이병준 Byung Joon Lee , 민경석 Kyung Sok Min , M. C. Wentzel , G. A. Ekama

DOI: Vol.20(No.3) 197-205, 2004

Batch test methods have developed for a long time to measure kinetic and stoichiometric parameters which are required to perform steady state design and mathematical modelling of activated sludge processes. However, at various So/Xo ratios, abnormal behaviors of ordinary heterotrophic organism in batch tests have been reported in many researches. Thus, in this research, abnormal behaviors of heterotrophs in batch tests were investigated at various So/Xo conditions by measuring and interpreting oxygen utilization rate. As So/Xo ratio increased, the calculated values of maximum specific growth rates, μ_(H.max) and K_(MP.max), increased. However, at a certain point of So/Xo (around 10㎎COD/㎎MLAVSS), μ_(H.max) and K_(MP.max). values started to decrease. According to this observation, three prominent behaviours of heterotrophs were identified at various So/Xo conditions. (1) At low So/Xo region (below 5 ㎎COD/㎎MLAVSS), the oxygen utilization rate of heterotrophs in batch tests were almost stable and consequently yielded lower maximum specific growth rate. (2) At high So/Xo region (up to 5~10 ㎎COD/㎎MLAVSS), oxygen utilization rate incresed sharply with time and indicated more upward curvature than the predicted OUR with conventional activated sludge model, which consists of single hetetrotrophs group. Thus, in this region, competition model of two organisms, fast-grower and slow-grower, seemed to be appropriate. (3) At extremely high So/Xo region (over 10㎎COD/㎎MLAVSS), significant oxygen utilization rate was still observed even after depletion of readily biodegradable COD. This might be caused by retarded utilization of intermediates which were generated by self inhibition mechanism in the process of RBCOD uptake.

Batch test, So/Xo ratio, Maximum specific growth rate, Competition, Inhibition

이현동 Hyun Dong Lee , 배철호 Chul Ho Bae , 홍성호 Seong Ho Hong , 황재윤 Jae Woon Hwang , 곽필재 Phill Jae Kwak

DOI: Vol.20(No.3) 206-214, 2004

Residual wall thicknesses, corrosion rates, and residual life of thirty four samples of cast iron pipes(CIPs) and ductile cast iron pipes(DCIPs) collected from water mains of B city were studied to estimate their remaining service life or optimum time of rehabilitation. The internal maximum corrosion depths of samples measured using a dial gauge after shot blasting were twice higher than the external in most cases. Therefore corrosion of water pipes was much more affected by internal water quality than soil. Residual wall thicknesses of DCIPs were higher than those of CIPs. That reason was thought to be that DCIPs have been protected from internal corrosion by lining cement mortar. Residual life calculated by maximum corrosion rate was ranged up to 44 years with 12.40 years average. Since most CIPs were much deteriorated, rehabilitation plan should be established soon in B city. Residual life of DCIP was 33.52 years average. When cement mortar lining is used up by neutralization of DCIPs. DCIP also should be rehabilitated.

Remining service life, Residual Life, Residual wall thickness, Corrosion rate

손대희 Dae Hee Son , 정윤철 Yun Chul Chung , 신정훈 Jeong Hoon Shin , 정진영 Jin Young Jung , 안대희 Dae Hee Ahn

DOI: Vol.20(No.3) 215-222, 2004

The sewages produced from small villages, rural community, drinking water reservation area and park which doesn`t have sewage piping system can be caused a serious water pollution at the restricted areas. The objective of this research was to suggest an economical and effective sewage treatment method by investigating the removal of the organics, nitrogen, and phosphorus in the multi-soil-layering reactor. Soil, natural zeolite, and iron slag were used as a supporting media of multi-soil-layering in this research. The purpose of natural zeolite addition was to maintain the consistent ammonium exchange capacity by providing a sequential environment, and that of iron slag addition was to remove phosphorus by adsorption. Continuous experiment of lab-scale single-soil-layering (S-1), multi-soil-layering (S-2), and mixed-soil-layering (S-3) methods were studied to compare and optimize three different types of the reactors. The organic removal efficiencies showed more than 90% in all three reactors. While S-1 and S-3 reactors showed about T-N removal of 31%, 45%, respectively, the average T-N removal efficiency of the S-2 reactor represented an 87%. In conclusion, that results suggest that the multi-soil-layering reactor could be effectively utilized as a plant for treatment of small village sewage.

