한무영 Moo Young Han

DOI: Vol.11(No.4) 263-268, 1995

박희경 , 남궁완 Hee Kyung Park , Wan Namkoong

DOI: Vol.11(No.4) 269-277, 1995

Wasteload allocations(WLA) and total maximum daliy load(TMDL) determined with the lowest streaflow(e.g., 7Q10) may violate water quality standards as streamflow increases. Traditionally, streamflow increase is considered to monotonically improve the worst water quality (e.g., dissolved oxygen) which occurs at the lowest streamflow. This conventional worst case assumption might not be held because of parameter changes with streamflow increase which include increased non-point source discharges, varying decay (k₁ and reaeration (k₂ coefficients and reduced residence times. These parameter changes were hypothetically tested here to see the possible violation of the assumption. The results of this study indicate that unless the dependence of decay coefficient on streamflow is high and positive($gt;0.11), the worst case assumption will be valid in most natural channels. However, in highly regulated and polluted streams, the possibility of the violation was also observed. Since some of our major streams are well regulated for many purposes and sometimes observed highly polluted, the study results suggest that use of the lowest streamflow might be inappropriate for wasteload allocations. Rather, a trial and error approach is suggested. The approach develops wasteload allocation plans; tests them for a number of low streamflow conditions; and finds a best one. For this, computer models will be iteratively used.

이창호 , 임수길 Chang Ho Lee , Soo Kil Lim

DOI: Vol.11(No.4) 279-285, 1995

In order to investigate the behavior of N,P,K fertilizers applied in submerged paddy soils and the water pollution caused by these leachate, Ammonium sulfate(AS), Urea, Superphosphate(SP), Fused phosphate(FP), Potassium chloride(PC) were applied in three levels in the columns filled with silty clay loam(SiCL) and sandy loam(SL), respectively. Distributions of N,P,K in soil were detertmined, and concentrations of N,P,K in leachate were also analyzed, separately. The obtained results were summarized as follows. In terms of residual amounts in soils, AS induced decreasing amount NH₄-N from top to bottom whereas Urea revealed reverse phenomenon. SL soil rather than SiCL soil and AS rather than Urea had a much effect on the water pollution. Residual amount of NO₃-N showed higher amount in SL soil than in SiCL soil regardless of fertilizer and application rates. In SiCL soil, main source of soluble phosphorus was SP whereas FP was the one in SL soil. Conc. of phosphorus in leachate were very small due to high adsorption ability of soils for phosphorus, the soil pollution was more considered than the water pollution. Leaching conc. of K^+ was higher from SL soil than SiCL soil, leaching conc. of K^+ increased as fertilizer application rates increasing on both SiCL and SL soils. Leaching concentrations(Y) of K^+ decreased with increasing leaching frequency(X), fitting the equation of exponential function could be expressed as Y=aX^b egardless of soil textures and potassium fertilizer application rates. The value of b is in between 0.41 and 0.63.

우광제 , 염혜정 , 강구영 , 박갑성 Kwang Je Woo , Hye Joung Yeum , Gu Young Kang , Kap Song Park

DOI: Vol.11(No.4) 287-293, 1995

A survey of micro-organic pollutants was conducted in the Kyoungan River from Aug. 1994 to Dec. 1994. 19 Unknown Synthetic Organic Chemicals (SOCs) were detected in the Kyoungan River. Four chemicals identified by GC/MS technique were methyl iso-butylketon, 3,3-methyl-1-butene-2-ol, alkyl hydrocarbon and alkyl amine. These fourcompounds consisted 64% of total SOCs contamination level. 6 VOCs were detected. Mean concentration ranges for the VOCs were : trichloroethylene 20.1-177㎍/ℓ, tetrachloroethylene 4.3-105.6㎍/ℓ, and chloroform 0.4-2.9㎍/ℓ. 1,1,1- Trichloroethane, 1,2-Dichloroethane, and Carbon tetrachloride were at trace and below detection limit level. Detection frequencies for trichloroethylene, tetrachloroethylene, and chloroform were 41.7%, 25%, and 16.7%, respectively. VOCs concentrations in winter were generally higher than those in summer and fall. The concentration of micro-organic chemicals (SOCs and VOCs) were increased between Supo-kyo and Opo-kyo area where many industrial factories were located.

