곽동희 , 김영철 , 이성우 , 정팔진 Dong Heui Kwak , Youngchul Kim , Sung Woo Lee , Paul Gene Chung

DOI: Vol.14(No.2) 111-120, 1998

General type of processes treating a water for its public use in Korea, are chemically aided sedimentation tanks followed by rapid sand filters. Settled sludge from a coagulation/flocculation and sedimentation process is easily drained into the sludge treatment train from the bottom of tanks but sludge floated along with numerous micro-bubbles on the surface of coagulation/flocculation tanks and head-part of sedimentation tanks, initially built and operated without a skimmer and barrier against moving floats, has caused serious aesthetic and operational problems. In this study, sources of the micro-bubbles combining with floc particles and causing floating sludge, and factors affecting formation of those bubbles were investigated. There are several factors which can produce gas bubbles in the water treatment plant. Pumps and conduits highly pressurized during water intake and transport to the water treatment plant might be one of the possibilities which can produce micro-bubbles due to the pressure differences. The amounts of nitrogen and carbon dioxide gases evolved during prechlorination and coagulation processes were calculated by using actual plant operational data. Changes of interfacial properties of coagulated water were examined as a possibility of enhancing micro-bubbles production. Among these three factors, it was found that changes of surface characteristics had a significant and direct effect on the formation of micro-bubbles at this plant.

곽동희 , 전훈 , 정팔진 Dong Heui Kwak , Hoon Jeon , Paul Gene Chung

DOI: Vol.14(No.2) 121-128, 1998

Many water bodies used for water supply may contain solid particles with a lower density. These solids are hardly removed in the sedimentation unit due to the own tendency of floating. In order to treat this type of water, the dissolved air flotation (DAF) unit is known to be an effective method. A series of laboratory experiments has been performed to investigate the characteristics of solid separation followed by simplification of DAF models in water treatment processes. Results of DAF treatment studies show that total solids removal efficiency depended on the amount of solids attached to bubble on the water surface and residual floating solids in the water. For the enhancement of solid removal efficiency, It is to be desired that surface loading should be operated less than rising velocity of residual floating particles as well as air volume concentration enough.

이종현 , 남해욱 , 김영규 , 박태주 Jong Hyun Lee , Hae Uk Nam , Young Gyu Kim , Tae Joo Park

DOI: Vol.14(No.2) 129-136, 1998

A new biological nutrient removal system combining A²/O process with fixed film was developed in this work and the characteristics of phosphorus removal were especially investigated in the combined fixed film reactor(CFFR). Media was added in the anaerobic, anoxic and aerobic reactors, respectively. Tests were made to establish the effluent level of T-P, COD, pH, SS and nitrate effects on phosphorus removal in the CFFR by decreasing hydraulic retention time (HRT) from 10 to 3.5 hours and by increasing internal recycle ratio from 0% to 200%. The influent was synthesized to levels similar to the average influent of municipal wastewater treatment plants in Korea. SARAN media with a porosity of 96.3% was packed 40%/30%/25% based on its reactor volume, respectively. It was found that T-P removal efficiencies were 39.4% 20.5% as HRT decreased from 10 hours to 3.5 hours and optimum range of pH for effective phosphorus removal was 6.8∼7.7. Nitrate inhibited the P release in anaerobic reactor. As the internal recycle ratio increased from 0% to 100%, T-P removal efficiency increased in CFFR process, while T-P removal efficiency decreased at the condition of the internal recycle ratio, 200%. Further study especially on P uptake by denitrifying phosphorus removal bacteria in anoxic reactor is needed to enhance T-P removal efficiency in CFFR process.

최명수 , 윤여진 , 방기웅 , 이준호 Myung Soo Choi , Yeo Jin Yoon , Ki Woong Bang , Jun Ho Lee

DOI: Vol.14(No.2) 137-144, 1998

Experimental measurements were conducted for two apartments area with their own on-site sewage treatment plants in order to quantify the unit loading factors of various pollutants. The influent sewage discharged from the apartment areas was sampled three days a week at two sites and during four seasons. The daily experimental measurements for flowrates were carried out every 30 minutes. The analysis of the pollutant loadings such as BOD_5, COD_(Cr) and SS were made every two hours. The components of TKN and TP in the influent sewage were also analyzed in the preparation for the further improvement of current sewage treatment systems which may be applied as diagonostic tests for conversion toward advanced treatment systems. The result of the study were as follows ; (1) The average unit sewage flowrate 178. 1L/capita/day, (2) The average unit loadings for BOD_5, COD_(Cr), SS, TKN and TP were computed to be 32.4, 58.5, 19.9, 6.3 and 0.9g/capita/day, respectively.

