최용 Yong Choi , 이승희 Seung-whee Rhee

DOI:10.9786/kswm.2019.36.8.713

Abstract

Globally, mercury management at the national level in Korea (Republic of) has been required by ratifying to the Minamata Convention. In particular, it is necessary to identify the sources of mercury waste. Red stamping inks in Asian countries such as China, Japan and Korea have been used to prove identification. However, there is a lack of information on mercury content and hazardous characteristics of mercury in red stamping ink. To evaluate hazardous characteristics of mercury in red stamping ink, leaching tests such as Korea Extraction Test (KET) and Toxicity Characteristic Leaching Procedure (TCLP) were carried out as well as mercury content analysis. The mercury content in red stamp ink was estimated to be 0.664 mg/kg. The leaching concentrations of mercury were detected to be 0.4 μg/L or less in KET and 2.1 μg/L or less in TCLP. From these results, it was found that the leaching concentration of mercury in red stamping ink was satisfied with the regulatory level prescribed by KET and TCLP. Hence, the red stamping inks in Korea were generally verified to be non-hazardous wastes.

Key Words

Mercury-added product, Mercury content, Red stamping ink

박영규 Young Gyu Park

DOI:10.9786/kswm.2019.36.8.717

Abstract

Biogas is a gaseous mixture produced from microbial digestion of organic materials in the absence of oxygen. Raw biogas, depending upon organic materials, digestion time and process conditions, contains about 45-75% methane, 30- 50% carbon dioxide, 0.1% of hydrogen sulfide gas and fraction of water vapor. To achieve the standard composition of the biogas the techniques of both absorption and membrane separation were performed for the recycling studies of biogas. The several experimental works for the optimal membrane technologies have performed using biogas producing in the environmental digestion facility of food waste. The membrane module has been imported from oversea and the studies of two stepwise membrane process have been achieved in order to purify up to 98% of methane. The membrane process can have a motivation to prevent global warming effect and obtain energy recycling business. Chelate chemical was utilized to get and to treat the H2S concentration of less than 0.1%.

Key Words

Biogas, Membrane, Methane, Carbon dioxide, Hydrogen sulfide

유미영 Mi-yeong Yu , 박종진 Jong-jin Park , 황선진 Sun-jin Hwang

DOI:10.9786/kswm.2019.36.8.731

Abstract

The A₂O process, which is used to treat most of the wastewater generated in Korea, induces the luxury uptake of phosphorus-accumulating organisms (PAO) through anaerobic-aerobic conversion. Moreover, it can remove phosphorus by wasting microorganisms containing large amounts of phosphorus. However, when the nitrate in the return sludge enters the anaerobic tank, the diminished reducing power of the anaerobic tank inhibits phosphorus release, which limits the phosphorus removal efficiency. In this study, the possibility of enhanced phosphorus removal is explored under the anaerobic-aerobic method by using the cyanobacterium Synechococcus sp., which can synthesize polyhydroxybutyrate (PHB) like PAO. If Synechococcus sp. can remove excess phosphorus according to the same mechanism as PAO, it can possibly have a synergistic effect on phosphorus removal through photosynthesis metabolism as well as luxury-uptake due to anaerobic-aerobic conversion. The study results indicate that there was no significant difference in growth and carbon and phosphorus removal efficiencies, regardless of exposure to anaerobic conditions. Therefore, it the anaerobic condition can be considered to not inhibit the growth and metabolism of Synechococcus sp. Under anaerobic conditions, Synechococcus sp. released 28 mg-P/g-MLSS/day of phosphorus, which is lower than the amount released by PAO bacteria. There was no significant difference in the amounts of phosphorus removal between the anaerobic-aerobic conversion experiment and the control. In addition, the trend of carbon consumption was not consistent with the trend of phosphorus release. Therefore, at the very least, phosphorus release by Synechococcus sp. might follow a different pathway, or Synechococcus sp. does not release phosphorus, unlike PAO. Therefore, according to the results of this study, the application of Synechococcus sp. for phosphorus removal, similarly to PAO bacteria, through the anaerobic-aerobic conversion method is inappropriate.

