고영재 Youngjae Ko , 강준구 Jun-gu Kang , 권영현 Young-hyun Kwon , 유하녕 Ha-nyoung Yoo , 전태완 Taw-wan Jeon

DOI:10.9786/kswm.2018.35.2.95

Abstract

Recently, the concept of “sustainable resource circulation society” has become a global issue and a key part of waste management policy. For resource circulation, Korea has established the primary foundation via the enactment of the “Framework act on resource circulation.” Waste energy recovery is attracting considerable attention because of such policy changes, and efforts are being made to maximize the use of heat at incineration facilities. Moreover, to ensure the objectivity and validity of the estimation method’s results, the ministry of environment has recently revised the guidelines for the energy recovery rate estimation method and lower heating value (LHV) of waste at incineration facilities. In the revised guidelines, for estimating the LHV of waste, a formal formula is presented at general incineration facilities for municipal solid waste (MSW). However, generally, the LHV-formula at incineration facilities is difficult to apply to pyrolysis-melting facilities because it does not reflect characteristics of the pyrolysis-melting treatment method. Thus, in this study, the actual condition of pyrolysis-melting facilities was investigated, and the LHV-formula for pyrolysis-melting facilities was derived using the derivation method of the EU’s NCV-formula.

Key Words

Lower Heating Value (LHV), Energy recovery rate, Pyrolysis-melting facility, Incineration facility, Municipal Solid Waste (MSW)

안정원 Jeong Won An , 오민아 Minah Oh , 이영진 Youngjin Lee , 오승진 Seungjin Oh , 오화수 Hwa-soo Oh , 김용화 Yonghwa Kim , 이재영 Jai-young Lee

DOI:10.9786/kswm.2018.35.2.103

Abstract

The amount of sewage sludge that is emitted is gradually increasing every year. However, since 2012, because of the London Protocol, the oceanic dumping of sewage sludge has been prohibited. Therefore, for recycling organic waste, either the ground disposal method has to be used or technological solutions that develop energy from such waste have to be identified. Heat is generated when the sewage sludge has decomposed by aerobic microbes. In this study, to dehydrate sewage sludge, heat was applied and the drying efficiency was evaluated according to the air flow rate (AFR) and the proportional mixing of the returned sludge. For the experiments, returned sludge that was dried to 40% moisture content was used; consequently, the highest temperature was obtained when the moisture content was 30% and, for maintaining aerobic conditions, the optimal AFR was 200 ml/min·kg. During biodrying for 14 days, the highest temperature of reactor was 46℃, which was maintained at higher than 40℃ for 5-7 days; moreover, 18.8% of moisture was eliminated. These results show that using biodrying for treating sewage sludge has economic potential compared to hot-air drying; moreover, with additional treatment, biodrying can be one of the methods for producing Bio Solid Refuse Fuel (Bio-SRF).

Key Words

Biodrying, Sewage sludge, Aerobic treatment

최형진 Hyeong-jin Choi , 이승희 Seung-whee Rhee

DOI:10.9786/kswm.2018.35.2.110

Abstract

Using a mixture of sewage sludge and woody waste, optimal conditions for the bio-briquette process of carbonization residue were evaluated by compressive strength and bulk density. For the bio-briquette process, the optimal conditions were determined to be a molding temperature of 110oC and a moisture content of 10%. As the lignin in the carbonization residue can be used as a natural binder because of its plasticizing property, the bio-briquette process uses this property. To increase the compressive strength to >3.50 MPa, binders such as polyvinyl alcohol (PVA), guar gum, and starch were mixed in the carbonization residue. At 3 wt.% of PVA, 3 wt.% of guar gum, and 5 wt.% of starch, the conditions of binder usage were evaluated. To examine the cost in the bio-briquette production with the addition of the binder, the proportion of binder cost for the bio-briquette production were evaluated at 9.2% for PVA, 8.6% for guar gum, and 3.3% for starch, and starch was determined to be the best binder for the bio-briquette process.

Key Words

Bio-briquette, Optimization, Carbonization residue, Woody waste, Sewage sludge

정준혁 Jun-hyeok Jeong , 황용우 Yong-woo Hwang , 이익모 Ik-mo Lee , 천영우 Young-woo Chun , 김준범 Jun-beum Kim

DOI:10.9786/kswm.2018.35.2.119

Abstract

Since the 1990s, waste policies of the South Korean government have focused on resource recycling societies that reduce the amount of waste landfill and increase the amount of waste recycling. In South Korea, the implementation of various environmental policies and efforts has led to the highest recycling rate in the world; however, after 2011, the recycling rate of household waste has been stagnant. Therefore, to convert such waste disposal problems into a resource recycling socioeconomic regime conforming to the national policy, establishing a tool to evaluate the appropriate management policy of household waste is necessary. In this study, a waste management evaluation index was developed and applied to identify and evaluate trends in the waste disposal methods. For the evaluation index, we considered two points of evaluation, i.e., “waste recycling increases and waste landfill decreases” and “the current waste recycling rate is taken into consideration.”. The data of waste disposal of 2007, 2012 and 2015 in 16 municipalities was used. The results shows that the highest absolute index was (+)28 in Chungbuk, whereas the lowest was analyzed as (-)10 in Daegu. Moreover, the cities with high recycling rates and low landfill rates were Seoul and Busan, while Jeonnam had the low recycling rate and the high landfill rate. Furthermore, Chungnam and Chungbuk were very likely to develop further, whereas Daegu and Incheon had a very low possibility of development. This waste management evaluation index and method can be one important tool and approach and can support more sustainable and resource recycling socioeconomic.

