• Journal of Korean Society for Atmospheric Environment
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• v.22 no.4
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• pp.431-439
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• 2006

Catalytic oxidation of benzene, toluene and xylene (BTX) using regenerated metal oxide catalysts (ZnO-CuO, NiO, $Fe_2O_3$, ZnO, CrO) were investigated in a fixed bed flow reactor to evaluate their feasibility for the purpose of removing volatile organic compounds (VOCs). Four kinds of pre-treatment methods such as gas (air and hydrogen), acid aqueous solution, alkali aqueous solution and cleaning agent were used to find out the optimal regeneration conditions. The physico-chemical properties of the used and regenerated catalysts were characterized by BET and TPR (Temperature Programmed Reduction). The used catalysts showed high conversion ratio and the catalytic ability of toluene oxidation was in the order of ZnO-CuO>$Fe_2O_3$>NiO>ZnO>CrO. We found that the acid aqueous pre-treatment (0.1 N HNO$_3$) was the best way to enhance the catalytic activity of $Fe_2O_3$. In addition, air and hydrogen gas treatment were optimal for NiO and ZnO-CuO catalysts, respectively. Furthermore, the decomposition of BTX depends on the type of a catalyst and a gas molecule.

• Membrane and Water Treatment
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• v.7 no.1
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• pp.11-22
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• 2016

The characterization of treatment performance with respect to mixed liquor suspended solids (MLSS) concentration enables greater control over system performance and contaminant removal efficiency. Hybrid membrane bioreactors (HMBRs) have yet to be well characterized in this regard, particularly in the context of greywater treatment. The aim of this study, therefore, was to determine the optimal MLSS concentration for a decentralized HMBR greywater reclamation system under typical loading conditions. Treatment performance was measured at MLSS concentrations ranging from 1000 to 4000 mg/L. The treated effluent was characterized in terms of biochemical oxygen demand ($BOD_5$), chemical oxygen demand (COD), turbidity, ammonia ($NH_3$), total phosphorus (TP), total kjeldahl nitrogen (TKN), and total nitrogen (TN). An MLSS concentration ranging from 3000 to 4000 mg/L yielded optimal results, with $BOD_5$, COD, turbidity, $NH_3$, TP, TKN, and TN removals reaching 99.2%, 97.8%, 99.8%, 99.9%, 97.9%, 95.1%, and 44.8%, respectively. The corresponding food-to-microorganism ratio during these trials was approximately 0.23 to 0.28. Operation at an MLSS concentration of 1000 mg/L resulted in an irrecoverable loss of floc, and contaminant residuals exceeded typical guideline values for reuse in non-potable water applications. Therefore, it is suggested that operation at or below this threshold be avoided.

• Korean Journal of Microbiology
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• v.44 no.1
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• pp.22-28
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• 2008

Cutting oils are emulsionable fluids widely used in metal working processes. Their composition is mineral oil, water, and additives (fatty acids, surfactants, biocides, etc.) generating a toxic waste after a long use. Cutting oils also affect colour, taste and odour of water, making it undesirable for domestic and industrial uses. In these days, conventional treatment methods as evaporation, membrane separation or chemical separation have major disadvantages since they generate a concentrated stream that is more harmful than the original waste. In this study, our purpose is to reduce cutting oils by using biological treatment. Eighty one strains were isolated from cutting waste oil of industrial waste water sludge under aerobic conditions. Among these strains, KS47, which removed 90.4% cutting oil in 48 hr, was obtained by screening test under aerobic conditions(pH 7, $28^{\circ}C$). KS47 was identified as Pseudomonas aeruginosa according to morphological, physiological and biochemical properties, 16S rDNA sequence, and fatty acid analysis. P. aeruginosa KS47 could utilize cutting oil as carbon source. In batch test, we obtained optimal degradation conditions(1.5 g/L cell concentration, pH 7, and temperature $30^{\circ}C$). Under the optimal conditions, 1,060 mg/L cutting oil was removed 83.7% (74.1 mg/L/hr).

