• Journal of the Korean Applied Science and Technology
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• v.18 no.2
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• pp.118-126
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• 2001

Micelle formation and adsorption at the $Ti0_{2}$ interface of a series of polystyrene-polythylene oxide(PS-PEO) block copolymer in aqueous solution was studied using fluorescence probing and small-angle X-ray methods. Further, the stability of aqueous $Ti0_{2}$ dispersion in the presence of copolymer was investigated by microelectrophoresis, optical density and sedimentation measurements. The dissolution of pyrene as fluorescent probe in aqueous surfactant solution leads to a slow decrease of the $I_{1}/I_{3}$ ratio, as the copolymer concentration increase; $I_{1}$ and $I_{3}$ are respectively the intensities of the first and third vibrionic peaks in the pyrene fluorescence emission. The behaviour was due to the characteristics of the copolymers and/or to the copolymer association efficiency in water. Moreover, the adsorption at the plateau level increases with decreasing PEO until chain length. The zeta potential of $TiO_{2}$ particles decreases with increasing copolymer concentration and reaches a plateau value. Finally, stabilization using block copolymers was more effective with samples having higher weight fractions of PS block.

• Korean Journal of Materials Research
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• v.31 no.7
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• pp.386-391
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• 2021

The formation of CaCO₃ in microalgal culture is investigated and applied for effective separation of microalgae. The presence of several cationic ions in the culture medium mediates the formation of 3 types of mineral precipitates depending on the concentration of mineral precursors, Ca²⁺ and CO₃^2-, amorphous nano-flakes, rhombohedral calcites, and spherical vaterites. While amorphous phased precipitates are formed for all concentrations of mineral precursor, only calcites are formed for 30 mM solutions of mineral precursor, and mixtures of calcites and vaterites are formed for 50 and 100 mM solutions of mineral precursor. The harvesting efficiency is also dependent on the concentration of the mineral precursor: from 90 % for 10 mM to 99 % for 100 mM after 60 mins' of gravitational sedimentation. The formation of nano-flakes on the surface of microalgal cells induces the flocculation of microalgae by breaking the stable dispersion. The negatively charged surface of the microalgal cell is compatible not only with nano-flake attachment but also with the growth of calcitic crystals in which microalgal cells are embedded.

• Progress in Superconductivity and Cryogenics
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• v.11 no.4
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• pp.8-11
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• 2009

This study introduced wastewater treatment method by High Gradient Magnetic Separation (HGMS). HGMS treatment was high efficient method for various industrial wastewaters. The system is currently research state, but we have surveyed commercialize the technology for industry. In rolling plate process, coolant wastewater was recycled by sedimentation and sand filter system. It needs several large reservoirs and long time to remove suspended solid (SS) like metal fines and iron oxide in hot rolling plate making process. If removing rate of suspended solid in rolling coolant wastewater is improved by using HGMS system, the productivity of working process can be increased and the area of reservoir can be reduced. We manufactured high temperature superconducting HGMS system that had a purpose to treatment of coolant wastewater in rolling plate process. We fabricated the prototypes of magnetic matrix filter consisting of stainless steel 430 mesh, which is a core component in the magnetic separation system, In our basic preliminary experiment using HGMS system, it has been clear that the fine paramagnetic particles in the coolant wastewater obtained from rolling plate process of POSCO can be separated with high efficiency.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.167-167
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• 2020

Annual sediment deposition in reservoirs behind weirs poses flood risk, while its accurate prediction remains a challenge. Sediment management by hydraulic flushing is an effective method to maintain reservoir storage. In this study, an integrated approach to predict sediment inflow and sediment flushing simulation in reservoirs is presented. The annual sediment inflow prediction was carried out with Artificial Neural Networks (ANN) modelling. RESCON model was applied for quantification of sediment flushing feasibility criteria. The integrated approach was applied on Sangju Weir and also on estuary of Nakdong River (NREB). The mean annual sediment inflow predicted at Sangju Weir and NREB was 400,000 ㎥ and 170,000 ㎥, respectively. The sediment characteristics gathered were used to setup RESCON model and sediment balance ratio (SBR) and long term capacity ratio (LTCR) were used as flushing efficiency indicators. For Sangju Weir, the flushing discharge, Q_f = 140 ㎥/s with a drawdown of 5 m, and flushing duration, T_f = 10 days was necessary for efficient flushing. At NREB site, the parameters for efficient flushing were Q_f = 80 ㎥/s, T_f = 5 days, N = 1, El_f = 2.24 m. The hydraulic flushing was concluded feasible for sediment management at both Sangju Weir and NREB.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.6
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• pp.719-726
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• 2009

