• Journal of Korea Water Resources Association
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• v.35 no.2
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• pp.213-220
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• 2002

This reserch was focused upon experimental study for wastewater reuse and conducted to evaluate optimum operating conditions of rapid filtration process such as filter flow rate, filtration time and backwashing condition for reuse of secondary-treated effluent using the pilot plant installed in real wastewater treatment plant. Also, the experiment on treatment char-acteristics of coagulant-added activated sludge process was performed to compare with activated sludge succeeded to rapid filtration. As the filtration velocity was 100m/day, the filtration time of the rapid filter connected with activated sludge system was revealed to 40 hours. Backwashing of filter was conducted by water wash and air scour. The optimum backwashing time and backwash flow rate were 10min and 10LPM, respectively. The quantity of backwashing water of the rapid filter was about 2% of total treated water.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.07a
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• pp.57-68
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• 2004

A demonstrative operation of a membrane system with its caparity of 3,600m$^3$/d was carried out using reservoir water as raw water for the application of membrane filtration system to drinking water treatment. The operation was undertaken at a constant flux of 0.9 m$^3$/m$^2$/d for three months. Backwashing with NaClO of 3 ppm was allowed for 30 seconds every 20 minutes of filtration. Physical cleaning was introduced after 69 times of filtration/backwashing cycle with air-scrubbing and backwashing for 1 minute, and flushing for 2 minutes. In this study, water treatment performance was investigated compared with the existing rapid sand filtration process. The membrane system was operated with no significant problems during the test period. Higher water quality was obtained in the membrane filtration than in the rapid sand filtration in terms of particulate matters such as turbidity and microbes. Although the finished water of the membrane filtration contained slightly higher concentration in dissolved matters than that of the conventional one, it met the drinking water standard. The demonstrative operation showed that membrane filtration has a reliability in drinking water treatment. Researches should be needed on cost analysis through long-term operation and optimization of operation condition for further application.

• Journal of Environmental Health Sciences
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• v.22 no.3
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• pp.103-115
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• 1996

The purpose of this study was to establish acceptable criteria for the design of simple water treatment plant in rural areas. To develop efficient simple water treatment methods for rural areas, water quality in the study areas was investigated and rapid and slow filtrations in pilot-scale were tested under various conditions. The main results of this study are as follows. It was found that the water qualities of the study areas exceed the drinking water standards, which implies that some treatments are required in rural areas. Treatment efficiencies of both rapid sand and dual-media (sand and anthracite) filtration without pre-treatment such as flocculation and sedimentation are very low, which were turned out to be unadequate for the rural areas. Treatment efficiencies of both vertical and horizontal slow filtration without chlorination are very high for consumed $KMnO_4, NH_3-N, NO_3-N$, turbidity, and very low for coliform and bacteria. Treatment efficiencies of both vertical and horizontal slow filtration with chlorination are very high over the most pollutants. A slow filtration with chlorination is efficient for the rural areas. An adequate depth of sand layer is over 60 cm. A horizontal filtration is more economical than a vertical filtration. A horizontal filtration can be operated for a relatively long periods of time without sand washing or replacement because clogging is removed by simple back-washing.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.3
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• pp.359-366
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• 2007

Slow sand filtrations have been widely used for water treatment in small communities, however their capacity is often limited by high turbidity in the raw water. For this reason, several pre-treatment facilities were required for a slow sand filter. Turbidity removal from the highly turbid raw water was investigated in roughing filters as a pre-treatment process. The roughing filters followed by rapid mixing tank were operated in the form of a contact filtration. In several jar tests, the predetermined optimum aluminium sulfate (alum) doses for turbid water of 30 and 120NTU were 30 and 50mg/L, respectively. At the optimum alum dose, physically optimum parameters including G value of $220sec^{-1}$ and rapid mixing time of 3 minutes were applied to the contact filtration system. Without addition of alum, the filtrate turbidity from the roughing filters, packed respectively with different media such as sand, porous diatomite ball and gravel, was in the range of 5~30NTU at filtration velocities of 30 and 50m/day. However, the application of a contact filtration to roughing filters showed stably lower filtrate turbidity below 1.0NTU at filtration velocity of 30 m/day. Although the filtration velocity increased to 50m/day, filtrate turbidity was still below 1.0NTU in both single and double layer roughing filters. At influent turbidity of 120NTU, the filtrate turbidity was over 5 NTU in the triple layer roughing filter, which shortened the filter run time. The flocs larger than $10{\mu}m$, formed in the rapid mixing tank, were almost captured through the roughing filter bed, while the almost flocs smaller than $10{\mu}m$ remained in filtrate.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.2
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• pp.254-269
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• 2004

