Kraft lignin is a major biomass byproduct generated in large quantities from the kraft pulping process and has attracted attention as a renewable aromatic polymer with the potential to replace petroleum-based aromatic compounds. Since the kraft process accounts for the majority of global pulp production, large amounts of lignin are continuously generated, providing a stable supply of biomass-derived resources. Kraft lignin contains a complex aromatic structure and various functional groups; however, variations in molecular weight distribution and functional group composition caused by differences in feedstock species and pulping conditions lead to significant quality inconsistency. In addition, sulfur-containing structures and a high degree of condensation act as major technical barriers during separation, purification, and subsequent modification processes, thereby limiting its application in high-value materials. Various separation and purification technologies, including acid precipitation, membrane separation, and solvent-based fractionation, have been applied to obtain lignin fractions with properties suitable for specific applications. In particular, the abundant phenolic hydroxyl and carboxyl groups of kraft lignin have enabled its development as water-treatment adsorbents and porous carbon precursors for the removal of heavy metals and organic pollutants, demonstrating its potential as an environmental material. In applications such as adhesives, resins, and carbon materials, structural reproducibility is also an important requirement, emphasizing the importance of selective separation and structural control technologies. However, the high capital investment and production costs required for high-purity purification and modification processes remain major challenges for large-scale industrial utilization. Furthermore, quality standardization and the establishment of large-scale production systems are essential for practical applications. Future research should focus on the development of selective separation and fractionation technologies capable of precisely controlling molecular weight and functional group composition, along with the transition to continuous processing systems to enhance industrial applicability.
Rare earth elements (REEs) are essential resources for high-tech industries including semiconductors, batteries, electric vehicles, and wind power generation; however, the current global supply chain is overwhelmingly concentrated in specific countries. As environmental pollution from mining and refining processes and geopolitical risks continue to intensify, the importance of recycling technologies that utilize electronic waste (e-waste) as an ‘urban mine’ is rapidly increasing. Against this background, this study aims to comprehensively compare pyrometallurgical, hydrometallurgical, and next-generation eco-friendly recovery technologies, while presenting technical and economic challenges and future development strategies. Electronic waste contains high concentrations of REEs, offering greater recovery potential than natural ores. Analysis revealed that existing pyrometallurgical and hydrometallurgical processes, despite their high recovery rates and efficiency, exhibit clear environmental limitations including massive energy consumption and wastewater generation. Next-generation technologies — including bioleaching, ionic liquids, and deep eutectic solvents (DES) — were found to have the potential to substantially reduce the environmental burden by eliminating hazardous chemicals and enhancing selective recovery performance. Iodide-iodine and thiourea-based leaching systems are also attracting attention as subjects for future research. In particular, life cycle assessment (LCA) results indicated that bioleaching showed lower values in certain environmental impact categories compared to conventional chemical leaching; however, these results may vary depending on feedstock characteristics, functional units, and system boundaries, and caution is advised against generalization. The EU has set a target of 25% domestic recycling of critical raw materials by 2030 through the Critical Raw Materials Act (CRMA), and the U.S. Department of Energy (DOE) is expanding support for e-waste-based REE recovery and refining demonstrations. Korea likewise needs to consider developing e-waste-based REE recovery technologies and establishing demand-linked supply chains, building on existing rare metal development strategies. In summary, bioleaching and low-hazard solvent-based technologies are assessed as promising alternatives for next-generation eco-friendly REE recovery, and further efforts toward demonstration-scale expansion, downstream refining advancement, and techno-economic validation are needed. Based on the collected data, this study examines technical and policy challenges and aims to provide foundational data for future policy improvements and research directions.
