Water scarcity resulting from industrialization and population growth has increased the demand for advanced wastewater reuse technologies. Microfiltration (MF) systems are widely used due to their ability to effectively remove suspended solids and microorganisms, making them suitable for water reclamation processes. This study aimed to optimize the operational parameters of an MF system and evaluate the effectiveness of various chemical cleaning strategies to maintain long-term performance and membrane integrity. Pilot-scale experiments were conducted to examine the effects of different backwash flow rates and filtration times on membrane fouling and recovery rates. The system's performance was monitored using total membrane pressure (TMP) as a key indicator. When the backwash flow rate was reduced from 6.8 m³/h to 6.2 m³/h, the recovery rate increased from 91.1% to 91.8%, with a minimal TMP rise from 0.246 to 0.255 kg/cm². Extending the filtration time from 1,200 to 1,800 s resulted in a recovery rate of 93.9%, although the TMP significantly increased to 0.400 kg/cm², indicating a greater fouling risk. Chemical cleaning tests comparing maintenance cleaning and short-term cleaning revealed that periodic maintenance using a combination of sodium hypochlorite (NaOCl) and oxalic acid was the most effective method, achieving a TMP recovery rate of 90%. These results emphasize the importance of striking a balance between operational settings and chemical treatment to minimize membrane fouling while maintaining recovery efficiency. This study offers essential data to support the design and operation of MF systems in wastewater reuse applications, contributing to more sustainable and cost-effective membrane treatment processes.

This study evaluates a hybrid electro-oxidation-adsorption process for chlorate removal in wastewater treatment. Using a specialized reactor, we investigated the influence of operational parameters including current density, reaction time, granular activated carbon (GAC) dosage, electrode spacing, and pH. Optimal removal efficiency of 82.40 % was achieved under the following conditions: 75 A/m² current density, 5 min reaction time, 20 g/L GAC dosage, 2 cm electrode spacing, and a pH of 2. This method outperforms traditional adsorption and electrochemical oxidation, offering a promising solution for reducing chlorate-related environmental impacts.

Water scarcity resulting from industrialization and population growth has increased the demand for advanced wastewater reuse technologies. Microfiltration (MF) systems are widely used due to their ability to effectively remove suspended solids and microorganisms, making them suitable for water reclamation processes. This study aimed to optimize the operational parameters of an MF system and evaluate the effectiveness of various chemical cleaning strategies to maintain long-term performance and membrane integrity. Pilot-scale experiments were conducted to examine the effects of different backwash flow rates and filtration times on membrane fouling and recovery rates. The system's performance was monitored using total membrane pressure (TMP) as a key indicator. When the backwash flow rate was reduced from 6.8 m³/h to 6.2 m³/h, the recovery rate increased from 91.1% to 91.8%, with a minimal TMP rise from 0.246 to 0.255 kg/cm². Extending the filtration time from 1,200 to 1,800 s resulted in a recovery rate of 93.9%, although the TMP significantly increased to 0.400 kg/cm², indicating a greater fouling risk. Chemical cleaning tests comparing maintenance cleaning and short-term cleaning revealed that periodic maintenance using a combination of sodium hypochlorite (NaOCl) and oxalic acid was the most effective method, achieving a TMP recovery rate of 90%. These results emphasize the importance of striking a balance between operational settings and chemical treatment to minimize membrane fouling while maintaining recovery efficiency. This study offers essential data to support the design and operation of MF systems in wastewater reuse applications, contributing to more sustainable and cost-effective membrane treatment processes.

This study evaluates a hybrid electro-oxidation-adsorption process for chlorate removal in wastewater treatment. Using a specialized reactor, we investigated the influence of operational parameters including current density, reaction time, granular activated carbon (GAC) dosage, electrode spacing, and pH. Optimal removal efficiency of 82.40 % was achieved under the following conditions: 75 A/m² current density, 5 min reaction time, 20 g/L GAC dosage, 2 cm electrode spacing, and a pH of 2. This method outperforms traditional adsorption and electrochemical oxidation, offering a promising solution for reducing chlorate-related environmental impacts.

