최의소Choi Eui So

DOI: Vol.17(No.6) 643-645, 2001

N/A

김시준Shi Jun Kim

DOI: Vol.17(No.6) 647-651, 2001

Solute rejection of organic compound such as chlorophenols, nitrophenols and pesticides with a flat sheet composite polyvinyl alcohol nanofiltration negatively charged membrane by pKa of organic compound and pH change of feed solution was investigated. It was shown that 4-chloro-2-methylphenoxy acetic acid (MCPA), 2,4,5-trichlorophenol, 2,4-dichlorophenoxy acetic acid (2,4-D), 2,4-dinitrophenol and p-nitrophenol were rejected highly at the pH 9 of feed solution. But rejection of 4-chlorophenoi and phenol was very low at the same pH condition of feed solution. At the pH 3 of feed solution, its rejection was the lowest. When the pH condition of feed solution was more higher than the its pKa, the higher rejection of organic compound was shown. As a result, it was found that rejection of organic compound dissociation occurred was depended on both the pKa of organic compound and the pH of feed solution.

민경석Kyung Sok Min,정용준Yong Jun Jung

DOI: Vol.17(No.6) 653-663, 2001

The objectives of this study were to investigate the process performance of a bench-scale denitrifying sand filter like maximum filtration rate and effluent concentration with the variation of influent quality and to estimate its applicability for the add-on treatment process of BNR effluent polishing. During the whole experimental periods, SS, Turbidity and NO₃^--N concentration of effluent were obtained less than 2.5 ㎎/L, 2.5 NTU and 6.3 ㎎/L, respectively. The removal efficiency of NO₃^--N could be gradually increased from 78% to 91% by varing the requirements of theoretical external carbon source, which was in the range of 80% and 100%. In both cases that influent NO₃^--N was ranged from 10 to 15 ㎎/L at the filtration rate of 151.3∼171.1 m/d and NO₃^--N was 28.2 ㎎/L at the rate of 111.8 m/d, the NO₃^--N removal efficiencies were 78%, respectively. It is noticed that influent concentration of NO₃^--N was an important factor for NO₃^--N removal efficiency as well as filtration rate. Regardless of influent concentration and filatration rate, SS and Turbidity were less than 2.5 ㎎/L and 2.5 NTU, respectively. Therefore denitrifying sand filter could be of use an alternative post denitrification process targeting for the removal of SS as well as nitrogen.

오카자키 마사노리Masanori Okazaki,최이송I Song Choi,오종민Jong Min Oh

DOI: Vol.17(No.6) 665-674, 2001

Four electrode suggested for measuring electric conductivity of soil salinity is one of the very useful method to estimate movement of ion matter without destroying physio-chemical characteristics of soils directly. This paper was studied to determine more effective length, space and diameter of 4 electrode in order to measure soil suspension and variation of electric conductivity in stem part of plant by using 4 electrode. Based on the results of this study, the most suitable range of 4 electrode size were in the range of 3-7 ㎜ for length, about 0.55 ㎜ for diameter and 2-3 ㎜ for space by estimating from the accuracy and sensitivity of them. In the result of using 4 electrode to measure electric conductivity in suspension of soil with each other characteristic, the range of error was within 5 %. We also confirmed that 4 electrode can measure changing of electric conductivity in stem part of Oriza Sativa L. . Since electric conductivity, however, is greatly effected by water content in soil and plant, it was required more detail study and data for electric conductivity characteristics with water content in soil and plant.

황규대Gye Dae Whang,황선진Sun Jin Hwang,이지웅Ji Woong Lee

DOI: Vol.17(No.6) 675-682, 2001

Adsorption of Acid Red 337 as a specific dye onto hydrous TiO₂ in a distilled water was evaluated using a batch reactor. The amount of dye adsorption on TiO₂ was influenced by a pH value because of the strong dependance of surface charge of TiO₂ on the pH value. The high amount of dye adsorption by TiO₂ was observed below pH 6.0 because the positive surface charge (TiOH₂^+) of hydrated TiO₂ was expected as the pH value was lower than the isoelectric point of TiO₂(pH≒6.0). With a high amount of dye adsoption on TiO₂ at low pH value, the rate constant of dye photoremoval increased with going up pH value within this pH range. It was observed that the effect on adsorptivity by TiO₂ was greater than that of pH on the removal efficiency of Acid Red 337.

이상수Sang Soo Lee,김시현Si Hyeon Kim,정근진Kun Jin Jung

DOI: Vol.17(No.6) 683-692, 2001

Biofilm reactors were numbered in terms of temperature, and biofilm reactor No.1 represented 25℃ and No.2 15℃. At 24hr of HRT, BOD removal efficiency was 94.7% at biofilm reactor No.1 and 92.3% at No.2, respectively, while it was about 90.0% for biofilm reactor No.1 and No.2 at 18hr of HRT. However, BOD removal efficiency was decreased below 12hr of HRT. At 25℃ the half saturation constant(K_s) and maximum specific substrate removal rate(k_(max)) were 228 ㎎/L and 0.96 day^(-1), respectively. In addition, the microbial yield coefficient(Y), decay coefficient(K_d), and maximum specific growth rate(μ_(max)) were 0.248 ㎎VSS/㎎BODre, 0.048 day^(-1), and 0.372 hr^(-1), respectively. On the other hand, at 15℃ the saturation constant (K-s) and maximum specific substrate removal rate(k-max) were 600 ㎎/L and 1.82 day^(-1). The microbial yield coefficient(Y), decay coefficient(K-d), and maximum specific growth rate were 0219 ㎎VSS/㎎ BODre, 0.045 day^(-1), and 0.487 hr^(-1), respectively.

