윤형선 Hyung-sun Yoon , 송영채 Young-chae Song

DOI:10.9786/kswm.2016.33.6.527

Abstract

A bioelectrochemical anaerobic digester for food waste was developed by installing an anode (-250 mV vs. Ag/AgCl) and a cathode (-550 mV vs. Ag/AgCl) inside a conventional lab-scale anaerobic digester. The performance of the bioelectrochemical anaerobic digester was investigated at different organic loading rates of 0.70-4.25 g VS/L.d. The bioelectrochemical anaerobic digester was rapidly stabilized within 25 days after start up, and at an organic loading rate of less than 1.97 g VS/L.d., state variables such as pH (7.0-7.8) and alkalinity (10-12 g/L as CaCO₃) were very stable. The volatile fatty acids were maintained at 400-500 mg HAc/L with their main component being acetic acid (80%). At an organic loading rate of 1.97 g VS/L.d, the performance was significantly high in terms of the specific methane production rate (1.37 L CH₄/L.d) and the methane content in the biogas (around 74%). The removal efficiencies of volatile solid and chemical oxygen demand were also as high as 80.1% and 85.1%, respectively, and the overall energy efficiency was 91.2%. However, the process stability deteriorated at an organic loading rate of 4.25 g VS/L.d.

Key Words

Food waste, Bioelectrochemical, Anaerobic digestion, Organic loading rate

최형진 Hyeong-jin Choi , 이승희 Seung-whee Rhee

DOI:10.9786/kswm.2016.33.6.537

Abstract

Material flow analysis (MFA) of recycling material and of mercury from linear-type spent fluorescent lamps (SFLs was performed to estimate the material composition of the chain recycling process by an input-output approach. The recycling process system for linear-type SFLs was established using an end-cutting system, a hammer crusher, a screen separation system, a mercury distillation system, and an activated carbon adsorption component. From the results of the MFA of lineartype SFLs, 92% of materials used in linear-type SFLs such as glass, aluminum, and phosphor powder can be recycled. For MFA of mercury, the mercury content in the phosphor powder was the highest among material compositions tested and the total mercury amount in the recycling materials from 1 ton of SFLs was estimated to be 75.43 g. In the recycling process system for linear-type SFLs, the mercury amount in the vapor phase was analyzed and found to be 2228 mg in the end-cutting system, 172 mg in the hammer crusher, and 2585 mg in the screen separation system. The total mercury amount in the vapor phase was estimated to be 4985 mg, which was only 6.22% of the total mercury amount emitted from the recycling process system. Hence, it was estimated that the MFA of the total mercury amount obtained from the vapor phase and the recycling materials of 1 ton of SFLs using the recycling process system was 80.175 g.

Key Words

Linear type spent fluorescent lamp, Material flow analysis, Recycling, Mercury

민서현 Seo-hyeon Min , 박소연 So-yeon Park , 유승훈 Seung-hoon Yoo

DOI:10.9786/kswm.2016.33.6.547

Abstract

As economic growth and development of the living standard causes increasing production of organic waste, the desire to take advantage of organic waste to produce energy is also increasing. Organic waste-to-energy can contribute to improving energy independence through domestic energy security as well as improving the environment by reducing the need for landfills. This paper attempts to quantitatively analyze the non-market benefits arising from the organic waste-to-energy policy. To this end, we apply a contingent valuation (CV) that is most widely used to measure the nonmarket benefits. As for the willingness to pay (WTP) elicitation method, we employed the one-and-one-half-bounded dichotomous choice (DC) model, which produces higher statistical efficiency than the single-bounded DC model and yields greater consistency than the double-bounded DC model. In the CV survey result of 1000 Korean households, a total of 586 households (58.6%) revealed zero WTP. This implies that the use of the mixture model to deal with zero WTP responses was a suitable approach in our study. The yearly mean WTP was computed as KRW 3598 for the next ten years per household, which is statistically significant at the 1% level. Expanding the value to the national population gives us KRW 67.3 billion per year and this value demonstrates the non-market benefits of the organic waste-to-energy policy. This quantitative information could be utilized as a significant reference in the implementation of the organic waste-to-energy policy.

Key Words

Organic waste-to-energy, Non-market benefits, Contingent valuation, Willingness to pay, Mixture model

조윤아 Yoon A Cho , 김우일 Woo Il Kim , 김민선 Min Sun Kim , 강영렬 Young Yeul Kang , 신선경 Sun Kyoung Shin

DOI:10.9786/kswm.2016.33.6.558

Abstract

Koreans have sedentary lifestyles and use under-floor heating called Ondol as home heating systems. Sick Building Syndrome (SBS) caused by VOCs released from flooring material has been of significant interest in residential apartments. In this study, we measured exposure to VOCs by having test subjects breathe under conditions of high surface temperature. The results showed that the emission level of VOCs was high at 40℃ in the early stage of the experiment. However, 20 days after the experiment began, the emission level was reduced by 0.9-4 times in each product at 40℃. The exposure to VOCs released from floor coverings was measured by taking into account the average respiratory rate, weight, and activity hour of test subjects and presuming that people are exposed to VOCs all the time while staying indoors. The level of emission from FJR of low-cost PVC floor coverings was the highest among the tested coverings, but the exposure to VOCs emission from the covering was relatively low at 0.025 mg/kg/day at 40℃. The amount of toluene detected from this experiment was the highest among VOCs emitted from floor coverings. The hazard quotient (HQ) of toluene detected in this test was over 20 times smaller than the risk characterization level of 0.1. It was, therefore, estimated that the emission of toluene from the floor surface would not be critically harmful to residents.

