진용현Yong Hyun Chin,김경태Kyung Tae Kim,김석현Suk Hyun Kim,양동범Dong Beom Yang,홍기훈Gi Hoon Hong,이광우Kwang Woo Lee

DOI: Vol.16(No.4) 421-430, 2000

To study the distribution and the behavior of trace metals in Kwangyang Bay, surface water samples were collected four times from August 1997 to May 1998 and were analyzed for trace metals (Cd, Co, Cu, Fe, Ni, Pb, Zn) by Atomic Absorption Spectrometer and Inductively Coupled Plasma Mass Spectrometer. Dissolved Co and Fe concentrations were comparatively high near the Seomjin River mouth. Particulate trace metal contents were relatively high near the Sueochun River mouth and near the Yeochun industrial complex. Distribution coefficients (K_d; Lkg¹) between dissolved and particulate phases of Fe, Pb, Co, Zn, Ni, Cu and Cd were 1.67×10^8, 1.37×10^6, 7.25×10^5, 4.43×10^5, 1.39×10^5, 9.1×10⁴ and 1.8×10⁴, respectively. In Kwangyang Bay, particulate trace-metal concentrations were as high as dissolved ones and showed seasonal and geographic variations.

윤제용Je Yong Yoon,조순행Soon Haeng Cho,김해심Hae Shim Kim

DOI: Vol.16(No.4) 431-443, 2000

Water quality data from water treatment plants in Korea during 1994-1998 were investigated to find out the characteristics of their non compliance. The number of plants surveyed were approximately 600 and the number of samples were over 30,000. Ten parameters of water quality selected in this study and their non compliance % (inside parenthesis) were as follows : Heterotrophic plate count (0.14 %), Total coliforms (0.08%), NH₃-N (0.29%), NO₃-N (0.14%), THMs (0.02%), Turbidit(0.11%), Residual chlorine (5.5%), KMnO₄ consumption(0.04%), Hardness(0.03%), pH(0.07%). These levels of non compliance were compared to those obtained from WIDB (Water Industry Database, 1996) of American Water Works Association. This study strongly supported that small water plants ($lt;10,000 tons/day) were more vulnerable in meeting the regulation criteria of many water quality parameters such as Heterotrophic plate count, Total coliforms, NO₃-N, THMs, Turbidity, Residual chlorine, KMnO₄ consumption, Hardness and pH. The NH₃-N concentration was especially high in winter and its violation was frequently found in the specific areas such as the downstream of major rivers. The average THMs concentration was surprisingly low, indicating 13㎍/L which is 43% of US. Accordingly, these characteristics must be reflected in establishing the effective management of water quality policy of drinking water in Korea.

김영웅Young Ung Kim,손희종Hee Jong Son,유명호Myung Ho Yu,김성윤Seong Yun Kim,김철Chul Kim

DOI: Vol.16(No.4) 445-457, 2000

This study was carried out comparing with ozone oxidation and photocatalytic degradation for removal of geosmin. In the change of pH, Ozonation, UV-Germicidal lamp and Halogen lamp irradiation and Halogen lamp/TiO₂ Powder was very slowly changing, but UV-Germicidal lamp/TiO₂ Powder was rapidly changed from 7.0 to 7.7 until 300min of irradiation time, and varied a little after. Geosmin degradation ratio was as following, UV-Germicidal lamp/TiO₂ Powder_((200㎎/L)) ≥ O₃$gt; UV-Germicidal lamp/TiO₂ Pw_((100㎎/L)) $gt; UV-Germicidal lamp $gt; Halogen lamp. The result of investigation of generated by-products were 3-Heptanone, two sort of aldehydcs and three sort of alcohols by ozonation. But It was not generated by photocatalytic degradation.

문병현Byung Hyun Moon,김승현Seung Hyun Kim,이향인Hyang In Lee

DOI: Vol.16(No.4) 459-468, 2000

This study is to investigate the floc structure and removal of turbidity and organic matter by PACI coagulation. The turbidity removal by PACI coagulation was obtained at larger pH range than alum coagulation. And the removal of organic matter was obtained at smaller pH range than that of turbidity. The organic matter was removed by the adsorption of A1(OH)₃ precipitates. Floc structure was characterized by measuring fractal dimension and volume diameter using AIA and SALLS. Fractal dimension measured by AIA did not show the different characteristics of floc produced in sweep floc and charge neutralization region. Using SALLS, flocs in sweep floc region were found to be larger size and fractal dimension than flocs in charge neutralization region. As pollutant removal increased, larger fractal dimension and size of floc were measured. SALLS method was found to be more useful method to characterize flocs in coagulation than AIA method.

