We conducted this study to develope technique for removing fine mortar attached to waste reinforcing steel bar (D13). We observed the effect of the glycolic acid concentration (10 ~ 40%) and reaction time (0.5 ~ 4 hr) on the mortar removal. The reaction rate (-1.3089 hr-1) was the fastest at 20% of glycolic acid. The mortar was completely removed in 3 hrs. The reaction rate decreased with pH increase (1.4 ~ 2.0) at 20% of glycolic acid.
The 2013 statistics showed that about 19 million automobiles were registered in Korea and, among these, ELVs amounted to about 770 thousands. Therefore, the Korean government imposed ELV recycling rate of 95% to be implemented by 2015 according to ‘Act on the Resource Circulation of Electrical and Electronic Equipment and Vehicles’. However, plastics and non-ferrous metal scraps arising from ELVs are not properly recycled with no adequate reuse: they are becoming major environmental concerns to overcome prior to the enforcement of ELV recycling in Korea. In view of this, contemporary ELVs recycling status in Germany is introduced in detail with main emphases on the legal context regarding efficient disposal and recycling management of ELVs & ASR as part of a preceding investigation into the state of the art example for future Korean recycling model.
Due to a world trend on renewable energy, biomass that is one of renewable energy resources has to be applied at thermochemical process, actively. However, in commercial plant, one of many problems is an agglomeration production at biomass thermochemical process, because it leads to disturb continuous operation on thermochemical process. Thus, in this study, the EFB (empty fruit bunch), one of palm oil industry by-products was used as a biomass fuel, and washed by water and nitric acid solution (0.1wt.%) with different total washing times for resolving this problem at biomass thermochemical process. After washing, ash content was decreased from 5.9wt.% to 1.53wt.% using all of the washing treatments, and the Alkali & Alkaline Earth Metallic (AAEM) was removed over 80wt.% of total AAEM, such as potassium, magnesium, calcium and sodium. Additionally, SEM with XRD was analyzed to confirm the characteristics of produced agglomeration, and the agglomeration production ratio was measured: it revealed that the ratio was resulted in decrease over half, in the case of using all of washed EFBs.
This study evaluated the standard consistency, setting time, hydration heat, and compressive strength of binary blended cement concrete (general and high strength) using air cooled ladle furnace slag (LFS) of 3, 5, 7, 10wt.% as an admixture for ordinary portland cement (OPC). Results showed that binary blended cements using the LFS of lower than 5wt.% shortened the setting time and reinforced the compressive strength of concrete (general and high-strength) compared to OPC concretes although binary blended cements needed more water to achieve the standard consistency. This indicated that LFS could be used as a useful admixture for manufacturing binary blended cement. Thus, we expected that the upcycling of LFS would be contributed to save energy consumption and reduce the greenhouse gas emission from the field of cement industry.
This laboratory study showed the performance evaluations of a improved C12A7 based mineral accelerator (I-CA) by both mortar and shotcrete tests. Performance of I-CA as a shotcrete accelerator was excellent by KCI-SC-102, which is a Korean specifications of shotcrete accelerator. In addition, I-CA showed equal qualities to the setting time and the compressive strength when compared those of the existing C12A7 based mineral accelerator (CA). The I-CA was manufactured with 40wt.% of electric arc furnace reducing slag, 24wt.% of lime, and 36wt.% of bauxite, indicating that the commercialization of I-CA contributed to recycle electric arc furnace reducing slag and to reduce the manufacturing cost of C12A7 based mineral accelerator due to the use a cheap raw material(electric arc furnace reducing slag), and to reduce the greenhouse gas emission due to the reductions in usage of lime and bauxite.
