Only appropriate indicators can inform whether waste policies achieve their intended goals. Traditional indicators focused on recycling rates and landfill rates have limitations in terms of future policies. Both these indicators are based on waste only, and they are expressed as ratios, which limits analysis. In the future, waste policies should promote sustainable development. To do so, they must contribute not only to the stable treatment of waste but also to the actual substitution of natural resources, because waste policies are, directly or indirectly, related to the sustainable development goals (SDGs) adopted by the UN in 2015. Current policies should aim to create a resource circulation society which moves beyond waste treatment alone. For this purpose, evaluation indicators should follow four basic principles (prevention, material recycling, energy recovery, and disposal) in assessing the efficacy of future policies. In addition, evaluation indicators related to issues such as SDGs, climate change, and resource efficiency should reflect international trends. Indicators related to waste by domestic policies are dispersed, so it is necessary to integrate and focus them. Evaluation indicators should be established in a way that ensures future policies are implemented properly.
To establish a sustainable society, the United Nations adopted the agenda of setting sustainable development goals (SDGs) in September of 2015. The waste management sector relates directly or indirectly to several SDGs (Goals 7, 8, 12, and 13). Waste management policies will play an important role in sustainable development. One of the principles behind achieving SDGs is integrity, and policies should be established such that they reflect integrity. For this purpose, the actual statuses of SDGs related to waste management were identified based on several evaluation indices. This study demonstrates the inferiority of Korea compared to 15 other countries in terms of the evaluation indices. This inferiority is due to the fact that waste management policies in Korea have thus far been focused only on environmental aspects. For achieving SDGs, waste management solutions will need to be integrated with the economic and social sectors of society. At this time, waste management policies should prioritize integration, prevention, and material recovery, and there should be a willingness among policy makers to go beyond merely stable treatment.
China banned the import of solid waste at the end of 2017 due to serious environmental pollution problems caused by the illicit import and smuggling of solid wastes by illegal dealers. As a result of this measure, plastic wastes from Europe and other countries in the world have entered into the domestic plastic recycling market, and domestic recycling collection companies have refused to collect plastic waste. As a result, China’s import bans have reduced exports of domestic plastic waste by 57%, and have increased imports of plastic waste from Japan, Europe, and other countries. In addition, the prices of domestic PET, PE, and PP compression products fell due to the drop in international oil prices. Contract prices for recyclable resources in apartment complexes declined 25% in March of 2018 compared to March of 2017, and contract prices after the refusal of collection in April 2018 decreased 7% from March. In the case of solid fuel production of waste vinyl, which is difficult to separate, it is difficult to satisfy quality standards when manufacturing solid fuel because it contains foreign materials. Therefore, additional production is small in addition to the obligation to recycle due to the declining price competitiveness of solid fuel products.
In this study, the qualities of waste plastics pyrolysis oil before and after pre-treatment were compared. In addition, char byproducts and the odor impacts of non-condensable gases were evaluated. In the analysis of domestic pyrolysis oil quality criteria, the Case II oil, which did not undergo the pre-treatment process, was slightly above the criteria in moisture and chlorine content, this was improved in Case III oil, which was pre-treated. Pre-treatment is inevitable before the pyrolysis is processed to improve the quality of the oil. GC-MS analysis confirmed that the oil has characteristics of kerosene and diesel oil. In terms of the recycling possibility of char, the calorific value of char was slightly lower than the criteria of 4,500 kcal/kg, but the heavy metal content satisfied the criteria. Therefore, it should be taken into account that the char has the potential to be recycled in terms of energy recovery when mixed with other fuels. In the combustion of the pyrolysis oil, PM-2.5 exceeded the criteria. Therefore, it is necessary to install air pollution prevention facilities. In the analysis of odor in non-condensable gas, NH3, H2S, and CH3SH exceeded the emission limit. Therefore, a facility to reduce these odors should be installed before the non-condensable gas is discharged into the atmosphere.
This study aims to provide basic data to improve oil yields in the pyrolysis process. In order to compare the variation of the oil yields in relation to operating conditions, the experimental apparatus, a batch pyrolysis reactor, plastic flakes, and EPR plastic wastes as raw materials were used depending on the degree of contamination. As a result of pyrolysis in accordance with pre-treatment, the liquid yield of Case II, having undergone no pre-treatment, was 70.7%. For Case Ⅲ, having undergone pre-treatment, the yield was measured as 76.4%. This reveals that the yield is improved because pre-treatment removes moisture and contaminants from the plastic wastes. Measuring the yield in relation to temperature conditions, Case Ⅳ (proceeding at the lowest temperature condition) yielded 80.9% liquid and obtained the highest yield. Conversely, Case Ⅵ, which was conducted at the highest temperature, yielded 76.4% liquid, but the difference was negligible. In terms of yield, it is effective to conduct the pyrolysis under the lower temperature condition, but this presents the challenge that a greater reaction time is required. Therefore, from an economic point of view, setting the temperature within the range of approximately 360 to 400℃ is required in order to obtain more efficient oil yields in a given time.