Soil, Zeolite, Slag, Multi-soil-layering system, Nitrogen, Sewage treatment

정상만 Sang Man Jeong , 박정규 Jeong Kyoo Park , 박영기 Young Kee Park , 김이형 Lee Hyung Kim

DOI: Vol.20(No.3) 223-230, 2004

The QUAL2E and Box-Jenkins time series model were applied to the Miho river, a main tributary of the Geum river, to predict water quality. The models are widely used to predict water quality in rivers and watersheds because of its accuracy. As results of the study, we concluded as follows: Pollutant loadings in upper stream of Miho river were determined to 57,811 ㎏BOD/d, 19,350 ㎏TN/d, and 5,013 ㎏TP/d. The loading of TN in Mushim river was 19,450 ㎏TN/d, respectively. As the mass loadings were compared with pollutant sources, it concluded that the farming livestock contributed highly to mass emissions of BOD and TP and the population contributed to TN mass loading. The observed water quality values were applied to the models to verify and the models were used to predict the water quality. The QUAL2E Model predicted the concentrations of DO, BOD, TN and TP with high accuracy, but not for E-Coli. The Box-Jenkins time series model also showed high prediction for DO, BOD and TN. However, the concentrations of TP and E-Coli were poorly predicted. The result shows that the QUAL2E model is more applicable in Miho basin for prediction of water quality compared to Box-Jenkins time series model.

QUAL2E model, Box-Jenkins time series model, Pollutant load

윤석표 Seok Pyo Yoon , 최지용 Ji Yong Choi

DOI: Vol.20(No.3) 231-235, 2004

To investigate removal effects of nutrients in stormwater runoff by soil of riparian protection zone, soil column experiment was conducted for 20 months. Artificial stormwater runoff containing phosphate and nitrate was applied on the surface of soil column twice a week, and phosphate and nitrate concentrations were measured from the leached water. Soil of riparian protection zone reduced the released amount of infiltrated water to the surrounding water. After infiltration of 1m depth of soil column, average removal rates of phosphate and nitrate were 97.7% and 74.7%, respectively. As main mechanisms of phosphate are adsorption to soil particle and utilization by plants, periodical replacement of soil and harvesting of plant at the end of growing season are required. For the removal of nutrients in stormwater runoff by the soil layer, soil of riparian protection zone has higher hydraulic conductivity to infiltrate stormwater. Sandy soil having hydraulic conductivity of about 1？0^(-2)㎝/s range might be appropriate for this purpose.

Soil column, Riparian protection zone, Phosphate, Nitrate, Adsorption, Stormwater runoff

박호일 Ho Il Park , 김지성 Ji Seong Kim , 김동건 Dong Kun Kim , 박대원 Dae Won Pak

DOI: Vol.20(No.3) 236-240, 2004

Autohydrogenotrophic denitrification of high nitrate concentration contaminated wastewater in a batch-scale biofilm reactor has been investigated. High nitrate concentration decreased as pH increased from 7.01 to 9.45. The high nitrate concentrations continuously decrease from 150mg.1^(-1) to 0mg.1^(-1). Nitrite concentrations increase at about two-thirds way through the denitrification process and thereafter it decreases with time. Autohydrogenotrophic denitrification of high nitrate concentration is passible to use drinking water as well as wastewater, and to deal with wastewater treatment by hetrotrophic denitrification.

