• Journal of Korean Society of Environmental Engineers
• /
• 제33권6호
• /
• pp.447-452
• /
• 2011

In this study, the polymeric membrane module is used as a diffuser and an image analysis technique based on visual information is applied to get bubble characteristics. The bubble size generated passed through polymeric membrane module was smaller from 30 to 64% than that of air stone, and bubble volume over 70% was ranged from 0.2 to 0.82 mm. But over 80% the bubbles from air stone diffuser ranged from 0.77 to 1.08 mm. The air stone and polymeric membrane module used as diffuser for a flotation system. The floc size inside the flotation reactor using air stone diffuser was bigger than that of the polymeric membrane module, which means that the micro-bubbles generated from polymeric membrane module could provide better opportunities for collisions between colloidal particles than those from air stone diffuser. Therefore, there is a possibility to apply the polymeric membrane module as a diffuser to increase the removal efficiency in the flotation process. Also, the image analysis technique used in this study could be applied as a useful analytical tool for acquisition of an information about the bubble characteristic.

• Journal of Environmental Science International
• /
• 제23권1호
• /
• pp.97-104
• /
• 2014

The sludge flotation/thickening apparatus equipped a micro-bubble generating pump was used to investigate micro-bubble generating properties on operational parameters. We evaluated micro-bubble generating properties as results to be operated the apparatus by operational parameters which are pump discharge pressure, air/water ratio(A/W ratio), air flow rate, and water flow rate. Micro-bubble generating efficiencies in pumps without recycling flow and with 50% of recycling flow was found to be very efficient on optimum A/W ratio from 1.06 to 3.62% and optimum A/W ratio from 1.05 to 4.06%, respectively. In condition of 3.6% of A/W ratio, we showed that the apparatus could be generated 36,000 ppm of micro-bubble concentration to be optimum treatment efficiency in sludge thickening process.

• Journal of Korean Society of Water and Wastewater
• /
• 제20권2호
• /
• pp.303-309
• /
• 2006

Yongdam reservoir located in Jeoliabuk-do has had a lot of concerns for its algal blooming since it has started to fill water. Many water utilities near Yongdam area use reservoirs even though they have some problems with certain algae that cause tastes and odors and clog filters. In this research, dissolved air flotation (DAF) technology was examined for feasibility for removal of algae. OAF can save the capital cost for its compactness, because its hydraulic loadings (overflow rates) are 10 times higher than sedimentation, and hydraulic detention times are much shorter, typically 5 to 15 minutes. As a result of this research, PAC is effective rather than Alum to DAF for pretreatment. Higher DOC plays an important role to change zetapotential negatively to inhibit destabilization of particle to coagulation. The length of pipeline to carry pressurized water into reactor does not affect reaction.

• Resources Recycling
• /
• 제22권6호
• /
• pp.64-72
• /
• 2013

The purpose of this study is to confirm the possibility of obtaining high grade coal from 57.39% of fixed carbon fine coal. Also, the mineralogical, physical/chemical and liberation characteristics are to be identified to decrease in ash amount, during the pre-processing of clean coal technology. In this study, batch flotation and CPT column flotation proper for the processing of fine particles were used with the variation in kinds and quantity of frother, collector and depressant. Also air flow rate and feeding rates were examined. As a result of batch flotation using 20% of pulp density DMU 101 collector(100 mL/ton), AF65 frother(300 mL/ton), sodium metaphosphate depressant (1 kg/ton), 67.57% of ash rejection and 70.90% of combustible recovery were obtained. The result of CPT column flotation was 85.59% of ash rejection and 88.97% of combustible recovery under the conditions of 5% of pulp density, DMU-101 collector (100 mL/ton), AF65 frother(10 L/ton), SMP depressant(1 kg/ton), wash water(100 mL/min.) and air flow rate(1,200 mL/min.).

• Economic and Environmental Geology
• /
• 제35권6호
• /
• pp.581-588
• /
• 2002

• Journal of the Korean GEO-environmental Society
• /
• 제11권8호
• /
• pp.25-32
• /
• 2010

Contamination of soil and groundwater by the compounds of hydrocarbon petroleum has been widely accepted as the main cause that harms the environments and health. To remove those pollutants, absorbing clothes, activated carbons, or oil-water separation devices with the gravity method are employed for treatment. However, those materials and devices cannot remove the emulsion pollutants despite of their efficiency for removing free products. Therefore, we investigated the problems which occur during the groundwater treatment for the highly concentrated suspended solid particles, which can be resulted from excavation, and to propose methods to remove TPH(Total Petroleum Hydrocarbon). After coagulation experiment with high molecular polymers, the concentration of SS(Suspended Solids) and COD(Chemical Oxygen Demand) turned to satisfy the groundwater quality criteria within 5 minutes while the concentration of TPH failed to meet the water quality standard of effluent. Consequently, the water quality criteria for effluent could not be met by single DAF(Dissolved Air Flotation) process. However all water quality criteria could be satisfied after 20 minutes when coagulation reactions are carried out simultaneously in the DAF reactor.

