In 2018 the South Korean Government introduced the Resource Circulation Act that included a landfill levy (tax) in order to reduce the amount of waste going to landfill sites and to promote recycling. The objective of this study is to examine the negative and positive effects of landfill tax on national waste management by reviewing case studies from the European Union (EU). In December 2015, the European Commission proposed the Circular Economy Package that sets ambitious recycling rates of 65% and a maximum 10% landfill rate for municipal wastes by 2030, and the European Commission decided that the landfill tax could help move towards these aims. Indeed since the late 1990s, most of the countries in the European Union have introduced landfill taxes. Landfill rates of these countries showed a tendency to decrease gradually. Currently the landfill rates for the Netherlands, Sweden, Denmark and Norway are less than 5%, and those for the UK, France and Italy have fallen below 30%. However, the landfill tax also had negative effects. In the case of the Netherlands, too little waste was sent to landfills, and private companies can no longer profit. Consequently the companies will not be able to fulfil their financial obligations for closure and aftercare. Thus, based on the results of this study, it is necessary to further consider the landfill levy in Korea.
To improve the management of the transboundary movement of waste, the management system for the transboundary movement of hazardous waste in both Korea (Republic of) and other foreign countries was reviewed. It was found that, for the improvement in the listed waste, the revision of the HSK code for waste and the strategy for international situation should be considered in Korea. The listed waste in Korea was found to be lacking the detailed classification to accommodate the listed waste of Basel Convention. Therefore, it is necessary to improve the listed waste in Korea in accordance with the listed waste of the Basel Convention. The HSK code for waste should be revised to identify the different type of items between a new item and a used item. Hence, it is necessary to subdivide the HSK code for used goods and wastes. Each country has amended its laws and management systems for securing resources globally and for protecting the environment in its own country. Finally, the strategy for the international situation should be intensified in the management of transboundary movement because the prohibited wastes in transboundary movement were suddenly expanded in China.
The sanitary landfill method not only stops leakage of leachate and landfill gas to the outside, it also prevents water or air ingress. These methods significantly reduce the environmental contamination of landfills. Recently, landfilling of organic wastes such as sewage sludge and food waste has been forbidden, and landfilled wastes are dried. In addition, the water supply from outside is blocked, and the inside of the landfill remains very dry using the sanitary landfill method. At present, municipal solid-waste landfills have a generalized landfill-gas recovery and energy conversion. However, delayed decomposition of waste due to drying of the landfill will prolong the post-management period and reduce the amount of landfill gas after final disposal, which has a serious impact on the economics. In this study, a leachate recirculation facility was installed at the SUDOKWON landfill site in Incheon to prevent drying of the inside of the landfill. We investigated the effects of leachate recirculation on landfill gas evolution by observing the changes in water content and landfill-gas collection. As a result, the amount of landfill gas collected after recycling the leachate for about 34 months showed an increase of about 71% compared to the control. Therefore, the increase of water content through leachate recirculation greatly influences landfill-gas production, and it can increase the return from the landfill-gas energy project.
Preparation of Fibrous Filter Medium with Adsorption/Antibacterial Property by Photoinduced Graft Polymerization of Vim and Subsequent Quaternization(I) : Synthesis Condition and Functionality Evaluation
In recent years, the demand for advanced treatments in the water-treatment industry has increased, and physicochemicalseparation technologies have come into wide use. However, biofouling is a major problem for the separation processes in water and wastewater treatment. One anti-biofouling strategy is to construct antibacterial surfaces. In this work, polypropylene (PP) fiber was endowed with antibacterial/adsorption property by photoinduced graft polymerization of 1- vinyl imidazole (Vim) followed by quaternization with alkyl iodides. A concentration of Vim equal to 5 vol.% in 10-20 vol.% methanol, a photoirradiation time of 5 h and a reaction temperature of 80oC proved to be optimal for the grafting of Vim onto PP. The modified PP fibers were characterized by means of FT-IR, SEM, antibacterial and adsorption tests. We found that the quaternized PP-g-Vim fiber with methyl iodide exhibited high adsorption capacity for NO3-N and excellent antibacterial activities against both E. coli and S. aureus.
