropylene (PP) composite material was reviewed. Erianthus fiber was pulverized and the powder was sorted by sieve size, which was put through the process of complexation with polypropylene using a twin-screw extruder. The mechanical characteristics of the obtained composite material were evaluated by conducting a tensile strength test and a bending test. As a result of using the classified fiber as the filler, it is found that the difference in the surface area of the fiber has a great effect on the mechanical properties and the thermal decomposition properties. It is found to be sufficiently feasible to make Erianthus function as a polypropylene fiber reinforcement element by controlling the size of Erianthus fiber.

Key Words

Bio-composites, Cellulose-based, Agricultural waste, Fiber reinforced plastics

황연정 Yeonjung Hwang , 장용철 Yong-chul Jang

DOI:10.9786/kswm.2015.32.6.591

Abstract

Environmental concerns regarding mercury-containing fluorescent lamps have been raised in many countries, especially after International Minamata Convention on Mercury in 2014. Improper management and disposal of the waste such as landfilling and incineration may pose serious threats to the environment and human health. In Korea, mercury-containing lamps have been regulated by the expanded producer responsibility (EPR) system since 2004. However, only less than 30% of the lamps sold to consumers has been collected by municipalities. In order to provide additional measures related to proper management of fluorescent lamps, there is a need for a quantitative material flow study by life cycle stage. In this study, material flow analysis was conducted by collecting relevant data from literature review, available statistics, and field site visits to lamp recycling facilities. According to the results of this study, approximately 150 million units of fluorescent lamps were put on the market in 2013, while 36.9 million units of the lamps were recycled mainly from households in the year. It is estimated that approximately 3.5 million units and 2.3 million units of lamps in disposal bags are disposed and treated in landfills and incineration facilities, respectively. This study also found that there were significant amounts of uncollected lamps that were present in industrial sectors. The material flow of the industrial sectors are largely unknown and not properly regulated by government. Based on the mass flow of mercury in lamps, 1.6ton of mercury in lamps came into consumer markets in 2013. Approximately 407 kg of mercury was collected by the recycling process at the fluorescent lamps recycling facility. The mercury disposed in landfills and treated in incinerators were found to be 38.3kg and 25.5kg, respectively. Further study may be warranted to focus the material and mercury flow of lamps in industrial sectors in order to accurately determine the final destination and disposal of such waste in the environment because there are very few available statistical data regarding distribution flow and treatment of lamps in the sectors.

Key Words

Fluorescent lamps, Recycling, Material flow analysis, EPR, Mercury

권영현 Young-hyun Kwon , 손준익 Jun-ik Son , 윤영삼 Young-sam Yoon , 김기헌 Ki-heon Kim

DOI:10.9786/kswm.2015.32.6.599

Abstract

This study analyzed response characteristics of Nitrogen Oxide according to injection location and change of injection amounts by spraying food waste on the combustion platform and the latter part of the first combustion chambers in incinerators. The analytical results have found to have no major difficulties in keeping more than 850℃, the legal standard of the 2nd combustion chamber according to injection of food waste in all the test subject facilities. For spraying food waste in the combustion platform in the first combustion chambers, the removal efficiency of 14.76% was shown as NSR is 2.98. For spraying food waste in the latter part of the first combustion chambers, the removal efficiency of 46.40% was shown as NSR is 0.95. On the other hand, when food waste of 3 tons per hour respectively is sprayed on the combustion platform and the latter part of the first combustion chambers, the highest removal efficiency of 84.97% was shown as NSR is 1.02.

Key Words

Incinerator, Food waste, Heating value, NOx, SNCR

심성훈 Sung-hoon Shim

DOI:10.9786/kswm.2015.32.6.608

Abstract

Characteristics of exhaust gas of solid refuse fuel (SRF) burning in a commercial scale of 12 ton/day incinerator have been investigated. Combustion air for SRF burning is mixed with recirculated high temperature exhaust gas to dilute oxygen concentration and preheat itself. It is called high temperature EGR (Exhaust Gas Recirculation) combustion. It is known that low oxygen concentration of diluted air reduces flame temperature and NOx emission, but also makes flame unstable. Highly heated air by mixing with high temperature exhaust gas makes flame stable by enhancement of combustion reaction. Concentrations of nitric oxide (NOx), carbon monoxide (CO), oxygen (O₂) and carbon dioxide (CO₂) in flue gas have been measured at stack. High temperature EGR incineration of SRF dramatically reduces nitric oxide emission and residual oxygen. Average concentrations of NOx, and CO are 71.5 ppm and 86.6 ppm especially at reference oxygen concentration of 12% without any post treatment of NOx when the average outlet temperature of combustion chamber is 942℃. And average concentrations of O₂ and CO₂ are 9.59% and 8.3% especially.

Key Words

Solid refuse fuel, Incinerator, Nitric oxide, High temperature exhaust gas recirculation, Low NOx emission

오길종 Gil-jong Oh , 강영렬 Young-yeul Kang , 김우일 Woo-il Kim , 김용준 Yong-jun Kim

DOI:10.9786/kswm.2015.32.6.615

Abstract

Laws and regulations of radioactive waste management related to the Exemption system and the Clearance system between governing authorities in Korea and Japan were investigated to suggest better management of radioactive waste. Above both system, very low levels of radioactive wastes which have negligible risk can be decided on being Exclusion system and classified as a non-radioactive waste. As a result, the Exemption systems between two countries were similar, whereas the Clearance systems were different. With regard to laws related to the Clearance, Japan specify providing information and feedback among relevant authorities, but there is no specification in Korea. In addition, this study suggests to develop accredited analysis methods to improve the accuracy and reproducibility of the measurement, because two countries have not established the national accredited analysis method for determining the concentration of radionuclide.

Key Words

Radioactive waste, Non-radioactive waste, Exemption criteria, Clearance criteria

이우찬 Woochan Lee , 현승민 Seungmin Hyun , 윤균덕 Kyoonduk Yoon

DOI:10.9786/kswm.2015.32.6.628

Abstract

Due to the problems on BW (Bulky Waste) from SRF (Solid Refused Fuel) facilities in terms of operation and maintenance, we investigated the characteristics of bulky waste about physical composition ratio, discharge type and ratio, etc. BW are 5.83% in MSW (Municipal Solid Waste) and composition ratio is as below; fiber (28.22%), plastic (19.18%), paper (17.95%), wood (17.02%), metal (11.49%), vinyl (3.3%), styrofoam (2.84%). Paper was mostly packing box, wood; chipboard, pieces of wood, branch, vinyl; big vinyl bag, plastic; home appliance, toy, big piece of plastic, fiber; clothing, mattress, sponge, styrofoam; pieces of styrofoam box, metal; broken metal stuff. BW has characteristics that is bulky and mainly consist of recycle waste compared with general MSW. We compare the composition ratios of only BW, MSW including BW and not including BW in order to extend to which variation in BW affects on physical composition ratio of general MSW. As a result of these researches, physical composition ratio between MSW not including BW and BW has some difference but correspond closely with MSW including BW. This is because BW component ratio is so small that have little effect on composition ratio of total waste. Conclusively BW component and physical composition ratio, discharging type should be investigated for characterizing BW. But BW composition ratio needs not to be included only for analyzing physical composition ratio of waste.

Key Words

MSW (municipal solid waste), Physical composition, Bulky waste, Solid refuse fuel