Autohydrogenotrophic denitrification, High nitrate concentration, Biofilm reactor

정진호 Jin Ho Jung , 박남용 Nam Young Park , 조훈제 Hun Je Jo , 이선미 Sun Mi Lee , 김정규 Jeong Gyu Kim

DOI: Vol.20(No.3) 241-244, 2004

Radiation treatment with gamma-rays and electron-beams was used to remove polyvinyl alcohol(PVA), one of the main components of dyeing wastewater. PVA was effectively decomposed by radiation treatment, thus the removal was near 100% at an initial PVA concentration of 44 ㎎/L. However, total organic carbon(TOC) removal was less than 5% due to lower transformation of PVA to CO₂. This directly indicates the radiation treatment alone is not appropriate for the complete decomposition of PVA. In this sense, the improvement of biodegradability(BOD_5/COD) of PVA by radiation treatment was studied. Both gamma-ray and electron-beam treatments significantly increased the biodegradability of PVA by transforming non-biodegradable PVA to biodegradable by-products. This suggests radiation treatment, especially electron-beam treatment that showed better improvement of biodegradability, can be used as a pre-treatment of biological degradation process of PVA.

Biodegradability, Electron-beams, Gamma-rays, Polyvinyl alcohol

오병수 Byung Soo Oh , 김경숙 Kyoung Suk Kim , 주설 Seul Ju , 강준원 Joon Wun Kang

DOI: Vol.20(No.3) 245-250, 2004

This study investigated the micropollutants present in raw water supplied for the several drinking water treatment plants in Seoul. The target sample waters were collected from the several sites, such as Jayang (JY), Kuui (KI), Paldang (PD) and Kangbuk (KB) at the Han-River stream. The analytical method used in this study enable us to detect about 300 kinds of chemicals commonly found in surface water at ppt level by GC-ion trap MS. In this study, the consideration on the analytic results focused on the four hazardous organics, such as benzenes, phenols, phthalates and pesticides. The numbers of each detected micropollutant were 1~8 kinds for benzenes, 1~7 kinds for phenols, 5~7 kinds for phthalates and 1~9 kinds for pesticides. For the pesticides, the higher concentration was detected in the water samples collected from PD and KB adjacent to the farming area, and at June and July, which is the busy farming season. The total concentrations of each micropollutants detected at all the sites were significantly lower than those of drinking water regulation in Korea as well as other advanced countries. However, the frequently detected micropollutants requires the steady and precise monitoring for the effective management of drinking water source.

Micropollutants, Pesticides, Phthalates, Benzenes, Phenols

신진환 Jin Hwan Shin , 정영도 Young Do Jeoung , 연익준 Ik Jun Yeon

DOI: Vol.20(No.3) 251-255, 2004

Laboratory experiments were performed to investigate oxidation system using ozone and hydrogen peroxide for treating water contaminated with phenol. We were able to greatly improve the oxidation efficiency of the aqueous phenol using hydrogen peroxide and ozone. Two methods were compared and analyzed in this study. In the consequence through the methods, we concluded that the O₃/UV is superior to the hydrogen the results. The decomposition efficiency of aqueous phenol by H₂O₂. was exceeded at 83.3% in the concentration of phenol, 5, 15, 25 ppm, respectively. The rate of decomposition reaction by H₂O₂. was very slow. In the occasion of the fractional life, it was determined the value that 1.61×10^(-5)(1/mol)^(1.172)sec^(-1), 3.75×10^(-5)(I/mol)^(0.792)sec^(-1), 4.11×10^(-5)(1/mol)^(1.782)sec^(-1). The rate of decomposition reaction of aqueous phenol by O₃ was fast compared to the H₂O₂. We concluded that the O₃ method is useful with the consideration of the reaction time 30 minutes. In the occasion of the fractional life, it was determined the value that 1.094×10^(-4)(1/mol)^(0.933)sec^(-1), 2.1×10^(-4)(1/mol)^(0.842)sec^(-1), 7.22×10^(-4)(l/mol)^(1.332)sec^(-1).

