이광현 Kwang Hyun Lee , 강병철 Byung Chul Kang , 이종백 Jong Baek Lee , 김종팔 Jong Pal Kim

DOI: Vol.20(No.4) 307-312, 2004

This study was focused on experiment for the separation and concentration process of Cu(Ⅱ), Zn(Ⅱ) solution with the variation of applied pressure and concentration using reverse osmosis plate and frame modules. Rejection coefficient and degree of concentration for Cu(Ⅱ) component using single and multi-stage reverse osmosis process were showed 96.3 ~ 97.8%, 0.044 ~ 0.191(in single-stage), 96.3 ~ 98.4%, 0.400 ~ 2.264(in multi-stage) within the range of experimental condition, respectively. Those of Zn(Ⅱ) were 93.3 ~ 97.1%, 0.019 ~ 0.395(in single-stage), 96.3 ~ 98.2%, 0.365 ~ 1.454(in multi-stage), respectively. Degree of concentration of multi-stage were higher than those of single-stage. Heavy metal[Cu(Ⅱ), Zn(Ⅱ)] separation was very efficient in using reverse osmosis plate and frame type modules. Separation efficiency for a mixed solution Cu(Ⅱ) and Zn(Ⅱ) was higher than those of each one of Cu(Ⅱ) and Zn(Ⅱ).

Reverse osmosis plate and frame type module, Separation, Concentration, Cu(2), Zn(2)

이현동 H. D. Lee , 황재운 J. W. Hwang , 배철호 C. H. Bae , 김상진 S. J. Kim

DOI: Vol.20(No.4) 313-320, 2004

In this study, variable characteristics of drinking water and the influences on underground water reservoirs, rooftop water tanks, and service water pipes in the building were assessed. The influence of underground water reservoir material and water capacity on water quality also were assessed. The results are the following as; First of all, the drinking water passing through underground water reservoirs or service water pipes in the building, averagely metal component concentration more increased from percent of 41.3 to percent of 74.2 totally than other items of water quality. On the other hand, both residual chlorine and total solid highly decreased 65.6 percent and 35.3 percent, respectively. Therefore, it was thought that water quality could be getting worse for microorganism re-growth by residual chlorine reduction, and total solid also could be a cause for extraneous matters accumulated in water reservoir. Secondly, the variations on water quality of each stage for water supply system in the building were higher in water service pipes connected from rooftop water tanks to the tap than in underground water reservoirs. In addition to, among of twelve items on water quality, ten items on water quality except dissolved oxygen and residual chlorine increased. Therefore, it was thought that the influence of water service pipes connected from rooftop water tanks to the tap on water quality were higher than other stages of water supply system in the building. Thirdly, in case of materials of underground water reservoir, it was likely that the variation on water quality by stainless steel and concrete materials got some similar. In case of water capacity, the variations on water quality of underground water reservoirs over 1,000m³ higher than those under 1,000m³. That reasons was likely that the retention time(49.72 hours averagely) of underground water reservoirs over 1,000m³ was two times longer than it of those under 1,000m³(23.37 hours). Therefore, it was thought that the influence on water quality by materials were some similar, but in case of water capacity, the influence of underground water reservoirs were higher.

Underground water reservoirs, Rooftop water tanks, Service water pipes, Water quality

조용진 Yong Jin Cho , 연인성 In Sung Yeon , 이재관 Jae Kwan Lee

DOI: Vol.20(No.4) 321-326, 2004

The objective of this study is to test the applicability of neural network models to forecast water quality at Naesa and Pyongchang river. Water quality data devided into rainy day and non-rainy day to find characteristics of them. The mean and maximum data of rainy day show higher than those of non-rainy day. And discharge correlate with TOC at Pyongchang river. Neural network model is trained to the correlation of discharge with water quality. As a result, it is convinced that the proposed neural network model can apply to the analysis of real time water quality monitoring.

Neural network, Discharge, Water quality, Real-time water quality monitoring

강호 Ho Kang , 나은경 Eun Kyoung Na , 이면주 Myun Joo Lee

DOI: Vol.20(No.4) 327-332, 2004

This study was carried out to examine the effect of gamma irradiation on the physico-chemical characteristics and ultimate anaerobic biodegradability of sewage sludge. The results found that the solubilization rates of SCOD in wasted activated sludge(WAS) and thickened sludge(T-S) with gamma irradiation of 3kGy were 8 times and 7 times greater than these of the raw WAS and T-S without the irradiation, respectively; each soluble concentration protein were 4 times and 3 times greater than these of the raw WAS and T-S; each soluble carbohydrate concentration was 8 times and 6 times greater than these of the raw WAS and T-S. The ultimate anaerobic biodegradabilities of WAS and T-S with gamma irradiation were 51% and 50%, which corresponds to each 8% and 10% greater than these of the raw sludges. Approximately 83% and 81% of the each biodegradable substrates in the irradiated WAS and the T-S were degraded within 11 days with the first order decay rate coefficients, ki that ranged 0.143~164day^(-1) for WAS and 0.134~0.152day^(-1) for T-S. Based on the results, it can be concluded that when irradiated with gamma the solubilization of sewage sludge greatly increases resulting in substrates suitable for the subsequent biological treatment processes.