The current study comparatively evaluated the release characteristics of nano/microplastics and organic matter from non-metallic drinking water pipes. Accelerated aging experiments were conducted on polybutylene(PB) and impact-modified polyvinyl chloride(iPVC) to verify the effects of long-term operations on the pipe material. FT-IR spectra of particles detected after the aging conditions matched those of the original pipe materials, confirming the presence of pipe-derived particles. Subsequently, a continuous-flow system simulating drinking water distribution conditions was established, and a pipe circulation experiment was conducted for approximately 45 days under a residual chlorine concentration of about 4.3mg/L and a temperature of 40°C. The results showed that PB exhibited a higher cumulative release of nanoparticles and a greater number of microplastic particles than iPVC. Results also showed that the total organic carbon(TOC) release from was also higher in PB. In contrast, iPVC and stainless steel(STS) showed no substantial differences in TOC concentration or cumulative nanoparticle release. These findings demonstrate that the release characteristics of nano/microplastics and organic matter vary depending on pipe material under drinking water distribution conditions and suggest that the potential release of nano/microplastics should be considered when selecting materials for drinking water pipes.
Polyhydroxyalkanoate (PHA) is a biodegradable polymer accumulated by microorganisms and is considered a promising alternative to petroleum-based plastics. This study investigated the operating conditions governing PHA accumulation and the enrichment of PHA-accumulating microorganisms in mixed microbial culture (MMC) systems. Data from four sequencing batch reactors (SBRs), operated in two experimental runs with three stages each, were integrated, including 1,733 days of process data, 400 PHA measurements, and 16S rRNA gene amplicon sequencing data from 48 samples. A leakage-free machine learning framework was applied to interpret the relationships among operating conditions, PHA accumulation, and microbial community dynamics. Under reactor-wise cross-validation, XGBoost explained PHA content from operating conditions alone (R2 = 0.38), and SHAP analysis identified settling strategy, nutrient decoupling, solids retention time (SRT), and feast/famine duration as key factors. PHA-accumulating genera, including Thauera, Paracoccus, and Azoarcus, were enriched compared with the inoculum, but their relative abundance was not significantly correlated with measured PHA content (Spearman’s ρ = −0.34, p = 0.06). In contrast, Thauera abundance was predicted from operating conditions in unseen reactors with relatively high accuracy (R2 = 0.61), whereas most other taxa were not predictable. These results suggest that operating control selectively shapes key PHA-associated microorganisms rather than the entire community. This study provides a data-driven basis for defining operating windows for MMC-based PHA enrichment and AI-assisted process optimization.
Electrochemistry underpins energy storage, energy conversion, and environmental processes; therefore, precise electrode terminology is essential for both science education and industrial communication. In Korea, however, long-standing translation practices for anode and cathode have produced recurring conceptual confusion in classrooms, journals, and technical documents. The root cause is that two distinct categories of terms, function-based terms and potential-based terms, have not been consistently separated in Korean translation. Historically, Michael Faraday introduced anode and cathode as theory-neutral terms denoting the surfaces through which electric current, according to the convention of his time, enters and leaves the decomposing body. They were not introduced as fixed polarity labels. Modern IUPAC definitions follow this functional logic: anode is the electrode at which oxidation occurs, and cathode is the electrode at which reduction occurs, independently of electrode polarity. Consequently, during discharge in a galvanic cell, the anode is the negative electrode, whereas in an electrolytic cell the electrode connected to the positive terminal of the external power supply is the anode. In rechargeable batteries, the same physical electrode alternates between anodic and cathodic roles during charge and discharge, which makes function-based names inherently variable for a fixed material. To address this variability, battery standards and industrial documents widely use positive electrode and negative electrode as potential-based terms for fixed electrode materials and cell components. IEC 60050-482 likewise specifies that the anode is the negative electrode during discharge and the positive electrode during charge, while the cathode shows the opposite correspondence. A comparison of Korea, China, and Japan reveals three distinct patterns. China institutionalizes the distinction between 阳极/阴极 as function-based terms and 正极/负极 as potential-based terms in national battery standards such as GB/T 2900.41-2008. Japanese standards, including JIS K 0213:2014, explicitly describe context-dependent correspondences, while the Japanese electrochemistry community has long discussed the need for clear separation. Korea already has function-based definitions in the Korean Chemical Society terminology glossary and battery terminology standards in KS C IEC 60050-482, yet a consistent operational principle separating function-based terms from potential-based terms has not been firmly established across education, academia, and industry. On this basis, this paper proposes three principles: 1) anode and cathode should be used as function-based terms and translated as 애노드/산화전극 and 캐소드/환원전극, respectively. 2) positive electrode and negative electrode should be used as potential-based terms and translated as 양극(또는 정극) and 음극(또는 부극), respectively. 3) the symbols (+) and (−) should be used as polarity markers for electrodes or terminals, not as fixed equivalents of anode and cathode. Adopting these principles can improve conceptual clarity in electrochemistry education, increase precision in industrial communication, and reduce translation errors in international scientific exchange.
