This study aimed to prepare a non-sintered cement mortar made without using standard Portland cement and investigate its fluidity and strength characteristics by adding a high-performance water-reducing agent. The flow test results revealed that high fluidity was obtained by adding a PC-based water-reducing agent when two types of the water-reducing agent were added under the same W/B condition. The flexural strength test showed that the test mortar had a higher flexural strength value than plain mortar after 28 days when 0.5% of PC-based and lignin-based water-reducing agent was added. As the added amount of water-reducing agent increased, the test mortar’s strength showed a tendency to decrease little by little. As a result of the compressive strength test, the strength of the PC-based water-reducing agent decreased as the amount of agent added increased. In contrast, the strength of the Lignin-based water-reducing agent increased as the amount of agent added increased. It is appropriate to use a PC-based water-reducing agent for non-sintered cement mortar. This study concluded that adding 0.5% of the agent will be advantageous in securing fluidity and strength.
A 3-Year Survey on the Physical Composition of Household Waste into a Incineration Facility in a Small and Medium City 중소도시 소각시설에 반입된 생활폐기물에 대한 3년간의 물리적 조성조사
A 3-Year Survey on the Physical Composition of Household Waste into a Incineration Facility in a Small and Medium City 중소도시 소각시설에 반입된 생활폐기물에 대한 3년간의 물리적 조성조사
윤석표 Seok-pyo Yoon
DOI:10.9786/kswm.2022.39.5.395
Abstract
In this study, physical composition analysis was conducted on household waste collected from the storage pit of the household waste incinerator once a month (36 times in total) for three years. The main results obtained from the survey results are as follows. According to a survey of the physical properties of household waste, plastic was the highest at 30.2%, followed by food at 26.5%, paper at 14.1%, and fiber at 9.3%. The annual difference in food and plastics is attributed to an increase in food composition ratio and a relatively decrease in plastic composition ratio in 2021, which is presumed to be due to less eating out and ordering delivery food at home due to the COVID-19 situation. Since food waste and recyclable waste are discharged separably from other wastes, it can be seen that the variation of major wastes such as plastic, food, paper, and fiber, in the household wastes subject to incineration is no difference between seasons. The average weight of one discarded mask was 5.97 ± 0.94 g. The weight ratio of incineration standard garbage bags among household wastes was 1.33 ± 0.46%. The low calorific value of municipal solid waste estimated by the average physical composition was 3,762 kcal/kg, showing a result almost similar to the low calorific value of waste generated in the household part of the fifth waste statistical survey of Korea Ministry of Environment.
Key Words
Waste composition, Quartering and coning, Yearly and seasonal difference, Statistical difference
A Study on the Measures Used to Improve Old Clothes Disposal 폐의류 처리 개선방안에 관한 연구
Globally, only 15% of discarded old clothes are recycled, while the remainder is incinerated or dumped in landfills, resulting in severe deterioration of air and land quality. Korea’s old clothes export business boomed and expanded until 2013. As a result, there were not any social difficulties, such as “Not in My Backyard” (NIMBY), nor a lack of in-country landfill sites to dispose of old clothes. However, China’s export of old clothes has been surging since the early 2010s and caused an oversupply of old clothes in the world market. This resulted in the problematic management of the related companies as well as the old clothes disposal problem in Korea. Furthermore, the government’s administration system for old clothes has some issues, such as incorrect statistics of discarded amounts, unclear classification of textile wastes, and a lot of unlisted companies in the field. This study retrieved the total amount of discarded old clothes in Korea through related references and compared it with other countries. Additionally, the physicochemical properties of old clothes were analyzed to determine their suitability for bio-SRF. Finally, a legislative system for old clothing in Korea was reviewed, and some modifications were suggested to support related industries and to prepare for the upcoming old clothing disposal problem.