One of the alternative runoff management measures is on-site runoff mitigation, such as rainwater retention tank and infiltration facilities especially the latter that is possible to manage simultaneously runoff quality and quantity as a perspective of water-cycle. This study was conducted to develop a particle separator, inclined-pipe settling system, that could improve particle removal efficiency of road runoff as a pre-treatment device of stormwater infiltration. Solid particles larger than $100{\mu}m$ are separated by simple sedimentation; however, the significant amount of pollutants with a diameter less than $100{\mu}m$ remain in suspension. Without any treatment in that case of the runoff into infiltrate, groundwater would be deteriorated and also infiltration rate would be decreased by clogging. Therefore, we suggest optimal design parameters (inclined angle, pipe length, and surface loading rate) of inclined-pipe settling system which can be designed to effectively remove particles diameter smaller then $70{\mu}m$. Thus, the results showed TSS removal efficiency more than 80% with a particle diameter between $20{\mu}m$ and $70{\mu}m$, 100% above particle diameter $70{\mu}m$ for the inflow rate $0.018 m^3/m^2{\cdot}hr$ with pipe inclined at angle $15^{\circ}$.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.5
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• pp.531-540
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• 2008

The main advantage of dissolved air flotation (DAF) in water treatment process is the small dimension compared with conventional gravity sedimentation and it can be basically reduced by the separation zone performed with the short solid-liquid separation time. Fine bubbles make such a short time possible to carry out solid from liquid separation as a collector on the course of water treatment. Therefore, the dimension of separation zone in DAF process is practically determined by the rise velocity of the bubble-floc agglomerates, which is a floc attached with several bubbles. To improve flotation velocity and particle removal efficiency in DAF process, many researchers have tried to attach bubbles as much as possible to flocs. Therefore, the maximum number of attached bubble on a floc and the rise velocity of bubble-floc agglomerates considered as the most important factor to design the separation zone of flotation tank in DAF process was simulated based on the population balance theory. According to the simulation results of this study, the size and volume concentration of bubble influenced on the possible number of attached bubble on a floc. The agglomerates attached with smaller bubble was more sensitive to hydraulic loading rate in the separation zone of DAF process. For the design of a high rate DAF process applied over surface loading 40 m/hr. it is required a precise further study on the variation of bubble property and behavior including in terms of bubble size distribution.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.5
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• pp.598-607
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• 2004

In this study, the effects of two pre-treatment processes were observed prior to membrane filtration: pre-coagulation and pre-ozonation. To compare the effect of two above-mentioned pre-treatments, we adopted the four schemes: first one is direct membrane filtration of river surface water, second one is membrane filtration after pre-coagulation, third one is membrane filtration after pre-ozonation and fourth one is membrane filtration after pre-coagulation and pre-ozonation. There are two exceptional characteristics in applied processes. One is the usage of the MF membrane which has high ozone resisting characteristic. Therefore, ozone resides in membrane module during filtration. The other is adoption of Jet Mixed Separator (JMS) as coagulation-sedimentation process. The change in transmembrane pressure and permeate water quality were also examined. As a result, considering the filtration performance efficiency and permeate water quality, the process composed of filtration with combination of both pre-coagulation and pre-ozonation was proved most effective. The improved efficiency was due to the reduction of loading rate of fouling inducing materials to membrane module by coagulation process as well as variable reactions, such as degradation, particle destabilization and coagulation, occurred by residual ozone in membrane module. The additional effect of pre-coagulation before pre-ozonation is suppression of AOC, one of the by-products induced by ozonation. Therefore, combination of pre-coagulation and pre-ozonation is the effective process to overcome the major de-merit of ozonation i.e. by-products formation.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.4 no.4
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• pp.56-63
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• 2001

