생태융합환경공학연구실

A concentration-dependent dosing framework was developed for calcium polysulfide (CPS)-mediated immobi lization of cadmium (Cd) and zinc (Zn) in acidic, smelting-impacted groundwater. Batch experiments were conducted using three groundwater samples representing low, intermediate, and high Cd and Zn concentrations. The effects of initial metal loading on CPS demand, sulfide supersaturation, metal removal, precipitate forma tion, and immobilization stability were evaluated using geochemical interpretation, mass balance, and extraction analysis. Dosing with CPS rapidly transitioned aqueous chemistry from oxidizing to reducing, sulfide-favorable conditions. However, substantial Cd and Zn precipitation occurred only after the metal-sulfide ion activity product exceeded the solubility threshold, defining a critical CPS dosage threshold (C optimal CPS dosage (C CPS,Opt CPS,Cri ). A slightly greater ) promoted sustained precipitation and reduced metal extractability. As the initial metal concentration increased, the optimal CPS-to-metal mass ratio decreased markedly from 15.9 to 1.46 for Cd and from 5.33 to 2.47 for Zn, indicating greater CPS utilization efficiency at higher metal loadings. Solid-phase characterization by SEM-EDS, TEM-EDS, XRD, and XPS identified crystalline ZnS (s) , elemental sulfur, and Ca- bearing gypsum. Although crystalline CdS (s) was not resolved by XRD, Cd immobilization was evidenced by up to 99.7% aqueous Cd removal. Overall, the extractable metal fraction decreased with increasing initial metal concentration, indicating that immobilization stability depended on both CPS stoichiometry and supersaturation- controlled nucleation and precipitate growth. These findings demonstrate that CPS dosage should be based on both metal loading and site-specific geochemical demand rather than only stoichiometric sulfide requirements.

Antibiotic- resistant bacteria (ARB) and antibiotic resistance genes (ARGs) persist in wastewater as chemically stable contami nants that evade conventional treatment, driving a global health crisis. Photocatalysis offers a promising route to simultaneously inactivate ARB and degrade ARGs. However, its practical implementation stays hindered by fundamental gaps in understanding how material interfaces control their fate. This review critically analyzes the interfacial battlefield, where surface chemistry, charge dynamics, and nanoconfinement determine the efficiency and mechanism of resistance destruction. We establish a quan titative reaction–diffusion framework that reveals why photocatalytic degradation is governed not by bulk- phase kinetics but by coupled transport–adsorption–reaction processes at the nanoscale interface. Through Damköhler analysis, we demonstrate that short- lived reactive oxygen species (ROS, ●OH diffusion < 10 nm) impose transport- limited regimes where adsorption and nano confinement become as critical as charge separation. We evaluate the dual target challenge: ARB as complex, multi- layered cellu lar structures requiring membrane disruption, and ARGs as persistent polyelectrolytes demanding complete mineralization. By examining how ROS with distinct lifetimes and diffusion distances operate at material interfaces, we establish that adsorption and nanoconfinement are as critical as charge separation. The review synthesizes recent advances in doping, heterojunction engineering (Z- scheme, S- scheme), defect creation, and carbon- based mediators through the cohesive perspective of interfacial design. Key gaps include unverified eARG mineralization, matrix scavenging, catalyst fouling and regeneration, biofilm and dormant cell formation after sublethal treatment, and insufficient life assessment. A roadmap is proposed toward selective, re generable, matrix- tolerant and sustainability guided photocatalytic systems for antibiotic- resistance control.

Per- and polyfluoroalkyl substances (PFAS) pollution in South Korean water systems is emerging environmental and public health concern, yet nationwide assessments remain limited. This review systematic evaluates PFAS occurrence across South Korea's primary water bodies and wastewater treatment plants (WWTPs), integrating historical and recent datasets from 49 facilities. Surface water monitoring (2004-2006) revealed widespread contamination, with 1.3-45.2 ng/L for PFOS and 2.9-19.7 ng/L for PFOA, particularly in the Hangang and Nakdonggang rivers, where downstream gradients reached ~40 ng/L (PFOA) and 38-59 ng/L (PFOS). Temporal analysis demonstrated a compositional shift from legacy long-chain PFAS (2006) to short-chain alternatives (2023-2024), reflecting regulatory-driven industrial transitions. WWTP analysis (2010) revealed industrial facilities consistently exceeded domestic counterparts, with PFOS reaching 829.44 ± 1837.41 ng/L in electronics manufacturing, of which data, collected in 2010, may not fully reflect the current situation. Conventional treatment proved ineffective, as effluent concentrations being 84-191% of influent levels. Current South Korean guidelines list only some PFAS as monitoring substances, with outdated values (70 ng/L for PFOA and PFOS) compared to stricter global standards. These findings highlight widespread PFAS detection and a critical regulatory gap, underscoring the urgent need for enforceable standards and advanced treatment technologies to support effective PFAS management.