The Integrated Environmental Management System (IEMS) was introduced in Korea in 2017 to shift from a single-media regulatory framework to an integrated, facility-based environmental management approach. As part of this system, Best Available Techniques–Associated Emission Levels (BAT-AELs) provide reference ranges for achievable emission levels and serve as a basis for establishing sector-specific emission limits and facility-level permitted emission standards. However, in practice, permitted emission standards are finalized through emission impact assessments that consider local environmental quality. Nevertheless, it remains to be further empirically examined whether the stringency of BAT-AEL compared to permitted emission standards has been reflected in actual emission reduction outcomes. Accordingly, this study empirically evaluates the relationship between the stringency of permitted emission standards and environmental performance following the implementation of the IEMS, providing insights for future policy discussions. Municipal waste incineration facilities were selected as the study subject because relatively long-term operational data are available for this sector. Publicly available data from the CleanSYS and Integrated Environmental Permit System (IEPS) were utilized. Environmental performance was assessed using emission intensity (kg/ton-waste), defined as pollutant emissions per ton of waste incinerated. For five air pollutants (dust, sulfur oxides, nitrogen oxides, carbon monoxide, and hydrogen chloride), the stringency of permitted emission standards was quantified as a normalized value within the BAT-AEL range, and the reduction performance was evaluated based on its relationship with changes in emission intensity. Statistically significant association was not observed between stringency and changes in emission intensities across the examined pollutants. However, emission intensities for nitrogen oxides, dust, hydrogen chloride, and sulfur oxides showed significant reductions after the IEMS implementation, indicating overall emission reduction performance under the IEMS. These results suggest that although emissions improved after IEMS implementation, the magnitude of improvement was not directly associated with differences in the stringency of permitted emission standards. Thus, differences in environmental performance among facilities cannot be sufficiently explained by the numerical stringency of permitted emission standards based on BAT-AEL alone. It suggests that the actual level of BAT implementation, and the facility operating conditions should be considered together when interpreting the environmental improvement outcomes. The findings also provide practical implications into developing a management framework where BAT-AEL and monitoring data can be more effectively linked to the establishment and improvement of permitted emission standards.
The rapid growth of China-based e-commerce (C-commerce) has led to a sharp increase in cross-border direct purchases, resulting in a substantial inflow of packaging waste into Korea without a clear management framework. Using 2024 itemized customs clearance data, the volume of packaging waste generated through C-commerce is estimated at a minimum of 24,413 tons. With the 2030 ban on direct landfilling of municipal solid waste approaching, such uncontrolled inflows pose a significant burden on domestic sorting and treatment facilities. Under the current Extended Producer Responsibility (EPR) system, established by the Act on the Promotion of Saving and Recycling of Resources, obligations are limited to domestic manufacturers and authorized importers, effectively excluding overseas sellers from regulatory oversight. This structural limitation allows foreign operators to free-ride on environmental costs and exacerbates regulatory blind spots in waste management. As an alternative, this study examines the European Union’s Packaging and Packaging Waste Regulation (PPWR), which preemptively legislates environmental responsibility for offshore sellers, to derive insights for platform-based regulatory enforcement. Based on this analysis, the study proposes a “Korean EPR Enforcement Structure Extension Model,” which integrates: (1) an Authorised Representative system, (2) the Korea One-Stop Shop (K-OSS), and (3) Functionally differentiated Producer Responsibility Organization (Type-C PRO). The proposed model incorporates cross-border distribution into the domestic regulatory framework, offering a concrete policy alternative for future EPR system design.
