정종철Jong Chul Jeong

DOI: Vol.16(No.1) 1-8, 2000

The level of eutrophication of Lake Sihwa has been become worse, and the value of irrigation and for supplying of industrial use were ruined. For the water quality enhancement, water gate control carried out in Lake Sihwa. In this study, when polluted water of Lake Sihwa was released to near coastal area, Kyunggi Bay, using water gate control, the effect of water quality enhancement of Lake Sihwa was analysed. Modified MINLAKE model estimated the variation of water quality of Lake Sihwa in 1995 with in-put loaded and meteorological data. The estimated values were compared with in-situ data. The estimated values of modified MINLAKE model showed 10 ㎍/L decreasing of concentration of chlorophyll-a from surface to 2 m depth. Since 1995, polluted water of Lake Sihwa were released to near Kyunggi Bay, it is very important for assessment of effect of water gate control to evaluate variation of water quality. The Flushing effect of Lake Sihwa using water gate control showed from water gate to island of Hyeung.

이은주Eun Ju Lee,정팔진Paul Gene Chung,곽동희Dong Heui Kwak

DOI: Vol.16(No.1) 9-16, 2000

Massive amount of float are produced at water treatment plants adopting conventional gravity sedimentation. Not only does the float give bad aesthetic impression to public but also do sometimes serious operational problems occur in water treatment process. In this study, sodium alginate (Sa), a coagulant-aid which may increase specific gravity of flocs, was added to the conventional coagulation/flocculation using common coagulants, alum, PAC or PACS. The results revealed that the amount of float was reduced by 20%, 19.5%, and 77.5% (dry weight basis) for alum, PAC, PACS, respectively.

윤영삼Young Sam Yoon,구은화Eun Hwa Koo,이상훈Sang Hoon Lee,황종연Jong Yeon Hwang

DOI: Vol.16(No.1) 17-28, 2000

The adsorption experiment of p-chlorophenol (PCP) from aqueous solution on granular activated carbon was studied in order to design the fixed-bed adsorption column. The experimental data were analyzed by unsteady-state, one-dimensional heterog eneous pore and surface diffusion models. Both models could be applied to predicting the fixed-bed adsorption phenomena. However, the pore diffusion model is slightly better than the surface diffusion model in representing the experimental data. Therefore, the pore diffusion model was applied to analyse the sensitivity of parameters associated with adsorption process of p-chlorophenol on to granular activated carbon. The prediction model displayed similar sensitivity to mass transfer coefficient (k_f) and intra-particle diffusion coefficient (D_p) suggesting that both parameters present mass transfer rate limits for GAC-PCP system. The Freundlich constants on the model prediction were found to have a greater impact than kinetic parameters.

신호상Ho Sang Shin,박치후Chi Hu Park

DOI: Vol.16(No.1) 29-40, 2000

Powdered activated carbon (PAC) and granular activated carbon (GAC) were evaluated for a chlorite and chlorate control. From our batch experiments it showed that the reaction between chlorite and activated carbon yields chloride as end-product. The removal of chlorite depended on the initial concentrations of chlorite, the activated carbon dose, pH and the activated carbon used. Filtration of water containing chlorite and chlorate through beds of GAC was found to remove chlorite and chlorate. GAC effectively removed chlorite, but, depending on the contact time and pH. The removal of chlorite appears to be a result of chemical reduction. Removal of above 90% of chlorite was achieved at elution rate of below 60mL/min. No chlorinated species other than chloride were detected.

전승렬Seung Yul Cheon,정연규Youn Kyoo Choung,이병찬Byung Chan Lee,김진욱Jin Wook Kim,김한수Han Soo Kim

DOI: Vol.16(No.1) 41-48, 2000

Powdered activated carbon (PAC) and granular activated carbon (GAC) were evaluated for a chlorite and chlorate control. From our batch experiments it showed that the reaction between chlorite and activated carbon yields chloride as end-product. The removal of chlorite depended on the initial concentrations of chlorite, the activated carbon dose, pH and the activated carbon used. Filtration of water containing chlorite and chlorate through beds of GAC was found to remove chlorite and chlorate. GAC effectively removed chlorite, but, depending on the contact time and pH. The removal of chlorite appears to be a result of chemical reduction. Removal of above 90% of chlorite was achieved at elution rate of below 60mL/min. No chlorinated species other than chloride were detected.