박해식Hae Sik Park,박청길Chung Kil Park,송미경Mi Koung Song,백경훈Kyung Hoon Baek,신성교Sung Kyo Shin

DOI: Vol.17(No.6) 693-701, 2001

The study was conducted to evaluate water quality utilizing factor analysis in the Nakdong River. The relationships between BOD concentration and flow rate, weighted BOD concentration which it was considered BOD load and flow rate, show that water quality in the lower stream is affected by flow rate, especially, in winter and spring. The three factors derived from the factor analysis explained 75.0% of the variability within the data. Factor I (44.0%) was artificial pollution pattern by domestic sewage and industrial wastewater. Factor II (19.2%) was metabolism pattern. Factor III (11.75%) was hydrological variation pattern. The upper stream was influenced of hydrological factor and the water clarity in the middle stream was related to artificial pollution. The lower stream including Mulgum was strongly affected by the metabolised factor.

이병헌Byun Hun Lee,강성재Seong Jae Kang,감성희Seong Hee Kam,이동석Dong Seuk Lee,유평종Pyung Jong yoo

DOI: Vol.17(No.6) 703-709, 2001

This study was conducted to estimate the effects of real time control for AOAS SBR system. D0, pH and ORP were good indicators on nitrification and denitrification. Among these, ORP was the most effective and stable. To save the aeration energy and to promote the removal efficiency, the system was controlled on real time basis by using ΔORP as a control parameter. When the system was controlled on real-time basis, 31∼66% of energy was preserved. NH₄^+-N removal efficiency was 99%, but post denitrification rate was very poor because of deficiency in the carbon source. This process should select to add external carbon source or step-feeding method in order to improve the post-dinitrification reaction.

조진규Jin Kyu Cho,김성호Sung Ho Kim,김응호Eoung Ho Kim

DOI: Vol.17(No.6) 711-718, 2001

This study was performed to evaluate feasibility of fly ash as a solidifying agent for the solidification of sewage sludge. The unconfined compressive strength and pH were observed with during time and mixing ratio, and heavy metal leaching test was performed. Also, XRD, SEM and EDS analysis was performed for the microstructure analysis of the solidified sewage sludge. Immaterial increase of unconfined compressive strength was shown for the sewage sludge mixed with fly ash as a solidifying agent, but the unconfined compressive strength was increased highly for the use of quicklime as a solidifying aid. So, It is possible to use fly ash as a solidifying agent mixed with a small quantity of quicklime. The results of leaching tests was shown that the concentrations of leachate heavy metals(Cu, Pb, Cd and Cr^(6+)) were lower than the Korea toxic waste criteria. The microstructure analysis by SEM was shown that needlelike crystals appeared as the solidification proceed. The analysis of these crystals by EDS confirmed that these main components were Ca, Si etc. Also, XRD analysis was shown that the main solidification products was CSH.

박석균Suk Gyun Park,강선홍Seon Hong Kang,정태학Tai Hak Chung

DOI: Vol.17(No.6) 719-725, 2001

The characteristics of swine wastewater are different according to the type of pigsties, method of removing swine wastewater, quantity of washings, etc. It is difficult to get granular which is required for UASB because swine wastewater consists of high concentrations of solid and NH₃. A purpose of this study is to test the applicability and solve the problems in operating UASB in the field. Non-granular microorganisms acclimated to the substrate of swine wastewater, granular microorganisms produced in the brewing wastewater and their mixture were seeded respectively. In spite of high solid concentration, all reactors showed stable operations and 30% of COD removal rates were achieved regardless of HRT when granular microorganisms were fixed in the bottom of UASB.

이현동Hyun Dong Lee,배철호Chul Ho Bae,박정훈Jeong Hoon Park,신현준Hyun Joon Shin,조정식Chung Sik Cho

DOI: Vol.17(No.6) 727-736, 2001

It was estimated that cleaning effect in old service pipe by cleaning methods such as air pulse waves and cleaning solution (Disinfectants and Chemical cleaning solution) in the study. The results of cleaning experiments by air pulse waves showed that cleaning efficiency didn`t influenced by both increase of flow rate in pipe and hydraulic cross section and was about 0.8%. Cleaning experiments of batch system by cleaning solution alone also showed that hydraulic cross section was a little smaller in the same condition, the cleaning efficiency of cleaning solution in service pipe was more increased. And the cleaning efficiency of chemicals cleaning was a little higher than solution disinfectants (O₃, H₂O₂, MIOX). Hydraulic cross section by Carela-Bio-Plus of both chemical cleaning solutions was increased at 14%. The cleaning efficiency of Carela-Bio-Plus also was higher than any other cleaning solutions in loop system. Especially, cleaning efficiency of ozone was higher than Carela-Bio-Plus Forte, and the results showed that ozone was thought to depend on pH. In case of cleaning by air pulse waves with cleaning solutions together, hydraulic cross section of old service pipe was more increased from 0.08% to 2.8% than cleaning of cleaning solutions alone. Amount of scale in old service pipe also was decreased from 0.11g to 9.82g. And it was thought that cleaning efficiency by both ozone and chemical cleaning solutions usually was higher in strong acidic solution. Therefore neutralization treatment by alkaline solution should be required after pipe cleaning. Also those cleaning solution, especially their odors and gas, are known as lethal chemicals for humans. So the disposal of their odor and gas were thought to be very important for feasible application of pipe cleaning.