• Advances in environmental research
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• v.3 no.3
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• pp.199-206
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• 2014

Dewatering is an extremely important step in wastewater treatment process to reduce the final sludge volume in order to minimize the cost of sludge transportation and disposal. In the present study, the effect of different sludge solids content (1, 2 and 3.8%) on the dewaterability of anaerobically digested sludge using Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans was studied. The pH reduction rate was higher during initial process in the sludge having low solids content, but after 48 h of bioleaching, similar pH of below 3 was observed with all the different solids content. Bio-oxidation rate of $Fe^{2+}$ was initially higher in sludge with low solids content, but 100% $Fe^{2+}$ was oxidized within 60 h in all the three treatment levels. Compared to the control, specific resistance to filtration was reduced by 75, 78 and 80% in the sludge with a solids content of 1, 2 and 3.8% respectively, showing improvement in dewaterability with an increase in sludge solids content. Sludge effluent quality and sludge settling rate were also improved in treatments with higher solids content after the bioleaching process.

• Membrane and Water Treatment
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• v.13 no.6
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• pp.313-320
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• 2022

Theoretical calculation results are presented for the enhancement of the water mass flow rate through the hydrophobic micro/nano pores in the membrane respectively on the micrometer and nanometer scales. The water-pore wall interfacial slippage is considered. When the pore diameter is critically low (less than 1.82nm), the water flow in the nanopore is non-continuum and described by the nanoscale flow equation; Otherwise, the water flow is essentially multiscale consisting of both the adsorbed boundary layer flow and the intermediate continuum water flow, and it is described by the multiscale flow equation. For no wall slippage, the calculated water flow rate through the pore is very close to the classical hydrodynamic theory calculation if the pore diameter (d) is larger than 1.0nm, however it is considerably smaller than the conventional calculation if d is less than 1.0nm because of the non-continuum effect of the water film. When the driving power loss on the pore is larger than the critical value, the wall slippage occurs, and it results in the different scales of the enhancement of the water flow rate through the pore which are strongly dependent on both the pore diameter and the driving power loss on the pore. Both the pressure drop and the critical power loss on the pore for starting the wall slippage are also strongly dependent on the pore diameter.

• Membrane Journal
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• v.22 no.2
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• pp.95-103
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• 2012

To treat nitrate and non-biodegradable organics effectively in sewage, industrial wastewater and livestock wastewater, the activated sludge process integrated by a membrane separation and a porous electrode- electrolysis was proposed and its efficiency was investigated. The proposed system was consisted of 3 processes; activated sludge, membrane filtration and electrolysis. In the study, the membrane filtration played a role in reducing the load of the electrolysis to operate the proposed process stably. The electrolysis consisted of a porous electrode to increase the efficiency due to the extension of the specific surface area. Additionally, redox reaction in the electrolysis was induced by decomposing influent water as current was applied. As a result, hydrogen free radicals and oxygen radicals as intermediates were produced and they acted as oxidants to play a role in decomposing non-degradable organics. It was environmentally-friendly process because intermediates produced by porous electrode were used to treat waste matters without supplying external reagent. Experimental data showed that the proposed process was more excellent than activated sludge process. SS removal efficiencies of the proposed process, membrane filtration and activated sludge process were about 100%, about 100% and about 90%, respectively. COD removal efficiencies of the proposed system, membrane filtration and activated sludge process were about 92%, about 84% and about 78%, respectively. T-N removal efficiencies of the proposed system, membrane filtration and activated sludge process were about 88%, about 67%, and about 58%, respectively. The SS data showed that SS was efficiently removed in the single of the membrane filtration. The COD/T-N data showed that COD/T-N of membrane hybrid process was treated by removing a little soluble organics and SS, and that COD/T-N of electrolysis hybrid process was treated by oxidize organics with high removal rate.