Key Words

Household waste management, Recycling, Ternary diagram, WMEI (Waste Management Evaluation Index)

황재규 Jae Gyu Hwang , 이병규 Byung Kyu Lee , 최명규 Myung Kyu Choi , 최항석 Hang Seok Choi

DOI:10.9786/kswm.2018.35.2.126

Abstract

The fast pyrolysis of biomass (larch) in a circulating fluidized bed pyrolyzer was performed and the physico-chemical characteristics of biocrude-oil was investigated. Standard sand was used for fluidizing material and various reaction temperatures from 400oC to 550oC was applied. Wood (larch) sample was examined thorough proximate analysis and thermogravimetric analysis (TGA). From the results of the sample test, thermal decomposition characteristics of wood (larch) was investigated. Various analyses were carried out to determine the physicochemical properties of biocrude-oil such as Higher heating value (HHV), water content, viscosity, ash content and microscopic anaysis. The maximum biocrude-oil yield was 49.9wt.% at 550oC. At this temperature, HHV and water content were 4562.0 kcal/kg and 13.8wt.%, respectively. From the study results, wood (larch) has potential as an alternative energy source.

Key Words

Biomass, Biocrude-oil, Circulating fluidized bed, Fast pyrolysis

이창용 Chang Yong Lee , 황용우 Yong Woo Hwang , 이익모 Ik Mo Lee , 천영우 Young Woo Chun

DOI:10.9786/kswm.2018.35.2.134

Abstract

Landfill gases (LFGs), which consists of sulfur compounds, odorous substances such as ammonia and amines, and volatile organic compounds (VOCs), is generated during the natural process of bacterial decomposition of organic material contained in municipal solid waste (MSW) landfills. The VOCs in the LFGs cannot be only decomposed easily into the soil after landfilling but they also can cause serious problems for the surrounding atmosphere, soil, and groundwater because of their toxicity. Moreover, VOCs have been identified as precursors of photochemical smog and they are toxic and carcinogenic chemicals. Furthermore, VOCs comprise a low rate of the emissions, but they can cause cancer. Therefore, it is important to evaluate the hazard causing by VOCs in LFGs. This study is aim to identify chemicals in LFGs and the hazardous evaluation by mixing between chemicals in LFGs. The selected landfill site in the study is located in Daejeon. Waste generation data were obtained from the Ministry of Environment (MOE) of South Korea. To evaluate the amount of the selected VOCs (47) among the primary disintegration models, LFGs generation model in LandGEM program was used. For the gas mixing reaction, a program called CRW 4.0 was introduced by the NOAA in the United States was used. As a result, the cumulative capacity of landfills in 2015 was estimated at 7,650,682 tons. Therefore, the total LFGs generation in 2015 was 7.717 × 10⁷㎥. Also the LFGs showed almost all the hazardous reactions with NOx and O₃ in the atmosphere. As VOCs in LFGs mixed air emissions, we confirmed that toxic potential gases such as phosgene, hydrogen halides, halogenated organics, chlorinated amines and acidic fumes are generated.

Key Words

LFG, Reactivity, VOCs, CRW, New hazards

이혜정 Hye-jeong Lee , 김효진 Hyo-jin Kim , 유승훈 Seung-hoon Yoo

DOI:10.9786/kswm.2018.35.2.143

Abstract

In accordance with the 1996 London Protocol, the marine dumping of wastewater generated from food was totally banned from 2013. Therefore, establishing a food wastewater bio-gasification facility for stable and continuous food wastewater treatment is necessary. The biogas produced from the wastewater can be used as fuel for electricity generation or for heating in power plants and can be sold as gas in cities as well as fuel for vehicles after undergoing a refining process. Thus, the South Korean government is trying to expand the bio-gasification facility of wastewater generated from food. In this study, we try to obtain information about the public value of such an expansion. For this purpose, the household willingness to pay (WTP) for the expansion is determined by applying the contingent valuation (CV) approach. A total of 1,000 South Korean households were involved in the CV survey, which had questions with dichotomous choices. The mean yearly public value WTP for expansion is estimated at 2,564 KRW per household. If this WTP is extrapolated from the sample to the nation’s population, the expansion in the national value is worth 50.1 billion KRW per year. These results indicate that the expansion of food wastewater bio-gasification facility is supported by Korean households.

