류재근 Lyu Jae Geun

DOI: JANT Vol.20(No.1) 1-11, 2004

Water quality is monitored at 1,837 points which are streams and sources for water supply in Korea. The monitoring carry out the measurement of 16 parameters of pH, BOD, SS, DO and so on with once a month, and of other parameters such like heavy metal with once a quarter. But most of the monitoring is carried out uncontinuously, so it is very difficult to understand exactly the changes of water quality compared with continuous monitoring. Therefore, real time monitoring system was equipped with basic parameters such as pH, temperature, DO, turbidity and electric conductivity at 25 major sources of water supply after installation of Noryangjin and Dukdo in 1974. But the systems have some problems which cannot be considered the sampling sites to represent for water quality of stream of lake, and can be caused a change of water quality by long distance from analyzer to intake pipe. Therefore, it has carefully to evaluate selection of sample sites for real time monitoring system. Also, problems on the area has been to identify which parameters are best suited to monitoring stream of lake water and the differences, of analyzing results compared with manual analyzing. This paper presents some approaches to handle such problems, namely selection of sampling site and measurable parameters, to connect with bio-monitoring system solving a Limitation of measurable parameters, The bio-monitoring system of an early alarm that is desirable to perceive a toxic material inflow into stream can be applied to continuos water quality monitoring system effectively. Also, this paper presents to build a on line system transmitting immediately from a mobile a n a i m house or container to main monitoring center the results of analyzer by a telemeter.

최의소 Choe Ui So , 윤주환 Yun Ju Hwan

DOI: JANT Vol.20(No.1) 12-17, 2004

원성연 Won Seong Yeon , 이상일 Lee Sang Il

DOI: JANT Vol.20(No.1) 18-23, 2004

In this research, a 2-stage intermittently aerated activated sludge system(IA) and intermittently aerated dynamic flow activated sludge system(DF) were investigated for the removal of nutrients in domestic wastewater. Wastewater was characterized by low C/N(organics/nitrogen) ratio. COD,,, BOD_(5), TKN and TP concentrations of domestic wastewater were 235, 47, 32 and 5.4 ㎎/L , respectively. Three sets of LA and one set of DF were operated. Three of four systems were added with fermented settled sludge taken from primary settling tank as an external electron donor and the other(IA) for control reactor was operated without addition of electron donor. All systems were operated at same sludge retention time of 20 days and hydraulic retention time of 12hrs. The supplemental electron donor was supplied into the anoxic mode. A higher denitrification rate was observed from the reactors with fermented settled sludge as an electron donor for denitrification compared to that of without addition of organic source. The result of this study indicates that the settled primary sludge, if the fermented at the acid stage, was an excellent electron donor for denitrification. 81% of TN and 80% of TP were removed from the systems with the supplemental organic source added. However, the control reactor without addition of electron donor showed only 39% of TN and 43% of TP.

류홍덕 Lyu Hong Deog , 민경국 Min Gyeong Gug , 이상일 Lee Sang Il

DOI: JANT Vol.20(No.1) 24-31, 2004

This study was initiated to evaluate the efficiencies of DEPHANOX and Modified-DEPHANOX, which were devoloped to enhance nitrogen removal efficiency in municipal wastewater treatment. In the results, removal efficiency of organic matters was not affected much by increased loading rate of organic matters which is contained in influent. The nitrogen removal efficiencies according to the loading rate of influent TN was decreased drastically in conditions of over 0.2 kg/㎥ - day, which is T-N loading rate, and the DEPHANOX process was affected more sensitively than the M-DEPHANOX was. When the temperature was altered from 25℃ to 16 ℃ at HRT 6hrs, the removal efficiency of ammonia nitrogen was still over 90% and it was concluded that both DEPHANOX and M-DEPHANOX were strong enough to endure temperature variation. Moreover, both processes showed over 90% in ammonia removal efficiencies in over HRT Shrs, so it was concluded that they were strong in HRT variation. M-DEPHANOX process showed a higher value than DEPHANOX did in T-N removal efficiency to the extent of 4 -21 %, which resulted from differency of denitrification rates and the biosorption efficiency of organic matter in both processes. In the condition of HRT less than 4hrs, concentrations of ammonia nitrogen contained in effluents and nitrification reactors, might be sensitively affected by biosorption efficiency of organic matters in first separation tank. In the effect of effluent nitrate concentration in phosphorus removal, the more effluent nitrate concentration was decreased, the more phosphorus removal efficiency was increased. This result is related to the decrease of concentration of effluent nitrate which resulted from nitrification inhibition by decreased HRT.