This study systematically investigated the concentration-dependent effects of four metal oxides (Fe3O4, NiO, Al2O3, and CoO) on anaerobic fermentative biohydrogen production. Batch experiments were conducted using sucrose as the sole carbon source. All metal oxides exhibited Gaussian type–response patterns, indicating stimulation at low concentrations and inhibition at higher concentrations. These non-linear relationships were successfully quantified using a 3-parameter Gaussian model (R2≥0.79, p-value ≤ 0.0218). NiO showed the highest maximum cumulative hydrogen production (2629.30 mL/L) at an optimal concentration of 55.80 mg/L, followed by Fe3O4 (2194.34 mL/L), CoO (1876.57 mL/L), and Al2O3 (1696.82 mL/L). Gaussian-derived standard deviations indicated that NiO was the most concentration-sensitive, whereas Fe3O4 exhibited a broader tolerance range. Metabolite analysis revealed a strong positive correlation between hydrogen production and the butyric acid/acetic acid (B/A) ratio, reflecting a metabolic shift toward butyrate type fermentation. Enhanced hydrogen production was primarily observed in cultures dominated by anaerobic or facultative anaerobic bacteria such as Clostridium sp. or Klebsiella sp. which play a leading role in biological hydrogen production in the presence of NiO or Fe3O4. In contrast, cultures containing CoO and Al2O3 were characterized by the prevalence of the Enterobacteriaceae family, including Escherichia, Enterobacter, and Citrobacter. Overall, this study demonstrates that control of metal oxide type and dosage is critical for optimizing fermentative biohydrogen production.
This study applied a Bayesian Network (BN) model to identify the causal factors influencing the formation of trihalomethanes (THMs) during the chlorination process in water treatment plants. While conventional multiple linear regression (MLR) explains THMs concentrations based on linear correlations among variables, it is limited in representing probabilistic dependencies and directional relationships. In contrast, the BN approach allows probabilistic representation of dependencies and directional relationships through structural and parametric learning. Using twenty years (2003–2022) of operational data from the A Water Treatment Plant in the Han River basin, four structure learning algorithms—Hill-Climbing, Tabu Search, Grow–Shrink, and Max–Min Hill-Climbing (MMHC)—were compared. Tabu and MMHC yielded the best model fit (BIC=–1914.059). A consensus network combining common arcs across algorithms was constructed, and 500 bootstraps were performed to assess structural robustness. Edges satisfying strength ≥ 0.7 and direction ≥ 0.7 were retained, resulting in a double-robust causal network. The final DAG(Directed Acyclic Graph) identified O_IV (iodine number), O_Pre_CL (pre-chlorination dose rate), R_TEMP (temperature), T_pH(final treated water pH), and T_RCL (residual chlorine) as variables directly associated with THMs, while ammonia nitrogen of raw water(R_NH3) and COD of raw water(R_COD) acted as indirect (grandparent) nodes through O_Pre_CL and T_pH, respectively. Standardized coefficients (β) showed negative effects for O_IV (–0.449) and T_pH (–0.164), and positive effects for R_TEMP (+0.398), T_RCL (+0.153), and O_Pre_CL (+0.011). These results indicate that THMs formation is primarily governed by operational factors such as chlorine dosage, temperature, pH, and residual chlorine. The BN thus serves as a probabilistic causal model with both predictive accuracy and explanatory power, providing a theoretical foundation for data-driven decision-making in disinfection by-product control and process optimization in water treatment systems.
Nxumerous studies have investigated the formation mechanisms, influencing factors, and removal strategies of DBPs. However, most previous studies were based on laboratory-scale experiments or short-term data, which limited their ability to reflect actual water treatment plant (WTP) operating conditions and water quality variations, and thus failed to assess long-term effects. To address these limitations, this study analyzed 20 years of operational data from a full-scale WTP to evaluate the long-term impact of an advanced water treatment process (AWTP) on DBPs formation and removal Characteristics. Multiple linear regression (MLR) and interrupted time series (ITS) analyses were conducted to examine changes before and after AWTP implementation. Evaluation of individual unit processes revealed that the average removal efficiency of trihalomethanes (THMs) by granular activated carbon (GAC) was 17.2%, but it decreased sharply after 5-6 months due to breakthrough, while ozonation showed less than 5% removal efficiency under real operating conditions. The average THMs concentration decreased by approximately 28% (from 0.029mg/L to 0.021mg/L, p<0.001), indicating a statistically significant reduction. Furthermore, Hedges' g, MLR, and ITS analyses identified residual chlorine concentration and iodine number (an indicator of adsorption performance) as the most influential variables directly affected by AWTP implementation. These findings indicate that although the introduction of ozonation and GAC adsorption units significantly reduced THMs concentrations, the effect is largely attributable to the removal of THMs precursors (TOC) by GAC and the reduction of residual chlorine concentration—rather than direct THMs removal by ozonation or sustained adsorption performance of GAC.
