Sangyong Kim - Academia.edu (original) (raw)

Papers by Sangyong Kim

Journal of microbiology and biotechnology, Jan 28, 2017

Metabolic engineering with a high-yielding mutant, A. terreus AN37, was performed to enhance the ... more Metabolic engineering with a high-yielding mutant, A. terreus AN37, was performed to enhance the production of itaconic acid (IA). Reportedly, the gene cluster for IA biosynthesis is composed of four genes: reg (regulator), mtt (mitochondrial transporter), cad (cis-aconitate decarboxylase), and mfs (membrane transporter). By overexpressing each gene of the IA gene cluster in A. terreus AN37 transformed by the restriction enzyme-mediated integration method, several transformants showing high productivity of IA were successfully obtained. One of the AN37/cad transformants could produce a very high amount of IA (75 g/l) in shake-flask cultivations, showing an average of 5% higher IA titer compared with the high-yielding control strain. Notably, in the case of the mfs transformants, a maximal increase of 18.3% in IA production was observed relative to the control strain under the identical fermentation conditions. Meanwhile, the overexpression of reg and mtt genes showed no significant ...

Separation and Purification Technology, 2009

A solute can be deposited from solution by the addition of another soluble substance which effect... more A solute can be deposited from solution by the addition of another soluble substance which effectively reduces the solubility of original solute. The process is referred to as 'salting-out' and it is one of the proper methods for effective separation of synthetic reactive dyes in industry. To develop an efficient salting-out process for recovering representative anthraquinone-and azo-type reactive dyes, Reactive Blue 49 and Reactive Black 8 in high yields, various factors such as the kind and amount of inorganic salts, concentration of dye solution, operating temperature, stirring speed, complete time of crystallization were investigated. Reactive Blue 49 could be recovered from 15 wt% of dye solution in approximately 70% yield under the optimized conditions (15 wt% of NaCl, 25 • C, 100 rpm, 12 h) and Reactive Black 8 was obtained from 20 wt% of dye solution in over 90% yield by using 10 wt% of NH 4 Cl at room temperature and 100 rpm within 1 h.

Journal of Hazardous Materials, 2004

The composition of wastewater from the dyeing and textile processes is highly variable depending ... more The composition of wastewater from the dyeing and textile processes is highly variable depending on the dyestuff type and typically has high COD and color. This study examined the decolorization of some of the most commonly used disperse and reactive dyestuffs by combination of chemical coagulation and Fenton oxidation. In addition, performances between Fe3+ coagulation and Fenton oxidation of dye solutions were compared by measuring COD and dye removals, distributions of zeta potential, concentration of suspended solid were investigated. Fenton oxidation in combination with Fe3+ coagulation has shown to effectively remove COD and dye. About 90% of COD and 99% of dye removals were obtained at the optimum conditions. Compared to reactive dyes, disperse dyes have lower solubility, higher suspended solids concentrations and lower SCOD/TCOD ratios. The COD and dye removed per unit Fe3+ coagulant added for disperse dye solutions were higher than those for reactive dye solutions. Therefore, the disperse dye solutions are more easily decolorized by chemical coagulation than reactive dye solutions. Conversely, reactive dye solutions have higher applicability of Fenton oxidation than disperse dye solutions due to their higher solubility, lower suspended solids concentrations and higher SCOD/TCOD ratios. The COD and dye removed per Fe2+ Fenton reagent added for reactive dye solutions are respectively higher than those for disperse dye solutions.

Journal of Cleaner Production, 2005

In this study, nanofiltration membrane and reverse osmosis membrane were tested to investigate th... more In this study, nanofiltration membrane and reverse osmosis membrane were tested to investigate the optimal operating conditions for COD, color, salt rejection and permeate flux and evaluate the feasibility of nanofiltration and reverse osmosis membrane combined process to improve the permeate flux and separation efficiencies in reactive dye manufacturing process wastewater. Effects of pressure, types of membrane and dye solution on flux and rejections were investigated. Experiments showed that the type of membrane had a significant effect on both permeate flux and rejection efficiencies. Variations in the applied pressure also affected the COD, color and salt rejections, which increased with increasing pressure. Finally, the nanofiltration and reverse osmosis membrane combined process was found to be suitable for the removal of residual organics, color, salt and the water recycling from waste stream arising from reactive dye manufacturing process. The permeate can be recycled back into the process, thus offering economical benefits by reducing the water consumption and wastewater treatment cost.

