이기종 , 허우명 , 김범철 Ki Jong Lee , Woo Myung Heo , Bom Chul Kim

DOI: Vol.9(No.3) 139-144, 1993

Phosphorus loading into Lake Daechung was estimated by determining the phosphorus input via runoff from drainage basin and the phosphorus discharge from floating-net fishfarms. The loading from drainage basin was determined by measuring total phosphorus concentration in the four main inflowing streams on the monthly base. Phosphorus loading was concentrated in rainy seasons due to higher phosphorus concentration and higher flow rate. Phosphorus discharge from the dam was also high in August and September because of the discharge of intermediate turbid layer formed by storm runoff. P loading via four sites were 52, 32, 27, and 4 tP/yr for Kumkang, Suhwachun, Bochungchun, and Kusin, respectively. Phosphorus discharge of fishfarms was estimated from the amount of fishfeed applied annually and the unit rate of phospohrus excretion per feed weight. The loading from the watershed and fishfarms were calculated to be 138 and 35 tP/yr, respectively. The phosphorus loading of Lake Daechung far exceeded the critical loading for eutrophication. The amount of phosphorus discharge through outflowing water was 46 tP/yr. Thus the retention rate of phosphorus was 0.73.

김홍태 , 민경석 Hong Tae Kim , Kyung Sok Min

DOI: Vol.9(No.3) 145-152, 1993

This study was carried out to obtain the basic design and operating parameters of Moving Media Complete Mixing Activated Sludge (MMCMAS) system for the wastewater treatment. A laboratory MMCMAS reactor was operated at the hydraulic loading of 17∼340ℓ/㎡/d, and the rpms of the moving media were varied with the operational hydraulic loading. Following conclusions from this study were drawn ; (1) The laboratory MMCMAS reactor demonstrated that SBOD removal efficiencies of more than 90% were achieved at the hydraulic retention time(HRT) of 1.5 hours that was relatively shorter HRT than conventional activated sludge process. The nitrification rates of MMCMAS reactor varied in the range of 6 to 90%, depending on the hydraulic loading rates. (2) The optimum rotational speed of moving media were 5∼15rpm and 25rpm at the hydraulic loading rates of 17∼122ℓ/㎡/d and 169∼340ℓ/㎡/d, respectively. The organic removal efficiencies were little affected by the variation of rpms of the moving media at the lower hydraulic loading rates, whereas the organic removal efficiencies were reduced at higher hydraulic loading rates. It is therefore concluded that the rpm of the moving media would be an important operating parameter at higher organic loading. (3) The attached biomass on the moving media varied in the range of 32 to 94% of total biomass in the system depending on the hydraulic loading rates. The ratio of attached biomass to total biomass was increased with the increment of hydraulic loading rate. In addition, it was noticed that the concentration of suspended biomass in the system was strongly correlated with the rpms of the moving media. The finding indicates that the shear forces due to the rotational speed of moving media govern the suspended biomass concentration in the system. The biofilm thickness on the moving media was increased with the increment of hydraulic loading rates. It was also found that the density of biofilm was consistently 50±10㎎/c㎥ at the various hydraulic loading rates as well as rpms of the moving media.

박석순 , 최은주 Seok Soon Park , Eun Ju Choi

DOI: Vol.9(No.3) 153-158, 1993

Uncertainty analysis was performed for the Jisachun, a tributary of the Nakdong river, using QUAL2E-UNCAS model. Field data were obtained from two synoptic sampling surveys performed during February and March, 1991, and utilized for model calibration and verification. Monte Carlo simulation and First Order Error Analysis were conducted on the validated Jisachun model and the results were compared at five mainstream locations. The modeled water, quality parameters included Dissolved Oxygen, Biochemical Oxygen Demand, Nitrogen and Phosphorus series, and Total Suspended Solids, but selected parameters were displayed in this paper. Monte Carlo Simulation and First Order Error Analysis produced almost same values of standard deviation of the predicted water qualities in Jisachun. Monte Carlo simulation required much longer computer time than First Order Error Analysis but could produce frequency distributions of all predicted water qualities. The types and the relative significances of stream reactions which affected a specific water quality were determined from the First Order Error Analysis.