양천희Chun Hoi Yang,이철우Chul Woo Lee,홍필선Phil Sun Hong,이원묵Won Mook Lee

DOI: Vol.16(No.1) 49-56, 2000

TiO₂ and x TiO₂- y SiO₂ system photocatalysts were developed by sol-gel method based on the change of production parameters, and their structure of crystallization and the specific surface area were measured. Considering the efficiency of the ethanol and phenol degradation using the catalyst, the conclusions were obtained as follows: ①. By means of X-ray analysis of TiO₂ powder that is obtained from water and Titanium alkoxide with various molar ratios, it is shown that crystal structure of anatase type is a dominating structure and, on the other hand, the structure of rutile also partly exists. The specific surface area is at its maximum value at R=6, which is the molar ratio of water vs. alkoxide, whereas its value goes down as the molar ratio increases. ②. xTiO₂- y SiO₂ system photocatalysts were developed from Titanium and Silicon alkoxide by a hetero-condensation process. The increase of SiO₂ contents causes the decrease of the degree of crystallization of the gel, whereas the specific surface area preferentially increases. It is shown that more than 90% of ethanol and phenol are degraded when reaction time is about three and an hours, and the maximum degradation rate of ethanol and phenol is shown in 60TiO₂-40SiO₂ catalyst.

전항배Hang Bae Jun,김병군Byong Goon Kim,서인석In Seok Seo,이상형Sang Hyung Lee

DOI: Vol.16(No.1) 57-64, 2000

A Modified Intermittent Aeration Process (MIAP) composed of a intermittent aerobic reactor followed by aerobic and anoxic reactors in series was developed for removal nitrogen from the sewage having low TCOD/T-N ratio easily encountered in local area. The intermittent aerobic reactor of MIAP was operated in the several combinations of aeration/unaeration, such as 15min/15min, 30min/45min and 60min/60min. And organic loading effect on nitrogen removal was studied by adding glucose to the raw sewage. TCOD and SCOD removal was complete in any operating conditions, so the effluent TCOD showed below 30 ㎎/L. T-N removal efficiency was as high as 90% at TCOD/T-N ratio of 8.5 with glucose addition, however, that was lowered to 68% at TCOD/T-N ratio of 5.1 without glucose addition. In MIAP, the consumed COD to denitrify 1㎎ of nitrate was 6.6 ㎎, and total COD requirement to remove l.0㎎ of T-N was 7.8 ㎎. Nitrate in effluent was 12 ㎎/L without glucose addition, and it did not changed much at the different combinations of aeration/unaeration. Removal characteristics of COD and T-N did not changed at the different combinations of aeration/unaeration, however, nitrate was fluctuated at each beginning of the changed operating conditions.

서인석In Seok Seo,김병군Byong Goon Kim,박승국Seung Kook Park

DOI: Vol.16(No.1) 65-76, 2000

In this research, 5 types of intermittently aerated activated sludge system were operated for nitrogen and phosphorus removal in wastewater. Also, pH and ORP (Oxidation-reduction potential) behaviour was evaluated as a control parameter for nitrogen removal. Nitrogen and phosphorus removal efficiency is strongly dependent on COD/TN ratio of influent The behaviour of nitrogen concentration and ORP values during a aeration-nonaeration cycle is described by a typical profile with 3 bending points. Also, pH raised at nonaeration state and decreased at aeration state. From analysis of ORP or pH slope ( ΔORP/ Δt or ΔpH/ Δt), ORP was more critical at endpoint of denitrification than pH. As a results, ORP pattern is more useful than pH as a control method in intermittently aerated activated sludge system.

이종현Jong Hyun Lee,박재홍Jae Hong Park,남해욱Hai Uk Nam,김영규Young Gyu Kim,박태주Tae Joo Park

DOI: Vol.16(No.1) 77-86, 2000

The wastewater from a pigment industry has various organic compounds and one of the most hardly-treated wastewaters. As the characteristics of the pigment wastewater is almost non-soluble to any solvents and less biodegradable, it is difficult to treat the pigment wastewater by the conventional activated-sludge treatment facilities only. This study was designed to evaluate the characteristics of a nonbiodegradable organic and color removal by the ozone AOP and the ozone/hydrogen peroxide AOP and to identify the feasibility of these AOPs as a pretreatment or a tertiary treatment following the activated sludge process in the pigment wastewater. The study was divided into two parts of experiments. The first experiment was performed to know the characteristics of the organic and color removal on Red wastewater, Composite wastewater and Final effluent The second experiment of combined the ozone oxidation and the activated sludge process was performed to compare with the existing extended aeration treatment plant In the treatment of Red and Composite wastewater, the O₃ oxidation was more effective than the H₂O₂/O₃ oxidation on reducing loadings of COD_(Cr) and color. While, the H₂O₂/O₃ oxidation was more effective than the O₃ oxidation on reducing loadings of COD_(Cr) in the treatment of Final effluent In the Red wastewater, the O₃ oxidation resulted in 72.3% and 99% reduction of COD_(Cr) and color respectively, the O₃ oxidation of Composite wastewater resulted in 28.9% reduction of COD_(Cr). In the experiment of the Final effluent, the H₂O₂/O₃ oxidation resulted in 40.9 reduction of COD_(Cr) and the O₃ oxidation indicated 67.6% reduction of color. Also, the second experiment of combining the O₃ oxidation and the activated sludge process at 17hrs HRT was showed more effective than the extended aeration treatment plant at 34hrs HRT. Therefore, the ozone AOP can be the promising process for a pretreatment or a tertiary treatment in the pigment wastewater.