Journal of Bioscience and Bioengineering, 2009

Journal of Bioscience and Bioengineering, 2005

The purpose of this study was to increase the efficiency of anaerobic digestion of waste activate... more The purpose of this study was to increase the efficiency of anaerobic digestion of waste activated sludge (WAS). Either thermochemical or biological hydrolysis was used as a pretreatment and the effects of both were investigated and compared. Two different three-stage digestion systems showed improved performance, although thermochemical hydrolysis showed better results than biological hydrolysis in a bench-scale operation. After anaerobic digestion with thermochemical pretreatment, the total chemical oxygen demand (tCOD) reduction, volatile solid (VS) reduction, methane yield and methane biogas content were 88.9%, 77.5%, 0.52 m 3 /kg VS and 79.5%, respectively. These results should help in determining the best hydrolysis pretreatment process for anaerobic digestion and in improving the design and operation of the large-scale treatment of WAS by anaerobic digestion with hydrolysis systems.

Journal of Bioscience and Bioengineering, 2002

The purpose of this study is to determine the biodegradation kinetics of 2,4,6-trinitrotoluene (T... more The purpose of this study is to determine the biodegradation kinetics of 2,4,6-trinitrotoluene (TNT) by a newly isolated microorganism. Hundreds of microorganisms were isolated from explosives-contaminated soil in Korea. Examination of culture tests revealed that a few species of microorganisms have good ability to degrade TNT. The most efficient one was selected and identified as Pseudomonas putida KP-T201. Biodegradation of TNT was tested in a batch reactor using a pure culture of P. putida KP-T201. The effect of different concentrations of TNT on the rate of bacterial biodegradation was investigated. The Haldane equation seems to be an adequate expression for the cell growth data, and the kinetic constants obtained were m m m m m =0.65 h-1 , K S =0.62 mgl-1 , and K i =115 mgl-1. The dependence of the bacterial specific growth rate on the concentration of TNT could be explained as a conventional model of substrate inhibition.

Journal of Bioscience and Bioengineering, 2003

In this study, a strain of Pseudomonas putida KP-T202, isolated from the soil in a contaminated s... more In this study, a strain of Pseudomonas putida KP-T202, isolated from the soil in a contaminated site, degraded 2,4,6-trinitrotoluene (TNT). In order to make this biodegradation process commercially feasible and reduce biodegradation time, optimal environmental factors are determined. At an initial concentration of 100 mg/l, TNT was totally degraded within 15 h under aerobic conditions. The optimal conditions for the biodegradation of TNT were found to be 30 degrees C, pH 7, 1% corn steep liquor (CSL), 0.025% NH,CI and 0.1% Tween 80; the reaction rate constant was 0.348 h(-1) These environmental conditions can be used to improve the efficiency of large-scale reactors for the treatment of TNT-contaminated wastewater and soil. In addition, the intermediates were identified as 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, 2,4-dinitrotoluene and 2,6-dinitrotoluene.

Industrial & Engineering Chemistry Research, 2014

Petroleum-independent and economically viable production of 5-hydroxymethyl-2-furfural (HMF) from... more Petroleum-independent and economically viable production of 5-hydroxymethyl-2-furfural (HMF) from industrially supplied high fructose corn syrup (HFCS) using a wood powder-derived carbonaceous solid acid in an ethylene glycol (EG)-based solvent was developed. EG-based solvents were preferable to the dehydration of HFCS into HMF owing to stabilizing reversible intermediates. In addition, low boiling EG-based solvents were readily removed to isolate HMF. As a parametric study on the dehydration of HFCS into HMF in an EG-based solvent, effects of reaction temperature, initial concentration of fructose, catalyst dosage, and water content on reaction rate and HMF yield were investigated. Sulfonated amorphous carbonaceous materials (∼0.7 mmol of SO 3 H/g) were prepared from wood powder via incomplete hydrothermal carbonization and then sulfonization, and they were applied to the dehydration of HFCS in glyme, affording HMF in 80% yield. It was also found that a prolonged reaction enabled further conversion of HMF into levulinic acid in a highly selective manner.

Green Chemistry, 2012

Analysis data of isohexide-based chiral dopants Chemical structures of synthetic isohexide-based ... more Analysis data of isohexide-based chiral dopants Chemical structures of synthetic isohexide-based chiral dopants (IH-n, n= 1-4) were identified by NMR and mass spectrometers. The 1 H-NMR and 13 C-NMR spectra were measured using Bruker-600 (MHz) spectrometer with trimethylsilane (TMS) peak as reference. Mass spectra were recorded by using JEOL, JMS-600W spectrometer.

Enzyme and Microbial Technology, 2006

In order to achieve an effective decolorization with Funalia trogii, fungal immobilization and re... more In order to achieve an effective decolorization with Funalia trogii, fungal immobilization and repeated batch experiment were investigated. The activities of three enzymes, namely laccase, lignin peroxidase (LiP) and manganese peroxidase (MnP), were reported during decolorization of acid black 52 under the condition of immobilized and suspended fungal mycelia. When F. trogii were immobilized in Na-alginate, the cell viability increased as alginate concentration was increased, although the cell concentration decreased. Na-alginate of 4% (w/v) was an optimum concentration. Decolorization rate by fungal immobilization was higher than that by suspended cultivation. Decolorization could be stably maintained with the repeated batch experiments during long period (at least for 300 h).

