박정은 Park Jeong Eun , 박석순 Park Seog Sun

DOI: Vol.19(No.3) 247-256, 2003

This paper presents the results of modeling study to predict the flushing rate which is an indicator of self-purification capacity in a coastal embayment. They study was performed on the Mokpo harbor system and surrounded coastal area, utilizing the RMA-/RMA-4 models developed by U.S.Army Corps of Engineers. Two dimensional finite element grides(4,133 nodes and 1,296 elements) were constructed on the study area, based on the system geometry. Tidal flow and mass transport phenomena were simulated and validate against the measured tidal heights and water quality data. Model validation results showed reasonable agreements with the field measurements. Utilizing the validated models, tidal currents and water quality distribution were predicted spatially as well dynamically. The flushing rate was estimated from the water quality change within the embayment due to tidal movement. Two different flushing rates(with and without biochemical decay) were compared in order to examine the contribution of biochemical degradation to the self-purification. The flushing rate was computed at six locations during neap and spring tides. The results indicated that the flushing rates were significantly different by tidal pattern within the study area(neap and spring tides) as well as by locations. The biochemical degradation, however, does not cause a discernible impact on the flushing rate, indicating that tidal movement plays the major role in self-purificaton of pollution loads. From this study, it was concluded that the discharge location and time of pollution loads should be important parameters to be considered for the effective management of water quality in a coastal embayment.

Water quality modeling, Flushing rate, Coastal embayment, Tidal movement, Self-purification capacity

조일형 Jo Il Hyeong , 박재홍 Park Jae Hong , 김영규 Kim Yeong Gyu , 이홍근 Lee Hong Geun

DOI: Vol.19(No.3) 257-270, 2003

In order to treat the dyeing wastewater, the UV/TiO₂/H₂O₂ system was investigated, and proper protreatment methods were examined to reduce the load on the system considering economical and techical efficiency. Also, to obtain the maximize the removal efficiency of dyeing wastewater, optimal operating conditions for the photocatalytic degradation were investigated by using the responsed surface methodology(RSM) . The independent variables were TiO₂ dosage, H₂O₂ concentration and removal efficiency of dyeing wastewater was dependent variable. With the 2²-factional factorial experimental design, 11 experiments were carried out at various condition, with 4 factorial points, 3 center points and 4 axial points. Maximum removal efficiency(85%) of dyeing wastewater was obtained at TiO₂ dosage(1.82g/L), H₂O₂ concentration (980㎎/L) for photocatalytic oxidation reaction(20min).

Photocatalytic reaction, Response surface analysis, Optimization

윤상린 Yun Sang Lin , 김동하 Kim Dong Ha , 지덕기 Ji Deog Gi , 이상욱 Lee Sang Ug

DOI: Vol.19(No.3) 271-278, 2003

The coupling of an activated sludge reactor with a membrane unit (Membrane Bioreactor system) offers several advantages over conventional process. But the major disadvantage of this process in the extensive use is the continuous reduction of permeation flux caused by membrane fouling. The aim of this study is to investigate membrane fouling characteristics caused by the soluble organic materials in the membrane bioreactor System process. For the removal of the filterable organic materiais(FOC) less than 1㎛, coagulants and activated carbon were added. Gravity filtration and filtration under the pressure of 206kPa were conducted in the experiments. The rate of filtration flux increased abruptly with the decrease of FOC concentration. The flux with FOC 1.2㎎/l showed the 4.3 times higher compared to the results of FOC 3.7㎎/l. After addition of granular activated carbon (15min) and sedimentation (20min) of raw water 18% of FOC were removed while 54% and 67% of FOC were removed when 400㎎/l and 500㎎/l of PAC were added, respectively. From these results. PAC is superior in the FOC removal than GAC. By the addition of PAC after the coagulation reaction. more than 90% of organic particles less than 0.1㎛ was removed and the flux became 290 times faster than that of no treated water. This study showed that PAC addition after the coagulation reaction is the most elfective process to prevent membrane fouling problems.

membrane fouling, FOC, particle size distribution, PAC, coagulant

차재욱 Cha Jae Ug , 강선홍 Kang Seon Hong , 박종훈 Park Jong Hun

DOI: Vol.19(No.3) 279-286, 2003

This study was performed to remove color and turbidity and to increase the sludge settling characteristic for piggery wastewater. In the pie-precipitation experiments, four inorganic coagulants(alum, ferric chloride, ferrous sulfate. PACS) and polyelectrolytes(anionic. cationic, nonionic) were used. When 1% of TS wastewater was used, PACS(Poly aluminum chloride silicate) and cationic polymer we founded to be more effective than the others in the remwal of color and turbidity and in improving Sludge settling characteristic and in preventing drastic pH decrease. But when the biologically treated effluent was used, the removal efficiencies of color, turbidity and COD were 41 5%. 40.7% and 29.5% respectively. According to these results, the coagulation efficiency was better when using raw wastewater(TS 1%) than using biologically treated effluent. Whereas single coagulant(PACS) showed about 70% of color removal efficiency the mixture of inwganic coagulant(PACS) and cationic polymer showed the removal efficiency of more than 80%. Therefwe. the application of mixed coagulants showed higher removal efficiency and was cost-effective by using lesser coagulants.