The PP-g-Vim-CH3I adsorbent, which possesses antibacterial and ion-exchange functions, was synthesized by photoinduced grafting of 1-vinyl imidazole (Vim) onto polypropylene, non-woven fabric and subsequent quaternization using methyl iodide (CH3I). The adsorption properties of PP-g-Vim-CH3I for nitrate ion were studied in batch mode and fixed-bed columns. The adsorption equilibria of NO3-N on PP-g-Vim-CH3I were well described by the Langmuir isotherm model, and the adsorption energy was 9.03 kJ/mol, which indicates an ion-exchange process. Adsorption-kinetic data were fitted with a pseudo-second-order kinetic model. The Bohart-Adams model was found to be suitable for simulating the breakthrough curves obtained from the fixed-bed columns. The fixed-bed sorption capacity of nitrate ion from the model was in the range 100.8 ~ 108.6 mg/g without the presence of competing anions but decreased to the range 55.7 ~ 96.2 mg/ g in groundwater due to adsorption competition with the coexisting anions, especially SO42- ion. The PP-g-Vim-CH3I adsorbent could be regenerated by washing with 1.0 N NaCl without serious lowering the adsorption capacity.
Carbonaceous material prepared from oriental cherry can be used for the adsorption of zinc ion from an aqueous solution. Parameters such as pH (4-11), temperature (293-333 K), mixing intensity (10-120 rpm) and contact time (0.5- 90 min) were studied. Increasing pH (99.6% at pH 11) and temperature (99.8% at 333 K) caused an increase in adsorption capacity. A pseudo-equilibrium state was reached within 1 min of contact time. Removal efficiency of zinc ion remained constant regardless of mixing intensity. The adsorption equilibrium data were best represented by the Freundlich adsorption isotherm. The calculated maximum adsorption capacity was 3.541 mg/g. Thermodynamic studies demonstrated that the adsorption process was spontaneous with Gibb’s free-energy values ranging between -3.272 and -15.594 kJ/mol and endothermic with an enthalpy value of 86.984 kJ/mol. Therefore, carbonaceous material from oriental cherry was shown to have good potential for the adsorption of zinc ion.
This study discusses regeneration of mercury-contaminated, activated carbon from adsorption in the mercuryrecovery process. Mercury in activated carbon was desorbed by thermal treatment, and the regeneration efficiency was confirmed by mercury content and iodine adsorption comparing new and spent activated carbon. Up to 95% of mercury desorbed and up to 86% adsorption performance regenerated at 673 K. Therefore, it is expected that activated carbon can be reused many times by regenerating it through thermal treatment without disposing of mercury-containing activated carbon.
PFC (perfluorocompound) gases have an extremely high global warming potential (GWP). A study of the destruction of NF3, CF4 and SF6 gases emitted from the semiconductor industry was attempted by plasma power at 4.4 kW, 5.5 kW, 6.0 kW, 6.6 kW, 7.6 kW, 8.1 kW and 9.1 kW. As electric power increased, DRE (destruction and removal efficiency) of NF3, CF4 and SF6 was also increased. It was confirmed through experiment that the DRE of NF3 is 99% at 7.6 kW, 97% for CF4 at 9.14 kW and 100% for SF6 at 7.6 kW of plasma power. By-products formed by PFC destruction were mainly F2, SO2F2, NOx and CO gases. In addition, particulate matter was formed, and particle were proven to be AlF3.
