민경석 , 안영호 , 남광현 Kyung Sok Min , Young Ho Ahn , Kwang Hyun Nam

DOI: Vol.13(No.1) 1-8, 1997

In application of enhanced UASB(EUASB) reactor using fat-free milky waste(carbohydrate:protein=60:40) as substrate, degradation of carbohydrate showed priority as compared with that of protein. In HRT 20hrs, maximum SCOD removal was 92% at organic loading rate of 8 ㎏COD/㎥/d. For SCOD removal of 80% over in HRT 10hrs, allowable organic loading rate was to 20㎏COD/㎥/d and then, methane production was 0.27 ℓ CH₄/gCOD-(rm). Enhanced UASB reactor showed phase separation in hydrogen partial pressure phase, but at the lower sludge bed zone, nitrogen utilization was different with that of l00% carbohydrate. It might be due to deamination stage of protein. At the upper sludge bed and blanket zone, it could be found autolysis of organisms except for substrate as well as deamination process. Morphological characterization with SEM showed that biopellets with milky waste was less uniform and packed loosely. These characteristics might be due to deficient condition of directly utilizable nitrogen for production of extracellular materials as well as utilization priority between carbohydrate and protein involved in substrate.

오종민 , 이수환 Jong Min Oh , Soo Hwan Lee

DOI: Vol.13(No.1) 9-16, 1997

This study has been performed to investigate water quality and organic loading on Shingal reservoir and its tributries in order to collect basic data and to apply future hydrological and systemic water supply planning. Following results were obtaind, 1. The lower reaches of Shingal stream was more polluted than upper or middle reaches of a stream. Annual average BOD concentration of Site-4 which passed by Shingal Yub, was about 33.36㎎/1, and annual average COD concentration was 71.34㎎/1. The water quality of site-4 was worse than that of downstream(site-5), and proper measure is necessary to prevent water pollution. 2. For the vertical distribution of temperature in Shingal reservior, the stratification occurred in summer and winter, but not in spring and fall. 3. For the organic loading, domestic animals contributed most with 36% and residents contributed 34.1% of total BOD loading. 4. BOD loading estimation equation of Shingal reservoir was obtained from stepwise multiple regression analysis, and this equation was statistically significant(R²=0.7704, p$lt;0.001).

이상희 , 박석순 Sang Hee Lee , Seok Soon Park

DOI: Vol.13(No.1) 17-24, 1997

A water quality modeling study was performed for network stream located at western part of Lower Nakdong River. Model construction was based on SNSIM(Stream Network Simulation Model which was developed by United States Environmental Protection Agency. The study area includes Western Nakdong River, Joman River, and their tributaries. The area was divided into 22 reaches according to the model structure. Each reach was then subdivided into uniform computational element of 0.1km. In order to characterize study area, two synoptic field surveys were performed during February 6∼7 and March 29∼30, 1991 periods at network stream and input tributaries. The model was calibrated to the February survey data and verified to the March survey data. The water quality parameters simulated in the model included dissolved oxygen(DO), carbonaceous biochemical oxygen demand(CBOD), and nitrogenous biochemical oxygen demand (NBOD). Computer code of SNSIM model was modified in this study to be executable on IBM PC or comparable with metric input/output unit. The study indicated that the modified SNSIM model would be an effective tool to simulate the water qualities in the complicated stream network. The predicted water qualities displayed reasonable agreements with the field measurements during both surveys.

Jong Woon Kwak , Lars Gillberg

DOI: Vol.13(No.1) 25-34, 1997

The removal of ortho-phosphates(ortho-P) was conducted by several aluminum and iron salts at different pH on a laboratory scale. All experimental tests was conducted by jar tests. Three phosphorous compounds as the sources of ortho-P were used for the standard waters: Na₂HPO₄: 2H₂O, NaH₂PO₄, H₂O, and H₃PO₄. The molar ratio of Al/P (aluminum/phosphorus) in all doses was 1. The influence of pH on the removal of ortho-P was described when aluminum salts of different basicities, ferric and ferrous salts were added to solutions of ortho-P and in turn, when solutions of ortho-P to fresh hydroxides. More ortho-P was precipitated by the fresh hydrolysis products of the metal salts than by the metal hydroxides. Ferrous sulfate precipitated ortho-P in a narrow pH range, but aluminum and ferric salts precipitated ortho-P in a broad pH range. It was concluded that flashing mixing is critical to both high pH and low basicity of the coagulant in removing ortho-P. The removal of ortho-P by the ferrous salt was found to be more sensitive to the way of mixing than the other salts. In practice, removals of both non-ortho-P and suspended solid was enhanced with increasing coagulant basicity, but rather that of ortho-P was decreased.