The production of cheese generates copious wastewater with very high organic load, which requires a series of treatments prior to discharge. In this study, protein was ultrasonically treated and then recovered from cheese wastewater using isoelectric precipitation. After initial ultrasonic treatment with an ultrasonic energy of 1,800 kJ/L, the protein could be effectively precipitated at pH = 4.5, and about (67.7 ± 0.5) % of the protein was separated out. Because the chemical oxygen demand (COD) load remained high, the supernatant was treated by flocculation and coagulation. Treatment using polyferric sulfate (PFS) coagulation of 200 mg/L and nonionic polyacrylamide (PAM) flocculation of 4 mg/L reduced the turbidity by (98.6 ± 0.4)%, and COD by (89.2 ± 0.9)%.

본 연구는 글로벌 ESG 규제 강화가 국내 제조업의 근간인 뿌리산업과 그 전후방 공급망에 미치는 비대칭적 영향을 ESG 양극화 현상으로 규정하고 , 이로 인해 발생하는 공급망의 이중 리스크를 실증적으로 분석하고자 하였다 . 이를 위해 K-ESG 가이드라인 v2.0을 기반으로 대기업 , 최상위 뿌리기업 , 일반 뿌리기업 세 그룹의 3년간 (2021-2023) 환경 (E) 성과를 비교 분석하였다 . 분석 결과 , 그룹 간 환경경영 성과는 통계적으로 유의미한 계층 구조를 보였으며 , 이 격차는 시간이 지남에 따라 심화되는 양극화 양상이 뚜렷하게 나 타났다 . 특히 , 격차는 법규 준수와 연관된 운영적 항목보다 , 기후변화 대응 등 미래 경쟁력과 직결된 전략적 항목에서 더욱 두드러졌다 . 이러한 격차 심화 과정에서 각 그룹은 각각 선도자 , 추격자 , 정체 그룹이라는 뚜렷이 구분되는 동태적 변화 경로를 보였다 . 본 연구는 실증적 분석을 통해 이러한 ESG 역량 격차가 방치될 경우 공급망 단절 또는 경쟁력 동반 하락 이라는 이중 리스크를 야기하여 국내 제조업의 기반인 뿌리산업 공급망의 안정성을 위협할 수 있음을 시사한다 . 이를 바탕으로 각 그룹 (선도자 -추격자 -정체 )의 특성에 맞는 정부의 차별화된 지원방안과 기업의 단계적 ESG 도입 전략을 구체적으로 제언하고자 한다.

호기성 입상슬러지(Aerobic Granular Sludge, AGS)는 우수한 침강성, 높은 미생물 농도 유지, 다양한 오염물질의 동시 제거 능력으로 활성슬러지 공정의 대안으로 주목받고 있다. 그러나 입상화 속도, 구조적 안정성, 탈질 성능 확보 등 산업적 적용에는 여전히 기술적 과제가 존재한다. 본 연구는 실험실 규모의 AGS-SBR(Sequencing Batch Reactor) 반응조를 이용하여 총 4단계에 걸쳐 Feast/Famine 비율, 초기 MLSS 농도(500~2,500 mg/L), 교반 조건, 기포 크기, 침전시간(5~20 분), 유입시간(5~40 분), 응집제 투입 등의 운전 인자를 변화시키며 AGS 형성과 탈질 성능 간의 상호작용을 분석하였다. 유입 COD 300 mg/L 조건에서 HRT 4 h, MLSS 2,500 mg/L가 AGS의 안정적 성장을 유도하였으며, 평균 입자 크기는 약 546 μm로 확인되었다. 과도한 Famine 조건에서는 슬러지 유실이 발생하였다. 응집제 주입은 짧은 침전시간 조건에서도 입상화 및 침강성 향상에 기여하였으나, 탈질 효율 개선에는 한계가 있었다. 특히 초기 MLSS가 500 mg/L일 때 호기 시작 후 충분한 양의 유기물이 잔존하여 NO3-N이 5 mg/L 이하로 유지되며 안정적인 동시 탈질이 가능하였다. 반면 MLSS 2,000 mg/L 조건에서는 유기물이 급속히 소모되어 탈질 반응이 제한되었다. 본 연구는 AGS의 물리적 형성만으로는 탈질 성능 확보가 어려우며, 호기 시작 시점의 유기물 가용성 확보가 핵심임을 시사한다. 단일 인자 최적화보다는 운전 인자 간의 통합적 관리가 AGS-SBR 공정의 성능 개선에 필수적이며, 향후 실제 하수 조건을 반영한 장기 실험이 필요하다.