The energy efficiency of gas turbine using LNG as a fuel has reached to less than about 40% even for the H class gas turbine. To increase the energy efficiency, in theoretical analysis, the maximum value of fuel efficiency can be obtained via the equally large value of the mixing rate and reaction rate in the harmonic-mean type overall reaction rate expression. Even if the delayed mixing rate can be overcome successfully by the strategy of the practically proved lean-burn method, however, the critical problem caused by the retarded reaction rate caused by the excess air has to be solved in order to make any breakthrough of the engine or gas turbine fuel efficiency. To do this, a series of systematic numerical calculation has been made for the evaluation of the lean-burn CH4 flame feature with the addition of small amount of H2 or HHO (H2+1/2O2, water electrolysis gas). To maintain lean burn state, the flow rate of methane was greatly reduced less than 50% of the standard flow rate. The addition of HHO or H2 heating value has increased steadily from 5, 10 and up to 20% of the 100% CH4 flow rate. And investigation of flame characteristics such as peak flame temperature and its location together with the temperature profile has been made through numerical calculation for a gas turbine combustor. For the standard case of 100% CH4 injection, the flame temperature profile was observed to increase steadily from the primary combustor region to gas turbine inlet. This is exactly corresponds to the temperature profile appeared in a heating process with constant pressure assumption in a typical Brayton cycle. However, for the case of co-burning with H2 or HHO with only 40 and 50% CH4 injection, the peak flame temperature appears near the upstream primary region and decreases significantly along the downstream toward turbine inlet. A detailed discussion further has been made for the flame characteristics with the change of added fuel amount and its type. In summary, the addition of the H2 and HHO gas with the reduced amount of the CH4 flow rate results in quite different temperature profile expected from the standard Brayton cycle. Further this kind of flame feature suggests the possibility of high fuel efficiency together with the reduction of the metallurgical thermal damage of the turbine blade due to the decreased gas temperature near turbine inlet.
The rapid development of some industries generates a huge amount of useless biowastes. Recently, biosorption, which can use biowastes as biosorbents, has attracted attention as an environmentally friendly method for the removal of ionic pollutants from wastewaters. For this reason, many researchers have investigated the biosorption capacities of various biowastes. In this study, fermentation waste (Escherichia coli) was used as a biosorbent for the removal of various organic and inorganic pollutants: i.e., cationic dye (methylene blue (MB)), anionic dye (Reactive Red 4 (RR4)), cationic metal (cadmium (II)), and anionic metal (arsenic (V)). The uptake of the cationic pollutants by the biosorbent increased as solution pH was increased. The RR4 uptake increased with a decrease in solution pH. In the case of the anionic metal (As (V)), it was not well removed in the range of pH 2-7. To examine adsorption rates and mechanisms, kinetic and isotherm experiments were conducted, and various kinetic and isotherm models were used to fit the experimental data. The maximum adsorption capacities of MB and RR4 were predicted to be 231.3 mg/g and 257.6 mg/g, respectively. In conclusion, fermentation waste (E. coli) is a cheap and abundant resource for the manufacture of effective biosorbents capable of removing both cationic and anionic (in) organic pollutants from wastewaters.
Since 2005 the landfilling of food waste has been prohibited, and many recycling facilities (private, domestic, animalfeed conversion, public composting) have been constructed and operated as waste-treatment centers. However, due to the negative attitude of users on the domestic animal feed and compost produced from food waste, the byproducts of waste have created a vicious cycle, needing treatment themselves. In addition, the London Convention prohibited the discharge of organic waste such as sewage sludge into the ocean in 2012 and of food-waste leachate in 2013. An alternative to landfilling and incineration is to treat biomass with anaerobic digestion. However, the anaerobic-digestion efficiency of the Daejeon City bioenergy facility, which has adopted a mixed digestion process of food waste and food waste leachate, has not been reproduced in other municipalities due to a misunderstanding of anaerobic digestion and a lack of operating skill. Thus, the anaerobic-digestion efficiency of the bioenergy facility in Deajeon is analyzed, and it provides basic information for the anaerobic co-digestion of organic wastes.