Phenol, H2O2, O3

최근주 Keun Joo Choi , 김상구 Sang Goo Kim , 권기원 Ki Won Kwon , 지용대 Yong Dae Ji , 김승현 Seung Hyun Kim , 김창원 Chang Won Kim

DOI: Vol.20(No.3) 256-264, 2004

Adsorption characteristics of three endocrine disruptors, amitrol, nonylphenol, and bisphenol-A, were evaluated depending on the type and service duration of activated carbon (AC). Bituminous coal-, wood-, and coconut-based coals were tested. Bituminous coal-based AC (BCAC) had the greatest sorption capacity for the three chemicals tested, followed by wood-based AC (WAC) for nonylphenol and coconut palm-based AC (CAC) for bisphenol-A. During the column test, amitrol removal efficiency increased over time, indicating that hydrophilic endocrine disruptors are biodegraded in the AC column. Removal efficiencies of hydrophobic compounds such as nonylphenol and bisphenol-A decreased over time since the main removal mechanism was adsorption. The order of the amitrol removal was: BCAC-5.9 yr , CAC-3.1 yr ＞ BCAC-2.2 yr ＞ BCAC-virgin ＞ CAC-virgin ＞ WAC-virgin ＞ WAC-3.1 yr. In general, used AC had greater removals than virgin AC. The order of the bisphenol-A removal was: CAC-virgin ＞ BCAC-2.2 yr ＞ CAC-3.1 yr ＞ WAC-virgin ＞ BCAC-5.9 yr ＞ WAC-3.1 yr. The order of the nonylphenol removal was: BCAC-virgin ＞ WAC-virgin ＞ CAC-3.1 yr ,WAC-3.lyr＞ BCAC-2.2 yr ＞ BCAC-5.9 yr ＞ CAC-3.1 yr. Bituminous coal AC performed the best over time. Endocrine disruptors such as these three compounds appear to be removed effectively by activated carbon through biodegradation and adsorption. Wood and coal based among the virgin ACs and 3.1 years used wood base among the used ACs appeared the lowest carbon usage rate(CUR) for nonylphenol removal by prediction model. Virgin and used coconut base ACs except BCAC had the lowest CUR for removal Bisphenol-A. Biodegradation of nonylphenol and Bisphenol-A did not occurred during the 9,800 bed volume experiment period. BCAC had the highest biodegradation capacity of 46% for amitrol among virgin ACs and the used coal based ACs had 33-44% higher biodegradation capacity than virgin`s for amitrol so biodegradation is the effective removal technology for hydrophilic material such as amitrol.

Endocrine disruptors, Amitrol, Bisphenol-A, Nonylphenol, CUR, Biodegradation

조규석 Kyu Seok Cho , 박종호 Jong Ho Park , 김주찬 Ju Chan Kang

DOI: Vol.20(No.3) 265-268, 2004

Larva of Carassius auratus and Pungtungia herzi were exposed to mercury (HgCl₂), lead (PbCl₂) and copper (CuSO₄) to determine acute toxicity. The toxicity tests were conducted triplicate and the LC_(50) values (24, 48, 72 and 96 hours) were determined for two species. Data obtained from the toxicity tests were evaluated using the probit analysis. Although sensitivities of two species to mercury were relatively similar, C. auratus was more susceptible than P. herzi to the exposure of lead but P. herzi was more sensitive than C. auratus on copper. The sensitivity on three metals tested may be ranked in the following order from highest to lowest toxicity on larval stage of these fish: mercury > copper > lead. It is suggested that acute toxic test at the larval stage of C. auratus and P. herzi, indigenous species in Asia area, is an important part of the ecotoxicological assessment of some heavy metals.