• Journal of Environmental Health Sciences
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• v.27 no.2
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• pp.145-152
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• 2001

The purpose of this study was to determine nitrogen dioxide(NO$_2$) decay rate by reaction between NO$_2$ and interior materials in Korean residence. The results of this research could be helpful to choose the interior construction materials and to study on reduction of indoor air pollutants. The results of this research are as follows; For 30 residences in Seoul and Incheon from October 2000 to march 2001, the mean of infiltration rate was 0.70$\pm$0.44 ACH, and single-detached houses (7 houses) and apartments (19 houses) were 0.97$\pm$0.55 ACH and 0.61$\pm$0.34 ACH, respectively. The $CO_2$ decay followed approximately first-order process ($R^2$=0.97$\pm$0.02). There existed a statistic significance in filtration rate between houses built in 1980’s and built in 1990’s by t-test (p<0.02). Mean of NO$_2$ decay rates in 26 residence3s except 4 residences was 0.94$\pm$0.49hr$^{-1}$ , and also 0.86$\pm$0.49hr$^{-1}$ , 0.97$\pm$0.50hr$^{-1}$ in single-detached houses and apartments, respectively. Mean NO$_2$ decay rates in houses built in 1980’s were 0.78$\pm$0.37hr$^{-1}$ , 1.33$\pm$1.03hr$^{-1}$ , respectively. Nothing were showed statistical significance among indoor temperature, indoor humidity, and NO$_2$ decay rate. However, NO$_2$ decay rates had a tendency to increase by increase of temperature and humidity. Average volume/surface of participated houses was 0.55$\pm$0.07m and mean NO$_2$ deposition velocity was calculated as 1.46$\pm$0.59msec$^{-1}$ .

• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.2
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• pp.3-9
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• 2013

Purpose: Currently commercially available phantom can reproduce and evaluate only a static situation, the study is incomplete research on phantom and system which is can confirmed functional situation in the kidney by time through dynamic phantom and blood flow velocity, various difference according to the amount of radioactive. Therefore, through this study, it has produced the dynamic kidney phantom to reproduce images through the dynamic flow of the kidney, it desire to evaluate the usefulness of nuclear medicine imaging. Materials and Methods: The production of the kidney phantom was fabricated based on the normal adult kidney, in order to reproduce the dynamic situation based on the fabricated kidney phantom, in this study it was applied the volume pump that can adjust the speed of blood flow, so it can be integrated continuously radioactive isotopes in the kidney by using $^{99m}Tc-pertechnate$. Used the radioactive isotope was supplied through the two pump. It was confirmed the changes according to the infusion rate, radioactive isotopes and the different injection speeds on the left and right, analysis of the acquired images was done by drawn ten times ROI in order to check the reproducibility of each on the front and rear of the kidney and bladder. Results: Under the same conditions infusion rate 40 mL/min fixed to adjust the pressure of the pump when the radiopharmaceuticals between 2-3 minutes in the most integrated in the kidney phantom was excreted inthe bladder. Glomerular filtration rate (GFR), respectively, by each device SYMBIA 1,091 mL/min, FORTE 1,232 mL/min, ARGUS 1,264 mL/min, INFINIA 1,302 mL/min in that there isno statistically significant difference was found, Tmax values and T1/2 values stars from all equipment with no statistically significant difference was found. CV values of the coefficient of variation less than 5% was found to be repeatable, and to 2.67% of the lowest SYMBIA appeared, INFINIA was the highest in the 4.86%. Conclusion: Through this study, the results showed that the dynamic kidney phantom system is able to similarly reproduce renogram in the actual clinical. Especially, the depicted over time for the flow to be excreted through the kidney into the bladder was adequately reproduce, it is expected to be utilized as basic data to check the quality of the dynamic images. In addition, it is considered to help in the field of functional imaging and quality control.

