• Journal of Korean Society of Water and Wastewater
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• v.19 no.1
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• pp.78-91
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• 2005

Performance limiting factors (PLFs) derived from 161 drinking water treatment plants (DWTPs), assessed by International Technical Diagnosis & Assistance Center, were analyzed and evaluated in more detail in this study. In order to conduct study, 161 DWTPs were divided into five categories depending on their capacity, and into twelve groups according to processes and facilities. From the results of analysis, PLFs and their distribution ratio derived from each category were significantly different. Filtration was the most important performance limiting process in all DWTPs of five categories, and the PLFs in filtration were backwashing velocity, media configuration, bed depth, and formation of mud-ball. The PLFs in coagulation-flocculation process were found out to be coagulant dosage, mixing speed, mechanical problems, and others in the order of frequency of occurrence. Also, insufficient disinfection ability that is resulted from insufficient hydraulic detention time and improper chlorine dose and injection point, is the most significant among PLFs in a clear well. In the case of sedimentation, inappropriate baffle structure and excessive upward velocity were PLFs. In addition, the results showed that high turbid water and low alkalinity in a rainy season, ferric and manganese ions, and ammonia nitrogen have been contributed significantly on the performance of DWTPs.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.1
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• pp.38-46
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• 2005

In this research, we tried to combine the coagulation/sedimentation process as pre-treatment with UF membrane filtration to reduce the membrane fouling and to improve the permeate water quality. We used the Jet Mixed Separator (JMS) as coagulation/sedimentation process. We observed that the HPC and E.Coli can't be removed through the direct UF memebrane filtation of surface water. The removal efficiency of dissolved organic substances, indicated by E260 and DOC, was 40% and 15%, respectively. However, the removal efficiency of it increased two time as a result of combination of JMS process as coagulation/sedimentation pre-treatment. This was resulted from the formation of high molecular humic micro-floc through JMS process. The accumulation amount of irreversible cake layer which was not removed by backwashing was less than direct UF membrane filtration of surface water. Moreover, the loading rate of fouling induced substances, such as humic substances and suspended substances, on membrane surface decreased drastically through JMS process. As a result, the accumulation amount of irreversible cake on membrane surface was decreased.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.5
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• pp.565-571
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• 2005

The method to decide media sphericity on the filter has been investigated. The sphericity, the ratio of the surface area of an equal volume sphere to the real surface area of the particles, is one of major physical characters of media affecting the bed expansion during backwash. The media in each treatment plant may have different sphericity, and the sphericity of the media in the filter may be changed as backwashing has been conducted regularly for a long time. Media from twelve water treatment plants under KOWACO have been collected and selected to insure various and practical sphericities. The sphericity of each media has been calculated by using well known equations. For example, Kozeny equation, Dahmarajah equation and so on. The experiment results have indicated that the sphericity of each water treatment plant is different. Although the sphericity values measured by different methods were turned out to be diverse values, the order in the magnitude seemed to be the same. The sphericity values of sand media were in the range of 0.71-0.82 and those of anthracite were placed between 0.49 and 0.56 by the Dharmarajah equation.

• Journal of Environmental Science International
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• v.25 no.7
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• pp.999-1005
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• 2016

The H water treatment plant has been operating since 1982 and has had no renovation. It is assumed that the filters have been operated for more than 30 years and therefore are deteriorated. Many of the filters show an unequal state of air scouring during backwashing. For this study one filter, which was presumed most deteriorated among eighteen filters, was selected as a model filter for renovation. Some of the effects seen after renovation of the underdrain system were a lower average filtrated turbidity by approximately 0.02 NTU and an equal backwash state throughout the filter bed. Sand wash efficiencies by backwash before renovation of the underdrain system were 28%, 8%, and 5% at the surface, 50 cm depth, and 100 cm depth, respectively, and after renovation of the underdrain system were 94%, 26%, and 15%, respectively. The standard deviation of the effective sand size was 0.025-0.033 mm before renovation of the underdrain system and 0.002-0.011 mm after renovation of the underdrain system, meanings there was equal backwash pressure throughout the filter. Filtration time after renovation was approximately 2 times longer than before renovation.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.6
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• pp.573-580
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• 2005

This study was to investigate the removal characteristics of toluene in a gas stream by using a biotrickling filter packed with zeolite-contained polyethylene media. The specific surface area and the void fraction of the media were $500\;m^2/m^3$ and 82%. The surface roughness of the media was higher than that of pure polyethylene media. The toluene removal efficiency decreased with increasing the inlet toluene concentration and gas flow rate. The maximum elimination capacity of toluene in the biotrickling filter was $64\;g/m^3{\cdot}hr$. During 200 days operation, toluene removal efficiency was maintained from 90% to 98% until 167 days, hereafter, it was rapidly reduced with a rise in pressure drop due to an excess proliferation of biomass on the media. Pressure drop and removal capability of the biotrickling filter was fully recovered after backwashing.