To address the limitations of media-specific environmental management, Korea introduced the integrated Environmental Management System in 2017, with the pulp and paper industry designated in 2020 and integrated permitting process was completed in 2024. With the strengthening of global environmental regulations, such as the Carbon Border Adjustment Mechanism, the importance of greenhouse gas mitigation has increased; however, the dual regulatory structure that separately manages pollutants and greenhouse gases imposes burdens on industrial facilities. This study conducts a comparative analysis of best available techniques reference documents (BREFs) from Korea and the European Union (EU) to propose improvement directions tailored to the Korean pulp and paper industry. The analysis focuses on process classification systems, energy management approaches, BAT, and BAT-associated emission levels (BAT-AELs). The results show that the EU adopts a process-based structure and manages energy by distinguishing between thermal and electrical energy, whereas the Korean BREF employs a product-oriented integrated approach, limiting process-specific energy management. In addition, energy and greenhouse gas indicators are excluded from the current regulatory scope, resulting in a lack of quantitative performance levels for related BAT. To respond to carbon neutrality goals and global regulatory trends, it is necessary to expand the management scope to include energy and greenhouse gas indicators and to establish BAT for greenhouse gas mitigation.
As emission standards for fluorine compounds have become increasingly stringent in semiconductor and electronic component manufacturing facilities, and installation restrictions have been applied to facilities with large annual emissions, the importance of accurate quantification of fluorine compounds in industrial exhaust gases has increased. In particular, low concentrations of fluorine compounds in actual exhaust gases may fall below the calibration ranges specified in the standard test methods, requiring reliable quantification in these low-concentration ranges. The standard test methods of Korea specify ultraviolet-visible (UV/Vis) spectrophotometry and ion chromatography (IC) as analytical methods for fluorine compounds in exhaust gases. However, the quantification characteristics of these methods at low concentration levels that may occur in actual exhaust gases have not been sufficiently evaluated. In this study, the quantification characteristics of UV/Vis spectrophotometry and IC were compared at both the concentration ranges specified in the standard test methods and lower concentration levels. The coefficients of determination (R2) of repeated calibration curves and the agreement between nominal and calibrated concentrations were evaluated. Both methods demonstrated acceptable quantification performance within the concentration ranges specified in the standard test methods. However, at low concentration levels, UV/Vis spectrophotometry exhibited low R2 values and large discrepancies between nominal and calibrated concentrations. In contrast, IC showed relatively higher reproducibility and better agreement between nominal and calibrated concentrations. These findings suggest that IC may be more suitable than UV/Vis spectrophotometry for the analysis of low-concentration fluorine compounds.
This study evaluated the applicability of ferric chloride (FeCl3) as a coagulant for drinking water treatment using raw water from the lower Nakdong River and compared its performance with aluminum sulfate (alum). Jar-tests and pilot-scale experiments were conducted using raw water from the Maeri intake station. Water quality parameters including turbidity, total organic carbon (TOC), chlorophyll-a (Chl-a), color, alkalinity, and pH were monitored. Dissolved organic matter (DOM) fractions were characterized using LC-OCD, while disinfection by-product formation potentials (THMFP and HAAFP) were measured to assess the removal efficiency of organic precursors. The performance of a hybrid coagulant (alum mixed with FeCl3) was also investigated. Results showed that FeCl3 outperformed alum in removing turbidity, TOC, and Chl-a in both batch and continuous experiments. Notably, FeCl3 exhibited superior removal of humic substances (HS) and building blocks (BB) fractions, resulting in a more significant reduction in THMFP and HAAFP. Although the supernatant color increased initially with FeCl3 application, the filtered water color remained lower than that of alum, suggesting that residual color-causing agents were primarily particulate microflocs. Furthermore, FeCl3 effectively reduced the DOC load delivered to the subsequent granular activated carbon (GAC) process, enhancing overall treatment efficiency. FeCl3 is a promising alternative or supplement to alum for treating raw water with high organic and algal content, provided that alkalinity and pH are appropriately controlled during practical application.