Key Words
Old clothes, Disposal measures, SRF, Modification of legislation
Analysis of Eco-efficiency Change according to Waste Treatment Scenarios 폐기물 처리 시나리오에 따른 환경효율성 변화 분석 연구
Analysis of Eco-efficiency Change according to Waste Treatment Scenarios 폐기물 처리 시나리오에 따른 환경효율성 변화 분석 연구
이소라 Sora Yl , 임혜숙 Hye Sook Lim
DOI:10.9786/kswm.2022.39.5.410
Abstract
Eco-efficiency can be expressed as an economic value for environmental impact, and the eco-efficiency of each waste treatment method can be calculated using environmental and economic evaluations of waste treatment facilities. This study analyzed changes in eco-efficiency according to changes in the share of waste treatment methods in the future based on the results of eco-efficiency evaluation of the waste treatment method. As a scenario the changing of future waste generation and treatment methods, the forecast of waste generation and treatment according to the first “Master Plans for Resources Circulation” was used. Municipal solid waste was selected as the target waste, and incineration, landfill disposal, combustible waste-to-energy, organic waste biogasification, and food waste recycling were considered for the waste treatment methods. The results of the eco-efficiency evaluation, based on the share of waste treatment forecast for 2027 (the target year of the first “Master Plans for Resources Circulation”), showed that eco-efficiency improved when compared to the 2016 (the base year of the first “Master Plans for Resources Circulation”). Calculations for eco-efficiency in 2027 differed depending on the share of the waste landfill, with 4,118 thousand won/point for all waste landfills, 4,312 thousand won/point for incombustible waste landfills, and 4,084 thousand won/point for mixed waste landfills. These all improved when compared to 5,173 thousand won/point, 7,701 thousand won/point, and 4,744 thousand won/point, respectively, for the base year. The improvement in the eco-efficiency of the target year compared to the base year is because the eco-efficiency of the landfill facilities was evaluated as superior to other facilities. However, because the operating burden of landfill treatment facilities tends to be underestimated, further research on economic costs and environmental impacts will be required. The results of the eco-efficiency evaluation can be utilized for policy making on waste treatment and establishing a methodology for facility improvement and efficiency.
Key Words
Eco-efficiency, Waste treatment scenario, Municipal solid waste, Master plans for resources circulation
Study on the Application of Environmental Assessment of Recycling of Domestic Waste Plastic Pyrolysis Oil for Naphtha Utilization 국내 폐플라스틱 열분해오일의 나프타 활용을 위한 재활용환경성평가 적용 연구
전화연 Hwayeon Jeon , 김목연 Mock-yeon Kim , 이재우 Jae Woo Lee , 김재곤 Jae-kon Kim
Study on the Application of Environmental Assessment of Recycling of Domestic Waste Plastic Pyrolysis Oil for Naphtha Utilization 국내 폐플라스틱 열분해오일의 나프타 활용을 위한 재활용환경성평가 적용 연구
전화연 Hwayeon Jeon , 김목연 Mock-yeon Kim , 이재우 Jae Woo Lee , 김재곤 Jae-kon Kim
DOI:10.9786/kswm.2022.39.5.418
Abstract
Waste plastic pyrolysis oil is characterized by a wide-ranging boiling point, a high heavy metals content, and a low temperature flash point. It is more difficult to use directly compared to low-grade fuel because its quality differs by producer. In this study, the recycling of waste plastic pyrolysis oil as naphtha was analyzed in terms of hazardous characteristics, quality properties, and chemical compositions to produce an environmental assessment of recycling. A harmful characteristic of waste plastic pyrolysis oil is its average flash point of 3 degrees Celsius. That of raw naphtha is also low due to the presence of components with low boiling points, such as n-pentene and n-butane. Moreover, the results of the properties analysis showed that, in the majority of cases, the water content was less than 1% and the carbon residue was less than 0.15%. However, some samples were not homogeneous, so the kinetic viscosity could not be measured. Additionally, the elemental analysis showed that the oxygen contents of some samples were found to be high. The heavy metal analysis demonstrated that the phosphorus, arsenic, sodium, and chlorine contents were high, with chlorine reaching a notable concentration of 1,000 mg/kg. Furthermore, pyrolysis oil has a carbon number range with about 70% from C5 to C12. It is necessary to fractionate a high boiling point and remove arsenic and chlorine from heavy metals by use of a pretreatment process. In addition, the contents of oxygen, olefin, and aromatic must be converted and removed. In conclusion, waste plastic pyrolysis oil must be improved in terms of its harmful and physical properties.