Key Words

Floor covering, VOCs exposure, Emission, Temperature

심성훈 Sung-hoon Shim , 정상현 Sang-hyun Jeong

DOI:10.9786/kswm.2016.33.6.565

Abstract

Characteristics of the exhaust gas of a commercial scale (7.2 ton/day) municipal wastes incinerator with recirculation of its high temperature combustion gas were investigated. High temperature combustion gas made by incineration was entrained by an air jet and re-used for incineration. Air was preheated to 384-512℃ and diluted to have an oxygen concentration of 16-17%. Incineration of municipal wastes with the preheated and diluted air made extremely uniform and stable flames. Concentrations of nitric oxide (NOx), carbon monoxide (CO), oxygen (O₂), and carbon dioxide (CO₂) in flue gas were measured at the boiler exit and the stack, simultaneously. Averaged concentrations of NOx and CO were reduced to 54.2 ppm and 3.1 ppm at the boiler exit and to 49.8 ppm and 6.0 ppm at the stack, respectively, at a reference oxygen concentration of 12% without any post treatment of NOx and when the averaged outlet temperature of the combustion chamber was 904℃. The measured NOx emission was only 29% of that of a conventional municipal incinerator. Simultaneous reduction of NOx and CO is significant. Averaged concentrations of O₂ and CO₂ were 9.7% and 8.6% at the boiler exit and 14.6% and 4.9% at the stack, respectively.

Key Words

Municipal wastes, Incinerator, Nitric oxide, High temperature combustion gas recirculation, Low NOx emission

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

DOI:10.9786/kswm.2016.33.6.573

Abstract

In this study, a lower heating value for automobile shredder residue incineration facilities (12 facilities) was calculated using a heat balance method, and a recoverable energy potential was calculated after calculating the effective energy output and the effective energy use according to automobile shredder residue incineration. An analysis of the calculation results showed that the effective output and the effective use had average values of 64.5% (49.8-80.2%) and 31.3% (7.1-57.5%) in an ASR incineration plant, respectively. The calculated ratio of effective use to effective output was an average value of 33.2% (3.0-57.8%). Therefore, in order to improve the efficiency of effective energy used, it is necessary to make more effort to devise various measures.

Key Words

Incineration heat, Energy recovery, Lower heating value, Automobile shredder residue

원민정 Min-jeong Won , 김정권 Jung-kwon Kim , 이승원 Seung-won Lee

DOI:10.9786/kswm.2016.33.6.582

Abstract

Research was conducted on the characteristics of waste discharge in apartment houses with less than 200 households. Implementation of the meter-rate system of food waste for apartment houses was also investigated and an economic evaluation was carried out to reach the following conclusions. First, for the monthly characteristics of the overall amount of food waste in apartment houses with less than 200 households, December and January exhibited the maximum amount while February and March exhibited the minimum amount of discharge. The average amount of waste discharge per household was the lowest at 0.51 kg/day · household in apartment houses with 20 to 50 households, followed by 0.80 kg/day · household in apartment houses with less than 20 households and in apartment houses with 50 to 100 households. Apartment houses with 100 to less than 200 households had 0.71 kg/day · household of average waste discharge. The results showed that the amount of food waste discharge is dependent upon the economic conditions or environment of the regions concerned rather than upon the number of households. Second, two meter-rate systems of food waste were compared: the RFID system and the Chip system. When the comparison was made under the same conditions for the number of households in apartment houses in which meter-rate system was being implemented, the average reduction rate in the Chip system was 21.1% and that in the RFID system was 57.1%. A comparison of apartment houses under the meter-rate system and of apartment houses with less than 200 households with apartment houses with less than 20 households, 20 to 50 households, 50 to 100 households, and 100 to less than 200 households showed that the average reduction rates of the Chip system and the RFID system was 35.3% and 61.9%, respectively. Last, a comparison of the results of the field study and the rate of food waste reduction in regions where the meter-rate system was being implemented showed that the average reduction was 35.3% for the Chip system and 61.9% for the RFID system, with a difference in reduction of about 35.5%. In the case that the RFID system is adopted, the disposal cost of about 62.7 billion won per year would be reduced by about 19.4 billion won, which leads to a prediction of a reduction in disposal cost to about 43.3 billion won per year.

