With the enforcement of the Fundamental Act on Resource Circulation in January 2018, the Resource Circulation Fundamental Plan (Vision: Implementation of Circular Economy) was established in September of the same year. Consequently, the system for establishing a resource circulation society was formally prepared. In terms of the driving policy, various wastes must be controlled, with priority given to material recycling. Energy recovery should be maximized if material recycling is economically and technically difficult, but this is not the case in reality. As a typical example, the question of the best way to manage the role of solid recovered fuel (SRF) is an important consideration. Although SRF has already contributed to the safe processing of various wastes within the national infrastructure, several tasks still need to be addressed before the new policy can be introduced. From a policy perspective, it is necessary to re-establish the relationship between the Wastes Management Act and the Fundamental Act on Resource Circulation. From a social perspective, measures to ensure environmental safety from small-scale SRF commercial facilities are required. From an economic perspective, unlike in the European Union (EU) and Japan, SRF is specified as a recycling product in Korea. Therefore, the appropriate sale prices for SRF need to be determined, and its safety and quality secured to gain reasonable profits. From a technical point of view, it is necessary to increase the energy recovery efficiency of SRF rather than supporting incineration. If efficient measures for addressing these issues are put in place, the SRF industry will become a major contributor to the resource circulation policy.
Brominated flame retardants (BFRs) including PBDEs, TBBPA, and HBCD have been used in automobiles. As BFRs contain some persistent organic pollutants listed by the Stockholm Convention due to their toxicity for the environment and the human body, they have been identified as substances of great concern due to the possibility and potential of human exposure and environmental release during automobile use, treatment, and disposal. This study examined and summarized the PBDE levels and management of automobile-shredded residue (ASR) after disassembly and the shredding processes of end-of-life vehicles (ELVs). The results show that the concentrations of PBDEs detected from the ASR samples range from 313 mg/kg to 5,527 mg/kg, with an average of 1,037 mg/kg. Among the 13 isomers of PBDEs, high levels of deca-BDE were found in the samples. The results of the substance flow analysis of PBDEs show that 122 tons of PBDEs were generated after the disassembly and shredding process in 2016. The final destinations of PBDEs in ASR were energy recovery (68%) and incineration (32%). Further research is needed to determine the final fate and behavior of PBDEs during these processes. Specific management guidelines associated with ASR containing high levels of PBDEs should also be established in order to prevent the widespread dispersion of POPs in the environment as well as human exposure in improper disposal conditions.
Transactions of venous resources such as products, parts, materials, etc., which have been recently used and discharged as waste, are actively underway in the East Asian region. Venous resources have the potential to be both volatile and environmentally polluting, and there is a risk that the possibility of contamination will surface if international trade is activated without institutionalized regulations of the export/import system. This type of environmental pollution has been reported in some areas such as China. In order to prevent such a situation in advance, it is necessary to establish an accurate institutional infrastructure for domestic venous resources so that the quality of the market can be maintained smoothly. Therefore, it is necessary to appropriately control the illegal parts of the venous resource market through proper legal oversight of informal flow within the country.
The purpose of this study was to investigate the effect of gas composition with an iron hydroxide-activated carbon powder composite for the removal of hydrogen sulfide and siloxane (D4) in a fixed bed reactor. As a result of the breakthrough test that controlled the space velocity, initial concentration, relative humidity, oxygen, and gas mixture of methane/carbon dioxide, the adsorption capacity of hydrogen sulfide for the iron hydroxide-activated carbon powder composite was improved up to five times by 60% of the relative humidity. In addition, the space velocity and initial concentration were found to be important factors. The adsorption capacity of siloxane increased by 0.168 g siloxane/g adsorbent with increasing space velocity. In the case of simultaneous removal of hydrogen sulfide and siloxane, the adsorption capacity of hydrogen sulfide was negligible compared with that of siloxane, and the adsorption capacity of the siloxane was decreased by the hydrogen sulfide.
Fly ash, generated from the incineration of municipal solid waste, contains substantial amount of carbonic matter. High carbon content fly ash, when used as the cement admixture, causes adverse effect for the formation of concrete because carbon particles promote the consumption of air-entraining reagent and reduce the durability of the concrete. Therefore, in order to recycle the fly ash, it is essential to develop an effective technique to recover or remove the carbonic matter. In this study, oil agglomeration technique was applied to recover carbonic matter in the fly ash. Typical parameters, which affect the separation of carbonic matter from fly ash were investigated. The parameters are slurry pH, slurry density, agitation speed, an oil type and dosage. The separation effects were expressed in terms of recovery rate of carbonic matter from the original fly ash and the purity of aggregate. The study showed that oil agglomeration produced the best recovery of carbonic matter about 61.7% with high purity (90%), with the experimental conditions of pulp pH 5, agitation speed 3,000 rpm, use of kerosene with 20% dose (dry solid wt. basis). The 61.7% recovery of carbonic matter left over 3.9% of carbonic content in the fly ash which satisfied the guideline of 5% or less carbon content for recycling as cement admixture. However, further research is required to enhance the recovery of carbonic matter, considering the surface characteristic of both carbon and inorganic particles in fly ash.