Key Words
Waste plastic pyrolysis oil, Environmental assessment of recycling, Naphtha, Flash point, Chlorine
Analysis of Deposit Return Systems for Resource Circulation: Focusing on Schemes for Single-use Cups 자원순환 보증금제 특징 분석을 통한 1회용 컵 등 대상 확대 연구
Analysis of Deposit Return Systems for Resource Circulation: Focusing on Schemes for Single-use Cups 자원순환 보증금제 특징 분석을 통한 1회용 컵 등 대상 확대 연구
이소라 Sora Yl
DOI:10.9786/kswm.2022.39.5.431
Abstract
With the integration of the ‘Beverage Container Deposit Return System’ into the ‘Resource Circulation Deposit Return System’ in Korea, there is a need to differentiate the strategies for the soon-to-be introduced deposit refund scheme for single-use cups from existing systems. This study, therefore, reviews the characteristics and implementation of deposit refund schemes for beverage containers and single-use cups in Korea and abroad to suggest suitable differentiation strategies for the single-use cup deposit refund scheme as well as plans to expand the scope of the deposit return scheme. The success of a deposit return system is highly dependent on the size of the deposit: the larger the deposit, the higher the return rate as well as the possibility of fraudulent refunds. For this reason, the scheme for collecting empty bottles, which is focused on reuse, and that for collecting single-use cups, which is mainly for recycling, should be managed separately using different collection systems. Setting a large deposit to improve the return rate will increase the consumers’ perceived market price, so it is necessary to indicate the deposit fee separately on the receipt. Also, strategies need to be considered for dealing with fraudulent refunds, which directly connect to management costs, such as whether to set a small deposit to prevent such behavior from the beginning or to set a large deposit and introduce anti-counterfeiting tools. A transparent system for managing the deposit refund scheme could be established by installing a reverse vending machine for collecting beverage containers and having a dedicated agency to manage the installation and operation of the machine directly based on real-time information.
The Effects of Agitation Method on the Food Waste Leachate Treatment Efficiency of an Anaerobic Digester 혐기성소화조의 교반방식이 음폐수 처리효율에 미치는 영향
이상윤 Sangyoon Lee , 배재호 Jaeho Bae
DOI:10.9786/kswm.2022.39.5.440
Abstract
Anaerobic digestion is a method for the proper management of the continuously increasing amount of food waste leachate, although it is costly and time consuming and requires enormous sites. Therefore, improving digestion efficiency with proper operation can be a realistic alternative. In this study, the effects of agitation methods on the performance of anaerobic digesters treating food waste leachate were evaluated by comparing two agitation methods: gas agitation and mechanical agitation. After changing gas agitation to mechanical agitation, the daily amount of food waste leachate treated increased from 131 to 147 t. In addition, the organic removal efficiency was improved by up to 6%. Digestion gas production also increased from 0.33 to 0.50 Nm3/kg CODcr-added. Moreover, it was found that it was possible to reduce electricity consumption by 40%. The above results indicate that the mechanical agitation method is more advantageous for the treatment of food waste leachate than the gas agitation method.
Key Words
Anaerobic digestion, Food waste leachate, Agitation, SUDOKWON landfill site
An Analysis of the Optimal Thermal Pretreatment Conditions for Improving the Anaerobic Efficiency of Cow Manure Using the Response Surface Methodology 반응표면분석법을 이용한 우분 혐기소화효율 향상 열전처리 최적조건 분석
An Analysis of the Optimal Thermal Pretreatment Conditions for Improving the Anaerobic Efficiency of Cow Manure Using the Response Surface Methodology 반응표면분석법을 이용한 우분 혐기소화효율 향상 열전처리 최적조건 분석
배종훈 Jonghun Bae , 박병창 Byeongchang Park
DOI:10.9786/kswm.2022.39.5.451
Abstract
The response surface methodology based on a central composite design was applied to optimize the thermal pretreatment conditions for the anaerobic digestion of cow manure. It was found that the anaerobic digestion efficiency improved as the temperature and time increased during the thermal pretreatment of cow manure. However, when the temperature and time conditions increased above a certain value, the degree of biodegradability decreased. This is because melanoids generated during high-temperature or long-term thermal pretreatment act as an anaerobic digestion inhibitor. Therefore, it is important to maintain the appropriate temperature and time when applying thermal pretreatment. The appropriate temperature and time ranges derived from this experiment were found to be 124-168 ℃ and 40-50 min. The maximum biodegradability predicted through reaction optimization was y = 40.2, and at this time, the temperature and time were 145℃ and 45 min.