김동섭 , 김범철 , 황길순 , 박주현 Dong Sup Kim , Bom Chul Kim , Gil Son Hwang , Ju Hyun Park

DOI: Vol.11(No.4) 295-302, 1995

The trend of trophic state change was surveyed in a reservoir, Lake Paldang, that is water resource to capital area. Primary productivity of phytoplankton, chlorophyll a concentration, transparency, total phosphorus concentration, BOD, and COD were measured in 1988, 1990, and 1992-1994 at three sites; dam site, the inlet site of the North Han River, and the inlet site of the South Han River. Tophic state parameters of 1992-1994 showed trend of eutrophication compared with those of 1988. Trophic state was meso-eutrophic in 1988, but it was over eutrophic threshold in 1992. Chlorophyll a concentration at the dam site increased from 2-10 ㎍/ℓ in 1988 to 5-25 in 1992-1994, primary productivity increased from 500-1000 to 1000-2000 ㎎C/㎡/day, total phosphorus concentration increased from 10-30 to 20-120 ㎎/㎥, transparency decreased from 1.5-4 to 0.5-2.0m. Annual phosphorus loading increased from 297 tP/yr in 1988 to 938 tP/yr in 1993. 80% of phosphorus loading was contributed by the South Han River.

현길수 , 최정우 Kil Soo Hyun , Jeung Woo Choi

DOI: Vol.11(No.4) 303-309, 1995

The objective of this research was to evaluate the configuration of wastewater treatment processes for an advanced treatment of leachate with high chlorine concentration. The raw wastewater used was leachate from the landfill of incinerated ashes of municipal wastes and contained heavy metals, ions materials, and toxic substances as well as high concentration of salts and nitrogen. The advanced wastewater treatment system used in this research consists of activated sludge process, sedimentation basin, trickling filter, coagulation-flocculation-sedimentation basins, rapid sand filters, granular activated carbon (GAC) beds, and membrane filters. As a results of this researches, using anaerobic and aerobic conditions for denitrification and nitrification, the activated sludge process removed approximate more than 90% of total nitrogen (T-N) and ammonia nitrogen (NH₄-N), which indicated that it was considerably effective in removing nitrogen. Conventional contaminants such as BOD, COD, and SS were removed more than 80% through the flocculation-sedimentation processes. Through the filtration and the adsorption, the residual contaminants except for total dissolved solids (TDS) and ions almost never removed by them were reduced less than 1㎎/ℓ, TDS and ions of chlorine and calcium removals by membrane filter (reverse osmosis, RO) alone averaged 98%, which describes it was considerably effective in sperating saline solution from the wastewater containing high salts concentration. Based on these results, it describes that the proper configuration of wastewater treatment processes is important to produce the water adequated to effluent standards, which can be expected the application of the wastewater reuse as well as the protection of water environment.

오경미 , 조순행 , 유희찬 Kyoung Mee Oh , Soon Haing Cho , Hee Chan Yoo

DOI: Vol.11(No.4) 311-321, 1995

The purpose of this study is to investigate the applicability of water quality models which are commonly used for evaluation and prediction of water quality of stream and rivers in Korea. Three models, QUAL2E, WASP4 and STREAM, were used for comparison. Three different statistical methods were used to test the correlation between predicted results by model and field measurements. Field data were obtained from the south branch of Han River in between Chungju and Yangpyung. Parameters used for model comparison were DO, BOD, NH₃-N, NO₃-N, Org-P and Dis-P. The data predicted by QUAL2E generally showed better fit to the field data. However, this model can not predict the effect of highly polluted stream. Nitrogen and phosphorus data predicted by WASP4 were closer to the field data than those data predicted by other models, even though more input data were required to run WASP4. The main features of STREAM are ; 1) it can predict the change of DO concentration by bottom rooted plant and by denitrification. 2) it can be applied to predict the water quality of small stream rather than large river. From this study, it was found that all three models showed poor ability in predicting water quality change caused by nonpoint discharge.