The performance of a wet scrubber is influenced by ammonia loading associated with changes in swine barn ventilation rate and the timing of scrubbing water replacement; however, studies evaluating these factors under field-operating conditions remain limited. In this study, a water-based wet scrubber installed in a mechanically ventilated enclosed swine barn was evaluated under four ventilation fan operation rates, 30%, 50%, 70%, and 100%, simulating seasonal ventilation conditions. The basic performance, ammonia emission reduction efficiency, and changes in scrubbing water characteristics were assessed. Ammonia concentrations at the inlet and outlet air of the wet scrubber were continuously measured over 14 days for each condition, and ammonia emissions were calculated based on measured ventilation rates. As a result, the L/G ratio ranged from 0.72 to 2.23L/m³, which was within the recommended range reported in previous studies. The ammonia emission reduction efficiencies at exhaust fan operating rates of 30%, 50%, 70%, and 100% were 40.75%, 52.09%, 57.90%, and 60.58%, respectively. And the concentrations of ammonium nitrogen and electrical conductivity (EC) in the scrubbing water increased over the operation period, with the highest values observed under the 100% fan operation condition. Electrical conductivity showed potential as a practical indicator of scrubbing water condition, and its saturation indicates a reduced capacity for ammonia absorption. Based on the EC saturation observed on day 11 under the 100% fan operation condition, the replacement timing of scrubbing water for other fan operation rates was estimated. The results indicated that saturation would respectively occur after an additional 35, 37, and 9 days at exhaust fan operating rates of 30%, 50%, and 70% beyond the 14-day experimental period for the respective conditions. This study quantified the ammonia emission reduction performance of a wet scrubber under varying ventilation conditions based on ammonia emission rates and proposed a method for estimating scrubbing water replacement timing using EC saturation levels. These findings provided practical implications for decision-making in scrubbing water management to maintain wet scrubber performance under field conditions.
In modern climate, energy, and environmental fields, optimizing energy efficiency and utilizing renewable energy resources have become central challenges. However, the current Korean scientific and technological terminology system indiscriminately applies the suffix ‘ryeok (力)’ to energy (E) and power (P) — concepts with strictly distinct physical dimensions — thereby undermining dimensional transparency at the morpheme level and causing cognitive confusion in educational and practical settings. This review analyzes, from a comparative perspective, the technological terminology systems of Korea, China, and Japan, which belong to the major Sino-character cultural sphere of Northeast Asia, in order to diagnose the structural limitations of the ryeok (力)-based nomenclature system. It further proposes a complementary terminology system centered on neung (能, energy) for energy- and energy-source-related terms and on ilryul (率, rate) for energy-transfer-rate-related terms. Furthermore, to clarify the physical origin of energy, this review examines “haek-eneoji” (nuclear energy) and “haekneung” as complementary terms for “wonjaryeok” (nuclear power), and introduces “jeongi-ilryul” and its abbreviated form “jeonilryul” as complementary terms for “jeonryeok” (electric power), thereby enhancing conceptual consistency between the mechanical and electrical domains. Rather than advocating for the immediate abolition of established standards, this review explores the possibility of using dimensionally transparent alternative names in parallel, aiming to secure educational clarity suitable for the era of energy transition and enhance the efficiency of scientific communication.