Development of Demonstration Technology for Treatment of Sewage Impurities by Fermentation and Drying Process 발효·건조 공정을 이용한 하수처리장 협잡물 처리 실증화 기술개발 연구
서정식 Jeong-sig Seo , 윤종호 Jong-ho Youn , 반재형 Jea-hyung Ban , 이명오 Myoung-oh Lee
DOI:10.9786/kswm.2022.39.5.461
Abstract
In this study, a demonstration technology was developed for the treatment of sewage impurities by a fermentation and drying process. To treat the sewage impurities, fermentation and drying devices with a daily processing capacity of 100 kg and 300 kg, respectively, were installed at a public wastewater treatment facility. It was found that the weight loss rate and average water content of the fermentation dried residues from the sewage impurities ranged from 79-84% and 20-25%, respectively. The residues satisfied the quality standards of solid refuse fuel, meaning they could be reused as auxiliary fuel for coal-fired electrical power plants or cement factories. The fermentation and drying process was much more economical and environmentally friendly than the incineration process mainly used to treat sewage impurities. Compared with the incineration process, the fermentation and drying process was about 78% less expensive.
Key Words
Sewage impurities, Fermentation and drying process, Residues, Weight loss rate, Water content
Post-treatment Efficiency Evaluation of Anaerobic Digestion Effluent through Bio-electrochemical Biochemical Methane Potential Test 미생물 전기화학적 BMP test를 통한 혐기성 소화 유출수의 후처리 효율평가
차지환 Jihwan Cha , 천아인 Ain Cheon , 양현명 Hyeonmyeong Yang , 김민지 Minji Kim , 박병창 Byeongchang Park , 배종훈 Jonghun Bae , 전항배 Hangbae Jun
Post-treatment Efficiency Evaluation of Anaerobic Digestion Effluent through Bio-electrochemical Biochemical Methane Potential Test 미생물 전기화학적 BMP test를 통한 혐기성 소화 유출수의 후처리 효율평가
차지환 Jihwan Cha , 천아인 Ain Cheon , 양현명 Hyeonmyeong Yang , 김민지 Minji Kim , 박병창 Byeongchang Park , 배종훈 Jonghun Bae , 전항배 Hangbae Jun
DOI:10.9786/kswm.2022.39.5.470
Abstract
Bio-electrochemical anaerobic digestion (BEAD) is a technology that can improve the methane production of anaerobic digestion (AD) effluent by supplying a small amount of voltage, and its performance has been proven through many studies. However, most studies have used substrates with high biodegradability. In addition, there are few studies on AD effluent, which is difficult to treat due to its low biodegradation rate although it still has a high COD concentration. In this study, the posttreatment potential of AD effluent through BEAD was evaluated through a biochemical methane potential test, and optimal conditions were selected by supplying different voltages. As a result of the experiment, when a voltage of 0.4 V was supplied, the methane yield, coulombic efficiency, and biodegradation rate were the highest, and it was judged that the voltage supply contributed to the decomposition of non-degradable organic matter and rapid hydrogen and methane conversion of organic matter. However, when a voltage of >0.6 V was supplied, the efficiency was decreased, which was considered to be because the activity of microorganisms was inhibited due to the high voltage. Therefore, in this study, the optimum voltage was confirmed to be 0.4 V, and the possibility of the post-treatment of AD effluent through BEAD was confirmed.
Key Words
Bio-electrochemical anaerobic digestion, Post treatment, Voltage
