Publications by authors named "Sung-Ju Im"

Water distribution networks play a crucial role in ensuring a reliable water supply, yet they encounter challenges such as corrosion, scale formation, and biofilm growth due to interactions with environmental elements. Biofilms and corrosion layers are significant contaminants in water pipes, formed by complex interactions with pipe materials. As the structure of these contamination layers varies depending on the pipe material, it is essential to investigate the contamination layer for each material individually.

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Freshwater shortages are a consequence of the rapid increase in population, and desalination of saltwater has gained popularity as an alternative water treatment method in recent years. To date, the forward osmosis-reverse osmosis (FO-RO) hybrid technology has been proposed as a low-energy and environmentally friendly next-generation seawater desalination process. Scaling up the FO-RO hybrid system significantly affects the success of a commercial-scale process.

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While a variety of chemical cleaning strategies has been studied to control fouling in membrane-based water treatment processes, the removal of irreversible foulants strongly bound on membrane surfaces has not been successful. In this study, we firstly investigated the diluted aqueous solutions of ionic fluid (IF, 1-ethyl-3-methylimidazolium acetate) as a cleaning agent for three model organic foulants (humic acid, HA; bovine serum albumin, BSA; sodium alginate, SA). The real-time monitoring of cleaning progress by optical coherence tomography (OCT) showed that fouling layer was dramatically swelled by introducing IF solution and removed by shear force exerted during cleaning.

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Currently, forward osmosis (FO) is widely studied for wastewater treatment and reuse. However, there are still challenges which need to be addressed for the application of the FO on a commercial scale. In the meantime, with a strong capability to solve the complicated nonlinear relationships and to examine of the relations between multiple variables, artificial intelligence (AI) technique could be a viable tool to improve FO system performance to make it more applicable.

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Ultrafiltration (UF) membranes are considered a pre-treatment for brackish water reverse osmosis (BWRO) membranes because of the high rejection rate of particulates and the productivity of the final water quantity. This study presents the performance and membrane surface property analysis of UF membranes for commercial membrane manufacturers, and their structural strength and chemical resistance were evaluated. Moreover, the pilot-scale UF-BWRO process was operated for two months using real wastewater based on the results of this study.

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This study investigated the behaviour and simulation of low-molecular-weight (low-MW) micropollutants (MPs) in a powdered activated carbon (PAC)-assisted fertiliser-drawn OMBR. 10% increase in water recovery and two times thinner fouling layer were observed in OMBR with addition of 100 mg-PAC/g-MLSS. This amount of PAC also boosted the richness and diversity in microbial community (Chao1 and Shannon index increased 1.

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A new optimized ultraviolet (UV) technique induced a photooxidation surface modification on thin-film composite (TFC) polyamide (PA) brackish water reverse osmosis (BWRO) membranes that improved membrane performance (i.e., permeability and organic fouling propensity).

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Forward osmosis process in emerging technology which can applicable in wastewater reuse and desalination simultaneously. In this study, the development of fouling on the FO membrane surface was monitored in real-time. The investigation of fouling layer physical and chemical characteristics was assessed by performance evaluation and in-depth analysis of fouling layer.

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Trace organic compounds (TOrCs) and microplastics (MPs) have been recognized as emerging pollutants that cause severe water pollution related problems due to their non-degradable and bio-accumulative nature. Many studies on oxidation processes such as ozone have been conducted to efficiently remove TOrCs in water treatment. However, there has been a lack of research on the removal efficiency of TOrCs in the oxidation process when they co-exist with MPs and form transformation byproducts (TBPs) during this process.

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Monitoring fouling behavior for better understanding and control has recently gained increasing attention. However, there is no practical method for observing membrane fouling in real time, especially in the forward osmosis (FO) process. In this article, we used the optical coherence tomography (OCT) technique to conduct real-time monitoring of the membrane fouling layer in the FO process.

