• Journal of Korean Society of Water and Wastewater
• /
• v.20 no.4
• /
• pp.617-626
• /
• 2006

Compared with the sludge from gravity sedimentation, it is difficult for operations to settle the sludge occurred from dissolved-air-flotation (DAF). Even though there are some problems in treating DAF sludge with conventional gravity thickeners, those has been used until now. In this study, Solid Flux theory for gravity thickening was applied to the Solid Flux of DAF sludge through flotation in order to develop new methodology for treatment of DAF sludge. Also, characteristics of DAF sludge were investigated. From the experiment results, it was revealed that the higher the polymer dosage, at fixed the solid concentration, the greater the rising velocity becomes. When we applied solid flux theory, the relationship, which is similar to that of gravity thickening, has been achieved. Also, we could find the proper polymer dosage from the rising velocity is about 50 mg/L. Consequently, the limiting solid flux can be derived from the relationship between the total solid flux and the withdrawal velocity of DAF sludge. Furthermore, the factors, such as solid concentrations, bubble volume, pH, zeta potential, and temperature, have effects on the flotation and sedimentation for DAF sludge treatment.

• Journal of Korean Society of Water and Wastewater
• /
• v.22 no.6
• /
• pp.627-632
• /
• 2008

It is necessary to investigate methods for improvement by diagnosing sludge settling characteristics on inflow of slurry to thickener. The results of the settling tests are correlated to determine zone settling velocities at the various sludge solids concentrations. Conditioning of WTP residuals is generally done by either chemical or physical treatment. The settling test was conducted with 1m columns dosing polymer to WTP residuals at various solids concentration. The estimated results for dosing to WTP residuals for a sludge of 2,100 ~ 16,012 mg/L solids concentration were the zone settling velocities of 48.38 ~ 6.8 m/day, supernatant solid concentration of 3.2 ~ 19 mg/L and solid flux of $101.6{\sim}317.61kg/m^3{\cdot}day$. The values for non-polymer treatment were the zone settling velocities of 28.37 ~ 0.12 m/day, supernatent solid concentration of 8.5 ~ 108 mg/L and solid flux of $59.58{\sim}1.92kg/m^2{\cdot}day$. The limiting solid flux value by Yoshioka methods was $4.0kg\;TS/m^3{\cdot}day$ for Non-polymer and $228.0kg\;TS/m^3{\cdot}day$ for dosing polymer. These results are to indicate a possibility of improvement on the thickening characteristics and the quality of supernatant as increasing the settling velocities by dosing polymer to WTP residuals.

• Journal of Korean Society on Water Environment
• /
• v.25 no.5
• /
• pp.764-767
• /
• 2009

For a more effectively designed gravity thickener, thickening experiments were conducted for residuals produced by a ceramic membrane water treatment plant (WTP). Two kinds of residuals, one from backwashing (BW) and the other from chemically enhanced backwashing (CEB) procedure, were separately collected during a pilot plant experiment and their limiting solid flux ($SF_L$) measured. Batch thickening experiments showed that the BW and CEB residual had $SF_L$ of 10 and $25kg/m^2{\cdot}d$, respectively. Continuous operation of a pilot-scale gravity thickener proved that a mixed BW and CEB residual could be successfully thickened at the solid loading rate (SLR) of $12kg/m^2{\cdot}d$, allowing the concentration of the thickened residual to be about $15kg/m^2{\cdot}d$. From the experimental results and consideration of the seasonal thickening characteristics of the residual, SLR of $15kg/m^2{\cdot}d$ was proposed as a design parameter for full-scale gravity thickeners.