Livestock manure wastewater is a representative high-strength wastewater characterized by high concentrations of organic matter and ammonia, which can hinder stable biological treatment and nitrification. In this study, an immersed membrane bioreactor (MBR) equipped with an end-free hollow fiber membrane was operated to evaluate the effects of mixed liquor suspended solids (MLSS) concentration on nitrification and membrane filtration performance during livestock manure wastewater treatment. The influent wastewater had average concentrations of pH 8.6, CODcr 24,476 mg/L, T-N 2,593mg/L, NH3-N 1,979 mg/L, TS 21,851 mg/L, and TSS 12,519mg/L. The reactor was operated by stepwise increases in MLSS from approximately 4,050 to 18,872 mg/L. As MLSS increased, nitrification efficiency improved from 7.7% at 4,050mg/L to 70.3% at 15,828 mg/L, but slightly decreased to 66.2% at 18,872mg/L. This result indicates that increasing biomass concentration promoted nitrifier retention and nitrification, whereas excessively high MLSS likely limited oxygen transfer and reduced nitrification performance. Transmembrane pressure (TMP) increased gradually with increasing MLSS, and a marked acceleration in the rise of TMP was observed above approximately 15,000mg/L, indicating intensified membrane fouling under high-solids conditions. Under the MLSS condition of about 15,000 mg/L, the TMP increase rate of the end-free hollow fiber membrane was 0.05 kPa/d, which was lower than those reported at comparable operating points in previous MBR studies. These results suggest that an MLSS level of approximately 15,000mg/L can be considered an appropriate operating condition for balancing nitrification efficiency and membrane filtration stability, and that the end-free hollow fiber configuration may provide a useful structural option for mitigating fouling in high-strength livestock manure wastewater treatment.
This study investigated the concentration levels of PAHs emitted from the emission sources and the distribution characteristics between each measurement point and the site boundary and point of impact, with three Ascon manufacturing facilities in Busan as target facilities. Analysis of 16 PAH congeners designated by the US EPA revealed that the total PAH concentrations across the three Ascon manufacturing facilities ranged from 119.7 to 12,450.2μg/Sm3, with the observed variation attributed to differences in the type of fuel combusted in the aggregate drying units and the efficiency of air pollution control devices at each facility. For benzo(a)pyrene, where the air emissions acceptance criteria are applied from January 2020, the concentration level was 0.2 to 0.9μg/Sm3, which is lower than the emission acceptance standard of 50μg/Sm3. In addition, the concentration ratio of PAHs in the gas phase and particle phase was examined to be 1.5 to 2.5 times higher in the gas phase. According to the survey of PAHs in the atmosphere around the emission facilities, the concentration of PAHs in the atmosphere was not significantly different when the Ascon manufacturing facilities was in operation and in non-operation, but more detailed research is expected in the future because the climate conditions, wind direction and wind speed were not considered during air sampling. It was found that the concentration of PAHs on the gas rather than on particles at the site boundary point was higher, and the difference between the site boundary of the emission source and the point of influence was not significant. In addition, a survey of the distribution of PAHs by substance showed that unlike the emission sources, the characteristics of PAHs at the surrounding and affected points were mainly high in the case of PAHs in the gas phase, with many congeners present in the case of particle phase PAHs. The CALPUFF model was used to identify the impact of three Ascon manufacturing facilities on the surrounding areas on the surrounding areas. The modeling scenario was carried out by inputting the emission of point pollutants by major emission sources calculated above for February, when the highest concentration of exhaust was shown. In all facilities, the correlation coefficient with the actual measurement was found to be 0.9 (p<0.001) relatively high. Therefore, using the modeling results, it is considered reasonable to analyze the effect of PAH in the emission sources on the surrounding areas. After each PAH emission from the Ascon manufacturing facilities being considered in this study was calculated and the CALPUFF modelling by individual material was performed and the equivalent concentration of benzo(a)pyrene by grid was analyzed, and it was found that some areas affected the surrounding area according to the wind direction conditions. These results indicate that some areas around Ascon manufacturing facilities may be affected by PAH emissions under certain wind conditions, with BaPeq concentrations exceeding the UK guideline of 0.25 ng/m3.