오선경 , 김정숙 , 강임석 , 이병헌 Sun Kyoung Oh , Jeong Sook Kim , Im Suk Kang , Byung Hun Lee

DOI: Vol.13(No.1) 35-42, 1997

The purpose of this study was to investigate the efficiency of water treatment processes using the biofilm in recirculating aquaculture system, to find out the optimum treatment conditions for ammonia removing in recirculating water, and to estimate possibility of reduction the water treatment unit volume in the aquaculture system as maintaining an efficient treatment process. The upflow biofilm process was equipped with two different types of media, such as Saran media and Ceramic media. This study scaled down to the 20% of the original water treatment unit volume, was compared biofilm process using Saran media with using Ceramic media over conditions of 10 cycle and 20 cycle ratio. The experimental results showed that upflow biofilm process using the Ceramic media was appeared to be better for organic removal, whereas, the biofilm process with Saran media was found to be better for ammonia removal. The biofilm process with the Saran media showed above 90% ammonia removal efficiency. When the volume ratio of recirculating water treatment unit to rearing unit was scaled down to the 20% of the original ratio, the ammonia removal efficiency could be maintained to be similar. Therefore, it can be suggested that the treatment unit of the aquaculture recirculating system can be reduced if the upflow biofilm process with the Saran media is used.

조성렬 , 김충래 , 박순달 , 김학성 Sung Yul Jo , Chung Rae Kim , Sun Dal Park , Hag Seong Kim

DOI: Vol.13(No.1) 43-49, 1997

Among the many parameters describing water quality, total nitrogen content(T-N) is regarded as important one in relation to water quality management of the waterbodies far its role in eutrophication process. For that matter high accuracy in determining the total nitrogen content is imperative. Furthermore, Korean government put under the regulation the total nitrogen contents of the effluent from the wastewater treatment plants since 1996. Two methods are commonly used to determine the total nitrogen contents. One is based on the oxidation of all the nitrogen in the sample to nitrate with potassium persulfate under alkaline conditions being followed by spectrophotometric measurement with UV light of 220 ㎚ wavelength. The other is based on the separate determinations of the organic nitrogen, ammonia, nitrite, and nitrate being followed by summation to obtain total nitrogen contents. The two methods are studied for comparison. Following conclusions are made from the study. 1. The UV spectrophotometric method after oxidation appears to be more convenient and accurate in determination of the T-N contents than the summation method after separate determination. 2. The UV method suffers of the interference by Cr(VI) and bromide ions so that it cannot be recommended for the samples of sea water. 3. The interference of carbonate ions in the oxidized sample to the UV method can be overcome by adjusting the pH of the solution to be between 2 and 3. 4. The UV method seems to be more favorable in sense of time-saving and labor-saving. 5. For the determination of T-N, the UV method appears to be superior than the summation method. But summation method turns out to be indispensable in studying of the transformation of nitrogen species in the aquatic environment or in the water treatment processes.

황병기 Byung Gi Hwang

DOI: Vol.13(No.1) 51-61, 1997

Among the many parameters describing water quality, total nitrogen content(T-N) is regarded as important one in relation to water quality management of the waterbodies far its role in eutrophication process. For that matter high accuracy in determining the total nitrogen content is imperative. Furthermore, Korean government put under the regulation the total nitrogen contents of the effluent from the wastewater treatment plants since 1996. Two methods are commonly used to determine the total nitrogen contents. One is based on the oxidation of all the nitrogen in the sample to nitrate with potassium persulfate under alkaline conditions being followed by spectrophotometric measurement with UV light of 220 ㎚ wavelength. The other is based on the separate determinations of the organic nitrogen, ammonia, nitrite, and nitrate being followed by summation to obtain total nitrogen contents. The two methods are studied for comparison. Following conclusions are made from the study. 1. The UV spectrophotometric method after oxidation appears to be more convenient and accurate in determination of the T-N contents than the summation method after separate determination. 2. The UV method suffers of the interference by Cr(VI) and bromide ions so that it cannot be recommended for the samples of sea water. 3. The interference of carbonate ions in the oxidized sample to the UV method can be overcome by adjusting the pH of the solution to be between 2 and 3. 4. The UV method seems to be more favorable in sense of time-saving and labor-saving. 5. For the determination of T-N, the UV method appears to be superior than the summation method. But summation method turns out to be indispensable in studying of the transformation of nitrogen species in the aquatic environment or in the water treatment processes.

조용모 , 오정우 Yong Mo Cho , Jung Woo Oh

DOI: Vol.13(No.1) 63-71, 1997

It is desirable to measure the water quality of river continuously. At present, automated monitoring of water quality has been operated at 8 sites in Han river. In this study, using the automated monitoring data investigated the change characteristic of water quality in Han river. Following conclusions were obtained, 1. The results of comparison automated monitoring values with experimental values in order to confidence of automated monitoring values, good coefficient of correlation was obtained in 0.84∼l.0 each item. 2. The monthly mean values of concentration were change for the worse at downstream and tributary in Han river. 3. The distribution of seasons concentration was obtained that COD of maximum value was summer season and that minimum value was winter season.

