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.

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.

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.

Abstract Wastewater treatment plants face the challenge of controlling disinfection by-products, such as carcinogenic trihalomethanes, which are formed when disinfectants react with organic compounds and humic substances in water sources. To ensure the prevention of water pollution, effective control measures must be implemented to mitigate the release of these harmful by-products into water bodies. This study focused on the application of an electrooxidation-adsorption hybrid process for the treatment of chlorate, a prevalent disinfection by-product found in sewage plant effluent. The investigation aimed to evaluate the impact of various parameters including current density, empty bed contact time (EBCT), granular activated carbon (GAC) injection amount, electrode installation spacing, and pH on the treatment efficiency. Optimal operating conditions were determined, including a current density of 75 A/m2 , an EBCT of 5 minutes, a GAC injection amount of 2.0 w/v (%), an electrode installation spacing of 2 cm, and a pH of 2. These conditions demonstrated effective removal of disinfection by-products, even in the presence of coexisting pollutants. The findings highlight the viability of the electrooxidation-adsorption process as a promising approach for the treatment of disinfection by-products in sewage treatment plant effluent. This research contributes to the development of efficient strategies for mitigating the environmental impact of wastewater treatment processes and ensuring the protection of public water resources.

Objectives : By eliminating fluorine and other ions through precipitation of fluoride and UF, RO membrane filtration using the hydrofluoric acid wastewater generated from the semiconductor production processes, this study aimed to investigate the possibility of the reuse of the reclaimed wastewater for the processes.Methods : For the experiment, firstly, the 2-stage precipitation of fluoride was done using Ca(OH)2 and PAC and it aimed to judge whether the water quality standards for reuse by each market were satisfied by eliminating colloidal particles and then other metal ions through the UF and RO membrane filtration.Results and Discussion : About 93 % of F- was removed through the 1st and 2nd precipitation. It can be also removed ammonium, phosphate ions, through the UF membrane filtration, about 95 % of particulate matter was removed and finally, the water quality for reuse was satisfied through RO filtration.Conclusion : This study found that the fluorine wastewater generated from the semiconductor production processes can be reused by precipitation and filtration methods without going through the existing complicated treatment methods. In the future, through such treatment procedures, it is expected to be able to secure the reuse of the reclaimed wastewater in the process.

Objectives : Recently, the Fourth Industrial Revolution has been actively discussed in all fields around the world. And the related R&D(Research and Development) has been widely conducted in the environmental field. The core of the Fourth Industrial Revolution is hyperconnectivity, superintelligence, and convergence. Major technologies related with it are AI(Artificial Intelligence), IoT(Internet of Things), 5G(Fifth Generation communication technology), robots, blockchain, drones, 3D(Three Dimension) printers, big data, unmanned transportation, biotechnology, new materials, sharing economy, and VR/AR(Virtual Reality/Augmented Reality), etc. It is intended to seek development plans through the examples of the 4th industrial revolution technology’s environmental application.Methods : In concentration of the public technology development project, based on environmental policy, conducted from 2011 to 2020, some cases of the 4th industrial revolution technology’s environmental application have been analyzed and the future prospects have been derived.Results and Discussion : The 4th Industrial Revolution technology has been applied in various fields such as design, operation, maintenance, investigation, monitoring, and service provision in the environmental field. Therefore, in the future, it is expected that there will be working environment improvement, the progress of service quality and operational efficiency.Conclusion : With the transition to smart environmental technology, it is expected that it will be possible to advance the industry and create high value-added things. To do so, government policy support and technology development should be continuously executed.

Objectives : The purpose of this study is to analyze the environmental assessment through the LCA(Life Cycle Assessment) method targeting the bottled water products with the largest distribution proportion in the domestic beverage product in South Korea. In other words, by quantitatively evaluating greenhouse gas emissions and major environmental indicators during the entire life cycle of bottled water products, it is intended to be helpful in product environmental improvement measures by deriving applicable alternatives.Methods : Assessment method of the greenhouse gas emissions and major environmental indicators followed “Guidelines for Environmental Product Declaration of Products” in South Korea. In this study, Carbon footprint and other major environmental indicators(Resource footprint, Ozone depletion, Acidification, Eutrophication, Photochemical smog, Water footprint) of bottled water product were calculated. The life cycle assessment for bottled water products was considered for the Pre-manufacturing, Manufacturing, Distribution and End of life, and Use stage was excluded.Results and Discussion : As a result of analyzing Carbon footprint and other major environmental indicators, Carbon footprint of 500 ml of bottled water is 8.28E-02 kg CO<sub>2</sub> -eq./unit, Resource footprint(RF) is 2.34E-03 kg Sb-eq./unit, ozone depletion(OD) is 3.25E-05 kg CFC-11-eq./unit, Acidification(AF) is 3.81E-04 kg SO<sub>2</sub>-eq/unit eutrophication(EP) is 6.64E-05 kg PO<sub>4</sub><sup>3</sup>-eq./unit, photochemical smog(PS) is 6.85E-04 kg C<sub>2</sub>H<sub>4</sub>-eq./unit, Water footprint(WF) was evaluated as 1.19E-03 m<sup>3</sup> H<sub>2</sub>O-eq./unit.Conclusion : It was identified that the PET bottle manufacturing process occupies the highest environmental impact in RF, CF, AF, EP and PS. The transportation of bottled water products is the highest at 97.1% in OD, which is attributed to refrigerants such as CFC-114, which are used for cooling while driving vehicles. Based on the research results, in order to improve the eco-friendliness of bottled water, it is necessary to reduce the use of PET bottle resin and increase the use of recycled PET(r-PET) as an alternative technology. It is necessary to expand the introduction of eco-friendly vehicles for product transportation and to improve packaging technology.