권영석 Kwon Yeong Seog , 김동일 Kim Dong Il , 정연규 Jeong Yeon Gyu , 배범한 Bae Beom Han , 이인숙 Lee In Sug , 장윤영 Jang Yun Yeong

DOI: JANT Vol.20(No.1) 32-36, 2004

In this study, uptake and translocation of 2,4,6-trinitrotoluene(ThT) by plant in a hydroponic culture was quantified with two indigenous plant species, Aeschynomene indica and Abutilon avicennae on various initial concentrations of TNT ranging from 20 to 80 ㎎TNT/L. Experiments were sterilized to exclude the activity of microorganisms and conducted in duplicate. Weight loss of two plant species in added TNT culture media was higher than in control. At over 20㎎TNT/L, there appeared to be phytotoxicity from TNT as indicated by severe yellow-chlorosis and increase of falling leaves. TNT removal rate normalized(K) to the plant fresh weight of Abutilon avicennae and Aeschynomene indica was that the higher TNT concentrations resulted in lower TNT removal rate normalized(K) to the plant fresh weight. Approximately 96% of the TNT in viable microflora-hydroponic culture was removed after 96h of the experiments.

정팔진 Jeong Pal Jin , 이은주 Lee Eun Ju , 김민정 Kim Min Jeong

DOI: JANT Vol.20(No.1) 37-41, 2004

This paper was studied about the characteristics of treatment by ionized gas for livestock wastewater, aiming at the effects of ionized gas on organic matter, hydrophobic and hydrophilic organic matter in lviestock wastewater when the new process of advanced oxidation process was applied for meeting the improved the quality of effluent. The organic matter within treated livestock wastewater by ionized gas was partially mineralized according to the time increasement. The TCOD_(Mn) in the livestock wastewater was decreased from 840㎎/L to 340㎎/L when treated by ionized gas by the enhancement of time. We occupied the equations of TCOD_(Cr), SCOD_(Cr), TCOD_(Mn) as ti uibuzed gas treated time. As TCOD_(Mn) increasing ionized gas treated time, the concentration did not meet the water quality. COD_(Mn) 40㎎/L. So, for removing of the remaining organic matter in the effluent after ionized gas following process is necessary. After treating the livestock wastewater by ionized gas, coagulation was considerable for organic matter removal up to regulation water quality. From UV scans of the treated livestock wastewater by ionized gas, the wastewater has low aromaticity and good colour.

손동훈 Son Dong Hun , 임봉수 Im Bong Su , 박혜숙 Park Hye Sug

DOI: JANT Vol.20(No.1) 42-47, 2004

This study was accomplished to develope an advanced wastewater treatment process using high MISS in anoxic tank aimed to improve nutrient removal and to reduce wasting sludge. It was operated with 4 Modes with varing solid concentration and internal recycle ratios. Mode Ⅰ, Ⅱ, Ⅲ was operated 1.0 - 1.5% MLSS concentration at anoxic tank with 50% sludge recycle rate, however, each internal recycle rate were 100%, 200%, 300% and Mode Ⅵ was operated 1.5 - 2.0% MLSS concentration at anoxic tank with 50% sludge recycle rate and 100% internal recycle rate. The COD removal efficiency didn`t show any big difference from Mode Ⅰ to Ⅵ. The average COD removal rate was over than 90%. The T-N removal rate was 73%, the highest rate in all mode. The 36% of SCOD is used for the denitrification and phosphorus release in the anoxic tank. Specific denitrification rate was 3.5㎎ NO₃^(-)-N/g M v h and denitrification time was 0.7hr. As MLSS concentration is higher in anoxic tank as denitrification time would be shorter. The T-P removal rate was average 70%. The phosphorus release accomplished from the anoxic tank because the anaerobic condition was prevalent in the anoxic due to the prompt completion of denitrification. Sludge production was 0.28 ㎏VSS/㎏ BOD_(removed) under the 1.5% MLSS and 17 day SRT. It is prominent result which has 40% sludge reduce comparing with traditional activate sludge system.