Coagulation, Color, Turbidity, Piggery wastewater

정진아 Jeong Jin A , 박청길 Park Cheong Gil , 김동명 Kim Dong Myeong

DOI: Vol.19(No.3) 287-292, 2003

It is necessary to develop a standard method for determination of total nitrogen (T-N) and total phosphorous (T-P) in seawater because the T-N and the T-P have been adopted in marine water quality standards since 2001. Precision and recovery of the simultaneous determination of T-N and T-P by alkaline persulfate oxidation in seawater and freshwater were assessed. Relative standard deviation and recovery of eleven seawater and freshwater standards of known nitrogen concentration were ±1.59∼±6.45% and 93.0∼100.6%, respectively. Relative standard deviation and recovery of eleven seawater and freshwater standards of known phosphorus concentration were ±0.62∼±4.95% and 96.0-1 00.8%, respectively. Relative standard deviation of five samples of seawater collected from Nakdong estuary and five samples of freshwater collected from Nakdong river were ±3.14∼±5.52% for nitrogen and ±3.98∼±6.67% for phosphorus. We can find that this method has a good precision and recovery below the acceptance limits for total nitrogen and total phosphorus in analyzing seawater and freshwater samples.

total nitrogen, total phosphorous, alkaline persulfate method

윤종섭 Yun Jong Seob , 김승현 Kim Seung Hyeon , 윤조희 Yun Jo Hui

DOI: Vol.19(No.3) 293-299, 2003

Feasibility of using alginic acid for red-tide removal was investigated in this study. Ammonium-calcium salt form of alginic acid was used instead of free acid form because this caused less pH decrease. This study found that alginic acid was more effective than loess in red-tide removal. This was related to the removal mechanism. Microscopic examination showed that loess removed red-tide through adsorption. while alginic acid achieved the removal through floc formation. Using alginic acid together with loess could not degrade red-tide removal efficiency. The combined use resulted in 10% improvement of the removal Compared to use of alginic acid alone. The combined use is expected to make alginic acid more economically feasible. Red-tide removal efficiency was different depending upon species. Flagellate was easy to remove than diatom. This was realted lo the Shape. Flagellate has a sphere-like shape. Red-tide density also affected the removal. Higher density resulted in better removal efficiency.

alginic acid, red-tide, diatom, flagellate

류장현 Lyu Jang Hyeon , 강선홍 Kang Seon Hong

DOI: Vol.19(No.3) 301-310, 2003

In this study, Anoxic/Oxic type MBR(Membrane Bioreactor) was applied to overcome a defect of conventional wastewater treatment and to treat wastewater stably. The flowrate of influent to plant used in this study is 200 cubic meter per day. The plant is located in public livestock treatment plant in C country. A goal of this study is to investigate organics, T-N, T-P and NH₄^(+)-N removal rates as C/N ratio changes when MBR combined with NO treats livestock wastewater. MLSS in aerobic reactor was maintained at about 7000 ㎎/L. Tubular Membrane process filtered by cross-flow in the membrane was used to treat livestock wastewater. Membrane (area : 0.5㎡ and velocity : 1.5-4 m/s) was made of polysulfone. Wastewater passed through anoxic reactor(l.064㎡) and aerobic reactor(3.352㎡) was transferred to drum screen to remove solid in there by pump, then, wastewater removed solids was continuously transferred to UF concentrator. The last process is membrane process. BOD, SCOD, T-N, T-P, NH₄^(+)-N, and SS removal rates are 99.9%, 79.5%, 98.3%, 54.9%, 99.6%, and 99.9%, respectively. As C/N ratio increased, T-N and NH₄^(+)-N removal rates increased directly, too.

livestock wastewater, MBR, C/N ratio, UF, cross-flow

이영옥 Lee Yeong Og , 박지은 Park Ji Eun , 신승필 Sin Seung Pil , 안영희 An Yeong Hui

DOI: Vol.19(No.3) 311-320, 2003

For conducting the comparative analysis of the eubacterial community structure including nitrifying bacteria at 8 sampling sites throughout the N마-Dong River, FISH(fluorescence in situ hybridization) method was employed. The total ratio of each determined eubacterial group such as α·β·γ-subclasses protebacteria and Cytophaga-Flavobacterium(CF) group to total counts stained by DAPI at each site varied 9.3∼42.5% with the highest value at uppermost part. And each ratio of determined eubacterial groups reached mostly under 10% except those of CF group(23%) at uppermost part. Futhermore, compared to lower part, upper part represented higher proportions of γ-subclass proteobacteria comprised in most of fast growing bacteria on degradable organics. Also the variations of ammonia-oxidizing bacteria ranged from 2.7×10⁴to 18.3×10⁴ cells/㎖ with the lowest value in lower part and the highest value in mid part whereas those of nitrite-oxidizing bacteria varied 5.2∼7.7×10⁴cell/㎖ without noticeable differences throughout the sites. Additionally, the ratio of nitrifying bacteria to total counts ranged from 1.3% to 13.6?%, regardless of those of ammonia/nitrite-oxidizing bacteria. Overall, it implies that the upper part of Nak-Dong River represented comparatively better degradabilities of organic materials than their Lower part except at one site in upper part passed An-Dong City. By the contrast, the other part of Nak-Dong River, especially after merging the Gum-Ho River revealed lower detectability of FISH resulted from their cellular activity. So it could be said that the lower part of Nak-Dong River might be a ecosystem of which physico-chemical environment may have inhibited the activities of bacteria functioned as decomposer of organic matter.

