• Korean Chemical Engineering Research
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• v.55 no.5
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• pp.685-689
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• 2017

We studied the removal of zinc ions from synthetic brackish water by an adsorption method using natural Algerian Bentonite (NAB). The effect of the main physico chemical parameters-contact time, pH, temperature, ionic strength, clay weight and initial metal ion concentrations on the removal of $Zn^{+2}$-were investigated. The results showed that equilibrium was attained within 10 min of stirring time. The retention capacity of $Zn^{+2}$ increased with the increase of pH, the adsorbent dose and ionic strength. A modelization study showed that the adsorption follows Langmuir isotherm, while its kinetics was pseudo-second-order. Based on the results, it was concluded that NAB, which is natural and available, could be used as an alternative for the removal of zinc from saline aqueous solutions.

• Journal of Environmental Health Sciences
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• v.17 no.2
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• pp.41-47
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• 1991

A study on the effects of volumetric loading rate, surface loading rate and hydraulic. retention time (HRT) for the anaerobic treatment was conducted with the anaerobic fixed-film process using synthetic wastewater at lower temperature than that of conventional anaerobic treatment. The results are as follows 1. Alkalinity and pH value decreased as the hydraulic retention time increased 2. Increase of the volumetric lodaing rate led to increasl of effluent COD concentration and decrease of COD removal efficiency. 3. The removed volumetric loading rate increased linearly according to the increase of the volumrtric loading rate. 4. Similarly, the linear increase of the removed surface loading rate was noticed with an increase of the surface loading rate.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.267-270
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• 2003

Oleanolic acid is a triterpenoid compound that exists in Oldenlandia diffusa. Recently, oleanolic acid has been noted for antitumor effect. Application of both plant growth regulators, 2,4-D and kinetin, was found to be essential for the induction of callus and suspension cells. Optimum induction condition for callus and suspension cells of Oldenlandia diffusa was determined to be 0.5 mg/L 2,4-D and 0.1 mg/L kinetin. Chromatographic separation of oleanolic acid from its derivatives was achieved using Rexchrom S5-100-ODS column. The retention time of oleanolic acid was 12.6 min and the specific content of oleanolic acid was 0.41 mg/g dry weight.

• Journal of Korean Society of Water and Wastewater
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• v.12 no.2
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• pp.67-75
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• 1998

The purpose of this study is to develop a system for treating industrial wastewater with high carbonaceous and nitrogenous materials. To investigate the potential of using this system, a number of experiments are conducted for about 7 months with the varieties of COD and $NH_3-N$ concentrations, and hydraulic retention time. In the system, 1,500mg/L of COD is remover over 95% in a retention time as low as 9 hours, and the $NH_3-N$ removal efficience is nearly 100% with 90mg/L of $NH_3-N$ in the influent. These results illustrate that the system can effectively be used to treat industrial wastewater containing high concentration of COD and $NH_3-N$.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.3
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• pp.74-80
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• 2005

The compositions of residual extractives in woodmeal, unbleached and oxygen-delignified aspen kraft pulps were investigated with gas chromatography(GC) and gas chromatography-mass spectrometry (GC-MS) with focus on fate of extractives in kraft pulping and oxygen delignification. Steryl esters and shorter retention time (shorter than palmitic acid) extractives were main extractives in aspen woodmeal. Shorter retention time extractives were well removed in kraft pulping. Sterol esters were hydrolyzed to sterols and fatty acids. Sterols and fatty acids were two major extractives classes in unbleached kraft pulps. Linoleic acid was main fatty acids in unbleached pulps compared with palmitic acid which is generally found in aspen woodmeal. Sterolsand fatty acids were also two major extractives classes in oxygen-delignified kraft pulps. However, linoleic acid was well removed in oxygen delignification.

