정용 Yong Chung

DOI: Vol.12(No.2) 107-118, 1996

이승은 , 이성규 Seung Eun Lee , Sung Kyu Lee

DOI: Vol.12(No.2) 119-126, 1996

Biological sensors have been becoming more important to monitor the quality of the aquatic environment, especially the presence of hazardous compounds. This study was designed to develop a biomonitoring system based on the respiratory and movement responses of carp (Cyprinus carpio) to monitor water quality. Diazinon, phenol, cadmium, and LAS were selected as test chemicals and exposure concentrations was ranged from acute toxicity level to one 100th of the highest concentration. When exposed to the acute level concentration, the first response were detected within 3 hr for LAS, 0.5 hr for cadmium and phenol and 15 hr for diazinon in this system. In case of cadmium, the significant response was shown at the chronic level and this system, therefore, could detect not only the acute level of LAS, cadmium, and phenol within 3 hr but also the chronic level of cadmium within less than 4 hr after exposure. In conclusion, present study proved that this biological monitoring system using fish respiration and movement as a sensor could be one of the promising approach to detect and prevent a toxic pollutant release into the aquatic environment.

이승목 , 이주광 Seung Mok Lee , Ju Goang Lee

DOI: Vol.12(No.2) 127-133, 1996

A Markov process coupled with interaction between molecules is developed to simulate bisolute adsorption kinetics. This model is relatively simple in that estimates of all model parameters except interaction parameters are obtained from single solute experiment. Transient behavior of molecules can be evaluated by analytically solving a system of the governing ordinary differential equations of the present stochastic model. Adsorption rate profile is not affected by interaction parameters at low concentration range.

정규혁 , 노경신 Kyu Hyuck Chung , Kyoung Sin Ro

DOI: Vol.12(No.2) 135-140, 1996

We investigated the aerobic and anaerobic biotransformation of atrazine using laboratory -scale batch reactors containing wetland water and sediment. After 38 weeks of anaerobic incubation, atrazine in the water phase dropped from the initial 10 ㎎/L to 4.2㎎/L. In contrast to the aerobic biotransformation, a significant level of hydroxyatrazine was detected in the sample reactors during 38 weeks of anaerobic incubation. Furthermore, a trace amount of a possible deethylhydroxyatrazine was detected in the anaerobic BSM sample reactor. However, none of the dealkylated metabolites were observed. In contrast to the anaerobic condition, atrazine disappeared rather rapidly within 21 days of incubation after 42 days of stationary phase under aerobic conditions. BSM increased the atrazine biotransformation rate under anaerobic conditions, but decreased the rate under aerobic conditions.

전항배 , 김학성 , 이태용 Hang Bae Jun , Hag Seong Kim , Tae Young Lee

DOI: Vol.12(No.2) 141-149, 1996

Yeoncho dam, a small reservoir for industry and domestic water supply, located at Geoje island in the southern part of Korean peninsula was constructed and have been operated since 1979. Odor and taste problem was occurred 2 years after the initiation of storage of water. For the improvement of water quality, forced circulation of water throughout the reservoir was made by using a 5 air-lifters. In this study, the influences of air-lifters operation on the water quality control were investigated by monitoring physicochemical and biological factors. Operation of air-lifters removed odor and taste completely since 1992. During the first year(1992) operation, however, there was evidences of occurrence of algal bloom in spring and autumn due to the turnover of the reservoir, while no significant variations in water quality were detected in 1993. Odor and taste in this case seems to be originated from anaerobic decomposition of benthic decompositions and from algal growth. The forced circulation supplied DO to the bottom layer of the reservoir and prevented the layer from anaerobic condition. Total nitrogen showed apparent decrease right after the start-up of the air-lifters, while total phosphorus(T-P) and Chlorophyll-a showed very high concentrates in the early 1992. The last two parameters were still high even after 1993, however, they showed a tendency of gradual decrease as the operation time prolonged.

정정권 Jhung Kwon Jhung

DOI: Vol.12(No.2) 151-157, 1996

The objectives of this research were to determine the organic compound sorption capacity of ground tires, to assess the effects of humidity and biomass growth on the surface of ground tires on the VOCs removal efficiency, to evaluate the desorption rate, to estimate the service time at various operational conditions, and to propose potential application methods for removal of VOCs emitted from a wastewater treatment plants. The sorption capacity increased logarithmically with the increase in the octanol-water partition coefficient. The VOC removal efficience by a ground tire layer were more than 95 for nonpolar compounds and more than 80% for polar compounds at the Qa/Qw ratio between 5 and 10. A biomass grown ground tire layer removed approximately 2 to 20% less VOCs in the off-gas than a wetted ground tire layer. The Qa/Qw ratio affected the off-gas VOC removal efficiences by 25 to 40% for polar compounds but slightly for nonpolar compounds. The service times for a 30cm thick ground tire layer with the Qa/Qw ratio of 10 were all less than three weeks for the organic compounds tested and thus, the sorbent utilization rate was low at this ratio. However, when the ratio was decreased to 5, the service times almost doubled.