Key Words

Eutrophication, EBPR (Enhanced biological phosphorus Removal), PAO (Phosphorus accumulating organisms), Synechococcus sp., PHB (Polyhydroxybutyrate)

Hatsue Minato Braatz , 박진규 , 김란희 , 문세흠 , 정민정

DOI:10.9786/kswm.2019.36.8.737

Abstract

Until a couple of years ago, industrial solid waste (ISW), which is produced in the process of maintaining and repairing machines, was dumped below industrial areas, where it mixed with the soil. To redevelop such affected areas, ISW-soil mixing materials should be identified as components of industrial waste or soil to establish a strategy for waste treatment. However, proper identification of some industrial wastes (such as coal ash) and soil can be challenging and confusing. Therefore, in this study, we suggest a method to determine whether a material (referred to as “suspicious substance”) is a component of ISW or soil to achieve proper waste treatment. Samples were collected from a railroad depot. First, the elemental compositions of the suspicious substances were determined with scanning electron microscopy-energy dispersive spectroscopy. Second, the substances were grouped based on their chemical profiles by conducting hierarchical cluster analysis. Finally, the elemental compositions of the soil samples obtained from the study site were compared to those of the groups to identify the soil.

Key Words

Industrial solid waste, Soil, SEM-EDS, Chemometric analysis

박병수 Byung Soo Park

DOI:10.9786/kswm.2019.36.8.749

Abstract

This paper describes the development of anti-stripping agents for asphalt pavement to recycle minerals, waste limestone powder (ENS), and other industrial byproducts such as flue gas desulfurization gypsum (S25) and byproduct lime (D2). The optimal mixing ratio of 1.5% D2, 0.75% S25, and 0.75% ENS powder, as determined from the results of an indirect tensile strength ratio test, was injected into an actual asphalt production line to analyze the performance indicators. The analysis results showed that all performance indicators, such as anti-stripping resistance and indirect tensile strength ratio, were satisfied. In addition, in an analysis of the tensile strength ratio according to the S25 and D2 contents, the ratio increased as the S25 content increased up to 70%, and it peaked at the S25 content of 70%. As the S25 content increased further to 100%, the tensile strength ratio decreased. When amount of D2 added was more than 25%, the tensile strength ratio was more than 83%. The effects of the amounts of D2 and S25 added as anti-stripping agents on the degree of aging were investigated. As a result, D2 was found to have an effective inputs of 30 to 40% of the filler, whereas at least 70% of S25 was found to be essential to reduce viscosity.

Key Words

Anti-stripping agents, Wasted limestone, Flue gas desulfurization gypsum, By-product lime

고영재 Youngjae Ko , 강준구 Jun-gu Kang , 권영현 Young-hyun Kwon , 유하녕 Ha-nyoung Yoo , 이영진 Jin-young Lee , 권준화 Jun-hwa Kwon , 전태완 Tae-wan Jeon , 신선경 Sun-kyoung Shin

DOI:10.9786/kswm.2019.36.8.760

Abstract

There is a growing interest in waste recycling and energy recovery worldwide. Especially, efforts are being made to maximize energy recovery through incineration. However, in a few industries, it is difficult to separate wastes due to physical and economic reasons. Specifically, several incombustible wastes are introduced into incineration facilities, and as a result, according to statistical data, the incidence of incineration residues exceeds 40%. Moreover, the introduction of incombustible wastes into an incinerator causes plant deterioration and negatively affects the recovery of incineration heat energy owing to the supply of reduced calorific value to the incinerator. In this study, the survey results of three industrial waste incineration facilities in Korea are presented to determine the characteristics of waste and material flows. The ratio of incineration residues estimated through moisture correction was approximately 22.4%, which is similar to the incombustible fraction of input waste (20.1%). Based on the analysis of each constituent material, the calorific value of the industrial wastes supplied to the incinerator was estimated to be 3,500 ~ 4,100 kcal/kg.

Key Words

Industrial waste, Incineration facility, Calorific value, Material flow analysis

이재희 Jae-hee Lee , 이종철 Jong-chul Lee , 이도승 Do-seung Lee , 양경식 Kyoung-sik Yang , 이윤지 Yoon-ji Lee , 이승학 Seung-hak Lee , 이종두 Jong-du Lee , 윤원종 Weon-jong Yoon , 정용환 Yong-hwan Jung

DOI:10.9786/kswm.2019.36.8.768

Abstract

An electric dryer was used to recycle citrus pressed cakes generated by a citrus juice extractor. The drying process was optimized by applying an automatic termination algorithm written in programmable logic controller (PLC) ladder logic language. The drying experiment was carried out under the “cooking oil” added conditions (0wt.%, 1wt.%, 3wt.%, and 5wt.%) because the operating time was prolonged owing to the presence of substances such as pectin and free sugar in the citrus pressed cakes, which reduced the drying rate and specific moisture evaporation rate. The operating conditions of the electric dryer were set as follows: heating temperature 170oC, cooling time 1 h, 50 Hz blower inverter, and vapor temperature difference 2.0oC/10 min. The design conditions of the dryer were derived by using the following operating parameters: operating time, electricity consumption, drying rate, specific moisture evaporation rate and drying efficiency.

