• Journal of Korean Society of Water and Wastewater
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• v.25 no.4
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• pp.471-478
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• 2011

A series of laboratory experiments carried out to investigate the particle separation efficiency and flotation characteristics using $CO_2$ bubbles. The primary objective of this study was to find out the feasibility of $CO_2$ bubbles as an applicable unit of flotation process in tap-water and wastewater treatment plant. The fundamental measurements were conducted to characterize the $CO_2$ bubble from the physical viewpoint in water including bubble size distribution and rising velocity under various operational conditions. In addition, the removal efficiency of solid was experimented using the lab scale plant applied $CO_2$ bubbles, namely the dissolved carbon dioxide flotation (DCF) process. The DCF process using carbon dioxide bubble, which is an advantage as the decrease and the reuse of Green-House gas, can be a promising technology as an water treatment process. On the other hand, the further research to decrease the bubble size distribution of $CO_2$ is required to enhance the particle separation efficiency.

• Journal of Korean Society on Water Environment
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• v.37 no.1
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• pp.10-19
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• 2021

In the flotation process to remove microplastic (MP) particles, the attachment and separation efficiency is determined by the basic physicochemical characteristics of MP particles as well as bubbles. To evaluate the flotation characteristics of MP particles, we carried out a series of simulations using the population balance (PB) model. The initial attachment coefficient (αo) of MP particles was in the range of 0.2-0.275, and it was slightly lower than that of typical particles, such as clay, debris and algae particles, which exist in water bodies, αo, 0.3-0.4. The relative bubble number (RBN) attached to the surface of the typical number of bubbles was 0.30 and 0.32 for MP 30 ㎛ and MP 58 ㎛, respectively. In comparison, the RBN of larger MP particles (138 ㎛) was as high as 0.53. Furthermore, smaller microbubbles were required to separate properly or additional treatment needed to be applied to enhance collision and attachment efficiency since the flotation of MP particles was found to be difficult to treat as high-rate. As a result of comparing the removal rate (experimental value) of MP particles obtained from the batch-type flotation apparatus and the flotation removal rate (predicted value) of MP obtained through the PB model, the final particles by the particle size of MP overall except for the initial separation time area. With respect to the removal efficiency, the observed and predicted values were similar, and it was confirmed that the floating separation characteristics and evaluation of the MP particles through the PB model could be possible.

• Korean Journal of Materials Research
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• v.16 no.8
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• pp.497-502
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• 2006

Recently, many attention have been focused on illite as a material for the well-being industry. Illite contains various kinds of iron bearing materials and they restrict their usage. In this study, Fe impurities in the illite produced in Yeongdong-gun, Chungcheongbuk-do were characterized and their removal experiments were performed. According to the characterization of illite raw ore, it contained 1.54 wt.%$Fe_2O_3$ due to the existence of iron oxide($Fe_2O_3$) and pyrite($FeS_2$). The raw ore was crushed into 3 mm or less using cone crusher and then ground by rod mill for the liberation of impurity mineral. For the removal of iron bearing minerals, an acid treatment, a flotation, a magnetic separation, and a flotation combined with magnetic separator were performed respectively. When the illite raw ore was treated with magnetic separation and various kinds of acid, 1.54wt.%. $Fe_2O_3$ content was reduced to 0.78 and 1.0 wt.%, respectively. On the other hand $Fe_2O_3$ content was reduced to be 0.52 wt.% after flotation. These results indicate that iron bearing minerals cannot be reduced below 0.3wt.%$Fe_2O_3$. However, combination of magnetic separation and flotation enable us to get 0.24wt.% of illite concentrate. It is concluded that, for the refinement of illite from Yeongdong-gun, the flotation combined with magnetic separation is good for high purity illite.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.5
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• pp.649-655
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• 2004

The behavior of biological particles in DAF (dissolved air flotation) process was analyzed by employing PBT (Population balance theory). After decline growth phase of activated sludge, the value of the initial collision-attachment efficiency was increased over than 0.35 corresponding relatively high value in the whole life cycle of microorganism. For practical application of DAF as a solid separation process. It is desirable that microbial particles should be operated to perform high solid removal efficiency in biological wastewater treatment.