윤제용 , 송명석 Je Yong Yoon , Myoung Suk Song

DOI: Vol.12(No.2) 159-166, 1996

Trihalomethanes(THMs) are formed with the reaction of natural organic matter when chlorine is added as disinfectant in water treatment plant. This study was designed to evaluate the removal efficiency of THMs formation in the conventional water treatment plant with the use of Jar test simulation. The characteristics of THMs formation in each unit process of the K water treatment plant were presented. The formation of THMs in water treatment plant was predominant in the rapid mixing chamber and flocculation basin, and the relative ratio of THMs formation in the rapid mixing chamber and flocculation to that in settling basin ranged from 3.3 to 22.3. The estimated removal efficiency of THMs with Jar test results was 33∼58% which may be interpreted as that much of THMs formation precursor could be removed out in the conventional water treatment process. The aspect of the potential effectiveness of the conventional water treatment process for the control of disinfection by products may be considered in introducing the advanced water treatment process in the conventional water treatment plant. Chloroform was the most dominant species in THMs and Bromodichloromethane comprises of l/5 of the total THMs.

이건모 , 김구열 , 이재기 Kun M . Lee , Gu Y . Kim , Jae K . Lee

DOI: Vol.12(No.2) 167-173, 1996

Pyrolytic oil from the pyrolysis process of municipal wastewater sludge is a low grade oil which is high in moisture content and viscosity, and relatively low in calorific value. The oil upgrading experiment was performed in this study to upgrade the quality of the pyrolytic oil. The role of the catalyst, and the effect of reaction temperature, WHSV(Weight Hourly Space Velocity) and oil feed rate on the oil upgrading process were evaluated using a bench scale micro reactor. The ZSM-5 catalyzed the upgrading reaction of the pyrolytic oil and simple heating without catalyst did not upgrade the quality of the pyrolytic oil. The viscosity of the oil appears to be dictated not only by the COOH content but also by the other unknown compounds. The O content, moisture content, viscosity, and COOH/CH₃ ratio of the upgraded oil was decreased by 60, 37, 68 and 17%, and the calorific value was increased by 21%, over the feed oil, when ZSM-5 was used in the upgrading reaction.

강선홍 , 최상일 Seon Hong Kang , Sang Il Choi

DOI: Vol.12(No.2) 175-181, 1996

Prior studies at Iowa State University tend to indicate that petroleum products such as gasoline, diesel fuel, and crude oil can be removed from soil by bioremediation. These studies also indicate that gasoline would largely be removed by volatilization and that diesel fuel would not. In order to investigate volatilization as a competing process for the removal of fuels with bioremediation, the movement of gasoline in the sand was investigated and a model based on a material balance was developed to predict the evaporation of petroleum products from contaminated sand. The results show that the fuel was drying out from the top down and at the level where the liquid fuel is found, the air in the pore space in the sand is saturated with fuel vapor. Diffusion moves the vapor to the surface of the sand where the flow of air maintains the fuel vapor concentrations near zero. The model explains that the evaporation pressure is an important factor and why the rate of volatilization of gasoline is much higher than that of diesel fuel.

강준원 , 박훈수 Joon Wun Kang , Hoon Soo Park

DOI: Vol.12(No.2) 183-189, 1996

A bench scale investigation was conducted of by products of trichloroethylene(TCE) and tetrachloroethylene(PCE) oxidation by the ozone/hydrogen peroxide advanced oxidation process(AOP). Post-chlorination of ozone/peroxide treated water was also investigated. Byproducts analyzed for TCE and PCE destruction in the ozone/peroxide experiments were chloral hydrate and di-and trichloroacetic acid (DCA and TCA). In TCE spiked (500∼700 ppb) ozone/peroxide runs, chloral hydrate was formed up to the level of 0.2 ppb and was slowly destroyed as the run progressed. Dichloroacetic acid and trichloroacetic acid was produced by the oxidation of TCE and PCE, respectively. In the post-chlorination experiments of PCE Spiked ozone/peroxide runs, concentration of chloral hydrate, DCA, and TCA were higher in the chlorinated water, but the levels seems to be quite below the maximum contamination level goal(MCLG) of USEPA.