박종호 Park Jong Ho , 이상일 Lee Sang Il , 조영옥 Jo Yeong Og

DOI: JANT Vol.20(No.1) 48-54, 2004

Two methods, a Cerioduphniu algal uptake suppression test (CAUST) and a new toxicity test based on temperature control (TTBTC) which are based on feeding behaviour and temperature control, respectively, were developed and compared for the adoption as the better methodology for short-term toxicity screening. As previously published by Lee et al., (1997), the CAUST method is based on the feeding behaviour of C. dubiu and requires as little as 1 hour of contact time between C. dubiu neonates and toxicant. However, even though CAUST requires only 1 hour of contact time, this method still take many hours for the preparation and measurement. Before the test starts, neonate digestive tracts were cleared by feeding yeast to the daphnids. Neonates were then exposed to toxicant, followed by addition of Scenedesrnus subspiatus into the bioassay vessels. Daphnids were examined under the bright-field microscope with the presence of algae (indicated by a green colored digestive tract) or the absence of algae. Uptake indicated no toxic effect, whereas, absence of uptake indicated toxic inhibition. Unlike CAUST, the newly developed method (TTBTC) is based on just temperature control for the toxicity test of C. dubiu. Initially, neonates are exposed to toxicants while the temperature of water bath containing media increased to 35.5 ℃. After 1.25 hour of contact time, the number of the daphnids, either live (no toxic effect) or dead (toxic effect), is counted without the aid of any instrument. In both methods, median effective concentrations (EC_(50) values) were computed based on the results over a range of dosed toxicant concentrations. It showed that TTBTC was as sensitive as the standard 48-hour acute bioassay and CAUST. TTBTC and CAUST were much more sensitive than the I-hour I.Q. test and 30-minute Microtox. This study indicates that TTBTC is an easier and more rapid toxicity test than the standard 48-hour acute bioassay and even CAUST.

이동석 I Dongseog , 민병섭 Min Byeong Seob , 박선구 Park Seon Gu , 김정화 Kim Jeonghwa , 류재근 Lyu Jaegeun

DOI: JANT Vol.20(No.1) 55-62, 2004

This study was carried out to investigate the formation of DBPs(Disinfection By-products) such as trihalomethane(THMs) and haloacetic acid(HAAs) by chlorination in raw water and finished water of Water Treatment Plant(WTP). The formation of THMs was increased with the increase of pH and reaction time. HAAs was found as a high formation at a pH 7 and low formation pH 9/ THMFP(Trihalomethane Formation Potential) was the highest formation potential in raw water of Pu-1 and the lowest in raw water of Pa-1. In case of HAAFP(Haloacetic acid formation potential), So-1 showed the highest value, while Pa-1 showed the lowest value. It was investigated the relationship between HAAs and organic matters which were described as DOC(dissolved organic carbon) and UV_(254). In both DOC and UV_(254) versus HAAFP, Pu-1 showed the good correlation coefficients(r²) with 0.95 and 0.84, respectively. For three WTP investigated, DBPs(THMs+HAAs) was shown over the range of 42.00∼49.36㎍/L. This result might be due to different characteristic of organic matters in raw water and the difference of chlorine dosage for a water treatment.

김주화 Kim Ju Hwa , 박석순 Park Seog Sun

DOI: JANT Vol.20(No.1) 63-71, 2004

The long-term trend analyses of water qualities were performed for 49 monitoring stations located in Nakdong River. Water quality parameters used in this study are the monthly data of BOD(Biological Oxygen Demand), TN(Total Nitrogen) and TP(Total Phosphorus) measured from 1990 to 1999. The long-term trends were analyzed by Seasonal Mann-Kendall Test and Locally WEighted Scatter plot Smoother(LOWESS). Nakdong river was divided into four subbasins, including upstream waershed, midstream watershed, western downstream watershed and eastern downstream watershed. The results of Seasongal Mann-Kendall Test indicated that there would be no trends of BOD in upstream waershed, western and eastern downstream watershed. Trends of BOD were downward in midstream watershed. For TN and TP, there were upward trends in all of watersheds. But LOWESS curves suggested that BOD, TN and TP concentrations generally increased between 1990 and 1996, then resumed decreasing.