In November 2025, our government announced the 2035 National Greenhouse Gas Reduction Target (NDC). This target sets a very challenging goal: a 53% to 61% reduction in 2035, depending on the industrial sector, compared to net emissions in 2018. As a follow-up measure to achieve this goal, the government plans to establish the “Korea Green Transformation (K-GX),” which includes detailed tasks for fostering green industries such as solar power and energy storage systems (ESS), in collaboration with relevant ministries and industries in the first half of 2026. In particular, this reduction target includes a 34% reduction in international emissions, necessitating systematic support alongside government-level efforts to reduce overseas greenhouse gas emissions. In this context, we will examine the environmental and climate change policies of Ghana, an African country with the most well-established institutional and administrative framework for implementing greenhouse gas reduction projects under Article 6 of the Paris Agreement, and explore opportunities for Korean companies to explore the country. The Ghanaian government has established a more systematic system than any other developing African country to manage and support the project discovery, registration, and other aspects of greenhouse gas reduction projects undertaken by developed countries in accordance with Article 6 of the Paris Agreement. This well-established system has resulted in rapid results, with carbon credit trading generating revenues reaching $800 million. By analyzing these successful cases in developed countries and Ghana's administrative system, potential opportunities for mutual cooperation can be explored. Through an analysis of the Ghanaian government’s greenhouse gas reduction policy in accordance with the Paris Agreement, we aim to establish a strong mutual cooperation and strategic policy measures between the Korean government and Korean companies with the Ghanaian government and other developing countries to achieve the Korean government’s 2035 NDC international reduction goals.
Polylactic acid (PLA) is a biodegradable plastic widely used as an alternative to conventional plastics due to its high biodegradability; however, when treated by anaerobic digestion, PLA waste exhibits limited degradation and energy recovery efficiency. Therefore, this study evaluated the anaerobic co-digestion of PLA waste with food waste (FW) or waste activated sludge (WAS) to enhance energy recovery from PLA waste. Batch experiments were conducted under mesophilic conditions, and methane production characteristics, methane yields, and synergistic effects were compared between mono-digestion and co-digestion systems. The significance of synergistic effects was evaluated using analysis of variance (ANOVA). The mono-digestion results showed that methane yield and methane production rate followed the order of FW, WAS, and PLA waste. In PLA–FW co-digestion, methane yield decreased with increasing PLA fraction; however, synergistic effects ranging from 16.2% to 21.9% were observed. In contrast, PLA–WAS co-digestion exhibited a similar decreasing trend in methane yield with increasing PLA fraction, but no consistent pattern in synergistic effects was observed with respect to the mixing ratio. One-way ANOVA indicated that differences in synergistic effects among mixing ratios were observed under the FW added conditions, whereas no significant differences were found under the WAS added conditions. Two-way ANOVA with replication further revealed that synergistic effects differed significantly depending on substrate type, while the overall main effect of mixing ratio was not significant (p>0.05). These results quantitatively demonstrate that food waste acts as a more effective co-substrate than waste activated sludge in the anaerobic co-digestion of PLA waste and suggest that co-digestion performance strongly depends on the degradation kinetics of the combined substrates.
Optimal conditions for turbidity removal from synthetic wastewater were investigated using a mixed plant-based coagulant. Synthetic wastewater was prepared by suspending kaolin powder in distilled water and adjusting the final turbidity to 500 NTU. The mixed coagulant was prepared by extracting Clerodendrum powders and cactus powders in a 0.5mol/L NaCl solution followed by filtration. The experimental ranges of the key factors were pH 3-8, coagulant dosage 30-120mg/L, and cactus ratio 30-90%. A face-centered response surface design was employed to evaluate factor interactions and to determine the optimal conditions. In the single-factor experiments, the highest turbidity removal efficiency (96%) was obtained at pH 3, and the efficiency progressively decreased with increasing pH. The maximum removal efficiency was 84% at 90mg/L of dosage and 78% at 50% of cactus ratio. In the response surface analysis, all independent variables significantly influenced turbidity removal (p< 0.05), with pH (p<0.001) and dosage (p<0.001) exerting stronger effects than the cactus ratio (p=0.006). Significant two-way interactions were observed for pH × dosage (p=0.005) and pH × cactus ratio (p=0.006). The response surface model (R2=0.93) predicted optimal conditions of pH 3.0, dosage 75 mg/L, and cactus ratio 65%, yielding a predicted turbidity removal efficiency exceeding 99.9%. These findings demonstrate that Clerodendrum (charge neutralization) and cactus (bridging effect) act synergistically, providing enhanced turbidity removal performance and overcoming the limitations of single plant-based coagulants.
