최중대Joong Dee Choi,장석오Seok Oh Jang,최병용Byung Yong Choi,류순호Soon Ho Ryu

DOI: Vol.16(No.3) 283-294, 2000

The effects of land use in a small agricultural alluvial watershed on groundwater quality were investigated. Existing 20 farm wells were selected as monitoring wells representing different land uses. EC, T-N, NO₃-N, NH₄-N, Org-N, T-P and Cl^- concentrations were monitored every 2 weeks or 1 month for 1 to 2 years. EC was low at the upper watershed and increased towards the lower watershed. Average EC of natural water quality area of the upper most watershed was 0.077 dS/m and was 14∼38% of the ECs of the other land uses. Average NO₃-N concentrations of greenhouse, livestock and residential land uses exceeded the 10 ㎎/1 limit for drinking water. Org-N and NH₄-N concentrations were relatively small compared to NO₃-N concentration and T-N concentration was mostly affected by NO₃-N concentration. NO₃-N concentration occupied more than 90% of T-N concentration of paddy and upland areas. T-N concentration was higher after growing season than during growing season. T-P concentrations did not show any trend with respect to time and land use. Correlations between EC and T-N and EC and Cl^- were analyzed and the R² were 0.7706 and 0.6567, respectively. Monthly amount of rainfall appeared to be influential to groundwater quality and long-term monitoring studies were suggested to consider the effect of rainfall on groundwater quality.

이인철In Cheol Lee,장선덕Sun Duck Chang

DOI: Vol.16(No.3) 295-304, 2000

Water and sediment qualities were surveyed for the water quality modeling from April, 1996 through March, 1997 in Hakata Bay. The seasonal variations of water-sediment qualities were discussed and the ability for water quality purification at the Wajiro tidal flat zone was estimated. The amount of organic matter removed by benthos at Wajiro tidal flat was about twice as large as that at the reference area. The amount of COD removed by benthos at Wajiro was the same order of magnitude as that at Banzu tidal flat.

송미경Mi Kyung Song,박청길Chung Kil Park,이석모Suk Mo Lee,백경훈Kyung Hoon Baek,신성교Sung Kyo Shin,송교욱Kyo Ook Song

DOI: Vol.16(No.3) 305-314, 2000

The study was performed to find the cause of high concentration of BOD and algal bloom during winter season at Mulgum in the downstream of Nakdong River since 1995. There was high correlationship between BOD concentration and Chl. a contents which shows that algal bloom makes Autochthonous BOD. The dominant algae during of winter blooming season was Stephanodiscus sp.. This algae maintained the blooming under the condition of low water temperature, long retention time with decrease of flow rate, and abundant nutrient concentration. To reduce the amount of Stephanodiscus sp. biomass, it is important to decrease the loading of TP and TN from the upstream, because of the possible approach to control.

윤조희Cho Hee Yoon,문성용Seong Yong Moon,김승현Seung Hyun Kim

DOI: Vol.16(No.3) 315-324, 2000

This study investigated effects of organic polymers on treatment of water treatment sludge. For this purpose, sludge samples were taken from two different water treatment plants: lake and river sources. This study found that polymers were able to improve thickening as well as dewatering characteristics of sludge. There was an optimum polymer dose which was dependent upon sludge TS. Cationic or anionic polymer was a better choice to improve the sludge characteristics than nonionic polymer. Polymer with molecular weight less than 10^5 was unable to improve the sludge characteristics while that with molecular weight greater than 4 × 10^6 was. Sludge thickening and dewatering characteristics were improved by 18% and 13% when polymer was used for thickening and dewatering stages instead of dewatering stage only. Unlike polymer, ferric chloride or alum was unable to improve the sludge characteristics. However, lime did improve the sludge characteristics. The performance of lime was dependent upon sludge pH. When sludge pH was increased over 10, sludge characteristics began to improve.

황갑수Gap Soo Hwang

DOI: Vol.16(No.3) 325-333, 2000

This study was performed to survey trihalomethane (THMs) formation levels in finished drinking water produced in K water purification plant and to examine its characteristics according to the application of GAC treatment process. During period before the application of GAC treatment process, total THMs formation level was highest in August, seasonally, in summer. It was decreased by GAC treatment significantly, but the average reduction efficiency of THMs formation was decreased with the lapse of operation time of GAC process, when THMs formation was compared with that before the application of GAC treatment. The ratio of CHCl₃ among total THMs was decreased from the 5th month after the application of GAC process, indicating the increased formation of Br-substituent, especially CHClBr₂ and CHBr₃, by GAC treatment Of the water parameters examined, water temperature showed the strongest correlation with THMs formation.