• Journal of Environmental Health Sciences
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• v.27 no.3
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• pp.43-48
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• 2001

Terephthalic acid and ethylene glycol resulting form the weight-reduction process of polyester make trouble in the operation of activated sludge process. Also, polyester weight loss wastewater shows high pH, high organic strength and wide variation of organic loading. Therefore, this study was conducted in order to improve treatment efficiency by activated sludge process with Pseudomonas sp degrading components of polyester weight loss wastewater. The CO $D_{Mn}$ and BO $S_{5}$ of the waste wastewater were 560~3,000 mg/$\ell$ and 8000~3,000 mg/$\ell$, respectively. pH was 11.8~12.3. COD removal efficiency by activated sludge-coagulation process with Pseudomonas sp was 94.1~95.8% for 35 hr of hydraulic retention time. Total organic carbon removal efficiency was 97.1%. Ethylene glycol and terephthalic acid in the wastewater were completely degraded during 32 hr of hydraulic retention time.e.

• Journal of Environmental Health Sciences
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• v.27 no.3
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• pp.11-20
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• 2001

An anaerobic sludge-aerobic fixed-bed biofilm(packed with ceramic support carrier of 1 inch size) reactor system was built up to treat textile wastewater. The efficiency of reactor system was examined by determining the effects of textile wastewater ratio(from 25% to 100% at HRT 24 h). The influent range of SCOD concentration and color were 1,036~1,357 mg/L, and 1,487~1,853 degree, respectively. When textile wastewater ratio was 100% and hydraulic retention time was 24 hours, SCOD removal efficiency by the anaerobic stage were 39.2% 100% and hydraulic retention time was 24 hours, SCOD removal efficiency by the anaerobic stage were 39.2% and the removal efficiency of the whole system were 75.8%. Color removal efficiency by the anaerobic stage were 45.4%(soluble color), and the removal efficiency of the whole system were 70.2%. In the A/A reactor system, the aerobic stage played an important role in removing both color and COD as well as anaerobic stage.

• Journal of Environmental Health Sciences
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• v.27 no.3
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• pp.81-85
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• 2001

The aim of this study was to evaluate on the removal effect of total nitrogen and posphorus in municipal wastewater by decreasing hydraulic retention time(HRT) from 6 hour to 4 hour on CNR process using influent as a Carbon Source. CNR(Cilium Nutrient Romoval) is the process combining $A^2$/O process with cilium media of H2L corporation. The removal efficiencies for BOD$_{5}$, T-N and T-P were 81.1%, 61.4%, 61.4%, respectively. The removal efficiency of nitrogen and posphorus were low by decreasing hydraulic retention time(HRT) from 6 hour to 4 hour on CNR process.s.

• Journal of environmental and Sanitary engineering
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• v.14 no.4
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• pp.172-179
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• 1999

In this research, biological treatability test was conduced using seawater flocculated tannery wastewater by fixed biofilm reactor. During one cycle, the removal efficiency of organic corbon obtained with fixed biofilm process for treating tannery wastewater was considerably greater than that with activated sludge process. As the hydraulic retention time increased form 0.5day to 4day, removal efficiency of organic carbon was increased from 72% to 87.3%. Attached biomass in media increased with influent organic loading up to 29g MLSS/L, that could reduce the specific organic loading rate. The continual measurement of attached biomass was possible for the operation of the biofilm reactor. Equal and low nitrication rates were observed in both suspended growth activated sludge process and fixed biofilm process, despite commercial nitrifier was seeded. Through the process of treating the tannery wastewater, EC50 values which is measured by the use of Ceriopdaphnia dubia, were decreased to the extent of 50% after treatment of seawater flocculation and of 83% after biological treatment, respectively, compared to those of the untreated wastewater.

• Journal of environmental and Sanitary engineering
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• v.14 no.4
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• pp.110-116
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• 1999

This study was conducted to investigate the contaminants removal efficiency and the optimal operating parameters by the internal recycle rate (IRR) in the combining A2/O process with fixed film. The average removal efficiency of BOD and COD was 92.5%~94.6%, 73.9%~87.0% in RUN 1 and 91.9%~94.7%, 77.7%~89.0% in RUN 2, respectively. Organic removal efficiency, at two different hydraulic retention time of 10 and 14hr, was similar. At 50% of the internal recycle rate, organic removal efficiency was somewhat higher than the other. Total nitrogen (T-N) and total phosphorus (T-P) were removed, highly, at 50% of internal recycle rate. It could be suggested by this study that the optimum internal recycle rate is 50% and hydraulic retention time is 14hr.