• Journal of Korean Society on Water Environment
• /
• 제23권6호
• /
• pp.837-842
• /
• 2007

This study was conducted to test the effect of residual Al on plankton community after dissolved air flotation (DAF) application. Growth rate of phytoplankton after DAF application ($0.37day^{-1}$) was about 2 times lower than that before DAF application ($0.70day^{-1}$). Under the condition of addition of nitrogen and phosphorus without light, growth rate phytoplankton in treatment without residual Al increased in difference with showing the negative growth rate in treatment with residual Al. Under the condition of light without addition of nutrient, growth rate of phytoplankton was no noticeable difference between the before and after DAF application. The relatively high settling rate (0.47 m/day) was observed in treatment after DAF application. Although the abundance of rotifer decreased, the abundance of copepod and cladoceran such as Daphnia galeata, Diaphanosoma sp. and Bosmina longirostris with relative higher grazing was no noticeable difference between the before and after DAF application. In the treatments before and after DAF application with zooplankton, growth rate of phytoplankton was $0.41{\pm}0.08day^{-1}$, $0.20{\pm}0.03day^{-1}$, respectively. This difference was in treatment after DAF application similar with those in treatments before and after DAF application without zooplankton. Those indicate that the filter-feeding effect of zooplankton on phytoplankton community may be not changed by residual Al after the DAF application. These results suggest that residual Al after DAF application be to improve water quality by inhibition of growth rate as well as increasing settling rate of phytoplankton.

• Journal of Korean Society of Environmental Engineers
• /
• 제30권7호
• /
• pp.743-750
• /
• 2008

In water treatment plant the Dissolved Ozone Flotation(DOF) System may be employed because this system has various abilities, such that it can remove SS using microbubbles, and it can exert strong oxidation power in removing taste and odor, color, and microbial agents. In order to investigate effectiveness of the DOF system in water treatment, removal characteristics of various water quality parameters were observed depending on the different levels of ozone concentrations. Removal efficiencies of water quality parameters in DOF system were compared with those in DAF(Dissolved Air Flotation) system and in CGS(Conventional Gravity Settling) system. Optimum ozone dose obtained in the pilot experiments was 2.7 mg/L. With increasing ozone dose higher than 2.7 mg/L, removal rates of turbidity, KMnO$_4$ consumption, UV$_{254}$ absorbance, and TOC were reversely lowered. High concentration of ozone dissociate organic matter in water, so that increasing dissolved organic level in effluent. Removal rates of water quality parameters at optimum ozone dose were obtained, such that removal rates of turbidity, KMnO$_4$ consumption, TOC, and UV$_{254}$ asorbance were 88.9%, 62.9%, 47%, and 77.3% respectively. Removal rate of THMFP was 51.6%. For all the parameters listed above, the DOF system was more effective than the DAF system or the CGS system. It is found that the DOF system may be used in advanced water treatment not only because the DOF system is more efficient in removing water quality parameters than the existing systems, but because the DOF system is also required smaller area than the CGS system for the treatment plant.

• Journal of Korean Society of Environmental Engineers
• /
• 제31권1호
• /
• pp.58-63
• /
• 2009

Dissolved air flotation (DAF) process is generally considered more effective than sedimentation process in raw water containing algae, humus materials, and low density particles. This study presents the treatment efficiencies by the coagulation and flocculation conditions at a drinking water treatment plant using a laboratory tester and the full scale DAF pump system. The full scale DAF pump system (F-DAF) in this study had a capacity of 5,000 $m^3$/d and a hydraulic surface loading of 10 m/hr. F-DAF in D drinking water treatment plant was continuously operated to determine the operational performance and pretreatment (mixing and coagulation) conditions. Results in the laboratory experiment showed that the optimum coagulant (PSO-M) doses required to 2.7~4.5 mL/$m^3$/NTU with raw water turbidity from 13.8 NTU to 56.3 NTU. F-DAF in the optimum coagulant dosage could be operated in effluent turbidity of 1 NTU or below for a month.

• Journal of Korean Society of Water and Wastewater
• /
• 제19권4호
• /
• pp.421-428
• /
• 2005

Dissolved air flotation (OAF) is a solid-liquid separation system that uses fine bubbles rising from bottom to remove particles in water. In this study, we investigated the effect of L/W (L; Length, W; Width) on the hydro-dynamic behavior in DAF system using CFD (Computational Fluid Dynamics) and ADV (Acoustic Doppler Velocimetry) technique. The factual full-scale DAF system, L/W ratio of 1:1, was selected and various L/W ratio (2:1, 3:1, 4:1 and 5:1) conditions were simulated with CFD. For modelling, 2-phase (gas-liquid) flow equations for the conservation of mass, momentum and turbulence quantities were solved using an Eulerian-Eulerian approach based on the assumption that very small particle is applied in the DAF system. Also, for verification of CFD simulation results, we measured the factual velocity at some points in the full-scale DAF system with ADV technique. Both the simulation and the measurement results were in good accordance with each other. As the results of this study, we concluded that L/W ratio and outlet geometry play important role for flow pattern and fine bubble distribution in the flotation zone. In the ratio of 1:1, the dead zone is less than those in other cases. On the other hands, in the ration of 3:1, the fine bubbles were more evenly distributed.