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Forward osmosis is an energy efficient process that is capable of recovering high-quality water from secondary wastewater treatment. However, regeneration of the draw solution (DS) is a problem that needs to be addressed. Herein, we developed and optimized a one-step process that does not require additional treatment for the DS.

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This study investigates a novel hybrid configuration of an osmotic membrane bioreactor-clarifier (OMBRC) to achieve the simultaneous reduction of salt accumulation and membrane fouling. Compared with the conventional OMBR, the OMBRC demonstrated 14 times lower conductivity after 40 d of operation, achieving maximum values exceeding 25,000 and 1800 μS/cm, respectively. The average water flux and flux recovery were approximately 3 and 6 times higher in the OMBRC than in the OMBR, respectively.

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This study examined an electrochemical method of H production and nutrient recovery from synthetic source separated urine (SSU). The efficacy of H production was examined through hydrogen recovery experiments (HRE) using Ni foam electrodes. Similarly, nutrient (N and P) recovery was also examined in post-nutrient recovery experiments (NRE) with sacrificial Mg electrodes.

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Perfluorinated chemical (PFC)-based materials have been widely applied in industry. In this study, the influence of PFCs on the physicochemical properties of membranes and that of the co-existence of organic matter and microplastics on the removal rate in the process of forward osmosis (FO) was examined. The water flux, reverse salt flux, and rejection of PFCs were evaluated under w and w/o contaminants.

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This study investigated the feasibility of applying a thin film composite (TFC) forward osmosis (FO) membrane in the dewatering of activated sludge (AS). Membrane fouling was investigated and controlled to enhance the system's performance. Investigations showed that the TFC FO membrane provided a water flux that was 120 % higher and a concentration factor that was three times higher compared to a cellulose tri-acetate (CTA) membrane.

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In general, cartridge filters (CFs) are installed before reverse osmosis systems as a safeguard to minimize fouling of the reverse osmosis membrane in seawater desalination plants. Depending on the retention time of microorganisms and various fouling matter in the storage tank, pipe, and filter housing, serious fouling of the CF may occur, decreasing its lifetime. More importantly, biofouling of CFs in a continuous process can have a significant impact on reverse osmosis membrane fouling.

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Recovery of heavy metals in acid mine drainage (AMD) such as Mn, Fe, Cu, Zn, As, Cd and Pb was evaluated using volume retarded osmosis and low-pressure membrane (VRO-LPM) process. In VRO-LPM process, the draw solution (DS) is regenerated by the naturally generated pressure, giving its economic value. Ethylenediaminetetraacetic acid tetrasodium salt (EDTA-4Na) and Poly (sodium-4-styrenesulfonate, PSS-Na) were used and compared to determine more suitable DS in heavy metal recovery from the AMD.

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This study evaluated the treatment of acid whey through a volume-retarded osmosis-low-pressure membrane (VRO-LPM) hybrid process. The VRO-LPM process uses pressure naturally generated inside the closed draw solution (DS) tank to regenerate the DS, making it an economic process. Poly (sodium-4-styrenesulfonate) (PSS) and carboxymethyl cellulose (CMC) were compared to determine which was a more suitable DS for acid whey treatment.

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A new concept of volume-retarded osmosis and low-pressure membrane (VRO-LPM) hybrid process was developed and evaluated for the first time in this study. Commercially available forward osmosis (FO) and ultrafiltration (UF) membranes were employed in a VRO-LPM hybrid process to overcome energy limitations of draw solution (DS) regeneration and production of permeate in the FO process. To evaluate its feasibility as a water reclamation process, and to optimize the operational conditions, cross-flow FO and dead-end mode UF processes were individually evaluated.

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We tested the possibility of energy-saving water treatment methods by using a pump-less forward osmosis (FO) and low-pressure membrane (LPM) hybrid process (FO-LPM). In this pump-less FO-LPM, permeate migrates from the feed solution (FS) to the draw solution (DS) through the FO membrane by use of osmotic pressure differences. At the same time, within the closed DS tank, inner pressure increases as the DS volume increases.

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