• Journal of environmental and Sanitary engineering
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• v.20 no.1 s.55
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• pp.64-75
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• 2005

The total production of food waste was about 11,398ton/day('03) in Korea. Also, food waste was treated by landfill, incineration, reuse and anaerobic digestion. The method of food waste treatment depended primarily on landfill. However, the method of landfill causing social problems was prevented to treat food waste in the first of January 2005.12) Thus, anaerobic digestion is an important method to treat food waste because of possibility of energy recovery as methane gas. In this study, the possibility of food waste treatment containing high organic material and low pH in the one stage anaerobic reactor to save cost and time and energy recovery using $CH_{4}$ gas by the hybrid anaerobic reactor (HAR) was measured. The HAR was designed by combing the merits of the anaerobic filter (AF) to minimize the microorganism shock when food waste of very low pH was injected and up-flow anaerobic sludge blanket (UASB) to prevent from plugging and channeling phenomena by large suspended solids when semi solids were injected. Granule was packed in the section of HAR. The purpose of the BMP experiment was to measure the amount of methane generated when organic material was resolved under anaerobic conditions, to grasp bio resolution of organic material. Total accumulated methane production per VS amount was $0.471(m^{3}/\cal{kg}\;VS)$. So, the value was about $81.2\%$ of theoretical methane production which was $0.58(m^{3}/\cal{kg}\;VS)$ by elementary analysis and organic matter removal velocity (K) was $0.18(d^{-1})$. From these results, food waste was treated by anaerobic treatment. From this study, $CH_{4}$ generation from food waste (11,398 ton/day) could be estimated. By using an energy conversion factor of Braun's study, $5.97KWh/m^{3}\;CH4,\;60\%\;of\;CH_{4}$ gas generation, the amount of total energy producing food waste is to 6,727MWh/day. It could be confirmed that energy recovery using $CH_{4}$ gas was possible. Above these results, food waste containing organic matters of high concentration could be treated in HRT 30 days under an anaerobic condition, using the hybrid anaerobic reactor and reuse of $CH_{4}$ gas was possible.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.6
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• pp.791-799
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• 2005

The phased isolation intra-clarifier ditch system used in this study is a simplified novel process enhancing simultaneous removal of biological nitrogen and phosphorus in municipal wastewater in terms of elimination of additional pre-anaerobic reactor, external clarifier, recycle of sludge, and nitrified effluent recirculation by employing intrachannel clarifier. Laboratory-scale phased isolation ditch system was used to assess the treatability on municipal wastewater. When the system was operated at the HRTs of 6~12hours, SRTs of 9~31days, and cycle times of 2~8hours, the system showed removals of BOD, TN, and TP as high as 88~97%, 70~84%, and 65~90%, respectively. The rainfall in Korea is generally concentrated in summer because of site-specific characteristics. Especially, the wet season has set in on June to August. In combined sewers, seasonal variations are primarily a function of the amount of stormwater that enters the system. In order to investigate the effect of hydraulic shock loading on system performance, the laboratory-scale system was operated at an HRT of 6hours (two times of influent flowrate) during two cycles (8hours). The system performance slightly decreased by increasing of influent flowrate and decreasing of system HRT. Nitrification efficiency and TN removal were slightly decreased by increasing of influent flowrate (decreasing of system HRT), whereas, the denitrification was not affected by hydraulic shock loading. However, the higher system performance could be achieved again after four cycles. Thus, the phased isolation technology for enhanced biological nutrient removal in medium- and small-scale wastewater treatment plants suffering fluctuation of influent quality and flowrate.

• Journal of dental hygiene science
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• v.1 no.1
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• pp.7-11
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• 2001

Streptococcus mutans is one of the primary bacteria that cause dental caries which further result in plaque build up. Acid production resulted from carbohydrate metabolism can threaten survival of the bacteria. However some populations of S. mutans which are exposed to low acidic condition for a period of time would develop resistance and tolerance of cells to acidity that will enhance the chance of survival. Similar acid tolerances has been reported in case of Salmonella enterica serovar typhimurium, E. coli, Shigella flexneri. These acid tolerance responses(ATR) have been evolved in a similar manner as S. mutans. The protein produced in acidic condition has been proven to be important for ATR and confirmed by using chloramphenicol procedure. We hypothesize here that proteins synthesized in response to acid shock and other elements are important for ATR of cells. In this study we have confirmed that S. mutans developed acid tolerance and resistance against anaerobic condition. Mutational DNA analysis responsible for acid tolerance should be additionally required in the future. Since the development of acid tolerance that is essential for the survival of S. mutans and development of dental caries, ATR of S. mutans shoule be farther to prevent dental caries.