방기웅 , 이준호 , 최명수 , 윤여진 Ki Woong Bang , Jun Ho Lee , Myung Soo Choi , Yeo Jin Yoon

DOI: Vol.14(No.2) 145-152, 1998

The purpose of this study is to determine the periodic components for an apartment sewage flowrate and water quality parameters. The subjects considered include (1) Measurements of the sewage flowrate and water quality parameters from an apartment area. (2) Periodic and spectrum analysis of sewage flowrate and water quality data using Fourier series. Experimental measurements were carried out Dunsan apartment area in Daejon city with it`s own sewage treatment plant to measure the sewage flowrate and to analyze water quality components. The sewage was continuously sampled daily every 2hours, and the whole samplings were performed for 12days, each representing spring, summer, autumn, and winter. The results of this study were as follows ; (1) The water quality range for BOD_5, COD_(Cr), and SS were measured to be 61∼331㎎/L (average 177㎎/L), 109∼665㎎/L (average 345㎎/L), 42∼345㎎/L (average 121㎎/L), respectively. (2) Spectral density showed that the dominant 12hours periodicty and the 24hours periodic variation were observed.

김시준 , 이병헌 Shi Jun Kim , Byung Hun Lee

DOI: Vol.14(No.2) 153-159, 1998

A high concentration of inorganic substances of calcium, sodium and chloride are contained in leachate from solid waste landfill. That causes various problems of corrosion or scaling of inside and outside treatment facilities. It is seldom removed that conventional leachate treatment system with biological, coagulation, sand filtration and activated carbon adsorption process. Therefore, we studied the removal of high concentration of inorganic substances by electrodialysis process. An effective membrane surface area was 1.72dm²× pairs. And desalination time was 60min. with 1.5ampere and 15volts. As the results, stable desalination was achieved above 95percent up to 3,000㎎/L as calcium, 3,000㎎/L as sodium and 10,000㎎/L as chloride respectively. And also flux was in constant values and increased with the increasing in the concentration of inorganic substances. Removal efficiency of NH₄^+-N was 80percent in leachate.

김상구 , 류재익 , 류병순 Sang Goo Kim , Jai Ick Ryoo , Byung Soon Ryu

DOI: Vol.14(No.2) 161-166, 1998

Coagulation is a very important process in rapid filtration system for effective removal of turbidity and organic matters in the sequential sedimentation and filtration processes. The purpose of this research is to find both coagulant consumption factors and to determine coagulant dosing equation with characteristics of water. Many coagulation factors are proposed such as pH, alkalinity, TOC, temperature, velocity gradient, mixing time, among these factors we have studied on the alkalinity and natural organic matter (NOM) as humic acid in pH 7.0∼7.5 value using two different coagulants; poly sulfate organic-magnesium (PSO-M) and poly aluminium chloride silicate (PACS). The results for coagulants consumption rates with alkalinity and NOM concentration showed that the dosing equation of PSO-M and PACS is as 10^((0.722log(alk)+0.00497)), 10^((1.06log(alk)-1.0)) for alkalinity and 6.1 ㎎/1, 5.l㎎/l for NOM, respectively.

박진용 , 이진원 Jin Yong Park , Jin Won Lee

DOI: Vol.14(No.2) 167-175, 1998

To develop the lake water clean technology by ultrafiltration, the performances of polysulfone and polyacrylonitrile hollow-fiber type modules (Koch Inc.) were investigated using dextran and polyethylene glycol solution, and we found the optimum operation conditions of this ultrafiltration system. Then, the ultrafiltration was operated using water of Gongjee-stream, that was the branch of Euam-lake in Bukhanriver. As the results, the molecular weight cutoffs confirmed in these tests were a little higher than those suggested by the manufacturers, and the optimum transmembrane pressure were 18.5psi in this system. In the ultrafiltration of lake water the rejection rate of turbidity was above 94% and that of BOD, was 24∼50%. However, the rejection rate of TS and TDS were low values, that were 19∼34% and 10∼17%, respectively. Therefore, the suitable module investigated in this study seemed to be polysulfone PM10, which showed the highest rejection rate of BOD_5.