The MOE (Ministry of Environment) had classified 4 types of solid fuels as RDF (Refuse Derived Fuel), RPF (Refuse Plastic Fuel), TDF (Tire Derived Fuel) and WCF (Wood Chip Fuel) in Korea at 2012. However, the MOE has reclassified, the solid fuels with SRF (Soild Recovery Fuel) and Bio- SRF. Since the qulity standard for SRF has moderated, it is easier and more economical to recycle the waste. In this study, investigation for the generating, collecting, transporting, and treatment system of bulky waste in Seoul were performed. Moreover, experiments conducted to the analysis of collected bulky waste for assessment of SRF. According to the report of waste -meter-rate system in 2010, amount of bulky waste from to Dongdaemun-Gu is similar to average emissions in Seoul, and have an important facilities of transshipment for bulky waste, so that is the reason to select Dongdaemun-Gu for this research. According to process of Dongdaemun-center, bulky waste is classified into four-case, as metals, sponges, woods, and inclusion. Because the potion of inclusion is the difficult material to recycle, the entire quantity generated has been incinerated in Dongdaemun-Gu. the incinerating cost for inclusion was about 300 million won in 2012. Thus, inclusion from bulky waste was taken the target material to apply for SRF. So selected as inclusion that was incinerated to apply the SRF fuel standard. This research was analyzed the change in characteristics related to bringing location and period in order to evaluate the potential of energy of bulky waste in seoul. As a results of evaluation, there is not any differences related to changes of location and period. In addition, the results of conformity assessment of quality standards. Assessment items were satisfied with quality standards without moisture content. Moreover, low caloric value that is the primary factor to apply SRF was about 4,000 Kcal/kg Which is the homogeneous energy to utilize as fuel. However, taking steps as shield system for control of increasing moisture content by rainfall would be required.
This study was conducted to determine physico-chemical properties and degree of heavy metal contamination of sediments collected at Yeosu harbor. Outside of harbor (Y1, Y2, and Y3) showed relatively lower ignition loss than those for Y4 and Y5. All sediment samples had similar oxides and minerals based on the XRD and XRF analyses. Heavy metal contamination of the sediments was evaluated using USEPA, Ontario sediment quality guidelines, index of geoaccumulation and total enrichment factor. In summary, sediment Y5 was classified as moderately contaminated region based on index of geoaccumulation and heavily polluted based on standards of USEPA, Ontario sediment quality guidelines, and total enrichment factor. Sample Y5 obtained from the inner side of harbor showed the highest heavy metal contents. Among five heavy metals measured at Y5, Cu concentration was extremely high, which indicated that harbor activity might influence the Cu concentration in harbor sediment.
This paper attempted to elucidate pyrolysis reaction characteristics of waste paper laminated phenolic-printed circuit board (p-PCB). Thermogravimetric analysis was performed for the pyrolysis kinetic analysis of waste p-PCB and Pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS) was also employed to analyze the product distribution of waste p-PCB pyrolysis reaction under isothermal condition (230, 350, 600℃). Kinetic analysis and isothermal Py-GC/ MS results showed that the pyrolysis reaction of waste p-PCB has three reaction temperature regions: 1) low temperature decomposition region (< 280℃), 2) medium temperature decomposition region (280 ~ 380℃), 3) high temperature decomposition region ( > 380℃). At the first region, triphenyl phosphate used as fire retardant, water, and phenol were vaporized. At the second region, phenolic resin, tetrabromobisphenol-A (TBBA), and laminated paper are decomposed and produce phenols, brominated compounds, and levoglucosan which were the specific pyrolysis reaction products of phenolic resin, TBBA, and laminated paper, respectively. In the final region, cresol and alkyl benzene were detected which can be considered as the decomposition products of phenolic resin. By above results, pyrolysis reaction pathway of waste p-PCB is accounted for a series reaction with four independent reactions of phosphate based frame retardant, TBBA, laminated paper, and phenolic resin.
CO2 emitted from building materials and construction materials industry reaches about 67 million tons, which occupy about 30% of CO2 emitted from the construction field. Controls on the use of consumed fossil fuels and reduction of emission gases are essential for the reduction of CO2 in the construction area as we reduce the second and third curing to emit CO2 in the construction materials industry. Accordingly, this study applied the low energy curing admixture (hereinafter “LA”) to the extruded panels to observe the physical properties, depending on the mixing amount of fiber, type of fiber and mixing ratio of fiber. The type of fiber did not appear to be a main factor to affect strength, while the LA mixing ratio and mixing amount of fiber appeared to be major factors to affect strength. Especially, the highest strength was developed when the LA mixing ratio was 40%, whereas the test object with the mixing ratio of 50% resulted in the decrease of strength. In addition, it appeared that the mixing ratio of fiber greatly affected flexural strength and strength increased as the mixing ratio increased.