This paper presents treatment efficiency and plant growth of a subsurface-flow constructed wetland system (23 m in length, 6.5 m in width, 0.65 m in depth) over one year after its establishment on floodplain of a stream in June 2000. An upper layer of 10 cm in depth was filled with course sand and the main biological layer of 50 cm depth with crushed stone with 8 - 15 mm in diameter. The system was planted with common reeds (Phragmites australis) grown on pots. Effluent discharged from a secondary-level treatment plant was funneled into it. Reed stems emerging in April 2001 grew up to 145.9cm until July 2001. The number of reed stems in July 2001 increased by about 11 times compared with that just after planting. The system was inundated seven times by storms over the monitoring period. Reeds were slightly bent after flooding, however they returned to almost upright standing in a couple of weeks. Small portion of inside slope of berm was eroded and the system surface had a sedimentation of 2 - 3 mm in depth. The average removal rates for SS, $BOD_5$, T-N and T-P was 73%, 70%, 53%, and 72%, respectively. The purification efficiencies for SS and $BOD_5$ were fairly good. The reduction rates for T-N was relatively low for the period of late fall through winter until early spring due to lower water temperature which retarded microbial nitrification and denitrification mechanisms. Reduction in the concentration of T-P during fall and winter was relatively higher than that during spring. Leach of phosphorous from plant litters lying on system surface and slight resuspension of precipitated phosphorous in substrates resulted in lower reduction for T-P in spring.

• Nutrition Research and Practice
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• v.2 no.3
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• pp.165-170
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• 2008

Protein-energy malnutrition is regarded as one of the public health problems in developing countries as a result of poor feeding practices due to poverty. This study, therefore, aimed at evaluating nutritional quality of a potential weaning food formulated from locally available food materials. The cooking banana fruit(CB) and bambara groundnut seeds(BG) were purchased from local market in Akure, Ondo State, Nigeria. The CB and BG were processed into flours, mixed in ratios of 90:10, 80:20, 70:30 and 60:40 and subjected into proximate, sensory and biochemical analyses using standard procedures. Nutrend(a commercial formula) and ogi(corn gruel, a traditional weaning food) were used as control. The nutritient composition(g/100 g) of the food samples were ranged as follows: moisture 2.94-6.94, protein 7.02-16.0, ash 1.76-2.99, fat 0.76-8.45, fibre 1.52-3.75, carbohydrate 63.84-88.43 and energy 1569.8-1665.7 kcal. The biological value(BV), net protein retention(NPR), protein efficiency ratio(PER) and feed efficiency ratio(FER) of the experimental food samples were significantly(p<0.05) lower than nutrend, but higher than ogi. The haematological variables of rats fed with formulated food samples, commercial formula(nutrend) and traditional weaning food(ogi) were not significantly(p>0.05) influenced by the dietary treatment. However, the values obtained for red blood cell(RBC), white blood cell(WBC), pack cell volume(PCV) and erythrocyte sedimentation rate(ESR) were higher in the experimental food samples than the commercial food. The growth rate of animals fed with experimental food samples were lower than those fed with the nutrend, but higher than those fed with ogi. In conclusion, the nutritional quality of CB and fermented BG mix of 60:40 ratio was better than ogi; and comparable to the nutrend. This implies that it can be used to replace low quality traditional weaning food and the expensive commercial weaning formula.

• Journal of Life Science
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• v.19 no.3
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• pp.373-377
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• 2009

Poliovirus, coxsackievirus, and ecovirus isolates from environmental sources were compared with laboratory strains to determine their removal rate in the water treatment process. The recovery efficiencies of poliovirus, coxsackievirus and echovirus using positive strains ranged from $72{\sim}108%$. Regarding virus removal efficiency in water treatment of pilot-plants, about 99% of all of the viruses were removed in the sedimentation step and 100% of viruses were clearly removed through post-ozonation and BAC filteration. Using six cell lines tested viral sensitivity in cell line and showed different sensitivity as viruses. Polioviruses showed higher sensitivity in the BGMK cell line than other cells, and coxsackieviruses were detected in higher level in the BGMK and Vero cell lines. On the other hand, the RD cell line was useful in the isolation of ecoviruses.