황병기 , Byung Gi Hwang , W . S . Lung

DOI: Vol.14(No.2) 177-186, 1998

EPA`s WASP/EUTRO5 modeling framework was applied to assess water quality problems of Maryland Coastal Bays, which were developing rapidly in areas adjacent to Ocean City and are an area of concern due to the potential effects of such development and resulting landuse changes on environmental quality. The model was utilized to determine subwatersheds that most impact water quality conditions in the bays and contribute to the eutrophication problem in receiving waters. Model results were used to develop nutrient budgets for the study area. The analysis of the results shows that nutrient release from the sediment is the single most important nutrient source. Further, projected landuse was used in the model to determine water quality impacts from the future land use changes in 2005. According to model simulations, only a small reduction in total chlorophyll a from the present condition was expected due to the reduction of nutrient loads.

배병욱 , 김영일 , 임봉수 , 방미란 Byung Uk Bae , Young Il Kim , Bong Su Lim , Mi Ran Bang

DOI: Vol.14(No.2) 187-195, 1998

The seasonal variations of natural organic matters(NOM) in drinking water source and their removal characteristics through water treatment processes were investigated for two kinds of source waters in Kum-River. The quality of raw water at the Chungju water treatment plant(WTP) was stable throughout one year of sampling period. However, the source water at the Puyo WTP showed higher variations in DOC(dissolved organic carbon) and turbidity compared to the Chungju WTP. The SUVA(specific UV absorbance) values of both raw waters were less than 3 and had a trend to decrease after coagulation/sedimentation process. This results indicate that relatively large organic matters which have higher absorptivity per unit DOC might be easily removed during coagulation process. The AHS(aquatic humic substance) contents of both raw waters varied seasonally, but the Puyo WTP had a relatively higher AHS contents than the Chungju WTP. Results from the change in molecular weight distribution(MWD) before and after AHS measurement showed that AHS was mainly composed of organics higher than MW 1,000. The PAC(powdered activated carbon) might be used as an effective method for removing organic matters, especially for AHS, and the addition of PAC before coagulation showed the most satisfactory result with respect to DOC removal.

박선구 , 류재근 Sun Ku Park , Jae Keun Ryu

DOI: Vol.14(No.2) 197-208, 1998

This study was performed to change Mn method of Korea at present into Cr method comparing testing methods in each country for the measurement of COD. Office testing method for water quality contamination was newly proposed that advantages were considered by comparing, assessing and evaluating the JIS of Japan, standard method(closed reflux, open reflux) and EPA of U.S.A., Experiments for the KHP standards, lake water and effluent water drained from wastes treatment plant were carried out several times successively to certain reproducibility of each testing method, in result, standard deviation of experiment by proposed method has shown good results more than other ones. The COD of lake and stream water for Han river, Nakdong river, Kum river, and Yungsan river was measured by Mn and Cr method, the concentration of COD was different in each sampling site. In case of lake water with class I∼II, the ratio of COD resulted from two methods was 2∼3times and concentration of COD by Cr method was about 10ppm. The concentration of COD by Cr method was 35ppm at the site contaminated with polluants considerably. Raw wastewater and effluent water of 15 discharge sources for 6 industries were measured for the COD by Mn and Cr method to compare the difference of two methods. The ratio of COD between Mn and Cr method for raw wastewater and effluent water was 2∼4times except industrial chemistry, leather and fur industry. The experiment was also performed to compare oxidation percent for six organic compounds including benzene, Cr method(above 95%) was higher than Mn method(60∼65%).

배민수 , 박수영 , 범봉수 , 조광명 Min Su Bae , Soo Young Park , Bong Su Bum , Kwang Myeung Cho

DOI: Vol.14(No.2) 209-214, 1998

When an anaerobic activated carbon fluidized bed biofilm reactor is employed for wastewater treatment, a reserve space is required above the fluidized bed to prevent the loss of media, and wastewater treatment efficiency may be affected by the attached and suspended biomass in the reserve space. Therefore, experiments were performed by increasing stepwise the organic loading rates(OLR) of two reactors with and without a reserve space from 2 to 16㎏ COD/㎥-day. Results of the research showed that treatment efficiencies of the reactors were almost similar until the OLR reached 8㎏ COD/㎥-day. At higher OLRs, however, the effluent quality of the reactor without a reserve space was worse than the one with a reserve space. This is due to sloughing-off and washing-out of the biomass in the reactor without a reserve space, but the reactor with a reserve space maintains more biomass because of the attached growth on the inside surface of the reserve space. Therefore, a reserve space for prevention of media loss in an anaerobic activated carbon fluidized bed biofilm reactor would provide an increase in treatment efficiency at high OLRs.