• Environmental Engineering Research
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• v.10 no.4
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• pp.181-190
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• 2005

Severe loss or hydrogen occurred in most anaerobic hydrogen fermentation reactors. Several selected methods were applied to suppress the consumption of hydrogen and increase the potential of production. As the first trial, pH shock was applied. The pH of reactor was dropped nearly to 3.0 by stopping alkalinity supply and on]y feeding glucose (5 g/L-d). As the pH was increase to $4.8{\pm}0.2,$ the degradation pathway was derived to solventogenesis resulting in disappearance of hydrogen in the headspace. In the aspect of bacterial community, methanogens weren't detected after 22 and 35 day, respectively. Even though, however, there was no methanogenic bacterium detected with fluorescence in-situ hybridization (FISH) method, hydrogen loss still occurred in the reactor showing a continuous increase of acetate when the pH was increased to $5.5{\pm}0.2$. This result was suggesting the possibility of the survival of spore fanning acetogenic bacteria enduring the severely acidic pH. As an alternative and additive method, nitrate was added in a batch experiment. It resulted in the increase of maximum hydrogen fraction from 29 (blank) to 61 % $(500\;mg\;NO_3/L)$. However, unfortunately, the loss of hydrogen occurred right after the depletion of nitrate by denitrification. In order to prevent the loss entangled with acetate formation, $CO_2$ scavenging in the headspace was applied to the hydrogen fermentation with heat-treated sludge since it was the primer of acetogenesis. As the $CO_2$ scavenging was applied, the maximum fraction of hydrogen was enhanced from 68 % to 87 %. And the loss of hydrogen could be protected effectively.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.2
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• pp.57-65
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• 2008

Wastewater containing strong organic matter is very difficult to treat by utilizing general sewage treatment plant. but the wastewater is adequate to generate biomass energy (bio-gas; methane gas) by utilizing anaerobic digestion. EcoDays Plug Flow Reactor (E-PFR), which was already proved as an excellent aerobic wastewater treatment reactor, was adapted for anaerobic food wastewater digestion. This research was performed to improve the efficiency of bio-gas production and to optimize anaerobic wastewater treatment system. Food wastewater from N food waste treatment plant was applied for the pilot scale experiments. The results indicated that the efficiency of anaerobic wastewater treatment and the volume of bio-gas were increased by applying E-PFR to anaerobic digestion. The structural characteristics of E-PFR can cause the high efficiency of anaerobic treatment processes. The unique structure of E-PFR is a diaphragm dividing vertical hydraulic multi-stages and the inversely protruded fluid transfer tubes on each diaphragm. The unique structure of E-PFR can make gas hold-up space at the top part of each stage in the reactor. Also, E-PFR can contain relatively high MLSS concentration in lower stage by vertical up-flow of wastewater. This hydraulic flow can cause high buffering capacity against shock load from the wastewater in the reactor, resulting in stable pH (7.0~8.0), relatively higher wastewater treatment efficiency, and larger volume of bio-gas generation. In addition, relatively longer solid retention time (SRT) in the reactor can increase organic matter degradation and bio-gas production efficiency. These characteristics in the reactor can be regarded as "ideal" anaerobic wastewater treatment conditions. Anaerobic wastewater treatment plant design factor can be assessed for having 70 % of methane gas content, and better bio-gas yielding and stable treatment efficiency based on the results of this research. For example, inner circulation with generated bio-gas in the reactor and better mixing conditions by improving fluid transfer tube structure can be used for achieving better bio-gas yielding efficiency. This research results can be used for acquiring better improved regenerated energy system.

• Journal of Korean Society on Water Environment
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• v.28 no.6
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• pp.781-785
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• 2012

This study was carried out to treat the thermal elutriated acids of piggery wastewater using UASB process. The UASB reactor was operated at an organic loading rate (OLR) of $7.4\;kgCOD/m^3-day$ (6.5 ~ 9.0). During the start-up period, the low COD removal efficiency (20%) was caused by shock loading and instability in the reactor. It was mainly due to the high concentration amounts of ammonia nitrogen, which caused inhibitory and toxic effects to toward the anaerobic bacteria. In steady state, the UASB reactor showed a SCOD removal efficiency of 71% and a VS removal efficiency of 39%. The gas production and methane content were 1.3 L/day $(0.21\;m^3\;CH^4/kg$ COD removed) and 77%, respectively.

• Journal of Veterinary Clinics
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• v.28 no.5
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• pp.516-518
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• 2011

A survey was conducted to examine the normal intestinal bacterial flora of captive Oriental white storks (Ciconia boyciana) maintained at the Korea Institute of Oriental White Stork Rehabilitation Research, Cheongwon, South Korea. From the cloaca of 44 healthy storks, 44 fecal samples were collected and cultured under aerobic and anaerobic conditions. The 16S ribosomal RNA gene sequences and the heat shock protein 60 gene were cloned and sequenced for bacterial identification. Under aerobic conditions, Enterococcus faecalis, Escherichia coli, Bacillus spp., Enterococcus avium, Enterococcus gallinarum, Pseudomonas spp., Alcaligenes spp., Enterobacter spp., Corynebacterium spp., and Proteus mirabilis were identified. Under anaerobic conditions, E. coli, Clostridium tertium, En. faecalis, and P. mirabilis were identified. E. coli, En. faecalis, or both were isolated from all samples. These results will add to the information available on this stork species and help for the interpretation of fecal culture results.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.1
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• pp.90-96
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• 2000