Polysilicato-iron coagulant (PSI) is receiving attention in Japan as a substitute for aluminum-based coagulants. In the first part of this article, coagulation, sedimentation and filtration experiments were carried out using kaolin clay particles as the turbidizing material and four types of PSI with various molar ratios of polysilicic acid to ferric chloride (Si/Fe ratio). Results demonstrate that use of a PSI with a high Si/Fe ratio can cause a more dramatic decrease in treated water turbidity but a higher suction time ratio (STR) than when PACl is used. However, optimization by increasing the rapid agitation strength GR is found to greatly improve the STR. In addition, the series of filtration experiments verified that optimization of GR is greatly effective in controlling rapid increases in filter head loss, and also formation of a thin aging layer in the upper part of the filter bed by slow-start filtration is effective in improving filtered water turbidity over the entire filtration process. The second part of this article describes two innovative filtration techniques to increase the particle separation efficiency; (1) coagulant-coated filter medium by enhancing the electrical potential of the surface of the filter medium, and (2) coagulant dosing in influent by controlling the electrical potential of particles entering the filter layer. From the results of the various filtration experiments using a pilot plant, these two techniques were found to be very effective to reduce the effluent water turbidity from the start to the end of a filter run. Moreover, in the filtration experiments using these two methods simultaneously, higher removal efficiency of approximately 3-log (99.7%) was realized, resulting that the finished water turbidity was accordingly reduced to 0.004mg/L.

• Journal of Korean Society on Water Environment
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• v.20 no.6
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• pp.652-656
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• 2004

Both surface wash and backwash are considered as one of the most important methods that can improve the filtration efficiency in the existing water treatment plant. This study has mainly focused on the improvement of filtering efficiency by controlling surface wash and backwash time, and water level before backwash (when drained up to the trough, when drained up to 10 cm above filter bed, and when drained below 10 cm filter bed). Filtration efficiency was shown a little bit of differences depending on the operating conditions like surface wash injection pressure, the distance control between filter bed and the facility, and the types of surface wash. When the water level before backwash was reached up to 10 cm below filter bed after draining, however, the filtration velocity and the turbidity removal efficiency in the filter bed was improved. When the surface wash followed by backwash is longer, it showed a similar result. Because the proper adjustment of surface washing time makes filtration efficiency higher, therefore, it is necessary to set up the backwash time moderately.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.2
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• pp.203-214
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• 2007

This study aimed at researching the process selection for two-stage and dual media filtration system, as a technology substituting the existing sand filter without expanding the site when retrofitting an old filter bed or designing a new one. In order to select the process for optimum complex filtration system, three running conditions have been tested. Test results demonstrated that Run 3 in which the 1st stage was filled with anthracite and coarse sand, and the 2nd stage was filled up with activated carbon and fine sand reduced the head loss and the load of turbidity substances. Also, Run 3 showed better performance in removing TOC, particle counts, THMFP and HAAFP, compared to other two conditions. 99 % of Cryptosporidium was removed. Bisphenol-A was rarely removed from the 1st stage of coarse sand and 2nd stage of fine sand, but 99 % of it was removed from the 2nd stage of activated carbon. In conclusion, when it is required to retrofit an old rapid filter bed or design a new one for the purpose of improving filtration performance, the following two-stage and dual media filtration system is suggested: the 1st stage of filter bed needs to be filled up with coarse sand to remove turbidity as the pretreatment for extending duration of filtering, the top part of 2nd stage needs to be filled up with granular activated caron to remove dissolved organic matters and others as the main process, and finally the bottom part of 2nd stage needs to be filled up with fine sand as the finishing process.