싱크홀은 도시 지반의 국부적 붕괴로 인명 및 사회ㆍ경제적 피해를 초래할 수 있으며, 특히 노후 하수관거 결함에 따른 누수는 내부침식과 공동 발달을 유발하여 지반 함몰로 이어질 수 있다. 본 연구에서는 하수관거 결함부 누수에 따른 토사 유실, 공동 발달 및 지반침하 거동을 실내 모형 실험을 통해 재현하고, 지오셀–지오텍스타일 복합 보강재(지오컴포지트)의 적용 위치에 따른 싱크홀 위험 저감 효과를 평가하였다. 실험은 무보강 조건, 하부 보강 조건, 상ㆍ하부 보강 조건으로 구분하였으며, 토사손실량과 침하율을 주요 지표로 하여 보강 조건별 지반 거동을 비교하였다. 무보강 조건에서는 누수 직후 결함부 주변으로 유동이 집중되면서 세립분 유출과 파이핑이 발생하였고, 공동이 빠르게 확대되어 급격한 붕괴형 침하로 이어졌다. 이 조건에서 누적 토사손실량은 약 14.5 kg, 최종 침하율은 약 67.33%로 나타났다. 반면, 지오셀–지오텍스타일 복합 보강재를 적용한 조건에서는 토립자 유실이 거의 발생하지 않았으며, 공동 발달과 국부 붕괴가 효과적으로 억제되었다. 특히 상ㆍ하부 보강 조건에서는 보강층의 여과, 유동 분산 및 구속 효과가 복합적으로 작용하여 붕괴 징후 없이 비교적 안정적인 소규모 균등침하 거동을 보였다. 본 연구 결과는 지오셀–지오텍스타일 복합 보강재가 하수관거 누수로 인한 토사 유실과 공동 발달을 저감하고, 급격한 지반 함몰을 완화하는 데 효과적인 보강 방안이 될 수 있음을 보여준다.

This study investigated the inhibition potential and repeated-use stability of a functional zeolite medium in which quaternary ammonium compounds (QACs) were immobilized on the zeolite surface through a Sol-Gel process. The prepared QACs-coated Zeolite was applied to Microcystis aeruginosa (M. aeruginosa) under laboratory-scale conditions, and its performance was evaluated based on visual changes, chlorophyll-a (Chl-a), phycocyanin (PC), pH, pseudo-first-order decay constants (k), surface characterization (SEM, EDS, and FT-IR), TOC-based leaching assessment, and microcystin analysis. The results showed that the QACs-coated Zeolite treatment promoted visible discoloration of the suspension. Compared with uncoated zeolite and sodium silicate-coated zeolite, the QACs-coated Zeolite induced greater reductions in both Chl-a and PC, with PC showing a more sensitive response. The pseudo-first-order decay analysis also indicated that the apparent pigment decay rate increased with increasing QACs coating concentration. In repeated-use experiments using the same medium for three consecutive cycles, similar trends were maintained, suggesting that the material retained a certain level of reactivity under repeated-use conditions. SEM, EDS, and FT-IR analyses suggested the formation of an organic-inorganic composite coating layer on the zeolite surface. TOC-based indirect estimation showed that Sol-Gel-coated samples exhibited lower leaching tendencies than the simply impregnated sample, implying that the Sol-Gel network may suppress the release of QACs into water to some extent. In addition, six major microcystin congeners were below the detection limit in all treatment conditions. Overall, the QACs-coated Zeolite showed the potential to induce pigment reduction, flocculation, and sedimentation of M. aeruginosa, while maintaining a certain degree of reactivity during repeated use. The Sol-Gel immobilization approach also appeared advantageous over simple impregnation in terms of leaching stability. However, because this study mainly relied on pigment-based indicators and qualitative observations, further studies are needed to evaluate cell viability, toxin partitioning, direct QACs quantification, ecotoxicological safety, and field-scale applicability.

This study investigated the mineral carbonation and neutralization behavior of red mud (RM) using CO₂ microbubbles (CO₂ MBs) under ambient temperature and pressure conditions, and further assessed the feasibility of utilizing carbonated RM as a cement substitute. Batch experiments were conducted at various solid-to-liquid ratios (S/L = 0.001–1.0), monitoring pH, electrical conductivity (EC), and aqueous carbonic acid (H₂CO₃(_aq)) concentrations. In the RM–CO₂ MBs system, pH initially dropped sharply and then recovered to the buffering zone (pH 7–8.5), while EC exhibited a rapid rise followed by gradual decline, indicating sequential ion release and carbonate precipitation. The H₂CO₃(_aq) concentration decreased over time due to both carbonation consumption and pH-induced speciation shift. In continuous experiments (reactor dimensions: D = 14.6 cm, H = 34 cm, S/L = 0.025), both powdered (RM-P) and sludge-type (RM-S) samples achieved neutralization (pH = 7) within 4 minutes, accompanied by a characteristic EC decrease–rebound pattern. The total inorganic carbon (TIC)-based CO₂ uptake of RM-S reached 8.87 g-CO₂/kg-RM, corresponding to approximately 84% of the theoretical maximum carbonation potential (TMCP). Mortar specimens incorporating carbonated RM as a partial cement replacement (0–15 wt%) exhibited decreasing compressive strength with increasing substitution ratio, yet 5 wt% replacement maintained adequate strength for non-structural construction materials. These results demonstrate that CO₂ MBs enable rapid (≤2 min), high-efficiency carbonation and neutralization of RM under ambient conditions without pressurized systems. The proposed process provides a low-energy, environmentally friendly pathway for simultaneous CO₂ sequestration and red mud valorization, contributing to sustainable carbon-neutral technology.