황규대Gye Dae Whang,최효수Hyo Soo Choi,이지웅Ji Woong Lee

DOI: Vol.16(No.1) 87-100, 2000

The objective of this study was to investigate the effectiveness of GAC in the anaerobic reactor and effect of the anaerobic-aerobic biological process. The role of GAC in the anaerobic reactor adsorbs toxic constituents on the GAC medium and increase biomass concentration, while the attached biofilm efficiently used the biodegradable compounds. Four sets of lab-scale anaerobic-aerobic biological reactors were operated. The packing density of GAC in the anaerobic reactors were 0%, 5%, 10%, and 20% (W/V) respectively. The hydraulic retention time (HRT) of the anaerobic and aerobic reactor was four hours, respectively and solid retention time (SRT) was seven days. The operating temperature of the anaerobic reactor was maintained at 40℃, during the experiment period. One aerobic reactor which was operated with 8 hours of HRT and 7 days of SRT was selected as a control to compare the performance with the anaerobic-aerobic process. The anaerobic-aerobic processes which contain GAC in anaerobic reactor showed about 10% higher SCOD_Cr and color removal efficiency than that of anaerobic-aerobic process which was not filled with GAC and showed less effluent quality fluctuation as the composition of wastewater was changed. As the packing density of GAC in the anaerobic reactors increased from 5% to 20%, efficiency did not improved. The average SCOD_Cr and color removal efficiency of the anaerobic-aerobic process which contain GAC in the anaerobic reactor was about 70%, 60%, respectively. Aerobic process showed 61% of SCOD_Cr and 19% of color removal efficiency respectively. Anaerobic-aerobic biological process is more effective in color removal than aerobic reactor process and addition of GAC in the anaerobic reactor is effective in SCOD_Cr removal.

이무강Mu Kang Lee,김영철Young Chul Kim,박준한Chur Young Kim,차기철Gi Cheol Cha

DOI: Vol.16(No.1) 101-110, 2000

This study was conducted to investigate the removal efficiency of COD and ammonia nitrogen in the wastewater discharged from tannery wastewater treatment plant by electrochemical oxidation process, which was used as pretreatment process for enhancing the J sewage treatment plant in Pusan. In this experiment, the effect of operating parameters including current density of 2.08∼8. 33A/dm², pH 4∼10 and chloride concentration of 3.0∼10.08g/ℓ were studied. With varying current density of 2.08A/dm², 4.17A/dm² and 8.33A/dm², COD removal efficiencies were obtained to 59%, 70% and 78%, respectively after electrolysis for 5 hours. Under the same operating conditions of current density and electrolysis time, the removal efficiencies of ammonia nitrogen were 55%, 78% and 99%, respectively. The removal efficiency of ammonia nitrogen increased about 10% with decreasing pH from 10 to 4. However, COD removal efficiency does not much effect on the pH change. When NaCl was added to the wastewater discharged from the tannery wastewater treatment plant, the removal efficiencies of COD and ammonia nitrogen increased by the electrochemical oxidation process. Also, the electrolysis time reaching to the maximum removal efficiency can be shorten with the addition of NaCl. When the chloride concentration was 10.08g/ℓ, COD removal efficiency was 95%, and ammonia nitrogen was also removed completely after 2 hours operation at current density of 4.17A/dm².

Sung Hyun Kwon,Duk Soo Choi,Dae Chul Cho

DOI: Vol.16(No.1) 111-119, 2000

Biodegradability of pentachlorophenol and its biological kinetic parameters were investigated using a chemical oxygen demand (COD) analysis. The experiments were performed in continuous stirred tank reactors with synthetic wastewater containing 30 and 60㎎/L of pentachlorophenol (PCP) and other carbon sources. Mean cell residence time (MCRT) and hydraulic residence time (HRT) were maintained from 4.8 to 26.2 days and 4 to 17 hours, respectively. While synthetic wastewater containing 30 ㎎/L of PCP showed over 90% S-COD removal efficiencies except at the 4.8 and 20.3 days of MCRT, 55% to 75% removal efficiencies were observed for 60 ㎎/L of PCP concentration. The respective values of Y and k_d were 0.15 and 0.010 day^(-1) for 30 ㎎/L PCP (r²= 0.90), and 0.13 and 0.014 day^(-1) for 60 ㎎/L PCP (r² = 0.86), respectively. In a substrate inhibition kinetics, Haldane model, the respective values of K_s, K_i and k were 60.8 ㎎ COD/L, 297.5 ㎎ COD/L and 0.93 day^(-1) for 30 ㎎/L PCP (r² = 0.30), and 262.2 ㎎ COD/L, 997.2 ㎎ COD/L and 0.053 day^(-1) for 60 ㎎/L PCP (r² = 0.78), respectively.