The Ministry of the Environment Notification on the conversion of loading boxes for waste collection and transportation vehicles to a sealed form (MOE, Notice No. 2016-237). This has been enacted to keep boxes from being blown off by wind or from leaking, during the course of collection, transportation, or storage of waste. This Notification also includes specific gravity criteria by loading mode of waste collection and transportation vehicle with the function of dumping. The specific gravities of compressed and non-compressed mode vehicles are 0.300 and 0.200, respectively. However, the recycling business has a significant issue with regard to the collection or transportation of some recyclable material, e.g., plastic waste, which has small apparent specific gravity and uses a non-compressed mode vehicle, making it difficult to meet the criteria of the Notification. Therefore, it is important to establish a standard based on the actual measurement data by waste item. The aim of this study is to suggest practical specific gravity criteria for different loading modes in household waste collection and transportation vehicles by not only investigating the current situation of waste collection and transportation but also calculating the apparent specific gravity of recyclable materials when subjected to collection and transportation vehicles. In this study’s results, the apparent specific gravities of mixed recyclable materials within compressed and non-compressed mode vehicles are 0.230 and 0.082, respectively, indicating that the existing criteria in this Notification are set too high.
This study was performed to develop a Phosphorus Recovery System (PRS) for the recovery of phosphorus from incinerated sewage sludge ash using struvite precipitation. Fly ash generated at the Seonam sewage treatment plant has a high P2O5 content (13.9%). We developed a PRS consisting of an ultrasonic extractor, solid-liquid separator, mixing tank, and phosphorus recovery tank. The ultrasonic extractor had a 28 kHz vibrator for high speed and efficiency, which could perform the extraction in one-quarter of the time required in the conventional stirring method. Results of tests on the ultrasonic extractor showed that up to 0.044 g of PO43--P per gram of ash could be extracted with 1 N NaOH at an L/S ratio of 10 mL/g and an ultrasonic output of 500 Wh for 0.5 hr. The PRS showed the fraction of Mg and P was >70% in struvite. The PRS utilizing leachate is an effective and low-cost process that removes and recovers NH4+ from landfill leachate. The PRS is needed to improve the operation method and economic analysis to commercialize the technology and its application through further studies.
Globally, there are environmental problems because of greenhouse gas emissions. The CO2 emissions rate of the cement industry is very huge, and a continued demand for cement is anticipated. In order to reduce the environmental impact of CO2 emissions from cement production, this study conducted experiments for the development of non-sintered cement (that has not undergone firing or burning) using granulated ground-blast furnace slag, high-calcium fly ash, and nonactivated hwangto (that has also not undergone firing burning). One experiment used acid resistance and a pH test due to durability, and it conducted a component analysis for the measurement of crystalline analysis and a scanning electron microscope at the mortar. From the experimental results, the mechanical and chemical properties were compared with those of ordinary Portland cement for applicability to construction sites. In the future, to solve the problem through continued research, it will be necessary to reduce cement’s environmental load and involve an economic analysis.
The Korean coastal sediment area is apt to be contaminated by prevailing aquafarming and inland eutrophic sources. Furthermore, oyster shells are being overproduced every year with little recycling. Oxygen-releasing compounds (ORCs) are paramount in bioremediation or bioaugmentation. Calcium peroxide, one of the primary ORCs, was prepared using recyclable oyster shells via acid?base reactions based on double replacement, and this was followed by oxidation with hydrogen peroxide. Hydrogen peroxide, which is known to be effective as oxidizing agent, required an optimum dose for higher content of oxygen in the final product, because the literature shows that the oxidative reaction is reversible. A variety of concentrations of HCl and NaOH were examined in stoichiometry for the breakdown of calcium carbonates (or CO2 production) and formation of calcium hydroxide in the initiation reaction. Acid and base overdoses helped the oxygenation reaction to be extended further, thus leading to calcium peroxide with the highest content of oxygen at a combination of 6 N-12 N acid-base treatment. With an elevated temperature, more oxygenated calcium peroxide was likely to be formed. Carbon dioxide and free oxygen during the experiments were determined with DO probing and gas capture in a water bath.
In Korea, more than 200,000 tons of red-mud are produced annually during the aluminum hydroxide manufacturing process. The red-mud produced contains valuable resources, including scandium; however, most of the red-mud is not recycled, causing environmental problems. The aim of this study is to investigate the leaching characteristics of scandium from red-mud produced in Korea. Leaching experiments on domestic red-mud were conducted under varying leaching times, leaching temperatures, liquid-to-solid (L/S) ratios, and acid concentrations. The recovery of scandium was higher when leached in H2SO4 solution compared to HCl solution. Whereas the dissolution of scandium was slightly affected by leaching time and temperature, changes in acid concentrations and liquid-to-solid ratios significantly enhanced the dissolution of scandium by approximately 40%. In 5 M acid solution and an L/S ratio of 10, the maximum dissolution efficiency of scandium was measured to be approximately 89%. The leaching data indicated that scandium dissolution was closely associated with acid concentrations and L/S ratios. This study investigated leaching process characteristics as a pre-treatment process to recover scandium from red-mud scrap. These results could have industrial applications through scaling up.
Optimized bench scale disassembly/separation technology has been developed for economically feasible and sustainable recycling of waste optical fiber cables. Ten batches of waste optical fiber cables have been randomly selected from a recycling company in order to characterize their components, identify their composition, and subsequently optimize the manual disassembly/separation processes. A manual cable cutter for randomly collected waste optical fiber cables has been designed and fabricated for bench scale operation in conjunction with (prior) induction heating of the waste optical fiber samples, which was deemed the most suitable means for an optimum disassembly/separation process. Actual test results on induction heating indicated possible disassembly/separation process optimization for the waste optical fibers under the conditions of 20 kW and 20 m/min of power and transfer rates, respectively.