Key Words

Food wastewater, Non-market benefits, Contingent valuation, Willingness to pay, Spike model

이지영 Ji-young Lee , 김수진 Su-jin Kim , 김진수 Jin-su Kim , 최승규 Seong-kyu Choi , 주천 Qian Zhu , 심재훈 Jae-hoon Shim , 이상일 Sang-ill Lee

DOI:10.9786/kswm.2018.35.2.153

Abstract

In this study, to evaluate the transboundary movement of magnetite waste, the treatment causing possible oxidation and reduction to the highly toxic Cr (VI), as well as other chromium ions must be considered. In this study, we tried to remove chromium using magnetite. The efficiency of chromium removal using magnetite, mixing time, mixing speed, and temperature was evaluated through a jar test. In case of magnetite, the total chromium and hexavalent chromium concentration were rapidly decreased to 0.7 g and 0.35 g, respectively. For mixing speed, the removal efficiency of total chromium was rapidly increased to 150 rpm, but that of hexavalent chromium was almost unchanged. For reaction time, the chromium concentration was almost identical. At 70℃, the removal efficiency of total and hexavalent chromium was 97.2% and 98.8%, respectively; therefore, application of magnetite to actual industrial sites where high-temperature industrial wastewater is generated can be considered.

Key Words

Magnetite, Total chromium, Hexavalent chromium, Optimum conditions

유하녕 Ha Nyoung Yoo , 고영재 Young Jae Ko , 권영현 Young Hyun Kwon , 전태완 Tae Wan Jeon , 이영기 Young Kee Lee , 강준구 Jun Gu Kang

DOI:10.9786/kswm.2018.35.2.159

Abstract

In the past, the role of incineration facilities was mainly to reduce waste and stabilize disposed material. However, as a key aspect of waste management policy, the concept of “waste Minimization and sustainable resource circulation society” has become an issue, and the effective use of waste has been emphasized. As a result, to promote the recycling of wastes from January 1, 2018, the Framework Act on Resource Circulation has been implemented. In this study, estimation factors that can affect the increase of energy recovery are selected by reviewing the estimation method of industrial waste incineration facilities having a separate boiler; moreover, the effect of calculation factors on energy recovery was quantitatively evaluated. According to this study, when the heat loss, condensate temperature, and power consumption decrease by 10%, the energy recovery of the target facilities increase by 0.4% (0.22 ~ 0.63%), 1.09% (0.57 ~ 1.32%), and 1.16% (0.52 ~ 2.13%) on an average.

Key Words

Industrial waste, Incineration facility, Separate boiler, Energy recovery

정밤빛 Bam-bit Jung , 박은규 Eun-kyu Park , 최태준 Tae-jun Choi , 최우진 Woo-zin Choi

DOI:10.9786/kswm.2018.35.2.170

Abstract

A great variety of plastics are used in IT products, which differ not only by plastic type but also by color and presence of additives such as brominated flame retardants (BFRs). In this study, to identify the plastics containing BFRs and heavy metals (i.e., Pb, Hg, Cd, Cr⁶⁺), laser-induced breakdown spectroscopy (LIBS) was used. Polypropylene (PP)-type black plastic samples that were obtained from three different types of used electric cookers were analyzed. The spectrum peaks observed in the LIBS system confirmed the presence of BFRs and heavy metals. The number of Br peaks were identified and the data were compared with the previous atomic spectra database. In the near future, the recycling of plastics from e-waste may become more important not only to reduce the amount of waste requiring treatment but also to eliminate the plastics containing hazardous components and compounds.

Key Words

BFRs, Heavy metals, Small household appliances, Plastics, Recycling

우희진 Hee-jin Woo , 윤혜리 Hye-ri Yoon , 박중구 Jung-gu Park

DOI:10.9786/kswm.2018.35.2.180

Abstract

Based on a survey of Korean waste-to-energy (WTE) firms, this article analyzes the R&D effectiveness of the WTE industry, which accounts for the largest proportion of new and renewable energy power generation in Korea, using multiple and logistic regression. A company’s R&D can be considered effective if its R&D inputs (e.g., R&D expenditure/sales, R&D manpower/employees, education/training, and reward systems) or R&D outputs (e.g., patent applications and approvals, the introduction of new products and services, and the redesign of products and processes) contribute to an increase in R&D outcomes (e.g., decrease in production costs, the creation of employment, and market entry). It was found that market entry is not affected by R&D inputs but is positively influenced by R&D outputs, indicating that Korean WTE firms have focused on market entry via the technology transfer of new products and services and/or the redesign of products and processes. In the WTE industry, the creation of employment does not have a statistically significant relationship with R&D expenditure/sales, R&D manpower/employees, or the redesign of products, but it does exhibit a positive relationship with education/training, reward systems, patent applications and approvals, and the introduction of new products and services. Finally, the decrease in production costs is not influenced by R&D expenditure/sales, R&D manpower/employees, reward systems, or patent applications and approvals, but is positively affected by education/training, the introduction of new products and services, and the redesign of products and processes. A policy implication of these results is that market entry show the virtual cycle on expanding R&D expenditure/sales and/or R&D manpower/employees.

Key Words

R&D, Input, Output, Outcome, Regression analysis