• Journal of Korean Society on Water Environment
• /
• v.28 no.1
• /
• pp.109-114
• /
• 2012

In this study, both sedimentation and thickening experiments were conducted for residuals produced from an advanced water treatment plant for more accurate and practical design of residual treatment train. In order to design a backwashed residual sedimentation basin (SRSB) in the filter backwash water recycle system, two kinds of backwash waters, one from sand filter (SFBW) and the other from GAC adsorption bed (GACBW), were separately collected and their surface loading rate measured. In addition, in order to design a gravity thickener, batch thickening tests were conducted for concentrated residuals taken from sedimentation basin and their limiting solid flux ($SF_{L}$) measured. From the experimental results and consideration of the seasonal characteristics of the residual, surface loading rate of $70m^{3}/m^{2}{\cdot}d$ was proposed as a design parameter for SRSB and solid loading rate of 20 kg $TS/m^{2}{\cdot}d$ was proposed as a design parameter for gravity thickeners. Finally, the material mass-balance was made for the design of each unit process in the residual treatment train.

• Journal of the Korean Professional Engineers Association
• /
• v.32 no.2
• /
• pp.99-109
• /
• 1999

The dried sea tangle added for soup prepatation to improved the taste in Korean and Japaness for long time. Attempts were made to develop the best procedures for extraction and removal of alginate by ultrafiltration and diafiltration. The summerized results of this study are as follows: 1) For hot water extraction in temperature range of 60～100$^{\circ}C$ for 4 hours, the higher temperature resulted higher yields in solids and protein. 2) Optimum sea tangle hot water extraction condition were 60～65$^{\circ}C$ for 1 hour which was cheap operating cost and high yield of good taste components. 3) The membrane flux was more higher GR 51 PP. and increase of flow rate permeate flow rate was accordingly increased. but limiting flow volume was 3.7 l/min. 4) It was found that ultration was relatively of higher recovery rate, solid and taste components, and low rejection coefficient rate than diafiltration.

• Journal of Korean Society of Environmental Engineers
• /
• v.22 no.7
• /
• pp.1285-1294
• /
• 2000

In this study, we investigated the possibility of the elimination of suspended solid and the factors affecting effluent water quality, and the amount of treated water, using the SS removal equipment adapted capillary-syphon phenomenon. Treated water quantity decreased as the accumulation time and the increase of head of capillary syphon, whereas the effluent water quality was improved. At coagulant dosage 0, 0.45, $1.82mg/{\ell}$ (as $Al^{+3}$) and limiting flux $107{\ell}/m/day$. turbidity of treated water was 2, 1, 0.5 NTU in each case. During operating period 15~17 days, the amount of washing water was just used 0.5~0.7% of the amount of treating water. So it is expected that coagulation & sedimentation and rapid filtration process can be replaced with the SS removal equipment adapted capillary-syphon phenomenon in water purification process.

• Journal of Korean Society of Environmental Engineers
• /
• v.30 no.9
• /
• pp.948-954
• /
• 2008

Membrane bioreactor(MBR) processes have been widely applied to wastewater treatment for last decades due to its excellent capability of solid-liquid separation. However, membrane fouling was considered as a limiting factor in wide application of the MBR process. Excess aeration into membrane surface is a common way to control membrane fouling in most MBR. However, the excessively supplied air is easily dissipated in the reactor, which results in consuming energy and thus, it should be modified for effective control of membrane fouling. In this study, cylindrical tube was introduced to MBR in order to use the supplied air effectively. Membrane fibers were immersed into the cylindrical tube. This makes the supplied air non-dissipated in the reactor so that membrane fouling could be controlled economically. Two different air supplying method was employed and compared each other; nozzle and porous diffuser which were located just beneath the membrane module. Transmembrane pressure(TMP) was monitored as a function of airflow rate, flux, and ratio of the tube area and cross-sectioned area of membrane fibers(A$_m$/A$_t$). Flow rate of air and liquid was regulated to obtain slug flow in the cylindrical tube. With the same flow of air supply, nozzle was more effective for controlling membrane fouling than porous diffuser. Accumulation of sludge was observed in the tube with the nozzle, if the air was not suppled sufficiently. Reduction of membrane fouling was dependent upon the ratio, A$_m$/A$_t$. For diffuser, membrane fouling was minimized when A$_m$/A$_t$ was 0.27, but 0.55 for nozzle.