정팔진 Jeong Pal Jin , 이은주 Lee Eun Ju , 김민정 Kim Min Jeong , 조선영 Jo Seon Yeong

DOI: JANT Vol.20(No.1) 72-77, 2004

Laboratory studies were carried out to find out the characteristics of humic acid treatment by activated carbon and ionized gas. In order to increase oxidation power of ionized gas for treating organic matter, we used granular activated carbon. By using UV_(254), easy analysis method, we calculated humic acid concentration and SCODcr concentration. For an initial concentration of humic acid, 10, 50 and 100ppm, the reaction rate constant by UV_(254) was 8.98×10 /min, 5.62×10^(-3) /min and 4.8×10^(-3)/min respectively due to the same flow rate of ionized gas. When we added activated carbon to the ionized gas for humic acid treatment, the reaction rate constant increased in 4.13, 3.65 and 3.15 times. So, by using activated carbon in treating humic acid by ionized gas, oxidation power of organic matter by ionized gas was increased. The hydrophobic fraction constitutes 98% of organic matter for humic acid at the beginning. After the treatment using ionized gas for humic acid, the hydrophobic fraction decreased by 63 -65% and the hydrophilic one increased by 35 -37%. So, it was proved that the treatment increased the hydrophilic fraction in organic matter.

변석종 Byeon Seogjong , 조순행 Jo Sunhaeng , 윤제용 Yun Jeyong , 김수명 Kim Sumyeong

DOI: JANT Vol.20(No.1) 78-85, 2004

As an ozone contactor, we newly adopted HJLR(High-performance Jet Loop Reactor) for the decolorization of Reactive black 5 and the mineralization of oxalic acid, which has been applied exclusively in biological wastewater treatments and well-known for high oxygen transfer characteristics. The ozonation efficiency for organic removals and ozone utilization depending on the mass transfer rate were compared to those of Stirred bubble column reactor, which was controlled by varing energy input in the HJLR and Stirred bubble column reactor. The results were as follows ; first, the decolorization rate of Reactive black 5 in the HJLR reactor was nearly proportional to the increasing k_(La) was increased by 25% from 13.0hr^(-1) to 16.4hr^(-1), 30% of the k¹(apparent reaction rate constant) was increased from 0.1966 to 0.2665min^(-1)(Stirred bubble column ; from 0.1790 to 0.2564min^(-1)). Ozone transfer was found to be a rate-determining step in decolorizing Reactive black 5, which was supported by that no residual ozone was detected in all of the experiments. Second, the mineralization of oxalic acid was not always proportional to the increasing k_(La), in the HJLR reactor is beneficial only when there are in ozone transfer limited regions. In addition, regardless of k_(La), the mineralization of oxalic acid was nearly accomplished within 60 minutes. It was interpreted as that the longer staying of residual ozone by whirling liquid in the HJLR reactor contributed to an high ozone utilization(83-94%), producing more OH radicals.

황규대 Hwang Gyu Dae , 조영무 Jo Yeong Mu

DOI: JANT Vol.20(No.1) 86-92, 2004

Lab-scale experiments have been carried out to investigate ammonia stripping with a modified spray tower for removing ammonia nitrogen from swine wastewater. The operating conditions such as initial pH, temperature, air flow, hole size of distributor determining the diameter of water drops, and influent solids concentration were closely examined focusing on removal efficiency of ammonia. As a result of the experiment, in order to achieve high rate of ammonia removal by the air stripping system the air flow rate must be supplied at high rate with sufficiently high initial pH, temperature. The optimum operating condition to meet the residual ammonia concentration of 300 ㎎/L was the initial pH of 1 1.0 at 35 ℃ with the air flow rate of 20 L/min. It also showed that the smaller hole size is, the higher removal rate of ammonia is expected. However, when used a small sized distributor (2 ㎜), the flooding problem at the upper column occurred due to clogging of the hole. With regard to the influent solids concentration, it was showed that the lower concentration of solids, the higher removal rate of ammonia. The removal of particulate materials in influent led to improve the removal efficiency of ammonia, rather than to control the operating condition including initial pH, temperature, and air flow. The empirical correlation between KLa and operating parameters would be driven as, K_(La) = (0.0003 T- 0.0047)·G^(0.3926) ·L^(-0.5169)·C^(0.1849). The calculated K_(La) from proposed formula can be used effectively to estimate the optimum reaction time and to calculate the volume of modified spray tower system.