Hyung-sool Lee - Academia.edu (original) (raw)

Papers by Hyung-sool Lee

Bioresource technology, 2015

The effect of two different anode-embedding orientations, lengthwise- and widthwise-embedded anod... more The effect of two different anode-embedding orientations, lengthwise- and widthwise-embedded anodes was explored, on the performance of sediment microbial fuel cells (SMFCs) using a chessboard anode. The maximum current densities and power densities in SMFCs having lengthwise-embedded anodes (SLA1-SLA10) varied from 38.2mA/m(2) to 121mA/m(2) and from 5.5mW/m(2) to 20mW/m(2). In comparison, the maximum current densities and maximum power densities in SMFCs having anodes widthwise-embedded between 0cm to 8cm (SWA2-SWA5) increased from 82mA/m(2) to 140mA/m(2) and from 14.7mW/m(2) to 31.1mW/m(2) as the anode depth became deeper. Although there was a difference in the performance among SWA5-SWA10, it was considered negligible. Hence, it is concluded that it is important to embed anodes widthwise at the specific anode depths, in order to improve of SMFC performance. Chessboard anode used in this work could be a good option for the determination of optimal anode depths.

Process Biochemistry, 2002

A new hybrid biological reactor (HBR) using powders as a bio-carrier was developed, and compared ... more A new hybrid biological reactor (HBR) using powders as a bio-carrier was developed, and compared to conventional activated sludge (AS) with increasing substrate organic loading rate (OLR) from 1.0 to 4.0 kg COD/m3 per day. The HBRs employed different powders of bentonite and clinoptilolite, respectively, and its concentration in an aeration basin was sustained at 500 and 4000 mg/l, separately.

Water research, 2002

Abstract}An attached growth bioreactor was designed to minimize the effect of suspended microorga... more Abstract}An attached growth bioreactor was designed to minimize the effect of suspended microorganisms on membrane fouling in submerged membrane bioreactor. Comparison of mixed liquor from attached and suspended growth systems was made to elucidate major factors giving rise to different filtration characteristics. Unexpectedly, the rate of membrane fouling of the attached growth system was about 7 times higher than that of the suspended growth system despite similar characteristics of soluble fraction from the two reactors. Filtration performance proved to depend on the concentration of mixed liquor suspended solids (MLSS). Better filtration performance with suspended growth was explained by the formation of dynamic membranes with suspended solids. A series of analyses such as hydraulic resistance, specific cake resistance, scanning electron microscope, and atomic force microscope were carried out to elucidate the different filtration characteristics of the two systems. #

Journal of Power Sources, 2015

h i g h l i g h t s g r a p h i c a l a b s t r a c t Miniaturized MFCs with three CNTbased anode... more h i g h l i g h t s g r a p h i c a l a b s t r a c t Miniaturized MFCs with three CNTbased anodes show high power density of 3320 W m À3 . Biofilm morphology on the anodes are studied and correlated with performance of MFCs. High CE and energy conversion efficiency of 69.8% and 22.7% are achieved. Power density and efficiencies are high compared with prior art of miniaturized MFCs. This research has potential to guide future MFC research with nanostructured electrode.

Water Science & Technology, 2008

The performance of electricity production from beer brewery wastewater in a single chamber membra... more The performance of electricity production from beer brewery wastewater in a single chamber membrane-free microbial fuel cell (MFC) was investigated. Experimental results showed that the MFCs could generate electricity from full-strength wastewater (2,239 mg-COD/L, 50 mM PBS added) with the maximum power density of 483 mW/m 2 (12 W/m 3 ) at 308C and 435 mW/m 2 (11 W/m 3 ) at 208C, respectively. Temperature was found to have bigger impact on cathode potential than anode potential. Results suggested that it is feasible to generate electricity with the treatment of beer brewery wastewater.

Water Research, 2003

Kam and Gregory (Water Research 35(2001) [3557][3558][3559][3560][3561][3562][3563][3564][3565][3... more Kam and Gregory (Water Research 35(2001) [3557][3558][3559][3560][3561][3562][3563][3564][3565][3566] reported on the removal of humic substances (HS) in the coagulation and flocculation process using cationic polyelectrolytes. The investigation was devoted to the dominant mechanism of HS removal in the process. The HS elimination was compared in a Jar test performed with cationic polymers of different charge and molecular weight under constant pH of 7. The experimental results showed that charge neutralization was a significant factor for the removal of aquatic HS in the coagulation/flocculation process, monitored by the colloid titration and the streaming current procedures, and indicated that a bridging mechanism was unlikely to play a major role in this process.

