Effect analysis on waste recycling by introducing a new policy, "Environmental Assessment of Recycling," for establishment of the ESG management system in the Republic of Korea.

To move away from linear system mining-manufacture-production-disposal, most countries have been trying to establish a circular economy, by reusing waste as resources. Responding to this paradigm change, the Ministry of Environment of Korea amended the Wastes Control Act in the 2010s. To increase the recycling rate in Korea, the environmental assessment of recycling (EAR) has been introduced to improve the Wastes Control Act. The whole process of new recycling technologies can be assessed in terms of environmental or technical aspects by assessment institutes of the EAR. Finally, the governmental research institute can approve of an application case, which proves environmental friendliness, even if the technology is not defined in the current act. Recently, 17 companies have been coassessed and approved to recycle steel codes in waste tires as resources for iron smelting via assessments of the whole process, such as environmental analysis and quality assessment. The EAR has been enforcing recycling materials for six years, and the total profit of the companies that were approved was estimated to be approximately 55 million USD. However, many amendments to the EAR continue to be requested by stakeholders. In this study, the effect of the EAR was evaluated, and additional tasks were found to enhance the EAR. Integr Environ Assess Manag 2024;00:1-13. © 2024 SETAC.

Applicability assessment of a plasma melting technology for a fly ash recycling system in the Republic of Korea.

ABSTRACTThe Ministry of Environment of Korea has proposed a ban on landfill disposal of municipal solid waste (MSW) from 2026. Thus, it is inferred that the amount of incineration ash will increase drastically. Against this backdrop, this study assessed the applicability of a plasma melting process to fly ash. Fly ash was collected from 14 incineration facilities to analyze its basic properties and perform melting experiments. Furthermore, scanning electron microscope (SEM) analysis and economic feasibility assessment were conducted. The molten fly ash slag exhibited a pH value of 9.9, and the ignition loss of fly ash was found to range from 14.5 to 25.7 wt.%. None of seven toxic elements (arsenic (As), cadmium (Cd), cyanide (CN), mercury (Hg), hexavalent chromium (Cr(VI)), copper, and lead (Pb)) was detected from the molten slag. In addition, 99.3 wt.% of chloride ion (Cl-), 97.9 wt.% of fluoride ion (F-), and 98.1 wt.% of sulphate ion (SO42-) were removed. The contents in the molten slag were found to be 0.19, 7.8, 27.8, 33.1, and 38 mg/kg for Cd, Pb, zinc, nickel, and F, respectively, and none of CN, Hg, and As was detected, thereby meeting the criteria for soil pollution. All of the environmental standards were met, and SEM analysis confirmed stable quality with high density and no surface pore. In the economic feasibility assessment, a profit of approximately 152.4 $/ton was also estimated compared to landfill disposal.

Evaluating the recycling potential of ashes discharged from waste incineration facilities and its dependency on pretreatment efficiency in Korea.

The amount of incineration ash (IA) is expected to increase in South Korea from the rapidly rising numbers and operation capacities of incineration facilities; therefore, it remains necessary to establish measurements for the enhanced recycling and circularity of IA. This study established a database of hazardous substances in IA by compiling discharge data and survey results from domestic incineration facilities, along with literature survey values. The recycling potential of IA was assessed considering leaching reduction efficiency of various pretreatment methods. In particular, 98.2% of bottom ash and 49.0% of fly ash satisfied the IA recycling criteria after melting. Also, when mixed at a ratio of âˆ¼ 78:22 natural soil to IA, the resulting material was usable for media-contact recycling by meeting the heavy metal content criteria of the Soil Environment Conservation Act.

Optimization of cobalt, nickel, and iron supplement for mesophilic and thermophilic anaerobic digestion treating high-solid food waste.