Gamma irradiation, Sewage sludge, Solubilization, Ultimate anaerobic biodegradability, First order decay rate

정용준 Yong Jun Jung , 남광현 Kwang Hyun Nam , 민경석 Kyung Sok Min

DOI: Vol.20(No.4) 333-338, 2004

This study was carried out to investigate the generation and discharge characteristics of non-point pollutants from farmlands in Nak-dong river basin. Annual unit generation load of nitrogen and phosphorus by fertilization in the test paddy field was almost similar to those calculated by the fertilization standards of district agricultural technology center, but it was extremely higher in case of the test dry field. By comparing annual total generation load of nutrients from fertilization to the data of fertilizer marketing, the accurate forecasting of generation load of pollutants was achieved by marketing data. The annual total discharge ratio of nutrients through infiltration and overflow from the farmland of the test paddy field were 9.5% and 1.1%, respectively, and those in the test dry field were 22.0% and 0.1%, respectively. The monthly discharge load of nutrients were shown the highest proportioned to the discharge load from lands, but it showed higher in phosphorus, which was caused by the intermittent discharge of phosphorus accumulated in drainage.

Generation and discharge load, Nan-point pollutants, Farmland

장영복 Young Bok Chang , 정태영 Tae Young Jeong , 차기철 Gi Cheol Cha , 정형근 Hyung Keun Chung , 김성헌 Seong Hun Kim , 김동진 Dong Jin Kim , 유익근 Ik Keun Yoo

DOI: Vol.20(No.4) 339-345, 2004

The characteristics of H₂ production from livestock wastewater were investigated through an anaerobic acid forming process using Clostridium beijerinckii and the photosynthetic process using Rhodobacter sphaeroides. The submerged separation membrane was installed in the acid forming reactor. The photosynthetic process is composed of two reactors(photosynthetic reactor 1 and photosynthetic reactor 2) which is connected continually. The removal rate of COD and the production of volatile fatty acid(VFA) in the acid forming process were approximately 50% and 1000㎎/ L, respectively. The 70% of COD in the effluent of acid forming process was removed through the photosynthetic process. The production of H₂ in the photosynthetic reactor 1 and 2 was 50 and 25mLH₂/gVFA_(COD), respectively. The values of Y in acid forming reactor, photosynthetic reactor 1 and 2 was 0.2263, 0.0601 and 0.0393, respectively. The acetic acid and butyric acid produced in acid forming process were converted to H₂ by photosynthetic bacteria.

Swine wastewater, Anaerobic acid forming reactor, Photosynthetic reactor, H2 production, Membrane

정용준 Yong Jun Jung , 목증상추 Yoshiaki Kiso , 민경석 Kyung Sok Min

DOI: Vol.20(No.4) 346-351, 2004

Because of being produced a great deal of excess sludges from biological wastewater treatment process, the subject regarding treatment and disposal of them has been significantly handled in real plants. It should be considered the alternative treatment with easy operating and cost effective process in rural areas. For the thickening of wasted activated sludge from small scale wastewater treatment facilities, thus, the provisional sludge thickening system was developed by the application of mesh filter module. Three meshes with different pore size(100, 150, 200μm) were prepared for filter modules that were used to withdraw effluent from thickening system. A filter module with 100μm mesh was chosen as the most effective thickening material in the viewpoint of volume reduction and effluent quality: the volume reductions of initially injected sludge with 3,600 ㎎/L and 9,100 ㎎/L were 95% and 85%, respectively, and the filtered effluents were enough good to be shown below 1.0 ㎎/L of SS and 1.0 NTU of turbidity. Since the filtration of thickening was influenced by the cake layer formed on mesh filter module and this system was operated in the combination of sludge thickening with gravity settling, the filter modules with smaller pore size and the larger floc size were required for long term operation safely.

Sludge thickening, Mesh filter, Cake layer, Flux, Small scale system

유호식 Ho Sik Yoo

DOI: Vol.20(No.4) 352-356, 2004

Variations of water quality parameters were investigated for last 13 years in Han river. Deviation from 3 month moving average was suggested for the variation analysis. Many parameters of mainstream and tributaries showed similar monthly fluctuations. Suspended solid of mainstream showed higher fluctuation than that of tributaries due to summer flood. Contrarily, the organic parameters such as BOD, COD, and TN showed lower fluctuations in the mainstreams. The magnitude of deviation was in the order of pH ＜ DO, COD, temp. ＜ BOD, TN ＜ IT, SS. Strong correlation was found in BOD data of adjacent sites. Main sites showed low deviation in comparison to adjacent common sites of mainstream (1:2.4). Mainstream showed low deviation in comparison to tributaries (1:1.7). Seasonal tendency of monthly BOD was confirmed using autocorrelation function. The deviation was in inverse proportion to the magnitude of BOD.