Korea has experienced incidents related to waste management twice, in 1992 and 2018. The government should have waste management in order to provide good service to the people, even though the management of industrial waste belongs to the discharger under the PPP (polluter pay principle). Although the industrial wastes are highly recycled and marine dumping is being abolished, the government should prepare for the abolishment by predicting and managing demand and supply in order to properly dispose of industrial waste. Therefore, this paper describes a study conducted on the optimal incineration capacity in metropolitan regions. The waste subject was industrial solid waste (ISW), and the study data were based solely on government statistics. The people have been told that it is difficult to economically dispose of waste in the metropolitan region. According to the diagnosis in this study, considering the current situation, it is estimated that at least 2,000 tons/day of on-site incineration should be added to the metropolitan region.
Drying experiments for the food waste collected from apartment complexes were conducted to optimize the operation conditions of batch-type dryers using the PLC (Programmable Logic Controller) ladder logic language. The experimental parameters for dryer were as follows: 1) the food waste input was 50, 75, or 150 kg, 2) the heating temperature of the dryer was 160, 170, 180, or 190oC, and 3) the cooling time was 0, 0.5, 1.0, 2.0, or 2.5 hr. Additionally, the experiments were performed under water vapor recirculation conditions with varying blower frequencies of 40, 50, or 60 Hz. The effective heat transfer area by the heating medium which filled in the outer wall of the dryer was 0.48 m2, and the water content of the food waste was 79.1 ± 3.1% (mean±standard deviation, n = 49). The average water content of the dried food waste tested under these various operating conditions was 6.5 ± 2.3% (mean±SD, n = 49). At the end of the drying experiment, the temperature (CH1) of the gas discharged from the dryer and the temperature (CH2) of the outlet air from the cooled condenser were monitored, and the temperature difference between CH1 and CH2 calculated as a moving average [(CH1-CH2)/10] was determined when the target value was reached. In this drying experiment, the drying time (operating time, hr), the specific moisture evaporation rate (kg-H2O/Mcal), the drying efficiency, and the drying rate (kg-H2O/m2 hr) were dependent on the amount of input food waste, the amount of recirculation steam, the drying temperature, and the cooling time.
As there are various materials which obstruct FGD (Flue Gas Desulfurization) waste water treatment in large scale (500 MW × 4) biomass and coal co-fired power plants, the process improvement of currently operating wastewater treatment systems is necessary to remove non-degradable contaminants such as T-N, Mn, F, etc. In this study, the influence of wastewater pH, inorganic coagulants, and anti-Ca agent, which are all related to the efficiency of FGD wastewater treatment systems, were analyzed. In addition, the eco-friendly and strong oxydant Ferrate (VI), was tested to verify the possibility of removing water pollutants in real operating FGD wastewater treatment facilities. Results indicated that increasing pH from 7.5 to 9.1 is more effective in reducing Mn concentrations in reaction tanks and T-N, SS, COD, TP were removed by 62.9, 70.9, 81.5, 66.7% respectively using 0.5% Ferrate(VI) rate injection.
The study area is located in Korea in a racepark and its surrounding areas, which had been continuously sprayed with deicing salts to prevent the freezing of raceway. The purpose of this paper was to examine groundwater quality properties affected by salt spraying on the racepark raceway. The groundwater beneath the racepark’s surrounding area had higher concentrations of calcium, sodium, chloride, and EC than did the uncontaminated area. Above all, the groundwater affected by the de-icing salts showed higher concentrations of calcium and chloride than sodium. This result is probably due to the cation exchange in soil environments. Based on the groundwater modeling results, it was inferred that the pollutants caused by the racepark course are recharged to the groundwater and are transported to the surrounding area over time. In conclusion, these results indicate that groundwater quality has been mainly contaminated by calcium, sodium, and chloride by the use of de-icing salts.
Spontaneous ignition of waste piles has been and continues to be a challenge in waste treatment. Spontaneous ignitions can pose a great threat to the safety of the surrounding environment and to human health. Thus, understanding the parameters that control spontaneous ignition is necessary to help predict and potentially mitigate these hazards. The objective of this study was to identify the mechanism of spontaneous ignition in waste piles. Two types of combustion can develop in waste piles: surface combustion, which is generally an occurrence of flaming combustion, and subsurface fires, which are generally occurrences of smoldering combustion. Smoldering combustion is a slow, low temperature, flameless form of combustion, and is self-sustained. Smoldering combustion can be continuously produced and it can change to flaming combustion if the air supply is not eliminated. Smoldering combustion also releases significant quantities of pollutants such as carbon monoxide. In order to extinguish these combustions effectively and cheaply, more parameters of the waste pile should be obtained, such as the temperature field and gas composition. Drilling holes at suspicious waste pile combustion areas can confirm whether these places are high-temperature areas or not. A carbon monoxide concentration of 1,000 ppmv can be utilized as an indicator of smoldering combustion. In addition, water in an amount ranging between 6.22 and 11.66 kg will be required at 25℃ to extinguish the heat produced by the flaming combustion of 1 kg of waste.
