김승재 , 이명진 , 이정전 Seung Jai Kim , Myung Jin Lee , Jung Jun Lee

DOI: Vol.10(No.1) 1-9, 1994

Removal of copper ions from wastewater was studied experimentally in the fluidized and semifluidized beds of 60mm in diameter. Dilute aqueous solution of copper sulfate(300ppm) and strong cation exchange resin particles (Amberlyst 200C) of 0.74㎜ in diameter were used as the synthetic wastewater and ion exchange resin. The inlet and exit concentrations of copper ions, bed heights and pressure drops were measured, and the breakthrough curves and mass transfer coefficients were obtained. Correlations for mass transfer coefficient were examined, and the effects of liquid flowrate, particle hold-up and height of retaining grid on liquid-solid mass transfer were discussed. The results show that the copper ion removal rate and mass transfer coefficient in the initial period of ion exchange in a semifiuidized bed are higher than those in a fluidized bed.

박석순 , 박배경 , 이상호 Seok Soon Park , Bae Kyung Park , Sang Ho Lee

DOI: Vol.10(No.1) 10-16, 1994

Multiple linear regression analysis was performed to compare stream water qualities relating to land-use types in the Han River watershed. Explanatory variables were ratios of each land use area per total watershed and response variables were water qualities of receiving streams. The computed regression coefficients of each explanatory variables were used as the degrees of water quality impacts by land use types. The watershed was classified into four (4) different land use types : urban and industrial area, agricultural area, forest area, and green belt area (which has been preserved from development). Ninety four (94) tributaries were sampled three times during different flow conditions from March to July, 1992. Water quality parameters included in this study were Biochemical Oxygen Demand, Total Suspended Solids, Anionic Surfactant, and Conductivity. Regression coefficients were computed for each water quality and significance of coefficient values were estimated using the t- test. Linear relationship between explanatory variables and response variable was also measured by the F-test. From this study, it was concluded that there were significant linear relationships between receiving stream water qualities and land use types such that regression analysis could be used as a good comparison tool. The computed values of regression coefficients could be used as quantitative measurements of land use impacts.

권이열 , 김미경 , 이성욱 Ee Yol Kwon , Mi Kyung Kim , Seong Uk Lee

DOI: Vol.10(No.1) 17-23, 1994

On the study, the neutralization ability of acid water and the removal of heavy metals were experimentally considered with concrete obtained from dismantlement of the existing concrete structures. From the result of being contacted and reacted 0.0l00g of concrete on each on 200㎖ of nitric and sulfuric solution of pH 4.00 for 1 hour at 16℃, the pH value was obtained pH 6.69 and 6.82, respectively. For contact time, equilibrium of reaction was made in 2 hours for change of temperature, pH somewhat increased as the temperature rise. Being contacted and reacted 4.0000g of concrete in 100㎖. of heavy metal solution of 0.03M-Cu^(2+), Zn² , Ni^(2+) for 15 minutes at 15℃, the removal rate of adsorption were 98.0% in Cu^(2+), 94.9% in Ni², 66.5% in Zn^(2+). Therefore waste concrete is able to help to the neutralization of acid water and removal of heavy metals.

정팔진 , 곽동희 Paul Gene Chung , Dong Heui Kwak

DOI: Vol.10(No.1) 24-30, 1994

In this study, the degree of polluted raw water treatment of microbes has been measured by dissolved organic matters, NH₃-N, ABS, phenol, and THM_(FP) etc., which not removed conventional water treatment plant effectively. The objective of this study is to investigate the removal characteristics and efficiency of the bio-filter processes. The estimated values for kinetic coefficients were K,=31.89㎎/ℓ, k=1.55day^(-1), μ_m=0.88day ^(-1), Y=0.57gVSS/gBOD_(removed) and k_d=0.08day^(-1). In the low loading rate of low substrate(0.02 -1.5㎏ COD/㎥·day), fixed-bed reactor could be operated at steady-state, but fluidized-bed reactor was hard to operate at steady-state for decrease of pellet growth rate and increase of specific pellet density. The removal efficiency was more sensitive to NH₃-N loading rate than KMnO₄ loading rate. It was possible to linearize the relationship between the water temperature and removal efficiency as well as the relationship between loading rate of substrates and removal efficiency.