• Journal of Korean Society of Water and Wastewater
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• v.14 no.3
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• pp.260-270
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• 2000

The objective of this study is to evaluate the effect of filter aids in the dual-media rapid filtration. Paper-filter tests were conducted to determine the proper dosages of coagulant and filter aid, and pilot plant tests using two dual-media filter columns were performed for a variety of filtration rates. Using a filter aid (non-ionic polymer), the maximum feasible filtration rate is 480m/day, while turbidity is less than 0.3 NTU and filter run-time is about 70 hours. It is possible to increase the filtration rate up to 360 m/day for keeping the turbidity less than 0.1 NTU. Turbidity increases for the filtration rate greater than 360m/day. In general, the quality of filtered water with a filter aid is stable, while the filter maintains a sufficient filter run-time for a maximum allowable head loss. Particularly, the initial breakthrough can be effectively controlled. The use of a filter aid may be one of the methods applicable if the turbidity of filtered water is required to be improved or if the filter breakthrough limits filter run-time.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.3
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• pp.341-349
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• 2010

It is well known that manganese is hard to oxidize under neutral pH condition in the atmosphere while iron can be easily oxidized to insoluble iron oxide. The purpose of this study is to identify removal mechanism of manganese in the D water treatment plant where is treating bank filtered water in aeration and rapid sand filtration. Average concentration of iron and manganese in bank filtered water were 5.9 mg/L and 3.6 mg/L in 2008, respectively. However, their concentration in rapid sand filtrate were only 0.11 mg/L and 0.03 mg/L, respectively. Most of the sand was coated with black colored manganese oxide except surface layer. According to EDX analysis of sand which was collected in different depth of sand filter, the content of i ron in the upper part sand was relatively higher than that in the lower part. while manganese content increased with a depth. The presence of iron and manganese oxidizing bacteria have been identified in sand of rapid sand filtration. It is supposed that these bacteria contributed some to remove iron and manganese in rapid sand filter. In conclusion, manganese has been simultaneously removed by physicochemical reaction and biological reaction. However, it is considered that the former reaction is dominant than the latter. That is, Mn(II) ion is rapidly adsorbed on ${\gamma}$-FeOOH which is intermediate iron oxidant and then adsorbed Mn(II) ion is oxidized to insoluble manganese oxide. In addition, manganese oxidation is accelerated by autocatalytic reaction of manganese oxide. The iron and manganese oxides deposited on the surface of the sand and then are aged with coating sand surface.

• Bulletin of the Korean Chemical Society
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• v.29 no.2
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• pp.352-356
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• 2008

An analytical method has been developed for measuring chlorostyrenes in fish tissue sample. Extraction of chlorostyrenes from fish tissue was carried out by ultrasonication using acetone/n-hexane (5:2, v/v) mixture. Most of the lipids in the extract were eliminated by freezing-lipid filtration, prior to solid-phase extraction (SPE) cleanup. During freezing-lipid filtration, about 90% of the lipids extracted from the fish samples were easily removed without any significant losses of chlorostyrenes. For purification, SPE using Florisil was used for the rapid and effective cleanup. Quantification was performed using gas chromatography-mass spectrometry in the selected ion monitoring mode. Spiking experiments were carried out to determine the recovery, precision, and limits of detection (LODs) of the method. The overall recovery was above 80% in the spiked fish tissue sample at 10 and 100 ng/g levels, respectively. The detection limits for chlorostyrenes were ranged from 0.05 to 0.1 ng/g. This developed method is demonstrated to give efficient recoveries and LODs for detecting chlorostyrenes spiked into fish tissue with high lipid content.