Key Words

Drying, Electric heat source, Citrus pressed cake, Specific moisture evaporation rate, Recycling

오정례 Jung-rye Oh , 김효수 Hyo-su Kim , 김도완 Do-wan Kim , 배재근 Chae-gun Phae , 이종연 Jong-yeon Lee

DOI:10.9786/kswm.2019.36.8.777

Abstract

In this study, the sewage sludge production unit was calculated in order to evaluate the sewage sludge reduction project promoted by the government. Sewage sludge production unit is an important factor for predicting the amount of sewage sludge produced. The unit of sewage sludge production was calculated by considering four characteristics, including the capacity of the facility , treatment method, installation of anaerobic digester, and administrative local area. The result of the analysis by facility capacity indicated a low unit level in the facilities of more than 100,000 m3/day, and a high unit level in the lower facilities. Additionally, the result of the analysis by treatment methods shows high level in OD(Oxidation Ditch), MS(Membrane Separation) and SBR(Sequencing Batch Reactor) applied facilities. In addition, the result of the analysis by installation of AD(Anaerobic digester) and the unit on AD installation plant was low. Finally, the result of analysis by administrative local area indicated a significant difference between regions such as Daegu and Chung-Buk.

Key Words

Sewage sludge, Production unit, Treatment processing, Anaerobic digester

이승아 Seung A Lee , 이지환 Ji Hwan Lee , 정연구 Yeon-koo Jeong

DOI:10.9786/kswm.2019.36.8.787

Abstract

This study was performed to investigate the proper conditions for the production of porous geopolymer when mixing organic particles into mortar and its subsequent thermal treatment. Sawdust was used as an additive for pore formation. Proper conditions of sawdust for mixing and thermal treatment were determined in terms of the water content of the sawdust added, the thermal treatment temperature, and time. The effects of the dosages and particle size of sawdust were also analyzed by measuring the compressive strength of the cured specimens. It was found that the optimal water content of sawdust was approximately 50 ~ 60%, judging by the compressive strength results. The proper thermal treatment time was also determined to be greater than 12 hours when the cube specimen of 5 cm was used. The compressive strengths of the thermally-treated specimens decreased as an increasing amount of sawdust was added. The dosage of sawdust to geopolymer mixtures should be less than 15% of the weight of metakalolin and fly ash in order to ensure a compressive strength of more than 20 MPa. After thermal treatment, the bulk density of the geopolymer decreased as the amount of sawdust added increased. In addition, the compressive strength of thermally-treated specimens increased as the size of sawdust added in an identical dosage to the geopolymer mixture decreased.

Key Words

Geopolymer, Metakaolin, Fly ash, Sawdust, Thermal treatment

이세현 Sea-hyun Lee , 최원영 Won-young Choi , 윤상혁 Sang-hyuck Yoon

DOI:10.9786/kswm.2019.36.8.795

Abstract

The modified CBR of cyclic soil produced using multistage wind force sorting and a rotating friction device increased by 3.8% on average after passing, and its compaction performance improved. The 5-mm sieve-passing rate, 0.08-mm sieve-passing rate, and compaction dry density were superior to those before passing through the multistage wind force sorting and rotating friction device, and it is possible to use the resulting product as recycled soil in embankments because it satisfies the quality criteria of recycled aggregates. The contents of organic foreign matter inorganic matter decreased to 69.1% and 11.2%, respectively, after passing. In addition, organic foreign matter can be removed more effectively than inorganic matter. It is considered that the recycled soil obtained after passage through the multistage wind force sorting and rotating friction device satisfies the criteria of recycled aggregate quality in terms of both the plastic index and the liquid limit, and it is resistant to bearing capacity and external force.

Key Words

Rotor impact, Multistage wind, Recycled soil, Modified CBR, Foreign material

서동천 Dong-cheon Seo , 김준표 Jun-pyo Kim

DOI:10.9786/kswm.2019.36.8.802

Abstract

In order to manage marine debris on beach, information on the types of coastal litter, accumulation rate, spatial and temporal variations, and sources and transfer paths of waste are required. For this reason, governments and national or international organizations regularly and continuously monitor selected survey points by individual methods. However, the standardized monitoring methods have not yet been established internationally, and monitoring data in countries or organizations can show differences due to their methods. In this study, we examined the monitoring methods of Korea, China, Japan, the United States, Europe, and the UNEP (United Nations Environment Programme), and compared and analyzed the details of them including strengths and weaknesses. Moreover, this study proposed improvement and research in the Korean monitoring method regarding survey transect, frequency, etc.

Key Words

Marine pollution, Marine debris, Beach litter, Beach monitoring, Monitoring method