• Animal Bioscience
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• v.35 no.7
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• pp.1048-1058
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• 2022

Objective: The present study was to investigate the extraction conditions of dietary fiber from dried cassava pulp (DCP) and cassava distiller's dried grains (CDG) under different NaOH concentrations, and the Fourier transform infrared (FTIR) was used to determine the dietary fiber components. Methods: The dried samples (DCP and CDG) were treated with various concentrations of NaOH at levels of 2%, 4%, 6%, and 8% using a completely randomized design with 4 replications of each. After extraction, the residual DCP and CDG dietary fiber were dried in a hot air oven at 55℃ to 60℃. Finally, the oven dried extracted dietary fiber was powdered to a particle size of 1 mm. Both extracted dietary fibers were analyzed for their chemical composition and determined by FTIR. Results: The DCP and CDG treated with NaOH linearly or quadratically or cubically (p<0.05) increased the total dietary fiber (TDF) and insoluble fiber (IDF). The optimal conditions for extracting dietary fiber from DCP and CDG were under treatment with 6% and 4% NaOH, respectively, as these conditions yielded the highest TDF and IDF contents. These results were associated with the FTIR spectra integration for a semi-quantitative analysis, which obtained the highest cellulose content in dietary fiber extracted from DCP and CDG with 6% and 4% NaOH solution, respectively. The principal component analysis illustrated clear separation of spectral distribution in cassava pulp extracted dietary fiber (DFCP) and cassava distiller's dried grains extracted dietary fiber (DFCDG) when treated with 6% and 4% NaOH, respectively. Conclusion: The optimal conditions for the extraction of dietary fiber from DCP and CDG were treatment with 6% and 4% NaOH solution, respectively. In addition, FTIR spectroscopy proved itself to be a powerful tool for fiber identification.

• Journal of the Korean Society of Clothing and Textiles
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• v.37 no.8
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• pp.1107-1116
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• 2013

This study examined the use of cutinase and lipase to process cotton/polyester blend fabric. Optimum treatment conditions for cutinase and lipase were investigated for cotton/polyester blend fabric. The properties of enzyme-treated fabrics were evaluated and compared in optimal treatment conditions. In addition, the possibility to provide an enzymatic finishing on blend fabrics using mixed enzymes in a two-step process were studied. The weight loss of cotton/polyester blend fabrics with Triton X-100 was 0.8% and the dyeing property of blend fabrics with calcium chloride increased by a factor of 1.2. The use of two enzymes in combination with cutinase and lipase in the presence of auxiliaries resulted in a cotton/polyester blend fabric weight loss of 0.8%. In addition, the dyeing properties of cotton/polyester blend fabrics improved by a factor of 1.5 and the moisture regain of cotton/polyester blend fabrics improved by a factor of 1.16. However, no marked loss was observed in tensile strength. The surface morphology of cotton/polyester blend fabrics is modified through a two-enzyme treatment. The treatment of cotton/polyester blend fabrics with cutinase and lipase maintains cotton strength and improves the moisture regain of polyester fabrics.

• Journal of the Korean Society of Clothing and Textiles
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• v.37 no.7
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• pp.852-863
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• 2013

We investigate the immobilization of trypsin on chitosan nonwoven using glutaraldehyde (GA). The conditions for trypsin on chitosan nonwoven and GA cross-linking were optimized depending on different conditions. The order of GA cross-linking was determined by the activity of immobilized trypsin. The characteristics of chitosan nonwoven were examined by Fourier-transform infrared (FT-IR) and surface morphology analyses (SEM). Results showed that the optimal treatment conditions for trypsin on chitosan nonwoven were as follows: pH 8.5; temperature $37^{\circ}C$; trypsin concentration 15% (o.w.f); and treatment time 60 min. Those for GA cross-linking were: pH 10.0; GA concentration 3% (v/v); and treatment time 120 min. FT-IR analysis showed that GA was cross-linked on chitosan nonwoven. The SEM analysis also showed that trypsin was immobilized on chitosan nonwoven.

