Advanced countries are introducing circular economic policies as ways to implement the agendas of Resource Efficiency (RE), the United Nations Convention on Climate Change (UNFCCC), and the Sustainable Development Goals (SDGs). The Circular Economy is a policy document prepared in December of 2015 by the European Commission. It consists of the action plans and propositions for the laws concerning waste management. The revised laws came into effect on July 5, 2018, following European Parliament and EU Council approval, and have progressed smoothly so far. In concordance , Korea has adopted the realization of a circular economy as a vision in the First Basic Resource Circulation Plan in September of 2018 because current conventional policies and laws place limitations on the conversion to a resource-circulating society. Given this context , we examined the potential influence of the implementation of the EU's action plans and the revision of laws on the future direction of waste management policies. First, the regulations in terms of policies and laws that mandate compliance with the basic principles were reiterated. As a way to observe such regulations, introducing economic means was suggested. Furthermore, to clarify the relationships among the laws, a revision (purpose and definition) focusing on the Framework Directive on Waste Management was performed. Second, as the implementation of a circular economy requires continuous negotiations with the government as well as stakeholders, a legal system was established with a focus on prevention across the basic principles. To direct domestic waste management policies towards the realization of a circular economy in addition to environmental conservation, the relationship between the conventional laws (Waste Management Act and Resource Recycling Act) that center around the Fundamental Act on Resource Circulation and the waste management policy should be clearly defined. Moreover, for the implementation of a circular economy, the policies incorporating economic incentives should consist of suitably designed upstream and downstream boundaries.
Changes in waste management policy are required to enforce the fundamental law of resource circulation introduced in January of 2018, the Framework Convention on Climate Change (Paris Agreement), which comes into force in January of 2021, and the United Nations Sustainable Development Goals (SDGs) established in September of 2015. Given the prospective changes, it is important to have a clear understanding of the role and contribution of waste energy in waste management policy. We studied the policies of the EU and Japan, the frontrunners in resource circulation and climate change mitigation. EU policies, such as the Circular Economy Package, prioritize product recycling over energy recovery. To resolve the issue of overcapacity in energy recovery facilities in EU member states, policy documents include provisions on discouraging facility expansion and enhancing the efficiency of the energy recovery process. Japan is also implementing policies to recover and use energy effectively through sustainable processes. Budget support and feed-in tariff (FIT) policies are part of Japan’s endeavors to increase the amount of energy recovered. To promote the effective use of waste energy, Japan established guidelines on how to plan for the utilization of waste energy, thus encouraging the participation of local governments in the recovery and reuse of waste resources. We recommend that Korea emulate best practices from the EU and Japan by setting clear policy priorities for managing waste energy and implementing consistent policies aimed at increasing the recovery and effective utilization of waste energy.
The wear of tires is a phenomenon in which a part of the tire is separated from the road surface by the frictional force applied to the tire tread rubber. Worn tire dust contains heavy metals such as zinc and cadmium, which are considered to have adverse effects on ecosystems through bioaccumulation and biomagnification. In addition, it has been confirmed that a large number of tire fragments as microplastics (defined as less than 5 mm of plastic) are detected at sewage treatment plants and on pavement sides. In this study, we aimed to quantify the tire dust discharged by the driving of vehicles. The emission factors of tire dust in other countries were verified and that of tire dust in Korea is established. As a result, it was confirmed that 39,000 ~ 76,000 tons of tire dust are generated annually in Korea.
According to statistical data from the Korea Paper Association, paper production in Korea exceeds 700,000 tons of paper per year, and is increasing with the demand for special packaging containers. The occurrence of papermaking sludge generated in the process of manufacturing paper products has inevitably increased. Paper sludge is recycled or incinerated. Most paper sludge is incinerated in order to recover the pulp necessary for the papermaking process, or is recycled to high fire, lightweight aggregate bricks, etc., using incineration residue. However, the recycling standard for papermaking ash incineration ash applies the same criteria as the incineration ash of living waste, and it seems difficult to recycle papermaking incineration ash from the present recycling method of 2019. In particular, it turned out that ignition losses from the recycling standard and chlorine standard are problematic. Therefore, in this study, we analyzed ignition loss and chlorine components of paper incineration ash generated at a domestic branch office and recycled incineration ash product, and we examined the adequacy of current recycling standards.