유춘만 , 위인선 , 이종빈 Chun Man Yu , In Sun Wui , Jong Bin Lee

DOI: Vol.14(No.2) 215-221, 1998

This study was done to evaluate the quality of offshore waters in Korea using gametes, embryos and early development system of Asterina pectinifera. Results of the quality evaluation of offshore waters of Korea by bioassay using A. pectinifera has shown that in spite of an inflow of many rivers from Korean topography, the west coast has maintained the second grade (II), because pollutant inflow was decreased due to purification of inflow rivers, control of waste water discharge, construction of wastewater treatment plants, and because pollution was decreased by smooth circulation of sea water with difference of the large ebb and flow of the tide. On the other hand, Asan, Hampyeung and Cheunsu Bay where water circulation is relatively poor, and Gunsan and Mokpo harbors which are inflowed by rich polluants from neighboring cities have shown third grade(III) because A. pectinifera was inhibited violently to early development. The South coast has maintained the second grade (II) or third grade(III) because A. pectinifera was inhibited moderately or strongly to early development. Also, Kangjin, Duekyang, Kwangyang, Masan and Jinhae Bay where water circulation is relatively poor have shown third grade (III) because A. pectinifera was inhibited violently to early development. The East coast has maintained the first and second grade (I), (II) because of simple coasts and smooth circulation of sea water. But Cheungcho Lake was worsened by he breakwater that was constructed in order to maintain port functions.

오정우 , 윤재홍 Jung Woo Oh , Jae Heung Yoon

DOI: Vol.14(No.2) 223-228, 1998

The characteristics of THM formation in a water distribution system is inspected by the analysis of measured data such as chlorine residual, DOC, UV_(254), temperature and pH. The result shows that THM concentration increases by 30% or less in the distribution system as the distance from water treatment plant increases. THM formation also increases with the increase of temperature, DOC, and UV_(254). On the contrary to the theoretically obtained result, in which THM formation increases as pH increases, the THM formation in the distribution system decreases as pH increases. This is caused by the complicated interactions among the factors of water quality. It is shown that UV_(254), is more effective than TOC or DOC as a measure of THM precursors. In addition, the effect of water quality on other disinfection by-products should be considered when THM formation is intended to be reduced by controlling water quality.

배석진 , 조영관 , 이정전 , 이진종 Seok Jin Bae , Young Gwan Cho , Jung Jun Lee , Jin Jong Lee

DOI: Vol.14(No.2) 229-236, 1998

In order to research the odor and taste substances naturally produced by algae in the surface water of the Dongbok reservoir, we studied relationship between algal biomass and taste and odors substances in culture fluids, which were analyzed by GC/MS. Alga producing musty or earthy odors in culture media was Anabeana macrospora, Oscillatora tenuis and Phormidium tenue. The slime-producing algae were Microcystis aeruginosa, and the algae causing fishy odor was Eudorina elegans. Odor of cucumber was detected in the culture media of Peridinium, and grassy odor was detected in Synedra acus. The musty odor substance, Geosmin(171ng/L), was mainly produced by Anabaena macrospora in the Dongbok reservoir at May, 1995 when the abundance was very large, 373,740cells/L(23,400 colonies). The products of Geosmin each their colony were 0.007ng/colony. In the culture fluids, Anabaena macrospora and Oscillatoria animals produced geosmin, and Oscillatoria tenuis and Phormidium tenue produced 2-MIB. When chlorinated in culture fluids of algae, about 80% of total amount of odor and taste substances was increased. It may be caused by the release of taste and odor substances inside algae body.

곽종운 Jong Woon Kwak

DOI: Vol.14(No.2) 237-243, 1998

학회자료

DOI: Vol.14(No.2) 245-248, 1998