배범한Bum Han Bae,최명수Myoung soo Choi,임남웅Nam woong Lim,정재훈Jae hoon Jeong

DOI: Vol.16(No.4) 469-477, 2000

Bisphenol-A(BPA), a known endocrine disruptor, is a main building block of epoxy resin which is widely used as a coating agent in residential water storage tanks. Therefore, BPA leaching from the epoxy resin may have adverse effects on human health. The possibility of BPA leaching from three epoxy resins were tested with a modified KS D 8502 method at 20, 50, 75 and 100℃ in deionized water and the specified test water, respectively. BPA leached to the test water was identified using GC-MS and quantified with GC-FID after a sequential extraction and concentration. The results showed that BPA leaching has occurred in all three samples tested. The quantify of BPA leaching from unit area of epoxy resin coating was in the range of 10.677∼273.120 ㎍/㎡ for sample A, 29.737∼1734.045 for sample B and 52.857∼ 548.778 for sample C depending on the test temperature, respectively. In general, the amount of BPA leaching increased as the water temperature increases. This result implies a higher risk of BPA leaching to drinking water during a hot summer season. In addition, microbial growth, measured by colony forming units, in epoxy coated water tanks was higher than that in a stainless steel tank suggesting that compounds leaching from epoxy resin may support the growth of microorganisms in a residential water holding tank.

김영웅Young Ung Kim,손희종Hee Jong Son,유명호Myung Ho Yu,이춘식Chun Sik Lee,김성윤Seong Yun Kim

DOI: Vol.16(No.4) 479-490, 2000

This study investigated the removal characteristics, Microcystin decomposition and generation of by-products when aqueous Microcystis sp. is oxidized by ozone. The concentration of Microcystin (MC) in aqueous solution has been found by HPLC analysis to decrease continuously by ozonation after the initial, abrupt increase. The kinetic constant of the decomposition of MC-RR and -LR were 0.0596 and 0.0243, respectively. This means that removal efficiency of MC-RR by its oxidative decomposition is preferable compared with that of MC-LR. On the other hand, it has been found that the decomposition product, TOC, exhibits the continuous decrease in the concentration by further ozonation, while DOC and UV-254 increase temporarily until 10 minutes before the decrease. Furthermore, the GC/MSD analysis has revealed that the ozonation of Microcystis sp. for 100minutes affords five kinds of aldehydes, six kinds of alcohols, and trans-1, 2-dimethyl-cyclopropane.

윤춘경C . G . Yoon,권순국S . K . Kwun,전지홍J . H . Jeon

DOI: Vol.16(No.4) 491-499, 2000

Effluent concentration estimation equations for treatment wetland were reviewed with 3 -year experimental data. Four equations from USEPA, WPCF, Kadlec and Knight, and this study were applied to the over 100 data points of 1996 to 1999 study at the pilot plant in Konkuk University. The system was a subsurface flow type and consisted of 60㎝ depth of sand and reeds, and it worked continuously including winter with domestic sewage from school building. Generally, all the equations demonstrated reasonable agreement with experimental data and they could be used for design process if selected carefully. Among them, the equation from this study showed the best fit for the data. The reason might be not only the equation was derived from the experimental data, but also it included plant coverage parameter in the equation while others did not. Plant coverage was proved to be an important parameter in the prediction of the treatment wetland system, and its inclusion in the estimation equation could improve the accuracy. Although existing equations could be used in the wetland design, pilot plant experiment for the anticipated condition and subsequent equation development can provide more reliable equation. It takes time to obtain meaningful data from wetland system. Therefore, timely onset of well organized study is recommended before, large scale application of treatment wetland system to either point or nonpoint source pollution abatement.

임봉수Bong Su Lim,어성욱Seong Wook Oa,정원문Won Moon Chung

DOI: Vol.16(No.4) 501-512, 2000

This study was carried out to develop the new process for RBC process which is capable of nutrient removal and to obtain its design parameters for Sludge Settling Type Rotating Biological Contactors by comparing RBC with RBC combined with HBR (Hanmee Bio-Reactor). To achieve more than 90% of organic removal efficiency, organic loading rate less than 6.0g BOD/㎡/d is recommended. Nitrification rate was about 90% at 6.0g BOD/㎡/d. TN removal efficiency of RBC+HBR was higher than those of RBCl and RBC2. TN removal efficiency at condition of 5.0g BOD/㎡/d was about 60% in RBCl. When BOD loading rate was 6.0g BOD/㎡/d, TN removal efficiencies in RBC2 and RBC+HBR were about 70%, 80%, respectively. TP removal efficiency was more than about 67% for RBC1, about 63% for RBC2 and about 71% for RBC+HBR at the same loading rate. From the blank experiment to observe removal efficiency in the first stage, it can be known that COD removal efficiency was about 30% and suspend solids settling rate was about 45%. It was proved that RBC+HBR is much better in sludge dewatering than RBC.