In situ methane enrichment systems, which consisted of a mesophilic kinetic phase separation digester coupled with a leachate recycle loop to an external CO2 stripper, were developed to upgrade biogas productivity. The effects of organic loading rate (OLR) and leachate recycle rate (LRR) on the resulting off-gas methane content, methane productivity, and total volatile solids (TVS) removal efficiency were quantitatively evaluated. The results indicated that an off-gas methane content of over 95.1% was achieved at the reactor OLR of 5 kgVS/m3-day and at an LRR of 4. Under these conditions, the methane productivity of the in situ methane enrichment system was 0.28 v/v-d (gas volume/reactor volume) of phase I, 0.33 v/v-d of phase II, and the TVS removal efficiency was between 76%and 81%. A further increase in OLR of 10 kgVS/m3-day reached a methane content of 88.3% at an LRR of 4. An increase in OLR requires more leachate recycling to achieve higher methane content. However, an excessively high LRR led to a decrease in methane productivity and TVS removal efficiency.
The role of conditioning agents, such as hydrogen, oxygen, and water vapor in the destruction of NF3 gas using electronbeam technology was assessed in terms of the destruction and removal efficiency (DRE%). The DRE of NF3 using electron-beam technology was studied in a flow reactor. Experiments were conducted at a flow rate of 50 Lm-1 at room temperature. The inlet concentration of NF3 was 1,000 ppm, and the concentrations of conditioning agents ranged from 500 to 3,000 ppm, respectively. In this study, the absorbed dose (electron-beam current) ranged from 0 (0 mA) to 424.7 kGy (20 mA). Among the conditioning agents, hydrogen gas was found to play a significant role in the destruction of NF3 gas. In the case of oxygen and water vapor, the water vapor increased the DRE of NF3, though by a small amount, and the oxygen decreased the DRE of NF3 gas. The DRE of NF3 gas increased with hydrogen gas concentration. The results presented here can be utilized to increase the effectiveness of electron-beam technology as a measure for reducing NF3, a toxic and potent greenhouse gas produced by the semiconductor industry.
Biofuel is attractive as a renewable energy source due to its sustainability. Bio-oil, one of the biofuels, is produced through the fast pyrolysis of biomass. It has a higher energy density than biomass, and is convenient for storage and transportation. Bio-oil can be transformed into high-quality syngas through the gasification process, which has a small amount of impurities. The bio-oil gasification process consists of the injection of bio-oil, atomization of the injected biooil, vaporization of atomized bio-oil droplets, and a gasification reaction by mixing the vaporized bio-oil and air. The performance of the nozzle plays a very important role in determining the efficiency of the entire gasification system. Although there are many studies on the direct gasification of biomass, studies of bio-oil gasification are very rare. In order to study bio-oil gasification, the injection characteristics of bio-oil using a twin fluid nozzle should occur. Therefore, in this paper, a twin fluid nozzle was modeled and the injection characteristics of bio-oil in the reactor were analyzed by using CFD. Specifically, an entrained flow type reactor was applied and the injection flow characteristics were calculated and analyzed with respect to the air flow rate.
As a part of CCUS (Carbon Capture, Utilization, and Storage) technology, mineral carbonation technology (MCT) has received research attention. Through MCT, CO2 is chemically reacted with calcium- and/or magnesium-containing minerals to form stable carbonate materials which do not incur any long-term liability or monitoring commitments. Moreover, MCT using industrial byproducts not only captures CO< SUB >2< /SUB > but also stabilizes heavy metal components contained in industrial byproducts. Therefore, interest in MCT research using industrial byproducts has gradually increased, and so it was evaluated as an eco-friendly byproduct treatment method. The aim of this research was the process optimization to find optimum experimental temperatures and reaction types in high-temperature carbonation, which is one of the MCT technologies. All experiments were conducted using fluidized and fixed-type reactors to obtain optimal reactor. The reaction temperatures were determined to be between 550℃ and 750℃, while CO< SUB >2< /SUB > and CaO reaction times were controlled by gas flow rates using a mass flow controller.