• Environmental Engineering Research
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• v.21 no.3
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• pp.311-317
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• 2016

A new type of biofilter packed with composite carriers was designed for tertiary denitrification of the secondary effluent with removal of both oxidized nitrogen and suspended solids (SS). At the empty bed residence time of 15 min and organic carbon to nitrate nitrogen ($C/NO_3-N$) ratios of 2, 1.5 and 1 g/g, the removal percentage of $NO_3-N$ was 67%, 58% and 36% in the ethanol biofilter, and was 61%, 43% and 26% in the acetate biofilter, respectively. The biofilters packed with composite carriers removed SS effectively, with the effluent turbidity in both biofilters of less than 3 NTU. During the operating cycle between the biofilter backwashings, the $NO_3-N$ removal percentage decreased initially after backwashing, and then gradually increased. Under $C/NO_3-N$ ratios of 2, 1.5 and 1 g/g, the $NO_3-N$ reduction rate was 1.75, 1.04 and $0.68g/m^2/d$ in the ethanol biofilter, and was 1.56, 1.07 and $0.76g/m^2/d$ in the acetate biofilter, respectively. In addition, during denitrification, the ratio of the consumed chemical oxygen demand to the removed $NO_3-N$ was 5.06-8.23 g/g in the ethanol biofilter, and was 4.26-8.6 g/g in the acetate biofilter.

• Journal of Environmental Health Sciences
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• v.31 no.4 s.85
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• pp.309-315
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• 2005

Volatile organic compounds (VOCs) and odor materials are major sources of air pollution in Ulsan city, where much chemical plants are located. Therefore, it is necessary to develop a new reactor which can remove VOCs and odor materials effectively and be equipped at the end of pipe easily. A modified reactor (bioscrubber trickling filter, BSTF), which have both characteristics of biofilter and bioscrubber, was developed and tested on its reactivity with several VOCs using two types of media, fiber and activated carbon 4- ceramic(A/C). It was observed that the removal efficiencies of several types of VOCs such as acetaldehyde, ethylalcohol, butanol, diethylamine and triethylamine were up to $95\%$ when they had about 100 ppm of initial concentration and 80 seconds of residence time. Good attachment of microorganisms to both media, where it is thought the reaction efficiency can be determined according to the amount of microorganisms attachment, observed with scanning electron microscopy(SEM). Initial pressure drops of the packed bed with both media were 229 $mmH_2O/m$ at A/C column and 670 $mmH_2O/m$, respectively. However, maximum pressure drop of fiber column during the operation was over 1,647 $mmH_2O/m$. Therefore, it was thought that the fiber material would not suitable to use in the local plant as a packed bed media.

• Membrane Journal
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• v.30 no.2
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• pp.131-137
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• 2020

In this study, effect of inorganic particles on organic fouling was investigated by a laboratory-scaled pressurized membrane filtration. In order to cause organic fouling, sodium alginate (SA) was used as a feed solution. Regardless of the presence of inorganic SiO₂ particles, the complete pore blocking played an important role in determining the fouling rate during the initial period of membrane filtration. However, the formation of cake layer resulted in the membrane fouling more dominantly as filtration time progressed. In the presence of inorganic particles, both specific cake resistance and compressibility associated with the membrane fouling formed were relatively lower than that without SiO₂ particles. Membrane fouling was more severe at constant flux mode of filtration than that observed at constant pressure mode probably due to the concomitant increase of compressibility of fouling layer with transmembrane pressure (TMP). It was found that the presence of SA and SiO₂ particles in feed solution provided the synergistic effect on the hydraulic backwashing to reduce membrane fouling as compared to the SA solution alone without the inorganic particles.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.465-469
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• 2006

Two mesophilic trickling bed bioreactors filled with two different types of media, hydrophilic- and hydrophobic-cubes, were designed and tested for hydrogen production via anaerobic fermentation of sucrose. Each reactor consisted of a column packed with polymeric cubes and inoculated with heat-treated sludge obtained from anaerobic digestion tank. A defined medium containing sucrose was fed with changing flow rate into the capped reactor, hydraulic retention time and recycle rate. Hydrogen concentrations in gas-phase were constant, averaging 40% for all conditions tested. Hydrogen production rates increased up to $10.5 L{\cdot};h^{-1}{\cdot}L^{-1}$ of reactor when influent sucrose concentrations and recycle rates were varied. Hydrophobic media provided higher value of hydrogen production rate than hydrophilic media at the same operation conditions. No methane was detected when the reactor was under a normal operation. The major fermentation by-products in the liquid effluent of the both trickling biofilters were acetate and butyrate. The reactor filled with hydrophilic media became clogged with biomass and bio gas, requiring manual cleaning of the system, while no clogging occurred in the reactor with hydrophobic media. In order to make long-term operation of the reactor filled with hydrophilic media feasible, biofilm accumulation inside the media in the reactor with hydrophilic media and biogas produced from the reactor will need to be controlled through some process such as periodical backwashing or gas-purging. These tests using trickling bed biofilter with hydrophobic media demonstrate the feasibility of the process to produce hydrogen gas in a trickle-bed type of reactor. A likely application of this reactor technology could be hydrogen gas recovery from pre-treatment of high carbohydrate-containing wastewaters.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.06b
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• pp.221-226
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• 2006

This study is about backwash condition and membrane fouling at continuous filtration process in ballast water treatment. Displayed result that handle particle contaminant and hydrospace organism included a number of ballast that is happened in ship using automatic back washing filter. Reason that removes first contaminant that is included in number of ballast is that heighten processing effect of after processing process of the filter. Another advantage is to drop off the solids with controlling revolution of drum screen in pretreatment filtration process. The capacity of pilot plant was $10m^3/h$. The result of the test, Backwash cycle time and duration time and a signification effect on the efficiency of system and backwash Backwash duration time was determined to be fixed in 6 seconds of the system with more than 95% removal rate, It needed 1hour backwash frequency. Filtration system removal aquatic organism over $70{\mu}m$ in ballast water. This study shows that the filtration treatment system has a potential for the treatment of ballast water.