서인석In Seok Seo,김병군Byung Goon Kim,박승국Seung Kook Park,권선웅Sun Woong Kwon

DOI: Vol.16(No.4) 513-521, 2000

Intermittently aerated activated sludge process was applied as a water reuse process of 70 ㎥ /day for the upgrade of organic, nitrogen and phosphorus removal efficiency and clarifier performance. After application of the intermittently aeration, removal efficiency of BOD, SS, T-N and T-P were achieved 95%, 90%, 80% and 60%, respectively. Removal efficiencies in intermittently aerated process were considerably increased, comparing to those of continuously aerated activated sludge process. Also sludge rising problem in clarifier was improved. Average concentration of supplied reusing water were BOD 5 ㎎/L, turbidity 4 NTU and after chlorination, residual chlorine 0.4 ㎎/L, coliform 0 MPN/100mL. Intermittently aerated activated sludge process could be one of the best alternative process for the retrofit of conventional activated sludge process for the removal of nutrient in water reuse system.

박종웅Jong Woong Park,송주석Ju Seok Song

DOI: Vol.16(No.4) 523-532, 2000

The purpose of this study was to investigate the effects of the hydraulic retention time (HRT) and organic loading rate (OLR) on microbial characteristics and treatment efficiency in sewage treatment using aerated submerged biological filter (ASBF) reactor. This reactor combines biodegradation of organic substrates by fixed biomass with a physical separation of biomass by filtration in a single reactor. Both simulated wastewater and domestic wastewater were used as feed solutions. The experimental conditions were a temperature of 17 to 27℃, a hydraulic retention time of 1 to 9hr, an organic loading rate of 0.47 to 3.84 ㎏ BOD/㎥ ·day in ASBF reactor. This equipment could obtain a stable effluent quality in spite of high variation of influent loading rate. Total biomass concentration, biofilm thickness and biofilm mass increased an exponential function according to the increasing OLR. The relationships between water content and biofilm density were in inverse proportion. The percentage of backwash water to influent flow was almost 9%. The separation efficiency of biomass was the percentage of 91 to 92 in ASBF reactor. The sludge production rates in feed solutions of simulated wastewater and domestic wastewater were 0.14∼0.26 ㎏ VSS/kcg BODrem, 0.43-0.48㎏ VSS/㎏ BODrem, respoectively.

양형재Hyung Jae Yang,신웅배Eung Bai Shin,정윤철Yun Chul Chung,최훈근Hun Geun Choi

DOI: Vol.16(No.4) 533-539, 2000

A bench-scale reactor using SBR process was experimented with an synthetic wastewater. The main purpose of this investigation was to evaluate applicability in the field and process removal efficiencies in terms of BOD and T-P and its corresponding kinetic parameters. Removal rate of phosphorus was 77% in terms of total phosphorus. Effluent concentrations were 9.8㎎/ℓ BOD and 1.1㎎/ℓ T-P. Effluent quality was maintained consistently stable by controlling decant volume and operating cycles. The efficiency for phosphorus removal was increased due to decrease in BOD-SS loading value in the range of 0.25≤aeration time ratio ≤0.52.

차기철Gi Cheol Cha,정형근Hyung Keun Chung,김동진Dong Jin Kim,김영철Young Chul Kim

DOI: Vol.16(No.4) 541-554, 2000

Experimental study of anaerobic digestion process combined with and without the submerged separation membrane was investigated by using laboratory-scale reactor at the hydraulic retention time of 0.5 day and 1.0 day. The removal efficiencies of carbohydrate at the digester without and with membrane were 84.4 to 86.8 % and 99.6 to 99.7 %, respectively, and the methane gas recovery efficiencies were 0.4 to 1.2 % and 12.3 to 28.7 %. According to the measurement by the most probable numbers method, the numbers of various groups of bacteria in the digesters with membrane were enumerated in the following ranges ; acidogens 1.7×10^9 to 5.0 × 10^9 MPN/㎖, homoacetogens : 5.0×10^7 to 2.4×10^8 MPN/㎖, H₂-utilizing methanogens : 1.3×10^7 to 9.2×l0^8 MPN/㎖, and acetate-utilizing methanogens : 2.3×10^6 to 2.0×10^8 MPN/㎖. The number of methanogens at the digester with membrane increased by approximately 10² to 10⁴ times in comparison with that of the digester without membrane.

정팔진Paul Gene Chung,곽동희Dong Heul Kwak,이재욱Jae Wook Lee

DOI: Vol.16(No.4) 555-563, 2000

The study was conducted to evaluate the adsorption equilibrium of heavy metals on bone charcoal made of livestock bone which was sintered at 550-600℃. Analysis of bone charcoal by XRD and FT-IR showed that crystal structure was similar to that of synthetic hydroxyapatite. Adsorprption equilibrium capacity of single component (Pb, Cd, and Zn) on bone charcoal could be expressed as Langmuir, Freundlich, and Sips equations. Sips isotherm was best among the three isotherms. The values predicted by IAST (ideal adsorbed solution theory) showed good relationship to the experimental data in multicomponent adsorption equilibrium. Adsorption affinity was in order of Pb. Cd, and Zn. The order was same in case of activated carbon or synthetic hydroxyapatite. Through the study results, it would be expected that bone charcoal made of livestock could be used in field of wastewater treatment plants as adsorbent to remove heavy metal.