This study aims to optimize the biological treatment of wastewater containing tetramethylammonium hydroxide (TMAH), a toxic and poorly biodegradable compound widely used in semiconductor manufacturing. A two-stage pilot-scale treatment system was developed and evaluated. In the first stage, aerobic treatment was applied to convert TMAH into ammonium (NH4+), and the effect of hydraulic retention time (HRT) was examined at 2.0, 2.5, and 3.3 days. The corresponding TMAH conversion rates were 71%, 84%, and 94%, respectively, indicating improved conversion efficiency with longer HRT. In the second stage, the effluent from the aerobic TMAH treatment was mixed with organic wastewater at ratios of 10%, 20%, and 30% and subjected to an anoxic/oxic (A/O) biological treatment. Total nitrogen (T-N) removal efficiencies remained above 87% across all ratios. These findings indicated that most of the toxicity associated with TMAH was alleviated during the aerobic stage, allowing stable nitrogen removal in the second stage. Overall, this study demonstrates that a two-stage biological treatment combining aerobic conversion and A/O processes is effective for treating TMAH-containing nitrogenous wastewater and provides practical guidance for designing and operating treatment systems in the semiconductor industry.

To raise the physical strength of alginate beads, this study manufactured alginate-cellulose bead by adding cellulose to alginate, and wanted to identify whether falginate-cellulose beads were sufficiently efficient in removing heavy metals. To find out optimal amounts of alginate and cellulose injection, this study conducted a pilot study, and repeated experiments proved that alginate 2 w/v% + cellulose 1 w/v% were the optimal amounts in manufacturing beads. Using micro materials tester, this study compared strengths of alginate beads and alginate-cellulose beads. Choosing Cd 2+ , Pb 2+ , and Ni 2+ as materials to be removed, this study analyzed concentrations of them before and after the treatment. Experiments showed that, compared with alginate beads, the strength of alginate-cellulose beads was 2.26 times stronger, and that the latter could remove 98.22%, 99.99%, and 92.57% of Cd 2+ , Pb 2+ , Ni 2+ , respectively. While addition of cellulose to alginate made the absorption rate drop by about 1%, the beads were still highly efficient in removing heavy metals. Accordingly, it seems that alginate-cellulose beads can be used in removing heavy metals.

This study analyzed the oxidation efficiency of dissolved ozone by applying different bubble sizes in relation to the transfer rate of ozone, which is a major influencing factor for the treatment efficiency of the ozone oxidation process. Air bubbles were injected into tap water to measure the oxygen mass transfer coefficient (KLa) and dissolved oxygen (DO) concentration. The dissolved ozone concentration was measured by injecting ozone bubbles into tap water. Oxidation efficiency was analyzed by injecting ozone bubbles of macro (3.7 mm), micro (44 μm), and nano (840 nm) sizes into soapy water and ink-mixed water. The smaller the bubbles, the higher the KLa, and concentrations of DO and dissolved ozone. When nano bubbles were injected, the total organic carbon (TOC) and color removal efficiencies were found to be the best at 41.7% and 90.1%, respectively. The results confirmed that for the same bubble volume concentration (BVC), the smaller the bubble, the better the material transfer and pollutant removal rates. In the case of nano bubbles, as the reaction tank grows, a stirrer device is required to confirm the mass transfer rate.

Abstract Despite numerous urban pollution sources, research on aquatic species bioaccumulation in the Han River is scarce. In this longitudinal study, we assessed baseline heavy metal (HM) concentrations in Cyprinidae, a major freshwater fish family in the Han River. Specifically, were evaluated copper (Cu), total mercury (THg), cadmium (Cd), lead (Pb), and chromium (Cr) levels in the muscle of common carp, crucian carp, and barbel steed. Common carp had the highest HM accumulation, with baseline concentrations of Cu, THg, Cd, Pb, and Cr at 0.877, 0.060, 0.003, 0.032, and 0.178 mg/kg, respectively. Larger fish exhibited greater bioaccumulation, with THg levels significantly correlated with fish length (correlation coefficients: 0.57 (p < 0.05)–0.74 (p < 0.001)). Notably, Cr accumulated more extensively in fish muscle than Pb, and the metal selectivity index (MSI) of THg in barbel steed was 2–3 times higher than in other fish species. The baseline concentrations determined in this study can serve as identifiers of the initial point of abnormal HM bioaccumulation in fish and provide foundational data for future long- or short-term fish monitoring.