김완중Wan Joong Kim,김영철Young Chul Kim

DOI: Vol.16(No.3) 335-344, 2000

In this paper, roles and functions of filamentous algae were studied when they were applied for treating rural stream water having relatively low concentrations of nutrients and organics. It was found that predominant species of algae was Spirogyra sp. As these algae grew, it was found that they formed porous, thick and gelatinous mat like a sponge, so that they were not lost into the effluent, which is a main advantage of this algae mat system. Excessive loss of algal particles from oxidation ponds and other modified pond systems has been recognized as one of the most troublesome operational problems. Dissolved oxygen of this system was saturated more than 200 % and pH increased to 10 due to the photosynthetic activity, which are equivalent to normal levels of dissolved oxygen and pH characterized by high rate algal ponds. It was found out that 85 - 95 % of T-N and T-P removal efficiency was obtained within four days of hydraulic residence time. In addition, filamentous algae mat system produced effluent with a very lower level of nutrients than aquatic plant ponds using water hyacinth and reed. Meanwhile, organic matters (COD_(cr)) was not significantly reduced, since the initial concentration was very low.

이인철In Cheol Lee,송현구Hyun Ku Song,내전유사Tadashi Uchida

DOI: Vol.16(No.3) 345-356, 2000

Presently, attempts are being made to use aquatic plants for the water purification at an inland water body, however, many problems exist in regard to the techniques and costs involved. In this study, the experiments of water purification using various kinds of aquatic plants at an inland water body site were carried out. Moreover, the application to the site of the water purification techniques using aquatic plants based on the experiment results was examined. The result indicated that some of the aquatic plants showed high removal rate of nitrogen, but it was difficult to achieve stable treatment due to differences of seasonal conditions. In the case of a real application of water purification technique using aquatic plants, it is shown that a very large site is necessary for water purification. Additionally, it is pointed out that using aquatic plants requires a high cost for the water treatment compared to the estimation of the cost of a traditional sewerage treatment system. Aquatic plants for polluted water treatment should be applied to support water purification, to improve the site environment and to construct a healthier biotope as a form of ecomanagement.

이승목Seung Mok Lee,최봉종Bong Jong Choi,이태우Tae Woo Lee

DOI: Vol.16(No.3) 357-364, 2000

Competitive adsorption between phosphate and phthalic acid onto goethite was examined in single-sorbate and in binary-sorbate system to determine the extent of competition between phosphate and phthalic acid as a function of pH and ionic strength (0. 0l M NaCl). In order to compare the experimental data, MINTEQA2 program employing the diffuse layer model is used. This is important for a better understanding of the competitive binding of phosphate and phthalic acid in natural systems. Alkalimetric titration was used to characterize the surface acidity of the goethite. The surface acidity constants, pK^s_(a1) and pK^s_(a2), were 4.02 and 7.7, respectively. For phosphate and phthalic acid, typical anionic type of adsorption was noted, respectively. Also, in the binary-sorbate system, the amount adsorbed decreases with an increase in pH. In the experiments with simultaneous complexation of phosphate and phthalic acid, the complexation of phosphate was not influenced by the presence of phthalic acid. On the other hand, the complexation of phthalic acid was decreased by the presence of phosphate. These results suggest that phosphate can significantly influence the adsorption of simple organic acids in natural aquatic systems. Therefore less mobility of phthalic acid is expected than phthalic acid with complexation of phosphate in competitive condition.

Sung Kyo Shin , Kyo Ook Song , Chung Kil Park

DOI: Vol.16(No.3) 365-375, 2000

The relationships between of the organic constituents were investigated at laboratory scale and by field study to determine the autochthonous BOD resulting from algal production in the eutrophic Nakdong River, Korea. From the results of growth and degradation of algae in laboratory, the ratio of particulate biochemical oxygen demand (PBOD) to particulate organic matter (POM) was 0.349 during culture and 0.213 during degradation, and it was 28.1% and 17.1% of theoretical oxidation ratio (1.244), respectively. This means that the consumption of dissolved oxygen (DO) was caused by algal respiration and detrital degradation during culture, but only by detrital degradation during degradation. From the relationship between chl-a and BOD (Total BOD (TBOD) = autochthonous BOD ( α·chl-a) + allochthonous BOD), we could determine the contribution of autochthonous BOD to total BOD. Autochthonous BOD ranged from 31.7 to 52.5% in the river reach and from 36.2 to 56.9% in each season. To apply a conversion factor for the calculation of autochthonous BOD, the algal biomass produced should be considered, as well as the activity of the algae, which changed with temporal and spatial conditions. From these results, the autochthonous BOD determined in the Nakdong River accounted for the majority of total BOD in the overall reach investigated.