Journal of Membrane Science, 2004

A number of municipal wastewater treatment systems were developed to improve effluent water quali... more A number of municipal wastewater treatment systems were developed to improve effluent water quality, however economic aspects should be considered. In this study, one of the membrane bioreactor (MBR) systems that have recently attracted much attention was compared to combined biological and chemical processes (CBCP), focusing on effluent water qualities and economic assessment. A HANT ® , modified MBR system, was composed of anoxic/anaerobic/oxic/anoxic stages with hollow fiber membrane, while the CBCP was consisted of anoxic and oxic steps with addition of clinoptilolite powder followed by rapid coagulation process. Both treatment systems showed enhancing efficacy in removing organic compounds and suspended solids. Due to membrane separation in the HANT ® , solids retention times (SRT) was increased up to 50 days. Such long SRT control along with high biomass concentration could enable to achieve nearly complete nitrification, where nitrogen removal was stably attained, as high as at average of 71.7%. However, effluent total phosphorus (TP) concentration in the HANT ® hardly met the requirement limiting eutrophication, which moreover presented instable effluent TP concentrations since biological phosphorus removal immediately reflected from temporarily varying influent COD/P ratio.

Advances in Environmental Research, 2003

An experiment was conducted to evaluate the feasibility of sludge reuse as a micro-medium in an a... more An experiment was conducted to evaluate the feasibility of sludge reuse as a micro-medium in an activated sludge (AS) process. Two experimental protocols were employed. A conventional activated sludge was tested as a control, while the other involved addition of clinoptilolite (ZR) of which 4000 mgyl was unvaryingly sustained in an aeration basin. Two experiments were performed for ZR. In one, clinoptilolite was used as micro-media for 60 days (Model 1). The other used dried excess sludge for 55 days (Model 2). For sludge being recovered as micro-media, organic matter in the sludge was eliminated by 86% at 300 8C. It was completely removed at 500 8C within 30 min, which was regarded as the optimal drying condition. For Model 1, the concentration of biomass was increased by 4720 mg MLVSSyl. It was greater by a factor of two than that of the control. Moreover, it is shown that organic matter could be removed up to 95%. In addition, the sludge settling properties were greatly enhanced by clinoptilolite being implemented as floc seeds. Nitrification was considerably improved by more than 90%, due to the high concentration of nitrifiers attached to micro media. For Model 2, the improved performance was sustained on applying burned sludge into the AS. It was concluded that dried sludge could be reused as micro-media in an activated sludge process. ᮊ

Journal of Clinical Gastroenterology, 2000

To investigate the pancreatic exocrine function in noninsulin-dependent diabetes mellitus (type 2... more To investigate the pancreatic exocrine function in noninsulin-dependent diabetes mellitus (type 2 DM), we evaluated the pure pancreatic juice obtained by endoscopic cannulation of the main pancreatic duct in 13 healthy control subjects and 22 patients with type 2 DM who had no evidence of pancreatic disease. Samples of pancreatic juices were collected in six fractions for 30 minutes at 5-minute intervals after an intravenous bolus injection of secretin (0.25 CU/kg) and cholecystokinin-8 (CCK) (40 ng/kg). The responses of plasma glucose, insulin, and C-peptide to intravenous administration of glucose (50%, 40 mL) were measured. The levels of plasma insulin and C-peptide levels in type 2 DM were the same as in healthy controls in the basal state but did not further increase in response to an intravenous glucose. This suggested that patients with type 2 DM had insulin secretion defect rather than insulin deficiency. Pancreatic secretions including volume, bicarbonate, and protein output in response to stimulation with secretin, and CCK were significantly reduced when compared to the healthy controls. We conclude that patients with type 2 DM exhibit impairment of pancreatic exocrine secretion and that this impairment might not be related to insulin deficiency. Therefore, we recommended that careful evaluation for exocrine pancreatic function in type 2 diabetics who have any clinically suspicious symptoms of pancreatic insufficiency.

Chemical Engineering Journal, 2014

A new refractory wastewater treatment process (UBER-ABOR) was developed. Alizarin Yellow R as the... more A new refractory wastewater treatment process (UBER-ABOR) was developed. Alizarin Yellow R as the mode of azo dyes was efficiently removed. The effect of cathode size on the performance of UBER was investigated. The HRTs of UBER and ABOR were optimized. The degradation mechanism of azo dye was discussed.

Bioresource Technology, 2002

This study was conducted to evaluate the eect of clinoptilolite on nitri®cation in activated slud... more This study was conducted to evaluate the eect of clinoptilolite on nitri®cation in activated sludge (AS), and was focused on a relationship between ammonium exchange capacity of this mineral and improvement of nitri®cation. In batch experiments, the adsorption property of bio®lm-attached clinoptilolite did not show substantial dierence from that of natural clinoptilolite, indicating that bioregeneration became completely achieved without any regenerant in the AS. The AS with added clinoptilolite (ZR) was compared to the control AS (CR) when the ratio of chemical oxygen demand (COD) to total kjeldahl nitrogen (TKN) of in¯uent, i.e. C/N ratio, was varied from 3.25 to 7.5 at a hydraulic retention time (HRT) of 3 h. Enhanced nitri®cation was comparatively observed for the ZR as C/N ratio gradually increased. The results indicated that the clinoptilolite provided a relatively low C/N ratio for nitri®ers, due to ammonium adsorption of this mineral, and consequently nitri®cation was accelerated. Ó