배재호 , 조광명 , 박수영 , 맹성민 , 송기봉 Jae Ho Bae , Kwang Meyung Cho , Soo Young Park , Sung Min Maeng , Ki Bong Song

DOI: Vol.11(No.4) 323-331, 1995

The treatment of leachate from solid wastes landfill is generally difficult because it contains high concentrations of organics, ammonia nitrogen and ionic materials. Experiments were conducted to characterize the leachate generated from Kimpo Landfill Site and to investigate the effects of hydraulic retention time and ammonia nitrogen concentration on the efficiency of the leachate treatment system consisted of anaerobic digestion and extended aeration processes. The leachate was characterized for three months after eighteen months of landfill operations, and CODcr, COD_(mn), BOD, TDS, and NH₄^+ -N were stable with the average values of 3,960㎎/ℓ, 920㎎/ℓ, 3,430㎎/ℓ, 14,230㎎/ℓ, and 1,090㎎/ℓ, respectively. For anaerobic digestion of the leachate, the hydraulic retention time was found to be a critical factor for the operation, and should be maintained longer than 20 days without significant changes in flow rate. The high concentrations of NH₄^+-N and ionic materials in the leachate appeared not to significantly affect the treatment efficiency. However, for the extended aeration process which receives the anaerobic digester effluent, the hydraulic retention time appeared not to affect the organic removal efficiency. Effects of the high concentrations of NH₄^+-N and ionic materials on extended aeration process were negligible over a long term, but a longer adaptation period was required with those compounds.

서보승 , 김치경 Bo Seung Seo , Chi Kyung Kim

DOI: Vol.11(No.4) 333-339, 1995

The kanamycin-resistant bacteria and genes were detected by Southern hybridization with Km gene probe from the less polluted Miho creek and Suknam creek heavily polluted with sewage and industrial waste. The average values of BOD, phosphorus, conductivity, and turbidity of Suknam creek water were much higher than those of Miho creek water. Standard plate count and Km bacterial count of Suknam creek water were 6.7 × 10^5 and 5.2 × 10⁴ CFU/㎖, respectively. Those counts were about 70 to 85 times higher than those of Miho creek water, but the ratios of Km` bacterial count to standard plate count in both creeks were almost the same to be 6.2∼7.8 × 10^(-2). The bacterial strains hybridized with Km` gene probe were detected to be 39.7% in Suknam creek and 31.8% in Miho creek. The highest ratio of the hybridization was observed in Autumn season in both creek waters. When the Km` gene was localized by DNA hybridization in the Km` strains, about 40% of them isolated from Suknam creek was found to have the Km` gene in the chromosomal DNA and 59% in both chromosomal DNA and plasmid. But in the Km` strains isolated from Miho creek 37% was observed to have the Km` gene in chromosomal DNA and 53% in both chromosomal DNA and plasmid. The strains which had the Km` gene in both chromosomal DNA and plasmid were observed at highest ratio in Autumn and Winter in Suknam creek, but only in Winter in Miho creek.

신항식 , 임경호 , 이의신 , 최계운 Hang Sik Shin , Kyeong Ho Lim , Eui Sin Lee , Gye Woon Choi

DOI: Vol.11(No.4) 341-349, 1995

Biofilm system is suitable for the pretreatment of water because biofilm can act as niches where slow-growing degraders can survive at low organic concentrations. In order to cope with stringent environmental standards, it became essential to improve the understanding of the phenomena governing biological degradation of organics. In this study, effects of hydraulic retention time (HRT) and temperature on the efficiency of submerged biofilm reactors were investigated. Removal efficiency total organic carbon (TOC), turbidity, and algae increased with the HRT. It is considered that over 1 hr HRT is needed to ensure the removal of higher than 30% TOC. In comparison to honey comb type media, fibrous media were more favorable to the attachment and growth of active microorganisms. The close relationship with chlorophyll-a concentration and particulate organic carbon (POC) concentration make POC a surrogate parameter for estimating the removal efficiency of algae.

정팔진 , 이영동 , 곽동희 Paul Gene Chung , Young Dong Lee , Dong Heui Kwak

DOI: Vol.11(No.4) 351-357, 1995

The biological treatment method for slightly polluted raw water was studied by using both a fixed-bed biofilter packed with filamentous media and a fluidized-bed biofilter packed with spongy media. The characteristic of this biofilter was able to be expressed as Se= So· e^( 0.0863◎), which was proposed as a kinetic model for thrickling filter by Eckenfelder. With the object to overcome a problem, the decrease of nitrification efficiency in the conventional biological treatment at low water temperature, a small-scale reactor with nitrifying bacteria immobilized in synthetic PEG beads was applied. The efficiency of the reactor for the nitrification of NH₃-N was found to be worse at wormer water temperature(2l℃, 24℃), but better at low water temperature(6℃, 12℃) than that of the conventional biofilter. In addition, it was confirmed that the process used in this study can be safe from intestinal pathogenic microorganisms and others, if all operation conditions for the conventional processes are satisfied.