Although many domestic industrial and incineration facilities utilize waste heat generated during processing, they only use waste heat and do not utilize waste heat of relatively low quality. In this study, we intended to develop a technology to store and supply waste heat by using latent heat and latent heat of inorganic PCM(Phase Change Material) as a means of utilizing low-quality waste heat generated by industrial processes. A PCM thermal storage device was built, and the heat storage and releasement performance were evaluated through repeated experiments. A manufactured PCM heat storage device used water as a heat transfer medium. The water was heated to an average temperature of 96.8℃ and supplied to the PCM heat storage system. The average heat storage amount of the PCM heat storage device during heat storage operation was 321.5 MJ, and 321.5 MJ of heat stored in the PCM heat storage device was discharged through water and air. It was able to heat to 283.4 MJ when heated through water and 300.7 MJ when heated through air. The overall efficiency of the entire system, calculated as the amount of heat releasement compared to the amount of heat stored, was 88.2% using water and 93.5% using air.
In this study, we studied the BFR (Brominated Flame Retardant) levels of WEEE (waste electronic and electrical equipment), automobiles, and construction and demolition waste, and compared these values to those of previous studies. In addition, we provide a proposed management plan for BFR-containing waste. The results showed that the concentrations of PBDEs (polybrominated diphenyl ethers) detected from CRT (cathode ray tube) TV samples ranged from 133 mg/kg to 18,467 mg/kg, with an average of 7,739 mg/kg, while the concentrations of PBDEs detected from the automobile samples ranged from 2,587 mg/kg to 37,498 mg/kg, with an average of 14,752 mg/kg. The construction and demolition waste samples contained significant levels of HBCD, ranging from 1,848 mg/kg to 20,085 mg/kg. In the case of CRT TVs and automobiles, the concentrations of BFRs were lower than those of previous studies. Further studies are still needed to determine the final fate and behavior of BFRs in waste-containing BFR streams. Specific management guidelines associated with waste that contains high levels of BFRs should be developed to deter the widespread dispersion of BFRs in the environment and human exposure upon improper disposal.
The UNFCCC on annual inventories require that Annex I Parties use the 2006 IPCC Guidelines for National Greenhouse Gas Inventories. The 2006 IPCC Guidelines provide a landfill gas generation model to estimate methane emissions from a landfill. There are several parameters in the IPCC landfill gas generation model. However, a major challenge in IPCC landfill gas generation modeling is the estimation of these parameter values. Thus, this study describes a method to determine these parameter values from the fitting of an iterative non-linear least square method (INLSM) to actual landfill gas data, using Generalized Reduced Gradient (GRG) and bootstrap methods. In this study, actual landfill gas data was collected at Sudokwon Landfill Site 2, and curve fitting was carried out to find the parameter values (DOC, DOCf, and k) for each waste component as well as OX values. We used the SOLVER of Microsoft Excel, which employs the INLSM fitting routine, to produce the optimal goodness-of-fit between the actual landfill gas data and the IPCC modeling results. This process was repeated several times to ensure that changes in the parameter values resulted in minimized sums of squares residuals (SSR) and a maximized coefficient of determination (R2). It should be noted that INLSM can never provide absolute certainty of having found the global SSR minimum unless a systematic sampling of all possible combinations of parameter values is carried out. Thus, mean values and ranges (95% confidence level) for the parameters were calculated using a bootstrapping method. The results of the study show that a combination of INLSM and bootstrapping can be used appropriately to estimate IPCC landfill gas generation model parameters.