신항식 , 오세은 Hang Sik Shin , Sae Eun Oh

DOI: Vol.12(No.2) 191-196, 1996

Batch test was performed to evaluate the activity of methane producing bacteria (MPB) and acetate producing bacteria(APB) according to change of sulfate and sulfide concentrations. MPB activity in the 100 and 150㎎S/ℓ was inhibited by 15 and 50%, respectively, while it was stopped at over 200㎎/ℓ. This indicated that the inhibition of sulfide concentration on methane producing bacteria increased as sulfide concentration increase. Different species of anaerobic microorganisms degrading organics showed different characteristics of acclimation and inhibition depending on the sulfide concentration. APB and MPB were much affected at the sulfide concentration over 100㎎/ℓ, resulting in accumulation of acetate in the reactor. This clearly showed that APB were more persistent than MPB to sulfide toxicity. Sulfate concentration less than 2000㎎/ℓ showed no inhibition to MPB in the anaerobic treatment of organics. Moreover, higher methane production was observed with sulfate concentration of 100㎎/ℓ in the batch than in the control, suggesting that small amount of sulfate was necessary for MPB.

김상구 , 류동춘 Sang Goo Kim , Dong Choon Ryou

DOI: Vol.12(No.2) 197-203, 1996

This study was conducted through jar-test and pilot-plant test to research coagulation effect of pre-ozonation on the contaminated water by organic matter (TOC), inorganic matter (kaolin) and algae specially diatom (chlorophyll-a). Pre-ozonation had not coagulation effect on the kaolin water further more acted as coagulation deteriorator on the organic matter water which imvolved humic acid more than 2㎎/ℓ as total organic carbon (TOC). But it had good coagulation effect on the nutriented water more than 40μ/ℓ as chlorophyll-a. Therefore pre-ozonation utility is desired for treating nutriented source water. We had added ozone to the netriented raw water increasingly 1㎎/ℓ from 1 to 5㎎/ℓ, About l∼3㎎/ℓ ozone treated water was appeared lower residual turbidity than of 5㎎/ℓ ozone contacted water and untreated water after jar-test. Compared residual turbidity of l㎎/ℓ ozone treated water to 3㎎/ℓ, we did not find significant difference of residual turbidity between two jar-test data. So we proposed 1㎎/ℓ as optimum pre-ozone dose for nutriented water. And pre-ozonation process had better coagulation effect to the higher chlorophyll-a concentration water. Authors also found out that pre-ozonation could save coagulant about 25%.

송지현 , 정태학 , 장덕 Ji Hyeon Song , Tai Hak Chung , Duk Chang

DOI: Vol.12(No.2) 205-213, 1996

Reaction characteristics of an anaerobic sequencing batch reactor(ASBR) process were studied using bench scale reactors maintained at 35℃. The experiments were performed with an equivalent hydraulic retention time of 10 days and the synthetic feed was mainly composed of glucose. The ASBRs were operated with a cycle period of 24 and 0.5, respectively. Volatile suspened solids in all reactors kept increased as the operation continued. However, methane fermentation efficiency was strongly affected by the MF/M ratio. Active methane production was observed for the ASBRs of long MF time, while methane fermentation was significantly inhibited by the excessive production of the volatile acids for the ASBR of short MF time. The ASBR of high specific organic loading rate(SOLR) was not able to absorb the shock and reached an operational failure. However, when COD of the feed was reduced to 10,000㎎/ℓ, little accumulation of volatile acids were observed and active methane fermentation continued in spite of relatively high SLR. It is believed that both SOLR and the organic level of the feed are major design parameters determining safe and stable operation of the ASBR. The solid-liquid separation efficiency was markedly reduced with an increasing gas production rate due to floating of volatile suspended solids.

양운진 Woon Jin Yang

DOI: Vol.12(No.2) 215-223, 1996

One hundred and thirty eight groundwaters from Masan and Changwon area have been assessed from 1993 to 1995. The statistical analysis were as follows: It was concluded that the groundwater quality was degraded in parameters of coliform bacteria, surfactant and ammonia nitrogen by the levels detected and variance analysis. This contamination was suspected to be caused by human activities due to the characteristics of parameters. 9.3 percent of groundwater data evaluated did not meet the Korean Standards by the parameter of chloride ion, which reflects some of sampling area to be reclaimed. The KMnO₄ consumption of groundwater obtained from this area was twice higher than that of Kangwon-do groundwater. The results indicate some urgent remedial action is needed for restoring groundwater quality in this area.

Gee Bong Han

DOI: Vol.12(No.2) 225-232, 1996

A computer model was modified to describe a biofilm distributed on the gas permeable support. The biofilm was assumed to grow in the direction perpendicular to the support as two homogeneous layers. Derivation and development of the multilayer biofilm model was illustrated by describing mass balance equations on substrate concentrations within the biofilm and reactor bulk liquid. A numerical evaluation was implemented on a computer to obtain simultaneous numerical solution of applicable differential equations. The equations described mass balance on biomass and substrates under non-steady state conditions and provided an illustration to indicate the effect of parameter and reactor condition of autotrophic nitrifiers to overall biofilm reactions. Model behavior was discussed according to the performance of each biofilm layer. Spatial distribution of homogeneous microorganisms and substrates in the film were described in each condition of developed layer. The completely developed multilayer biofilm included inner and outer layer dominated by nitrosomonas and nitrobacter respectively.