Carassius auratus, Pungtungia, Larval stage, Heavy metals, LC50

최용수 Yong Su Choi , 홍석원 Seok Won Hong , 권기한 Gi Han Kwon

DOI: Vol.20(No.3) 269-274, 2004

The performance of a newly designed wastewater treatment process equipped with an anaerobic and two intermittent aeration tanks operated alternately was investigated. During the experimental period, several types of cyclic operating schedules with different aeration and non aeration time were examined for the optimization. At all modes, the removals of organic matter and SS were highly achieved. With respect to T-N removal, however, the cycle length for aeration on/off affected the efficiencies. At the optimal operating mode, the ORP bending point indicating the disappearance of nitrate was observed. Considering the influent wastewater characteristics and cyclic operating schedules, it can be suggested that T-P removal is much more BOD/T-P ratio and/or its load dependant rather than the aeration on/off time. The results obtained from pilot-scale test showed the competitive advantage of this alternating process through an omission of nitrate recycle and operational flexibility against influent load variations when comparing with other continuous flow processes.

Alternately intermittent aeration, Bending point, Nitrogen and Phosphorus removal, Oxidation-reduction potential

백영석 Young Seog Beck , 송민형 Min Hyung Song , 정경훈 Kyung Hun Jung , 권동식 Dong Sik Kwon , 이기공 Gi Gong Lee

DOI: Vol.20(No.3) 275-280, 2004

This study was performed to investigate the disinfection efficiency and the formation characteristics of disinfection by-products(DBPs) by chlorination in the sewage effluent. The effluent was sampled from the sewage treatment plants operated in the activated sludge process and the advanced sewage process. The type of DBPs investigated were Trihalomethanes(THMs), Dichloroacetonitrile(DCAN), Chloral hydrate(CH), Dichloroacetic acid(DCAA), Trichloroacetic acid(TCAA). Major findings are as follows. First, the optimum injection concentration for chlorination in sewage effluent were found to be in the range 0.5 ~ 1.0 ㎎ Cl₂/L. Also, It was found that the chlorine dosage in the effluent of activated sludge process was higher than in the effluent of advanced sewage process. Second, the maximum formation concentration of THMs were 12.7 μg/L. The THMs formation reaction was finished in a short time of several seconds and chloroform was mainly formed. Also, it was found that the concentration of ammonium nitrogen is higher, the concentration of THMs is lower. Third, it was found that DCAA and TCAA were mainly formed as DBPs by disinfection.

Sewage effluent, Chlorination, DBPs, THMs, DCAA, TCAA

최용욱 Yong Wook Choi

DOI: Vol.20(No.3) 281-289, 2004

Optimal analytical conditions have been established for mixing and reaction coil length, concentrations of ECR, CTAB, and acetate, reaction temperature and pH in the determination of aluminum by using flow injection analysis(FIA). Detection limit and repeatability for this system were 3μg/L and better than 1% of relative standard deviation, respectively. The interference from iron(Ⅲ) was suppressed up to 6㎎/L of iron(Ⅲ) by 0.1μM ascorbic acid, and the interference from fluoride could be tolerated in absorption of Al/ECR/CTAB derivative by 10mM boric acid at pH 3.5 adjusted with nitric acid. This FIA system was applied to the determination of aluminum leached from cooking utensils by distilled and tap water containing fluoride ranged from 0.5 to 2㎎/L by measurement of absorbance for Al/ECR/CTAB at 585nm. The leached aluminum content was increased with increasing concentration of fluoride. The aluminum contents leached from aluminum utensils by tap water were about 9 fold higher than those leached by distilled water, whereas aluminum contents leached by distilled water containing fluoride were about 2 fold higher compared to those leached by distilled water. That represented that other dissolved substances as well as fluoride in tap water contributed to liberation of aluminum from aluminum utensils. A comparison between FIA data and ICP-AES data by correlation and paired t test showed that the FIA system could be accepted as a good alternative method for the determination of aluminum in tap water.