The composition of leachates varies depending on the waste characteristics, landfill age and landfilling method. Generally, leachates contain high dissolved organic substance and ammonia nitrogen whereas phosphorus concentration was very low. Leachate A produced from young landfill is characterized by high BOD5/COD ratio (0.8) whereas leachate C produced from old landfill has lower BOD5/COD ratio (0.1). Maximum biochemical methane potential of leachate A, B (from medium landfill) and C were 271,106 and 4 ml CH4/g-COD, respectively. On the other hand, the maximum biodegradability of leachate A, B, and C were 75,30, and 1%, respectively. These results indicated that anaerobic treatment of leachate from young landfill was effective in removing organic pollutants. In case of leachate C, carbon might reside in the form of large molecular weight organic compounds such as lignins, humic acids and other polymerized compounds of soils, which are resistant to biodegradation. The lag-phase period increased with the increasing organic concentration in leachate. In case of leachate A of concentration greater than 25%, the lag-phase period increased sharply. This implied that the start-up period of anaerobic process using an unacclimated inoculum could be extended due to the higher concentration of leachate. This relatively long lag-phase is probably related to the fact that most of the inhibitory compounds have been diluted beyond their inhibitory concentrations of less than 50%. Furthermore, the ultimate methane yield and methane production rate decreased as leachate concentration increased. It was anticipated the potential inhibition was related with the steady-state inhibition as well as the initial shock load.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.16 no.1
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• pp.104-111
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• 1994

Necrotizing fascitis is a severe soft tissue infection characterized by extensive necrosis of superficial fascia, suppurative fascitis, vascular thrombosis, widespread undermining of surrounding tissues. Associated systemic problems are widespread undermining of surrounding tissues, Associated systemic problems are common, with chronic alcoholism and diabetes being most prominent. Most commonly this disease presents in the extremities, trunk, and perineum. Necrotizing fascitis of dental origing is rare and its fulminating clinical course is not well documented in the dental literature. The present report is a case of necrotizing fascitis following vital extirpation of the pulp in a patient with uncontrolled diabetes mellitus and liver cirrhosis. Originally throught to be caused by hemolytic streptococcus organism or stphylococcus aureus, advances in anaerobic culturing have shown it to be a synergistic bacterial infection involving aerobic and ovligate anaerobes. it is relatively rare in relatively rare in haea and neck regions. If it was not diagnosed and treated in early stages, necrotizing fascitis can be potentially fetal, with a mortality rate approaching 40%. It's treatment requires early recognition, prompt and aggressive surgical debriment and proper supportive cares, such as, antibiotic therapy, fluid resuscitation and correction of metabolic and electrolyte disorder, resolving of the underlying systemic disease. Recently, we experienced two cases of necrotizing fascitis in cervicofacial region, One patient was 60 years old male with uncontrolled Diabetes Mellitus and other patient was 48 years old with steroid therapy during 30 years. Local surgical wound healing was successful but, patients were died after admission, because of lung abscess, gastrointestinal bleeding, septic shock and respiration hold.

• Journal of Korean Society of Water and Wastewater
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• v.10 no.2
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• pp.47-54
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• 1996

UASB reactor was operated for treating wastewater containing high sulfate to assess their performance, competition between sulfate-reducing bacteria(SRB) and methane-producing bacteria(MPB), and the change in the characteristics of microbial granules according to change of hydraulic retention time(HRT) in the reactor. The reactor was fed with a synthetic moderate strength wastes(glucose, 2000 mgCOD/l) containing high sulfate($2400mgSO_4{^{2-}}/l$). The organic loading rate(OLR) ranged from 1.5 to 3.0 gCOD/l.d as HRT maintained 15 to 30 hrs in the stage I. The COD removal efficiency was between 80 to 92%. During this period, methane yield rapidly decreased from 0.3 to 0.1 1 $CH_4$/gCODremoved. While sulfide concentration in the effluent increased from 80 to 200 mgS/l. This indicates that SRB becomes dominant over MPB at a relatively long HRT in the excess sulfate. When OLR of reactor maintained from 5 to 8 gCOD/l.d in the stage II, methane yield increased from 0.1 to 0.17 1 $CH_4$/gCODremoved regardless of decrease of COD removal efficiency. This indicates that SRB is more sensitive to the change of a short HRT than MPB. In the competition between SRB and MPB, about 30% of the removed COD was utilized by SRB at HRT of 30 hrs during the start-up period, while about 73% was used by SRB at HRT of 15hrs at the final step of second experimental stage. Whereas after shock exposure of OLR about 62% was utilized by SRB at HRT of 5hrs. It indicates that SRB is strongly suppressed by the wash-out of significant dispersed SRB since a large electron flow is distributed to the MPB. In addition, the granulation in the presence of high sulfate is unfavoured at a long HRT because of substrate transport limitations into MPB like Methanothrix spp. which is an important factor in the composition of the granules. Accordingly, granule sizes in the UASB reactor decreased with time due to weak network frame of granules by the decreased activity of MPB.