정용준Yong Jun Jung,민경석Kyung Sok Min,남광현Kyang Hyun Nam

DOI: Vol.16(No.1) 121-131, 2000

The filtration bio-reactor is a modified membrane bio-reactor in which a mesh was used as a filter media instead of a real membrane like MF or UF. In this system, solid-liquid separation was carried out by the sludge layer formed on the surface of the mesh, not by mesh itself. Mesh with pore size of 100㎍ was selected as the most adequate to filter media when reviewed that could get approximately 10㎎/L of SS in only 10 minutes later after filtration and able to form stable sludge layers regardless of MLSS concentrations. Besides, with the flux of 0.5 m/day and even at a very low pressure less than 1 kPa (10 ㎝ of head loss), this system was constantly operated without clogging. The wastewater treatment performance by the filtration bio-reactor was also examined on a laboratory scale. When the synthetic wastewater (BOD : 200 ㎎/L, T-N 50 ㎎/L, T-P : 8 ㎎/L) was fed to the reactor under following conditions : HRT of 4 hours, continuous feeding, continuous filtration, and continuous aeration, SS and BOD of the effluent were obtained less than 1.5 ㎎/L and 5.0 ㎎/L, respectively. Therefore, this system is fully suggested to be a useful one as an alternative wastewater treatment tool.

박승국Seung Kook Park,김병군Byong Goon Kim,원성연Seung Yeon Weon,이상일Sang Ill Lee

DOI: Vol.16(No.1) 133-142, 2000

2 stage IAAS (intermittently aerated activated sludge) and DynaFlow (dynamic flow intermittently aerated activated sludge) systems without anaerobic reactor were applied to treat swine wastewater of high strength of organic and nitrogen contents. COD_(cr), TKN and total phosphorus concentration in influent were averaged to 4, 300㎎/L, 650㎎-N/L and 68㎎-P/L, respectively. Removal efficiency of total nitrogen was obtained to over 92%. However, as increase of nitrogen loading to over 0.6㎏-N/㎥ ·day, nitrogen removal efficiency was dropped to 80%. NO₂-N and NO₃-N concentration were increased up to 55㎎/L and 30㎎/L, respectively. The increase of NO_x-N concentration can be attributed to low C/N ratio and toxic effect of free ammonia to Nitrobacter sp.. Sludge rising problem in clarifier was observed as increase of influent TKN of over 600㎎/L. The significant difference in nitrogen removals between 2 stage-IAAS and DynaFlows was observed in starting period. Adaptation period for DynaFlows was only 2 days, whereas that of 2 stage-IAAS was 20 days. This means that DynaFlow was better process to treat nitrogen in fluctuating strength of pollutants. From the experimental results, both 2 stage-IAAS and DynaFlow processes are supposed to feasible processes to treat nutrients in high strength wastewater, such as, poultry and swine wastewater.

김남천Nam Cheon Kim

DOI: Vol.16(No.1) 143-157, 2000

Municipal wastewater was treated by the method of aerated submerged biofilm process using PVDC (polyvinylidene chloride) or PEPP (polyethylene polypropylene) as the attachment media. Comparing with the conventional activated sludge process, the aerated submerged biofilm processes showed a higher removal efficiency in COD_(cr), BOD, and SS. The PEPP was superior to the PVDC in removing organic matters. For T-N and T-P, while the aerated submerged biofilm process gave 52.4-54.0% and 56.9-63.2% removal, respectively, with insignificant difference between the PEPP and PVDC media, the activated sludge process resulted in 15.9-21.4% and 29.5-37.4% removal, respectively. In the biofilm process, the attached biomass was 40.7-42.4% and 49.3-50.3% of the total biomass for PVDC and PEPP media, respectively. The adequate loading rate of organics in municipal wastewater seemed to be 1.0 ㎏ COD/㎥ ·day and 0.5 ㎏ COD/㎥ ·day. The total oxygen uptake and endogenous respiration rates in the biofilm process were 7.3-11.1 ㎎ O₂/L, and 5.4-8.2 ㎎ O₂/L, respectively, which were much lower than those in the activated sludge method. At a similar organics loading rate condition, the biofilm process gave a higher SV_(30) value and lower sludge product than the activated sludge process. In comparing dewaterability, specific resistance coefficient (γ) was 5.28 X 10^(13)㎝/g in the activated sludge and 3.65-5.22 X 10^(13)㎝/g in the aerated submerged biofilm process. Dewatering was relatively easy in the aerated submerged biofilm process, especially in PEPP media.