Sang Ho Lee , Louis E . Kovach , Judith B . Carberry

DOI: Vol.9(No.3) 159-166, 1993

A selected microbial consortium(SMC), using pentachlorophenol(PCP) as a sole carbon source was developed. For systems of nonpretreated and fungally or chemically pretreated PCP, the resulting growth rates were determined and compared. Pretreatment was accomplished using the white-rot fungus Phanerochaete chrysosporium or Fenton`s Reagent. Growth rate kinetics were described by the Haldane Model. Haldane constants were used as the basis of comparison. Results indicate that both fungal and chemical pretreatment effected a significant decrease in toxicity when compared with nonpretreated systems. In addition, fungal pretreatment decreased PCP toxicity to a greater extent than did chemical pretreatment at the chemical doses investigated for this study. At PCP concentrations above 47㎎/ℓ, for the fungal pretreatment system, at PCP concentration above 29㎎/ℓ, for the chemical pretreatment system, toxicity gradually increased. Possible mechanisms for these results are explained using cometabolism.

류청로 , 장선덕 , 이화운 Cheong Ro Ryu , Sun Duck Chang , Hwa Woon Lee

DOI: Vol.9(No.3) 167-177, 1993

The aim of this study is to give an overview of existing oil spill models that deal with the physical, chemical and biological aspects of fate/behavior of spilled oil, and to develop a feasible, sophisticated, design purpose model of oil spill in the coastal waters. The processes of oil weathering and movements are reviewed in detail, and the characteristics of existing oil spill fate and behavior models are examined and classified, so that an ideal model may be defined. After the evaluation of the existing models, a new model which can be practically applied to the coastal waters are developed considering meteorological and hydraulic factors in the coastal waters including advection and weathering mechanisms summarized in the review work. The wind field effect including land-sea breezes near the coastal area are considered by the comprehensive 3-D meteorological model. The oil-holding capacity and removal coefficient as well as the wave and current dynamics near the coast are included. Other parameters which may affect the advection and weathering of spilled oil are considered as same as in the typical conventional oil spill models. The applicability and feasibility of the model are discussed by comparative applications of the typical conventional model and the developed model to the South-East Coastal Waters of Korea.

김원규 Won Kyu Kim

DOI: Vol.9(No.3) 178-186, 1993

A mathematical model of nitrification and denitrification process in a tidal river was developed using lagragian coordinates. Using the developed model nitrification and denitrification process in suspended solids and sediments was quantatively evaluated in the tidal reach of Rokkaku river, Japan. From this study, it was concluded that nitrification was affected by the change of suspended solid concentration during spring-neap tidal cycles, and that the decrease in concentration of nitrate in water body was caused by denitrification process in the anoxic condition of sediment.

박영규 , 이철희 , 김동일 Yung Kyu Park , Chul Hee Lee , Dong Il Kim

DOI: Vol.9(No.3) 187-192, 1993

A system of the oxygen activated sludge process followed by the coagulation process was studied aiming at improving the treatment efficiency for the dyeing industrial complex wastewater mainly containing polyester weight reduction waste. Treating the wastewater in F/M range 0.34∼0.95㎏ BOD/㎏ MLVSS ·day and 0.14∼0.46㎏ COD_(Mn)/㎏ MLVSS ·day with the oxygen activated sludge process, it was found that the specific substrate removal rates were 0.33∼0.93㎏ BOD/㎏ MLVSS ·day and 0.1∼0.38㎏ COD_(Mn)/㎏ MLVSS · day, and the removal efficiency were 98% BOD and 77% COD_(Mn), respectively. The biomass yield coefficient(Y) and the microbial decay coefficient(Kd) were 0.40㎏ MLVSS/㎏ BOD and 0.13 day^(-1). The reactor temperature significantly effects the treatment efficiency. The filamentous microorganism, which was predominant species above 40, has resulted in the deterioration of water quality. It was confirmed that terephthalic acid remaining after the oxygen activated sludge process could be removed by the coagulation with alum at pH 5.

김응호 , 강선균 Eung Ho Kim , Seun Kyun Kang

DOI: Vol.9(No.3) 193-200, 1993

The effects of heavy metal ions on the growth of Microcystis aesuginasa have been investigated. The phosphate-limiting culture as a control is first carried out with CB media. The measured values of kinetic coefficients of Monod eq., μ_(max) and K, were 0.60 day^(-1) and 0.06㎎-P/ℓ , respectively. When heavy metal ions such as chromium, copper and cobalt are added to CB media, the specific growth rate of Microcystis aeruginasa increases while the level of heavy metal is still low. However, inhibition effect has been clearly appeared at above the critical (growthaccelerating) concentration. The critical concentration (Cm) varies with heavy metal ions. The measured values of Cm such as Cu and Co are found to be 0.2㎎ /ℓ and 0.4㎎ /ℓ, respectively. But, the Cm value of Cr is traceable. The type of growth inhibition is turned out to be noncompetitive-inhibition and the calculated growth inhibition constant of Cr, Cu and Co based on experiments have been 0.85㎎/ℓ, 3.23㎎/ℓ and 10.53㎎/ℓ, respectively.