• Journal of Microbiology and Biotechnology
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• v.27 no.7
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• pp.1209-1215
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• 2017

Microwave sterilization was performed to inactivate the spores of biofilms of Bacillus cereus involved in foodborne illness. The sterilization conditions, such as the amount of water and the operating temperature and treatment time, were optimized using statistical analysis based on 15 runs of experimental results designed by the Box-Behnken method. Statistical analysis showed that the optimal conditions for the inactivation of B. cereus biofilms were 14 ml of water, $108^{\circ}C$ of temperature, and 15 min of treatment time. Interestingly, response surface plots showed that the amount of water is the most important factor for microwave sterilization under the present conditions. Complete inactivation by microwaves was achieved in 5 min, and the inactivation efficiency by microwave was obviously higher than that by conventional steam autoclave. Finally, confocal laser scanning microscopy images showed that the principal effect of microwave treatment was cell membrane disruption. Thus, this study can contribute to the development of a process to control food-associated pathogens.

• Korean Journal of Plant Resources
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• v.26 no.5
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• pp.636-644
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• 2013

We examined the effects of soaking, saturation, and aging conditions of raw cowpea seeds, on the yield and growth responses of cowpea sprouts. The absorption caused rapid growth for the first two hours of soaking, then the growth slowed. The longer the soaking period (varied from 1 to 6 hours), the lower the germinability, yield ratio, and lateral root output became. A five-day saturation (moist $96{\pm}1%$, $20^{\circ}C$) treatment led to higher germinability, yield ratio, and lateral root output than no treatment and one- or three-day saturation treatment. High-temperature aging treatment led to lower germinability and yield ratio compared to no such treatment. Taking these findings into account, the optimal treatment conditions of raw cowpea seeds are a five-day saturation (moist $96{\pm}1%$, $20^{\circ}C$) treatment followed by cleaning and growing.

• Journal of the Korean GEO-environmental Society
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• v.7 no.3
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• pp.21-29
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• 2006

The treatment performance of ozonation and three types of advanced oxidation processes (AOPs) such as $O_3/H_2O_2$, $O_3/UV$, $O_3/H_2O_2/UV$ was experimentally investigated for the treatment of refractory synthetic dye wastewater. The removal efficiency of $COD_{cr}$, color and biodegradability ($BOD_5/COD_{cr}$) were relatively evaluated in each treatment unit with simulated dye wastewater. Optimal operational conditions of pH, temperature, dosage and circulation flow rate were also investigated. All suggested processes revealed an effectiveness for the removal of color within a short operational time, moreover, $O_3/H_2O_2/UV$ process showed the highest $COD_{cr}$ removal and biodegradability enhancement among proposed oxidation process.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.493-500
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• 2003

The effect of reductive treatment with elemental iron on the extent of mineralization by Fenton oxidation was studied for the explosive 2,4,6-trinitrotoluene (TNT) and hexahydro-l,3,5-trinitro-l,3,5-triazine (RDX) using a completely-stirred tank reactor (CSTR). The results support the hypothesis that TNT and RDX are reduced with elemental iron to products that are oxidized more rapidly and completely by Fenton's reagent. Iron pretreatment enhanced the extent of TOC removal by approximately $20\%\;and\;60\%$ for TNT and RDX, respectively. Complete TOC removal was achieved for TNT and RDX solutions with iron pretreatment under optimal conditions. On the other hand, without iron pretreatment, complete mineralization of TNT and RDX solutions were not achieved even with much higher $H_2O_2$ and $Fe^{2+}$ concentrations. The bench-scale iron treatment-Fenton oxidation integrated system showed more than $95\%$ TOC removal for TNT and RDX solutions under optimal conditions. The proposed zero-valent iron-Fenton process was evaluated with pink water from the Iowa Army ammunition plant. Results from batch and column experiments show that TNT, RDX, and octahydro-l,3,5,7-tetranitro-l,3,5,7-tetrazocine (HMX) were completely removed from the pink water and that triaminotoluene (TAT) and ${NH_4}^+$ were recovered as products in reduction with zero-valent iron. By using an integrated system, $83.3\pm4.2\%$ of TOC was removed in a CSTR with 10 mM of $Fe^{2+}$ and 50 mM of $H_2O_2$. These results suggest that the reduction products of TNT and RDX are more rapidly and completely mineralized by Fenton oxidation and that a sequential iron treatment-Fenton oxidation process may be a viable technology for pink water treatment.