FIA, ECR, CTAB, Aluminum, Cooking utensils, Tap water

이창근 Chang Geun Lee , 황은주 Eun Ju Hwang , 강성재 Seong Jae Kang , 빈정인 Jung In Bin , 이병헌 Byung Hun Lee

DOI: Vol.20(No.3) 290-295, 2004

In this study, ozone was adopted for the reduction and stabilization of waste sludge from the municipal sewage treatment plant. The waste sludge used in the experiments was primary sludge, excess sludge and a mixture of the two. The sludge cells and flocs were disrupted by ozonation resulting in the reduction of TSS and VSS concentrations. In the case of the primary sludge with a concentration of 20 gTS/L, the TSS and VSS concentrations were reduced 28%, 33% and the TCOD concentration was reduced 20% respectively. The consumption of ozone was 0.18 gO₃/gSS. In the case of the excess sludge with a concentration of 7.5 gTS/L, the TSS and VSS concentrations were reduced 37%, 41%, and the TCOD concentration was reduced 19% respectively. The consumption of ozone was 0.33 gO₃/gSS. In the case of the mixed sludge of 9.3 gTS/L, the TSS and VSS concentrations were reduced by 45%, 53%, and the TCOD was reduced 26% respectively. The desirable consumption of ozone was 0.27 gO₃/gSS. As ozonation proceeded, the level of SCOD increased due to the release of intracellular materials. However TCOD was reduced due to mineralization resulting from the transformation of organic materials to inorganic materials.

Reduction, Stabilization, Sludge(Exess, Primary, Mixed), Ozonation

정용준 Yong Jun Jung , 목회상추 Yoshiaki Kiso , 박순길 Soon Gil Park , 김종용 Jong Yong Kim , 민경석 Kyung Sok Min

DOI: Vol.20(No.3) 296-300, 2004

The rejection properties of 6 aromatic pesticides were evaluated by a continuous flow system equipped with a hollow fiber NF membrane. Different from the separation experiment of batch cell, the rejection and the removal could be calculated exactly because the concentration of feed, permeate and retentate was separately obtained. The lowest and the highest rejection were found in carbaryl(54.8%) and methoxychlor(99.2%), respectively, and the removals were always shown higher than rejections. This may be caused by some reasons such as the solute adsorption on the membrane, the variation of feed concentration. Although molecular weight, molecular width regarded as solute characteristics and log P(n-octanol/water partition coefficient) as hydrophobicity could be applied to explain the rejection property, these factors should be considered together for better analysis. According to the higher relationship between log B(solute permeability) and molecular weight, it was revealed that the solute separation with this membrane was influenced more by molecular weight.

Aromatic pesticides, Rejection property, Hollow fiber NF, Molecular weight, Log B

최선화 Sun Hwa Choi , 김호일 Ho Il Kim , 윤경섭 Kyung Seup Yoon , 최이송 I Song Choi , 오종민 Jong Min Oh

DOI: Vol.20(No.3) 301-306, 2004

The present water quality standards for agricultural were established without considering the effects of water quality on the safety, growth, yield and quality of crops. This study was carried out to investigate the effects of irrigation water quality on the growth, yield, and grain quality of rice, and to acquire basic knowledges to set up water quality standards for irrigation. The field and pot experiments were conducted with irrigation water that was previously adjusted four concentrations (control, 5, 10, 20 ㎎/L) and six concentrations (control, 5, 10, 15, 20, 30 ㎎/L) by NH₄NO₃ solution and replicated three and four times with randomized block design, respectively. The results of this study showed that the inorganic nutrient of rice plant, rice protein contents and number of panicle tended to increase as the T-N concentration in irrigation water was increased. In addition, grain yield at T-N 10 ㎎/L and 20㎎/L were significantly higher than the control at the field experiment. From the pot experiment at T-N 30 ㎎/L, the percentage of head rice was slightly lower due to the increase of green kernel and white belly/core kernel.

Agricultural water, Water quality standards, Total nitrogen, Rice culture, Grain yield, Rice grain quality