Key Words

Food waste, RFID, Chip, Apartment of less than 200 households, Meter-rate system

권진홍 Jin Hong Kwon , 김재용 Jae Yong Kim

DOI:10.9786/kswm.2016.33.6.590

Abstract

Since 2013, due to the London Convention prohibiting marine dumping of waste, many problems have occurred because food waste generated every day must be handled on the ground. Owing to recent institutional efforts and various technical studies for eco-friendly food waste treatment, various methods of treating food waste using insects have been studied. However, efficiency of Korean food waste treatment is in fact known to be low due to the high salinity of Korean food waste. In this study, we evaluated the treatment efficiency of food waste with various salt and moisture contents by the black soldier fly (Hermetia illucens). The results showed that the moisture content does not affect food waste treatment efficiency by the black soldier fly and the decomposition ability of food waste is good even at salt contents as high as 3%.

Key Words

London dumping convention, Hermetia illucens, Treatment of food waste, Salinity, Moisture content

김용진 Yong-jin Kim , 정승미 Seung-mi Jeong

DOI:10.9786/kswm.2016.33.6.598

Abstract

Marine wastes could be divided into coastal, sink and floating waste by the distribution location. From the results of standing stock estimation of the marine wastes, the amount of coastal waste was similar to the results of previous study, that of sink waste was higher in this study as much as 1.47 to 2.83 times, and that of floating waste was estimated to be higher up to approximately 2.3 times in this study. Overall, the total amount of marine waste in the sea of our country is estimated at 180,148 ~ 331,197 tons, being 1.43 to 2.63 times higher than the results of previous study.

Key Words

Marine wastes, Coastal waste, Floating waste, Sink waste, Standing stock

신미수 Misoo Shin , 박민정 Minjung Park , 장동순 Dongsoon Jang

DOI:10.9786/kswm.2016.33.6.606

Abstract

The synthetic gas obtained from the gasification of waste material becomes more important not only in waste reduction but also for the generation of clean energy directly applicable to industrial combustors firing LNG fuel without any major modification of the boiler system. Therefore, in this study, a systematic calculation was made for the turbulent reaction inside a conventional LNG combustor to determine the temperature distribution and fluid flow field. By doing this, the syngas obtained from gasification of combustible waste could be evaluated for the potential applicability of syngas as a substitute for LNG fuel in the industrial field. In this calculation, the ratio of the syngas amount to the LNG amount was fixed. That is, based on calorific value, 70% of the fuel was syngas and 30% was LNG. Since the calorific value of the syngas was different from that of LNG with a high energy density, the different volumetric flow rate was expected to give rise to a visible flow field change together with the local velocity. Thus, in this study, the swirl intensity and the inlet nozzle diameter were varied carefully in order to resolve the flow field and turbulence effects on the reaction characteristics of the co-burning flame. First of all, the calculation result of pure LNG combustion was made successfully as a reference and for evaluation of the code implementation. The results obtained from the numerical simulation of the burning of syngas in the LNG boiler could duplicate the combustion feature almost similar to that of 100% LNG fuels by changing the injection method of the syngas without any major change of the boiler system. The results suggested the high potential of syngas as an economic substitute for conventional LNG fuel.

Key Words

Syngas, Combustible waste, Gasification, Numerical simulation

김종범 Jong-bum Kim , 장성호 Seong-ho Jang , 손현근 Hyun-keun Son , 류재용 Jae-yong Ryu

DOI:10.9786/kswm.2016.33.6.613

Abstract

This study is to identify the effects of DRE (destruction and removal efficiency) and carbonization of Xylene when using the electron beam energy. The irradiation intensity of electron beam energy was 10 mA, 20 mA and irradiation time was 5.7, 11.4, 22.8, 45.6 sec (Absorbed dose are 41.41, 82.82, 165.64, 331.28, 662.55 kGy). The Xylene was completely removed at 331.28 kGy. Main by-products was carbon particles. Carbon particle formation was increased with irradiation intensity increasing. Most of the by-products of particle were Carbon black and Graphite.

Key Words

Volatile organic compounds, Xylene, Electron beam, Carbonization, By-product

정재훈 Jae-hoon Jeung , 정성엽 Seong-yeob Jeong , 문대헌 Dea-hyun Moon , 장순웅 Soon-woong Chang

DOI:10.9786/kswm.2016.33.6.621

Abstract

The purpose of this study was to evaluate the characteristic and efficiency of anaerobic digestion (AD) of various organic wastes, and to find a way to enhance the efficiency of AD. Ten types of organic wastes including slaughterhouse waste (SHW), agricultural by-products (AB), animal manure (AM), sewage sludge, and food waste (FW) were selected. Elementary analysis was carried out to confirm the effect of C/N ratio on AD. Elementary analysis of the AB of maize showed the highest C/N ratio of 42.55. The lowest C/N ratio of 3.41 and 3.46, respectively, appeared from the SHW of the blood from cattle and swine. The cattle rumen content of SHW had a C/N ratio of 19.2, which was included at range of optimum C/N ratio, and AM showed a low C/N ratio because of the lack of a carbon source. The AB of beets had the highest biogas yield of 0.81 m³/kgVS, which was measured by the BMP test. Biodegradability was also calculated based on the BMP test result. FW was found to have the highest biodegradability of 92.14%. However, cattle rumen contents had low biodegradability (34.02%) because their substrate material consists of fibroid, while AM had the lowest biodegradability (15.34%) because of its low C/N ratio.

Key Words

Anaerobic digestion, Biodegradability, C/N ratio, BMP test