Biomedical subjects

Chulhwan Park

Publications and source records attributed to Chulhwan Park.

8 recordsLinked to original sources

PubMed2005

Upgrading of anaerobic digestion by incorporating two different hydrolysis processes.

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 m3/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.

Anaerobiosis↗

PubMed2004

Comparison of disperse and reactive dye removals by chemical coagulation and Fenton oxidation.

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.

Coloring Agents↗

PubMed2003

Bioremediation of 2,4,6-trinitrotoluene contaminated soil in slurry and column reactors.

The bioremediation of 2,4,6-trinitrotoluene (TNT) contaminated soil was performed on a laboratory scale. To compare bioremediation methods, a soil slurry reactor and a soil column reactor were operated and the effects of supplemental sources were investigated. Optimal conditions for the two bioremediation systems for the removal of TNT were obtained. In the soil slurry reactor, about 60% of the 1000 mg/kg TNT contaminated soil was degraded after 10 d, nearly complete biodegradation (>99%) was achieved within 25 d, and the microorganisms grew and reached a maximum of 9.5 x 10(9) CFU/ml at 15 d. In the soil column reactor, about 50% of the 1000 mg/kg TNT contaminated soil was degraded after 25 d and nearly complete biodegradation (>99%) was achieved within 60 d. Microorganisms grew and reached a maximum of 9.8 x 10(10) CFU/g soil at 40 d. These results should help in determining the best bioremediation method and improving the design and operation of large scale clean up of contaminated sites by bioremediation systems.

Journal Article↗

PubMed2003

Effects of various pretreatments for enhanced anaerobic digestion with waste activated sludge.

The purpose of this study was to enhance the efficiency of anaerobic digestion with waste activated sludge (WAS) by batch experiments. We studied the effects of various pretreatment methods (thermal, chemical, ultrasonic and thermochemical pretreatments) on the biogas production and pollutants reduction owing to solubilization enhancement, particle size reduction, increased soluble protein, and increased soluble COD. The thermochemical pretreatment gave the best results, i.e., the production of methane increased by more than 34.3% and soluble COD (SCOD) removal also increased by more than 67.8% over the control. In this case, the biogas production, methane production and the SCOD removal efficiency were about 5037 l biogas/m3 WAS, 3367 l methane/m3 WAS and 61.4%, respectively. Therefore, it is recognized that higher digestion efficiencies of the WAS were obtained through thermochemical pretreatment of the sludge.

Journal Article↗

PubMed2003

COD reduction and decolorization of textile effluent using a combined process.

This study showed the effectiveness of biological pretreatment involving appropriate microorganisms and suitable support media in a combined process. The combined process consists of biological pretreatment, chemical coagulation and electrochemical oxidation. COD and color were reduced by 95.4% and 98.5% by the combined process, respectively.

Journal Article↗

PubMed2003

Optimization for biodegradation of 2,4,6-trinitrotoluene (TNT) by Pseudomonas putida.

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.

Journal Article↗

PubMed2002

Pilot scale treatment of textile wastewater by combined process (fluidized biofilm process-chemical coagulation-electrochemical oxidation).

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. FeCl3 x 6H2O, pH 6 and 3.25 x 10(-3) mol/l were determined as optimal chemical coagulation condition and 25 mM NaCl of electrolyte concentration, 2.1 mA/cm2 of current density and 0.71/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.

Biofilms↗

PubMed2002

Biokinetic parameter estimation for degradation of 2,4,6-trinitrotoluene (TNT) with Pseudomonas putida KP-T201.

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 mu(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 Article↗