Enzyme and Microbial Technology, 2011

A silica gel-based substrate feeding system was developed to prevent methanol inhibiting the cata... more A silica gel-based substrate feeding system was developed to prevent methanol inhibiting the catalyst during enzymatic biodiesel synthesis. In the system, silica gel swelled upon methanol addition and subsequently released it in a controlled manner to prevent excess methanol affecting the enzyme. Biodiesel was synthesized by the enzymatic transesterification of canola oil with methanol. For this reaction, enzyme loading, methanol/oil molar ratio, silica gel dosage, glycerol content, and methanol feeding method were tested using commercial immobilized enzymes (Novozym 435 and Lipozyme RM IM from Novozymes). The results showed that conversion was highest with controlled substrate feeding rather than direct methanol addition, suggesting that the method developed here can easily prevent enzyme inhibition by limiting methanol concentration to an acceptable level.

Desalination, 2007

ABSTRACT

Desalination, 2004

The composition of wastewater from dyeing and textile processes is highly variable depending on t... more The composition of wastewater from dyeing and textile processes is highly variable depending on the dyestuff type; typically it has a high chemical oxygen demand. This study examined the decolorization of some of the most commonly used disperse and reactive ...

Biotechnology and Bioprocess Engineering, 2010

Bioprocess and Biosystems Engineering, 2011

The recent rapid growth of the biodiesel industry has generated a significant amount of glycerol ... more The recent rapid growth of the biodiesel industry has generated a significant amount of glycerol as a byproduct. As a result, the price of glycerol is currently relatively low, making it an attractive starting material for the production of chemicals with higher values. Crude glycerol can be directly converted through microbial fermentation into various chemicals such as hydrogen. In this study, we optimized immobilization of a facultative hydrogen producing microorganism, Enterobacter aerogenes, with the goal of developing biocatalysts that was appropriate for the continuous hydrogen production from glycerol. Several carriers were tested and agar was found to be the most effective. In addition, it was clearly shown that variables such as the carrier content and cell loading should be controlled for the immobilization of biocatalysts with high hydrogen productivity, stability, and reusability. After optimization of these variables, we were able to obtain reusable biocatalysts that could directly convert the byproduct stream from biodiesel processes into hydrogen in continuous processes.

Applied Biochemistry and Biotechnology, 2013

A semi-pilot continuous process (SPCP) for enzymatic biodiesel synthesis utilizing near-critical ... more A semi-pilot continuous process (SPCP) for enzymatic biodiesel synthesis utilizing near-critical carbon dioxide (NcCO₂) as the reaction medium was developed with the aim of reducing the reaction time and alleviating the catalyst inhibition by methanol. Biodiesel synthesis was evaluated in both lab-scale and semi-pilot scale reactors (batch and continuous reactors). In a SPCP, the highest conversion (∼99.9 %) in four and a half hours was observed when three-step substrate (methanol) addition (molar ratio [oil/methanol] = 1:1.3) was used and the reaction mixture containing enzyme (Lipozyme TL IM, 20 wt.% of oil) was continuously mixed (agitation speed = 300 rpm) at 30 °C and 100 bar in a CO₂ environment. The biodiesel produced from canola oil conformed to the fuel standard (EU) even without additional downstream processing, other than glycerol separation and drying.

Water Research, 2002

The performance of pilot scale combined process of fluidized biofilm process, chemical coagulatio... more The performance of pilot scale combined process of fluidized biofilm process, chemical coagulation and electrochemical oxidation for textile wastewater treatment was studied. In order to enhance biological treatment efficiency, two species of microbes, which can degrade textile wastewater pollutants efficiently, were isolated and applied to the system with supporting media. FeCl 3 Á 6H 2 O, pH 6 and 3.25 Â 10 À3 mol/l were determined as optimal chemical coagulation condition and 25 mM NaCl of electrolyte concentration, 2.1 mA/cm 2 of current density and 0.7 l/ min of flow rate were chosen for the most efficient electrochemical oxidation at pilot scale treatment. The fluidized biofilm process showed 68.8% of chemical oxygen demand (COD) and 54.5% of color removal efficiency, even though using relatively low MLSS concentration and short sludge retention time. COD and color removals of 95.4% and 98.5% were achieved by overall combined process. The contribution of fluidized biofilm process to the overall combined process was increased over 25.7% of COD reduction and 20.5% of color reduction by adopting support media in biological treatment. It can be thought that the fluidized biofilm process was effective, and pollutant loading on post-treatment was pretty much decreased by this system. This combined process was highly competitive in comparison to the other similar combined systems. It was concluded that this combined process was successfully employed and much effectively decreased pollutant loading on post-treatment for textile wastewater treatment at pilot scale.