권효정 , 박수영 , 조광명 , 김홍선 Hyo Jung Kwon , Soo Young Park , Kwang Myeung Cho , Hong Sun Kim

DOI: Vol.13(No.1) 73-78, 1997

The effects of a drop-type toilet bowl cleaner(TBC) on the activity of microorganisms of sewage treatment facilities were tested by various experiments such as biochemical methane potential(BMP) measurement, oxygen uptake rate(OUR) measurement, a semicontinuous anaerobic digestion and an activated sludge treatment experiments. The results of the BMP test showed that the methane production rate gradually decreased as the TBC concentration increased, showing little gas production above 5,000㎎/L. In the anaerobic digestion experiment, the gas production and methane content decreased when the TBC concentration in the sludge fed increased to 6,667㎎/L. The OUR test failed to show a threshold TBC concentration which influences the activity of activated sludge. However, the CSTR activated sludge study showed that the activity of the activated sludge can be affected at TBC concentrations above 5,000㎎/L.

방기웅 , 이준호 , 유명진 Ki Woong Bang , Jun Ho Lee , Myong Jin Yu

DOI: Vol.13(No.1) 79-99, 1997

Combined sewer overflows (CSOs) are known for their overflow of untreated wastewater during storm events, therefore CSOs are composed of sewage and surface runoff wastewater, typically from urbanized areas. This study was performed to characterize the quantity and quality of the CSOs from urban watershed located in Hungduk-gu, Cheongju city and Dong-gu, Taejon city, respectively. Quantity and quality of CSOs were surveyed for two years and concentrations of biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids (SS), total nitrogen (TN), total phosphorus (TP) and n-Hexane extracts were measured. The runoff loading rate of BOD, COD, SS, TN, TP and n-Hexane extracts were estimated to be 0.189㎏/ha/㎜, 0.692㎏/ha/㎜, 2.540㎏/ha/㎜, 0.032㎏/ha/㎜, 0.017㎏/ha/㎜, 0.771㎏/ha/㎜, respectively, during the wet weather. Based on the pollutant runoff unit load and washoff concept, ILLUDAS-POLL model (Illinois Urban Drainage Area System and pollutograph model) was developed. The Illinois Urban Drainage Area Simulator (ILLUDAS) has been modified for water quality model (named POLL) has been added to it. Parameter, coefficients adjustments for model calibration executions with continuous 5-minute rainfall record. From the results of model application, correlation coefficients between the measured and estimated concentrations were 0.53∼0.96 for BOD, 0.24∼0.91 for COD,0.32∼0.89 for SS, 0.55∼0.81 for TN, 0.47∼0.72 for TP, and 0.35∼0.95 for n-Hexane extracts respectively. It was concluded that ILLUDAS-POLL model is a useful tool in CSO`s pollutograph estimation with storm events for a small urban watershed.

조주식 , 임영성 , 허종수 Ju Sik Cho , Yeong Sung Lim , Jong Soo Heo

DOI: Vol.13(No.1) 101-109, 1997

Cadmium-tolerant bacteria, Pseudomonas putida which possessed the ability to accumulate cadmium, was isolated from mine wastewater polluted with various heavy metals. The characteristics of cadmium accumulation in the cells, recovery of the cadmium from the cells accumulating cadmium, were investigated. Removal rate of cadmium from the solution containing 100㎎/ℓof cadmium by Pseudomonas putida was more than 87% at 48 hours after inoculation of the cells. A large number of the electron-dense granules were found mainly on the cell wall and cell membrane fractions, when determined by transmission electron microscope. Energy dispersive X-ray spectroscopy revealed that the electron-dense granules were cadmium complex with the substances binding cadmium. The cadmium accumulated into the cells was not desorbed by distilled water, but more than 80% of the cadmium accumulated was desorbed by 0.1M-EDTA solution. The residues of the cells after combustion at 550% amounted to about 21% of the dry weight of the cells. EDS analysis showed that the residues were comparatively pure cadmium compound containing more than 81% of cadmium.

이재우 , 정태학 Jae Woo Lee , Tai Hak Chung

DOI: Vol.13(No.1) 111-116, 1997

Effect of Dissolved Oxygen(DO) on the treatment efficiency of wastewater in the Sequencing Batch Reactor(SBR) process was investigated. The peak DO level was maintained below 1㎎O₂/L or above 6㎎O₂/L during the oxic period. Despite low D0, the organic removal efficiency was higher than 95%, but the nitrification was considerably inhibited. This resulted in significant increase in the phosphorus release and improvement of phosphorus removal efficiency. Biological phosphorus removal was accelerated by high organic loading. Large amounts of phosphorus were released during the idle period although there was no influent. When nitrate was used instead of ammonia as a nitrogen source, phosphorus release decreased because of phosphorus uptake at the later part of anoxic period. Polyhydroxyalkanoates(PHA) stored in the cell responded well in accordance with organic availability and phosphorus transport. It is possible to achieve high removal of organic and phosphorus by operation of the reactor at low DO.