진창숙Chang Suk Jin,문서연Seo Yeon Moon,강호Ho Kang

DOI: Vol.16(No.3) 377-385, 2000

This paper was to examined the possibility of anaerobic treatment of bisphenol A (BPS -containing wastewater and anaerobic metabolic pathway of BPA using Upflow Anaerobic Sludge Blanket (UASB) process. The results showed that BPA was easily biodegraded between 5-25㎎/L. At the BPA concentration above 30㎎/L, BPA was not degraded anymore owed to the defect of granules. The longer the UASB granules adapted the better BPA degrading activities observed in the UASB reactor. When became clear the BPA degradation was totally independent of co-substrate such as methanol. Two peaks were detected as anaerobic BPA degradation intermediate metabolites, but these were completely removed as the time proceeds.

이영대Young Dae Lee,최용수Yong Su Choi,윤현식Hyun Sik Yoon,홍석원Seok Won Hong,주봉현Bong Hyeon Joo

DOI: Vol.16(No.3) 387-400, 2000

A pilot-scale (50 ㎥/day) of a single sludge reactor, which contains an anaerobic, anoxic, and aerobic reaction zone in a cylindrical single reactor, was evaluated. This process has been developed and designed to remove nutrients as well as organic matters in a single sludge reactor. During the experimental period, special attempts were made to quantify nitrification and denitrification efficiencies and to evaluate factors affecting the performance of nitrogen removal. In the case of removing nitrogen, which consists of nitrification and denitrification reaction under steady-state conditions, the results indicated that seasons` variation of the temperature was a major factor affecting the performance of the nitrogen removal.

박재로Jae Roh Park,김응호Eoung Ho Kim

DOI: Vol.16(No.3) 401-411, 2000

The objective of this research is to show whether Alum-MBR (Membrane Bio-Reactor) system is a technically feasible and economically competitive process for organic and phosphorus removal of municipal sewage. In Alum-MBR system, organic material and phosphorus are removed by biological, chemical reaction and membrane separation mechanism. The advantages of Alum-MBR system were listed as high treability, easy maintanance and automatic operation. Membrane used in this system was polyethylene hollow fiber microfiltration which surface treated hydrophilic with a pore size of 0.1㎛ and surface area of 4㎡ and two module was immersed to aeration basin of 0.4㎥. Jar test was conducted to find out weather chemicals are suitable for phosphorus removal and optimal dosage rate of chemicals and back-up test in a small-scale pilot plant was conducted to confirm of removal effect of organic material and phosphorus. The operation conditions of Alum-MBR system were fixed at suction-idle time of l0min-5min, permeation flux of 0.015㎥/㎡/hr, aeration intensity of 300ℓ/㎥/min. As the result of dosing Alum into MBR, flux was stable and permeate pressure was bring down remarkably. T-P concentration of permeated water always lower than target water quality of l㎎/ℓ.

장윤영Yoon Young Chang,최상일Sang Il Choi,이철효Cheol Hyo Lee

DOI: Vol.16(No.3) 413-420, 2000

The treatment of landfill leachate with hydrogen peroxide catalyzed by iron metal which is different from Fenton reaction in that the form of iron used is not ferrous ion but zero valent iron was investigated using a jar tester. The leachate (COD 1100㎎/L, pH 8) in a process line between an aeration lagoon and a Fenton oxidation tank in Kimpo Landfill, Seoul was sampled for test The average size of the iron metal (99.9%, from Junsei Co.) used in this study was analyzed by scanning electron microscope (SEM) and showed 10-100㎛ in diameter. Iron enhances the decomposition of hydrogen peroxide with the reaction which proceeds in two steps: the oxidation of zero valent iron to ferrous iron followed by the oxidation of ferrous iron to ferric iron under reductive conditions. The effectiveness of the iron catalyst for the destruction of chemical oxygen demand (COD) of the landfill leachate was monitored, focused on the process variables of H₂O₂ and Fe° concentrations, and solution pH. The iron particles were pretreated before use by washing with 1 M HCl and then rinsing with distilled water and aceton followed by N₂ purging in a glass column. The oxidation reactions were almost complete within 30min and the more apparent change in H₂O₂ and COD consumption and pH was not observed. The most sensitive process variable on the COD oxidation reaction was solution pH and the oxidation of COD at low pH provided greater than 66% COD removal. The continuous treatment of landfill leachate in a glass column packed with Fe° and activated carbon shows that the Fenton-like oxidation can be an effective tool for either in situ or above-ground treatment of landfill leachate.