• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.36 no.2
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• pp.33-38
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• 2004

Toner particles used in laser and xerographic printing process is fused on paper surface so strongly that they tend not to detach easily from the recylced paper surface during pulping. Furthermore, the removal efficiency of detached toner particles by conventional screening and flotation process has limitation due to the platy shape and large size of detached toner particles. It has been shown that the removal efficiency of toners in the screening process can be increased by agglomerating the toner particles with fatty alcohol. It is not possible, however, to remove small and platy toner particles by screening process. These small and platy toner particles should be removed by flotation process. In this study the effect of fatty alcohol that used for toner agglomeration on flotation efficiency has been examined. It was shown that flotation efficiency decreased when fatty alcohol was used most probably due to its effect of reducing hydrophobicity of toner particles.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.2
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• pp.228-234
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• 2004

Dissolved air flotation (DAF), in which suspended solids are removed from water by means of micro-size air bubbles raising slowly up in water and lifting solids from water (smaller than those) attached onto the micro-bubbles as well as those (larger than solids) being attached on these, have been used in water and wastewater since 1920s. The dissolved air flotation technology was originally based on the laminar flow conditions prevailing in water to be treated, but the latest development in that technology has led now to a situation, in which the flow conditions may also be turbulent ones in the modem dissolved air flotation units. Despite of that, the flotation phenomenon used in this unit operation for removal suspended solids from water or wastewater is still the same.

• The KSFM Journal of Fluid Machinery
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• v.20 no.2
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• pp.41-46
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• 2017

The flotation performance of the induced gas flotation (IGF) machine is considerably influenced by geometric configurations of rotor and stator. The interaction of rotor and stator, which are the most important components in IGF, serves to mix the air bubbles. Thus, the understanding of flow characteristics and consequential analysis on the machine are essential for the optimal design of IGF. In this study, two-phase (water and air) flow characteristics in the forced-air mechanically stirred Dorr-Oliver flotation cell was investigated using ANSYS CFX. In addition, the void fraction and the velocity distributions are determined and presented with different blade configurations.

• Korean Chemical Engineering Research
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• v.59 no.2
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• pp.219-224
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• 2021

Ion flotation is an efficient method to remove metal ions from aqueous solution. In this work, ion flotation was applied to calcium removal from aqueous solution. The parameters used included sodium stearate (SS) and sodium dodecyl sulfate (SDS) as collectors, 1-butanol and 1-propanol as frothers, pH, and air-flow rate. An L16 orthogonal array was chosen according to the mentioned factors and levels, and experimental tests were conducted according to the Taguchi orthogonal array. The results showed that all of the factors except one had significant effect on the flotation performance. The percentage contribution of parameters showed that type of frother and type of collector made the greatest (43.14%) and the lowest (9.86%) contribution, respectively. In optimal conditions, the recovery of Ca (II) ion was 45.67%. Also, the results illustrated that the Taguchi method could predict calcium removal from aqueous solution by ion flotation with 2.63%. This study showed that the use of ion flotation was an effective method for Ca (II) ion removal from aqueous solution.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06a
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• pp.129-136
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• 2006

Although cleaner and cheaper deinking of ONP could be performed at the neutral or low alkaline condition excessive loss from froth-flotation is unavoidable and so reduction of alkali or caustic soda dosage sacrifices recycling yield. Now the new trade-off regarding alkali dosage versus flotation yield is urgently required in order to set the optimized neutral or low alkaline deinking process of ONP. Lipase from Thermomyces Lanuginosus has an effect on desizing and deacetylation reaction and it could be applied to the stock of pre flotation secondary stage in order to reduce the flotation reject without the sacrifice of optical properties of flotation accepts. Instead of inorganic base, lipase could be applied as a biochemical catalyst for the selective modification of valuable hydrophobic particles in deinking stock, for example cellulose fines and inorganic fillers covered by hydrophobic additives or contaminants. When the enzymatic hydrolysis of ester bond could be made on the surface of hydrophobic particulates, unwanted float of fine particles could be prevented. Now the enhancement of flotation selectivity or the modification of the hydrophobicity of deinking stock is expected to be promoted by the enzymatic pre treatment. And the reduction of recycling cost with the saves of raw material, recovered paper would be possible as a result.

• Journal of Environmental Science International
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• v.25 no.10
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• pp.1417-1426
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• 2016

Despite the low removal efficiencies reported by previous studies, electro-flotation still stands out among other microalgae removal methods for its economical and environmental benefits. To enhance removal efficiency, the important factors that limit the performance of this method must be investigated. In this study, the possible ways of increasing the removal efficiency of microalgae have been explored by investigating the effects of several important variables in electro-flotation. Eight parameters, namely flotation time, rising time, current density, pH, conductivity, electrode distance, temperature and initial concentration were evaluated using a one-parameter-at-a-time approach. Results revealed that the operational parameters that greatly affected the removal efficiency of microalgae were electro-flotation time, current density, pH, and initial concentration. The effect of conductivity, electrode distance, and temperature on removal efficiency were insignificant. However, they exhibited positive an indirect positive effect on power demand, which is nowadays considered an equally important aspect in the running of a feasible and economically efficient electro-flotation process.

• Journal of the Korean Professional Engineers Association
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• v.17 no.4
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• pp.50-55
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• 1984

• Journal of Korean Society of Environmental Engineers
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• v.31 no.9
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• pp.743-748
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• 2009

Chemical sludge conditioning is widely used to improve the dewatering efficiency. It is treated with commonly used conditioners, and then thickened and dewatered with a mechanical device. This paper aims to examine the flotation and thickening efficiencies of sewage sludge for conditioning conditions, such as unaerobic storage time, kinds of coagulant and dosages, and flotation conditions, such as sludge concentration and A/S ratio, using an dissolved air flotation apparatus. Experimental results showed that the specific surface area and specific resistance to filtration (SRF) were significantly increased and the flotation and thickening efficiencies were decreased with anaerobic storage time. However, the flotation and thickening efficiencies faintly decreased in sewage sludges conditioned as $Al_2(SO_4)_3$, $Fe_2(SO_4)_3$, and PSO-M. Flotation and thickening efficiencies in conditioned sewage sludge could be sustained up to 96% at A/S ratio of 0.01 mL/mg or over.

• 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.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2010.04a
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• pp.7-7
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• 2010

Flotation deinking is a common practice for removing ink from recovered paper, and it is becoming a key process in many recycling paper mills. Flotation deinking was successfully introduced to the paper recycling industry in the 1980s, and its applications in wax removal, stickies control, and fiber fractionation have attracted great research interest. A successful flotation process has three major efficient subprocesses: the detachment of the ink particles from the fibers, the effective adhesion of the ink particles onto air bubble surfaces, and the removal of froth and ink particles from flotation cells. Surfactants can affect these subprocesses either positively or negatively. To understand how a surfactant can positively and negatively affect the flotation deinking process, the basic chemistry of surfactant in solution should be discussed.