• Membrane Journal
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• v.12 no.1
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• pp.21-27
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• 2002

The formation of soluble microbial products(SMP) and molecular weight distribution on loading rate were observed in batch-type culture medium, which phenol was fed as a substrate. The molecular weight destribution was obtained by using 30K, 100K dalton and $0.45{\mu}$ membrane filters. When the phenol concentrationas a substrate was 120, 230 and 440 mg/L , the specific substrate utilization rate(q) showed 0.639, 1.281 and 1.744 mgTOC/mgMLSS/day, respectively. The endogenous biomass decay rate constant($K_d$) at each substrate concentration was 0.00536, 0.0661 and 0.0749($day^1$), respectively. The $SMP_e$ product rate constant($k_{SMP}_ e$) showed 0.006, 0.0058 and 0.0057($day^1$), respectively. The initial influent substrate during the course of time degraded and produced $SMP_s$. The $SMP_s$ was converted to the $SMP_{nd}$ and endogenous phase converted to the $SMP_e$ ingredients. The molecula weight distribution on loading rate was converted to a higher MW during the course of time.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.2
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• pp.200-208
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• 2005

In this study, a new submerged membrane bioreactor process packed with granular sulfur (MBR-GS) was operated to identify the biological nitrogen removal behaviors with plating wastewater containing high-strength $NO_3{^-}$ concentration. The continuous denitrification was carried out at $20^{\circ}C$ with various nitrogen loading rates using synthetic wastewater, which composed of $NO_3{^-}$ and $HCO_3{^-}$, but also actual plating wastewater, which was collected from the effluent of the H metal plating company. As a result, high-rate denitrification in the range of $0.8kg\;NO_3{^-}-N/m^3\;day$ was accomplished at nitrogen loading rate of $0.9kg\;NO_3{^-}-N/m^3\;day$ using synthetic wastewater. Also, higher-rate denitrification with actual plating wastewater was achieved up to $0.91kg\;NO_3{^-}-N/m^3\;day$ at the loading rate of $1.11kg\;NO_3{^-}-N/m^3\;day$. Additionally, continuous filtration was possible during up to 30 days without chemical cleaning in the range of 20 cmHg of transmembrane pressure. On the basis of the proposed stoichiometry, ${SO_4}^{2-}$ production could be estimated efficiently, while observed alkalinity consumption was somewhat lower than theoretical value. Consequently, a new process, MBR-GS is capable of high-rate autotrophic denitrification by compulsive flux and expected to be utilized as an alternative of renovation techniques for nitrogen removal from not only plating wastewater but also municipal wastewater with low C/N ratio.

• Journal of Wetlands Research
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• v.15 no.4
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• pp.535-541
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• 2013

The urbanization affects significantly on a natural water circulation system by increasing the imperviousness rate. It is also negatively affecting on urban temperature, environmental pollution, water quality, and aqua-ecosystems. The Korea MOE (Ministry of Environment) adapted a new environmental policy in order to reduce the impact of urbanization, which is the Green Stormwater Infrastructure (GSI) program. The GSI can be achieved by protecting conservable green spaces, enlarging more green spaces, and constructing more permeable pavements. The GSI is including many different techniques such as bioretention, rain garden, infiltration trench and so on. Also It is the infrastructures using natural mechanisms of soils, microorganisms, plants and animals on a water circulation system and pollutant reduction. In this research, a multi functional GSI technology with infiltration-filtration mechanisms has been developed and performed lab-scale tests to evaluate the performances about infiltration rate restoration and pollutant reduction. The most of pollutants including metals, organics and particulates were reduced about 50~90% due to water infiltration and storage functions. The clogging was found when the TSS loading rate was reached on $8.3{\sim}9.0kg/m^2$, which value is higher than the values in literatures. It means the new technology can show high performances with low maintenances.