Toxicity of polymer, Alum, Zeolite, Loess, Koalinite and Chitosan on earthworm and the effects of sewage sludges coagulated by several mixtures of those coagulants on the population growth of earthworm Eisenia andrei were evaluated. Under the concentration of 20,000 mg/L of Zeolite, Loess and Kaolinite, and under 1,000 mg/L of Chitosan were there no acute toxicities on earthworms. The concentration of Polymer over 160 mg/L showed acute toxicity upon earthworm, but the concentration under 80 mg/L showed no toxicity. The concentration of Alum over 125 mg/L showed acute toxicity. The mixture of ‘Polymer 80 mg/L + Kaolinite 500 mg/L + Chitosan 20 mg/L’ had higher coagulating efficiency than the ‘Polymer 80 mg/ L + Kaolinite 500 mg/L’ on sewage sludge, And the sewage sludge coagulated by former mixture induced higher growth rate of earthworm population than that coagulated by latter mixture when the sewage sludges were supplied to earthworms.
To carry out the Montreal Protocol, South Korea has completely prohibited the use of CFC which is a main refrigerant since 2010, and the use of HCFC is planned to be prohibited from 2040. Therefore, it is expected that dependency on HFC as an alternate substance of HCFC will be increased. Since HFC which is one of main substances causing global warming phenomenon may have a harmful influence on climate change, legal and institutional measures for totally managing HCFC and HFC are required. Therefore, in this study, the refrigerant management systems in EU, USA and Japan have been considered in three aspects, such as the legal system for refrigerant management, the management and regulation limits for products using refrigerant, and the reduction policies and trends, centering on HCFC and HFC which are international regulation and reduction objects. EU environmental law regulates over the entire process for ozone depletion substances, such as production, import, export, use, market release, recovery, landfill and decomposition thereof. The united states regulates forming agents, labeling agents or the like, pursuant to Article 608 of the Federal Clean Air Act (air conditioning and automobiles), and in the case of the state of California, PFC and SF6 including HFC are defined as high GWP, and separately classified and managed. Unlike EU and USA, Japan is characterized by applying the Freon recovery and decomposition law for totally managing the Freon-based gas such as CFC, HCFC and HFC, and regulations on the refrigerant recovery and decomposition for each product are also specified in separate law related to the recovery of End-Of-Life (EOL) home appliances and vehicles.
This paper describes the performance of the module-type drying apparatus for the composting of a food waste. The drying apparatus mainly consists of a screw-type food waste agitator, an air exhaust blower, a heat supply tube and a heat source. Two different discharging flow conditions of the drying apparatus, 4 and 5 m3/min, are introduced. Partly dried by-products after six hours drying operation in the drying apparatus is obtained while drying temperature keeps constant of 60℃. It is noted that the by-products needs to sufficient decay period for the composting. Deodorizing apparatus having a zigzag flow and a nozzle, which is connected to the drying apparatus, is also designed to enhance the removing performance of the odor. Throughout experimental measurements, time to the drying temperature of 60℃ near the screw-type food waste agitator is shortened as discharging flow rate of the system decreases. The moisture content decreases to 50 percent after operation for 4 hours. Furthermore, the odor of the food waste is satisfied with the environment exhaust standard through the deodorizing apparatus.
Development and performance evaluation of the hydrogen generator by autothermal reforming process for emergency PEM fuel cell using methanol from process waste were carried out. Supply of gaseous hydrogen has been a technical barrier for its wide application. As a result, conventional reformer has either a separate heat source such as a catalytic combustor or a parallel process in the same reactor to generate heat. The later device is called ATR (Autothermal reforming). Typical product gas of ATR still contains a large amount of carbon monoxide that poisons electro-catalyst of the MEA. In the present study, we used the decomposition of hydrogen peroxide as a parallel exothermic reaction in the same reactor as the reformer. The decomposition of hydrogen peroxide releases water vapor and gaseous oxygen with enormous heat. The heat sustains the reforming reaction and the oxygen is used to recombine the carbon monoxide by oxidation. By parametric study, at the condition of 200℃ and the rate of methanol to 40% of hydrogen peroxide is 4 to 1, the Carbon monoxide contents are reduced by less than 800 ppm. Using the present concept we could reduce the concentration of carbon monoxide in the product gas of the reformer by more than 80%. At that carbon monoxide contents, we can be possible to load the methanol-hydrogen peroxide ATR system without any devices.