Han river, Water quality, Seasonal tendency, Deviation analysis, Moving average

손희종 Hee Jong Son , 노재순 Jae Soon Roh , 강임석 Lim Seok Kang

DOI: Vol.20(No.4) 357-364, 2004

In this study, biodegradable organic matter was divided into a rapidly biodegradable fraction(BDOC_(rapid)) and a slowly biodegradable fraction(BDOC_(slow)) for various waters with different types of DOC. These fractions(BDOC_(rapid) and BDOC_(siow)) were defined by using a shaking incubation method modified from Carlson`s method. Also, in this study, optimum incubation time and accuracy were investigated to determine BDOC_(rapid) and BDOC_(slow). When suspended bacteria obtained from raw water and BAC effluent, or attached bacteria from BAC was respectively used as an inoculum, the difference in total BDOC(BDOC_(total)) was minimal. Therefore, total BDOC was determined in 7~8 days by the shaking method, which is comparable with Servais`s method by which BDOC was determined in 28 days. In addition, the difference of BDOC between these two methods was within 7%. Although BDOC_(rapid) and BDOC_(slow) were effectively determined by a method defined by Klevens, the difference in optimal incubation time was significant for different water samples. However, when using the shaking method, optimal incubation time for BDOC_(rapid) was found to be 3 days, therefore, the BDOC_(rapid) was defined as the difference between DOC_0 and DOC_(3days), and BDOC_(slow) was defined as the difference between BDOC_(total) and BDOC_(rapid). As a conclusion, for determining the fraction of BDOC using the shaking method, the concentrations of an inoculums and optimal incubation times used in this study were very effective.

Biofiltration, BDOC fraction, BDOCrapid, BDOCslow, Optimal incubation time

정용준 Yong Jun Jung , 배종홍 Jong Hong Bae , 민경석 Kyung Sok Min

DOI: Vol.20(No.4) 365-369, 2004

Submerged membrane bio-reactor equipped with a hollow fiber microfiltration was applied to reuse weaving wastewater of water jet loom, where two parameters such as the concentration of MLSS and the flux were controlled. While the flux at the concentration of MLSS around 900㎎/L was constantly kept over 0.4m/d and 0.8m/d in a short time, the stable flux at around 300㎎/L of MLSS was shown at the 8 days later. Regardless of MLSS and flux, BOO, CODcr and Turbidity of the permeate were l~2㎎/L, 7~10㎎/L and below 1 NTU, which were 85~90%, 87~90% and 98% of removal efficiency, respectively. The stable operation without fouling was achieved because the contents of ECP were smaller than those of common MBR processes and the composition(saccharide/protein) was kept constantly. In this study, 0.5~1.0m/d of flux and 400~900㎎/L of MLSS were considered as the most recommendable operating condition for the reuse of weaving wastewater.

Membrane Bio-reactor, Hollow-fiber, Weaving wastewater, Reuse, ECP

김성홍 Seong Hong Kim , 최영균 Young Gyun Choi , 정태학 Tai Hak Chung

DOI: Vol.20(No.4) 370-375, 2004

Synthetic organic polyelectrolytes can be used to condition sludges to enhance their dewaterability. When conditioning biological sludges, the charge on the polymer has a significant impact on the effectiveness of the polymer as a conditioner. The objectives of this investigation were to determine the most effective type and dosage of polymer for conditioning digested sludge prior to dewatering, and to investigate the relationship between dewaterability and particle size. 3 types of digested sludge were used under the different digestion processes like anaerobic digestion, aerobic digestion and intermittent aerobic digestion. CST(capillary suction time), 1T F`(time-to-filter) and SRF(specific resistance to filtration) were tested as a dewaterability index and the number of particle distribution was analyzed using particle size analyzer. The results indicate that cationic polymer appears to be required for effective conditioning of these 3 types digested sludge and the optimal polymer dosage is about 0.6% of SS. CST and TTF are well correlated with mean particle diameter of which the dimension order is 1.7.

Sludge conditioning, Particle size analysis, Dewaterability, Capillary suction time, Time-to-filter, Specific resistance to filtration

김유리 Yu Ri Kim , 한범수 Bum Soo Han , 김진규 Jin Kyu Kim , 강호 Ho Kang

DOI: Vol.20(No.4) 376-381, 2004

The use of electron beam irradiation was investigated to disinfect total coliforms in the secondary sewage treatment effluent. Unchlorinated secondary effluent was irradiated at different dose of 0.2~1.0 kGy by 1 MeV, ELV-4 Model electron beam accelerator. It is interesting to note that a 100% reduction in total coliforms and total colonies were achieved until a dose of approximately 0.8 kGy. Even at low dose of 0.2 kGy, the total coliforms and total colonies were successfully inactivated to the level of satisfying the new effluent discharge guideline. Besides disinfection of total coliforms, approximately a 50% removal in biochemical oxygen demand was pronounced at a dose of 0.2 kGy. More than 20% removal in suspended solids and turbidity was also observed at a dose of 1.0 kGy. The application of electron beam irradiation appeared to be one of options to reuse sewage treatment effluent as agricultural or industrial water.

Electron beam, Disinfection, Total coliforms, Total colonies, Secondary sewage treatment effluent, Dose