ABSTRACTThe effects of trace metals (iron (Fe), cobalt (Co) + Fe, and Co + nickel (Ni) + Fe) on mesophilic and thermophilic anaerobic digestion of food waste were quantified experimentally. Supplementation with 0 ≤ [Co] ≤ 5 mg/L, 0 ≤ [Ni] ≤ 10 mg/L, or 0 ≤ [Fe] ≤ 200 mg/L can significantly improve the productivity of mesophilic (MD) and thermophilic (TD) digesters. Addition of micronutrients increased biogas production, but excessive addition of trace metals hindered the production. Supplementation with Fe + Co or Fe + Co + Ni increased biogas production more than the addition of only Fe did. Within the design boundaries, the optimal concentrations for supplementation with three trace metals in MD were [Co] = 0.33 mg/L, [Ni] = 0.43 mg/L, and [Fe] = 5.35 mg/L, and in TD were [Co] = 1.41 mg/L, [Ni] = 3.84 mg/L, and [Fe] = 200 mg/L. TD required larger amounts of the trace metals than MD (4.3-37.4 times). The results can give quantitative information on trace metal supplementation for successful anaerobic digestion.

A Study on Safety Management Plan for Recycling of Medium-Contact Wastes via Ecotoxicity Assessment.

In South Korea, hazardous characteristics of wastes to be recycled are managed through the "Environmental Impact Assessment of Recycling" system. The ecotoxicity of medium-contact recyclable wastes, that is, those in contact with soil, groundwater, surface water, etc., is managed according to this system and is determined based on whether or not they exceed an ecotoxicity value (TU) of 2.0. The ecotoxicity of wastes is tested and determined by using pretreated eluate samples according to the Official Wastes Test Standard and applying the Official Water Pollution Process Test Standard. However, no ecotoxicity management limits are stipulated for medium-contact recycling using wastes in numerous other countries. This study aims to evaluate applicability and safety of the ecotoxicity test for wastes used in medium-contact recycling and establish an efficient management plan for hazardous characteristic wastes. Target wastes for the survey were selected based on the Wastes Control Act in South Korea. Nine types of waste were selected, which are representative types of wastes to which ecotoxicity is applied. In order to secure the representativeness of the target samples, a total of 45 samples were collected by selecting 5 cases each of the 9 waste types in consideration of the type of industry and amount of waste generated. Limit exceedance was calculated for each category of hazardous substances (leaching, total content), pH, and ecotoxicity of a total of 45 samples, and was found to increase in the order of leaching 2.22% < pH 9.09% < content 31.11% < ecotoxicity 37.21%. This indicates that the limit exceedance was maximum in the ecotoxicity category. Therefore, the application of ecotoxicity limit is efficient for identifying and comprehensively managing the environmental impacts of various types of hazardous substances contained in wastes from the perspective of comprehensive toxicity.

Improved mesophilic anaerobic digestion of swine wastewater by ammonia stripping with microwave irradiation.

Ammonia (NH3) stripping by microwave irradiation was used to increase the efficiency of anaerobic digestion. The effects of final temperature (FT) (80 ≤ FT ≤ 100°C) and microwave irradiation time (MIT) (2.5 ≤ MIT ≤ 5.5 min) of NH3 stripping, and hydraulic retention time (HRT) (7 ≤ HRT ≤ 20 d) in anaerobic digester were quantified. NH3 concentration decreased from 2794 to 140 mg/L within 5.5 min at FT = 100°C. The highest cumulative biogas production (>1800 mL/L) and efficiency of volatile solid removal (> 68%) were achieved at FT = 100°C and MIT = 5.5 min. The removal efficiency of volatile solid in digesters fed with untreated swine wastewater (control) and swine wastewater treated by NH3 stripping decreased as HRT decreased. The highest relative improvement of properties compared to the control occurred at 10 or 15 d HRT. Increases in biogas production compared to the control increased with the NH3 stripping as HRT was reduced to 10 d (243% higher at 10 d). The methane content of the produced biogas was 64-69% for control and 68-75% with NH3 stripping in the range of 10-20 d HRT. NH3 stripping using microwave irradiation is an effective pretreatment to improve the anaerobic digestion of swine wastewater.