FISH, fluorescence in situ hybridization, α,β,γ-subclasses proteobacteria, Cytophaga-Flavobacterium group, nitrifying bacteria, Nak Dong River

정현미 Jeong Hyeon Mi , 오상헌 O Sang Heon , 장영진 Jang Yeong Jin , 임연택 Im Yeon Taeg

DOI: Vol.19(No.3) 321-328, 2003

Investigating enteric viruses in water supply and its relationships with indicator bacteria and other Dhysicochemical parameters are of highly importance for public health. No organized studies on the virus occurrence and its relations to indicator organisms in Korean source of water supplies have been reported until this study. Water treatment plants in nationwide were selected encompassing most of the provinces and major cities. From 67 water treatment plants using surface water as their source water, a total of 103 samples of intake water were tested. Viruses were detected from about 43% of the samples. The concentrations Of viruses were highly variable ranged up to 1,200 MPN/100L, but the geometric mean and median were 2.5 MPN/100L and below the detection limits, respectively. According to the Spearman rank correlation analysis, the virus occurrences were Significantly correlated with those of all three indicator bacteria such as total coliforms, fecal coliforms and E. coli, but not with that of turbidity in this sites-dependent macro-scale study. These results suggest that conventional bacteriological indicators may provide an acceptable estimate of virus contamination among the sources of water Supplies. When the type of watershed were compared, virus occurrence in river was significantly higher than that in lake by Mann-Whitney U test(p<0.05). Therefore, river tends to be more vulnerable to virus contamination than lake in Korea.

Enteric viruses, culturable viruses, surface source water, fecal indicator, virus survey in Korea

정현미 Jeong Hyeon Mi , 오상헌 O Sang Heon , 박정환 Park Jeong Hwan

DOI: Vol.19(No.3) 329-338, 2003

Investigating seasonal variation of enteric viruses in source of water supply and its relationships with indicator bacteria and other physicochemical parameters are of highly importance, especially in Korea, where climatic change is extremely high due to the distinct four season and concentrated summer precipitation. We performed the quantitative study on the seasonal variation of virus and indicator organisms in three sites of H, K, and D: the sites H and K were chosen as the fecally contaminated, and the site D was done as the less contaminated. Samples were collected monthly or bimonthly for 14 months from April, 1999 to May, 2000. Total culturable viruses on Buffalo green monkey(BGM) kidney cell and six potential indicating bacteria such as E. coli, fecal coliforms(FC). total coliforms(TC), Clostridium perfringens(CP) spore, heterotrophic plate counts(HPC), aerobic spore formers(ASF) were analyzed along with general physicochemical parameters. In the less contaminated site D₁ viruses were never detected in 100L samples. However, in the fecally contaminated sites of H and K , viruses were detected in most of the samples and were highly variable. The levels of viruses tended to be raised in cold season and were also showed significantly negative correlation with temperature. When the occurrence of viruses were compared with the indicating bacteria, only CP showed significantly positive correlation with virus at both sites. Traditional indicators of fecal contamination such as TC, FC, and E. coli did not show any relations with viruses, which was coincident with the previous studies.

Enteric viruses, culturable viruses, surface source water, indicator bacteria, seasonal variation

홍일 Hong Il , 최이송 Choe I Song , 오종민 O Jong Min

DOI: Vol.19(No.3) 339-348, 2003

The pollutants in the stream are removed by its biological, chemical and physical self-purification. Therefore, it is required that self-purification in the stream is correctly estimated in the field for the effective management of stream water quality. In this study, we estimated mass balance and self-purification through various experiments in the Osan Stream, which is located in Kyunggi Do and shows the typical characteristics of urban stream. Based on the results, sedimentation in the Osan Stream was investigated as a major factor in the removal reactions of pollutants. Primary production by photosynthetic plankton in the Osan Stream corresponded to 12.6% for total organic matter, and degradation by microorganism did 4.8%. Although these values were lower than those in stagnated water`s such as lake`s and reservoir`s, if we consider that the hydraulic retention time of the Osan Stream is very short compared with those other bodies, they are high significant in estimating the origin of organic matters. Microorganisms attached on the various riverbed materials take an important role in consuming or producing organic matter, nutrients and DO in the stream.

Self-purification, Mass balance, Sedimentation, Matter cycle, Microorganism

학회자료

DOI: Vol.19(No.3) 349-350, 2003