성일화 , 최용수 , 박흥석 , 유명진 Il Wha Sung , Yong Su Choi , Hung Suck Park , Myong Jin Yu

DOI: Vol.10(No.1) 31-40, 1994

An experiment was conducted in order to examine the effect of commercial additive which contained humus plus minerals. The additive with the trade name $quot;Biothrough$quot; was used in this study. In reactors A and B, an additional aeration tank for 12 hours detention of recycle sludge was installed and $quot;Biothrough$quot; was submerged inside the tank. In reactor C, $quot;Biothrough$quot; was submerged inside reactor and was not used in reactor D, the control unit. The experimental results are summarized as follows ; SVI was lowest for reactor A at the FiM ratio of both 0.15 to 0.83 and 0.14 to 0.51 ㎏ BOD/㎏ MLSS·day. The biopolymer excretion per unit weight of activated sludge increased in accordance with the increase of HRT. The results indicated that the reactors attached with additive were more efficient in improving the settling characteristics of activated sludge. In that respect, it was thought that the attachment of additive in tank improved activated sludge characteristics and further detention led the microbes towards favorable endogenous phase where more excretion of biopolymer was possible. Such increase of biopolymer excretion improved the aggregation and in turn the settle ability of activated sludges.

임재명 , 권재혁 , 이정환 Jay Myung Rim , Jae Hyouk Kwon , Jeong Hwan Lee

DOI: Vol.10(No.1) 41-48, 1994

A correlation between the biofilm thickness and biomass density in a laboratory-scale submerged media aeration system was evaluted. The laboratory unit had Saran Lock^((TM)) media and the piggery wastewater was used as a substrate. The influent wastewater had COD and BOD concentration of 2,940 to 3,800 ㎎/ℓ and 1,310 to 1,730㎎/ℓ, respectively. HRTs of the laboratory unit were varied from 0.5 to 2 days. Following conclusions can be drawn from the operational results : ⅰ) the maximum biofilm density of 130㎎/㎤ was observed at biofilm thickness of 180 to 200 ㎛ ranges. ⅱ) The active biomass content represented as VSS per unit aera was increased up to 10 days of operating time. ⅲ) The COD removal rate was rapidly increased up to the 200 ㎛ of biofilm thickness, however no further increment of COD removal rate was observed between 200㎛ to 1,200㎛ of biofilm thickness.

이정식 , 변종각 , 조광명 Jung Sik Lee , Jong Gak Byun , Kwang Myeung Cho

DOI: Vol.10(No.1) 49-55, 1994

An adequate treatment is required for leachates from municipal solid waste landfills because they contain a high concentration of organics. This research was performed to investigate the effects of ozonation on removal of organics, especially refractory, in leachates. Ozonation of a raw leachate showed that both COD and BOD decreased during the first 2 hr contact period, then increased, and finally decreased again after 4 hr contact. Ozonation of an effluent, containing almost nonbiodegradable organics, from a batch activated sludge treatment resulted in increase in COD and BOD during a 4 hr contact period, and then the concentrations decreased. In addition, treatments of raw and ozonated leachates by an activated sludge process with a F /M ratio of approximately 0.1㎏ BOD/㎏ MLSS-day showed only a difference of 2∼3% in COD or BOD removal efficiencies. Most of the biodegradable organics formed from refractory organics during ozonation could he biologically removed. Therefore, it could be concluded that part of the refractory organics in leachates could be biologically removed after ozonation and that it would be more effective to ozonate leachate after an biological process.

임봉수 Bong Su Lim

DOI: Vol.10(No.1) 56-61, 1994

The results have established pH as a viable process control parameter for the AAA (Alternative Aerobic-Anoxic) process. During the course of aerobic-anoxic alternation, important features appear on both the ORP and pH profiles. Newly identified pH features applicable to the AAA process control include the ammonia valley, a well defined point for terminating aerobic cycles, and the nitrate apex which can be used to terminate anoxic cycles and initiate aerobic cycles. Such feature provide valuable insights into the respiratory state of the system, which is constantly changing between nitrification and denitrification. The reproducibility of the ORP and pH curves enables the use of these features to determine the aerobic and anoxic periods in the AAA process on a real-time basis. In addition, it has been shown that pH control processes certain advantages over ORP control. Two real-time AAA control strategies, namely fixed pH set points and dynamic pH variation, were briefly presented and discussed. Both strategies were found to be feasible for the real-time control of the AAA process. Results from labortory scale AAA sludge digestion using fixed pH set points(6-8) indicated that 36% MLVSS reduction, 39% TN reduction and almost 48% saving in aeration energy was achieved after 300 hrs of digestion.

정현미 , 윤제용

DOI: Vol.10(No.1) 62-71, 1994

송미우구 松尾友矩

DOI: Vol.10(No.1) 72-74, 1994