• The Korean Journal of Pharmacology
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• v.7 no.1
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• pp.67-76
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• 1971

The excretion of uric acid in man has been of great interest because of its importance as an end product in purine metabolism as well as of its role in causing gout. There are many differences in the modes of renal handling of urate among various species of animals. Uric acid actively secreted by the renal tubules of most vertebrate including amphibians, reptiles, and birds. On the other hand, in most mammals net tubular reabsorption of urate appears to be occurred with some exception, such, as Dalmatian dog. In the rabbits, however, the mechanism of renal excretion of uric acid has long been a subject of controversial results. Within a given group it was possible to find individuals with either net secretion or net reabsorption of urate depend on the experimental conditions. Excretion of urate can be depressed or enhanced by a variety of drugs belonging mainly to the aromatic acid group. Diodrast, probenecid, cinchophen and salicylates have been reported as uricosuric agents, on the other hand, lactate, benzoate, pyrazinoic acid, acetazolamide and chlorothiazide are known to be contraindicated to use for the patient with gout since these agents depress the excretion of uric acid from the kidney. However, complex and sometimes the paradoxical effects on the urate excretion by those above mentioned drugs are not uncommon. The experiments were designed to investigate the mechanisms of renal handling of urate as well as the effects of variety of drugs on the tubular transport of uric acid in the rabbits. Male or female white rabbits, from 1.5 to 2.5 kg in weight, were used. The experimental methods used in these studies were clearance, stop-flow, and retrograde injection techniques. The effects of saline, salicylate, chlorothiazide and probenecid were investigated in each experimental conditions. Results of the experiments were summarized as follows; 1. In the rabbits, the rate of urate clearance was always lower than the rate of inulin clearance. The filtration fraction of the urate was one third on an average, therefore, it is estimated that approximately two thirds of filtered urate was reabsorbed. 2. In the kidneys of rabbits, the urate clearance was increased significantly by administration of chlorothiazide and decreased by probenecid. The administration of salicylate had no effect on the rate of urate clearance. The filtration fraction of urate was increased by chlorothiazide and decreased by probenecid. 3. In the stop-flow studies, the U/P ratio of urate was higher than the U/P ratio of inulin in the proximal region, indicating the secretion of uric acid in the proximal tubules. The proximal peak was increased by chlorothiazide and inhibited by probenecid.4. In the retrograde injection studies, the reabsorption of urate in the proximal region was observed, and these reabsorptive transport of urate was depressed by either probenecid or by chlorothiazide. 5. No distal tubular activity was observed under any of these experimental conditions concerning urate transport. The results of these experiments show that probenecid inhibits both secretory and reabsorptive transport of uric acid in the kidney of the rabbits. The enhancement of secretory transport of urate by chlorothiazide in the clearance study was due to the secondary action of chlorothiazide which inhibits the reabsorptive transport of urate in the proximal tubules. It is evident that the urate transport in the kidneys of rabbits is bidirectional nondiffusive flux both secretory and reabsorptive directions in the proximal tubules.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.1
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• pp.13-20
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• 2010

Airborne particulate matters have two modes of size distributions of coarse mode and fine mode. The coarse mode which is formed by break down mechanism of large particles has a peak around the $100\;{\mu}m$, and the fine mode formed by condensation and build up mechanism of evaporated vapors has a peak at several ${\mu}m$. The coarse mode particles can be removed easily by conventional collecting equipments such as a cyclone, an electrostatic precipitator, and a filter, however the fine mode particles can not be collected easily. Usually the fine mode particles are generated in the high temperature conditions especially through boilers and incinerators, so the high efficient and temperature filter is essential for the filtration. In this study, a nano ceramic filter for the removal of fine particles in the high temperature is developed and tested for several characteristics. The nano ceramic filter has double layer of micro and nano structure and the pressure drop and the filtration efficiency for $0.31\;{\mu}m$ at 3 cm/s are 15.45 mmAq, and 96.75%, respectively. The thermal conductivity is $0.038\;W/m{\cdot}K$, and the coefficient of water vapor permeability is $3.63\;g/m^2{\cdot}h{\cdot}mmHg$. It is considered that the sensible heat exchange rate is very poor because the low thermal conductivity but it has high potential to exchange latent heat.