• Resources Recycling
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• v.7 no.5
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• pp.26-32
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• 1998

Recycline of used plastics is rather restricted due to their variety and difficulties in their separation. In this study, a reliable and economical method for the separation of PVC which utilizes an appropriate control of surface chemistry of pariticles was suggested. this method consists of modification of PET surface from hydrophobic to hydrophilic by NaOH solution and subsequent separation by a froth flotation technique. Flotation results were in terms of NaOH concentration, digestion temperature and time, temperature and pH of solution, PVC concentration. They could be separated up to 95~100% by this method.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.5
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• pp.621-629
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• 2013

Since algae had been issued an environmental problem, water blooms, deepened due to increase of retention water basin in Korea as well as a biomass resource for producing biofuel, this study conducted a series of experiments for Spirulina platensis using the flotation process with micro-bubble. To elevate utilization of collected-algae, this study focused on omitting or minimizing coagulant's doses as changing a cultivation period and condition affected on physical property change of algae. Two coagulants, PAC and Chitosan, were used to test the collecting rate of algae and the result found no difference between two rates. For flotation experiments without adding the coagulant, dried algae weight (passing 14 days after cultivation for 20 days) detected high separation efficiency 98.2 % and it (passing 7 days after long-term cultivation for 28 days) presented good separation efficiency 91.9 %. Chlorophyll's separation efficiency showed a similar tendency with the case of the dried algae weight. In endogeny conditions, a light source and a carbon source were not considerably affected on the flotation separation efficiency. Thus, this study confirms that algae biomass may be collected without the coagulant during the endogeny condition period after enough cultivation time, 3 weeks.

• 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.20 no.4
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• pp.501-507
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• 2006

Dissolved air flotation (DAF) has been well known for the gravity separation process. The solids to be separated are transferred from the water body to the water surface using micro-air bubbles. DAF has also been used for enhancing solids-liquid separation of industrial and municipal wastewater by adding a its unit parallel to a sedimentation unit to reduce the hydraulic loading in the sedimentation clarifier. This study was to investigate flotation characteristics of activated sludge by the recent DAF technique without chemical agents. In addition, the effect on temperature in flotation of activated sludge and the thickening degree of activated sludge were studied.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.188-192
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• 2001

Magnetic separation and sulphidization-flotation for recovery of nickel and copper from two types of scraped condenser wastes, containing 8- l4% nickel and 2-4% copper, were studied. The effects of magnetic field intensities, classification, and grinding on the recovery of nickel and copper were investigated. According to the characteristics of nickel and copper in the scraps, classification-magnetic separation, different magnetic field intensities, and stages-grinding-cleaning of rough concentrate were investigated. The nickel concentrates containing 38-65% nickel with 84-97% recoveries and the copper concentrates containing 25-43% nickel with 35-60% recoveries were obtained by classification-magnetic separation. In addition, copper concentrates containing 26-45% copper with 76-88% recoveries were obtained by sulphidization-flotation from magnetic tailings and middling products.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.581-589
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• 2003

The variable flotation response ores from different deposits results basically from mineralogical association and their differences. Development of new techniques for analyzing the metallurgical performance of flotation and other concentration processes is demanded even in the treatment of rather simple ores such as porphyry ores. Diagnostic metallurgical analysis can be used to quantify the most possible recovery processes. Several porphyry copper/gold ores around the world were used to examine the responses in flotation, gravity separation and cyanidation in order to define the linkage between the recovery processes for both copper and old values. Laboratory batch flotation, gravity separation and cyanidation tests were carried out on these samples. All results were used to correlate the relative recovery of copper and gold, and to predict the highest possible metal recovery in the system. The metallurgical predictions were made according to the flotation conditions used and gravity separation. The results of various concentration processes on each porphyry ore samples are presented and discussed. All seven samples have shown significantly different gold/copper metallurgy. The grade/recovery relationships of gold and copper in the laboratory batch tests for the best results and the plants are given in the Figures below. The results of laboratory tests show that the copper recoveries converged to about $90\%$, but the gold recoveries were spread over $55-80\%$, except the K S ore. Series of standard cyanidation tests on the flotation concentrate samples and gravity separation using Knelson Separator on heads ores were carried out to cross-link the metallurgy and mineralogy of gold in the porphyry ores.