안갑환 , 박태주 , 송승구 Kab Hwan An , Tae Joo Park , Seung Koo Song

DOI: Vol.8(No.1) 1-7, 1992

A number of experiments to treat wastewater of a dye-plant were conducted to evaluate the treatment efficiency of an aerobic fixed-film reactor, a fluidized bed reactor, and a completely mixed activated sludge reactor upon the variation of organic loading rates. The media used in this fixed-film reactor were SARAN 4000D(media A) of specific surface area, 153㎡/㎥ and SAEAN 1000D(media B) of specific surface area, 308㎡/㎥ and the supporting material of this fluidized-bed reactor was 0.6 - l.2 ㎜ in diameter granular activated carbon. The influent COD concentration was ranged from 1040 to 5365㎎/ℓ. Maximum COD removel efficiencies with 600% diluted wastewater were marked to 90% with a fluidized bed reactor, 83% with an aerobic fixed-film reactor and 77% with a completely mixed activated sludge reactor. But in case of 200% diluted wastewater, COD removel efficiency was 63-83% with an aerobic fixed-film reactor, 46-67% with a fluidized bed reactor 40-46%, with a completely mixed activated sludge reactor. It was assumed to be the toxcity of high concentrated influent of wastewater. Within the range of organic loading rates, average biomass concentration were shown as 7,000㎎/ℓ in an aerobic fixed-film reactor, 6,300㎎/ℓ in a fluidized-bed reactor and 1,700㎎/ℓ in a completely mixed activated sludge reactor.

정팔진 , 임봉수 , 김영철 , 김영규 Paul Gene Chung , Bong Su Lim , Young Chul Kim , Young Kyu Kim

DOI: Vol.8(No.1) 8-14, 1992

It has been confirmed that some Trihalomethanes(THMs) suspected as carcinogens, can be formed during chlorination for water supply through the reaction of chlorine and humic substances in water. A lot of researches have showed that the amount of THMs formed during chlorination can be reduced by the removal of humic substances in water, which are THM precursors. In this study, the removal efficiencies of THM precursors by 10 sets of water treatment processes were examined for artificial water samples prepared by dissolving humic acids in tap water aerated for 48 hours. The removal efficiencies were estimated by measuring the concentrations of THMs formed when sample was mixed with chlorine. The estimated removal efficiencies were ranged from 30% of simple ozonation to 96% of ozonation followed by flocculation and sand filtration. The best process selected in this study was extended to the treatment of water collected from Chonju water supply sources. The result also showed the removal efficiency of THM formation potential is higher than 95%.

이병헌 Byung Hun Lee

DOI: Vol.8(No.1) 15-21, 1992

The investigation of the temperature, organic lading and hydraulic loading rates effects on a high-rate anaerobic reactor was the main purpose of this experiment. The high-rate anaerobic reactor was composed of two compartments : upflow anaerobic sludge blanket and downflow anaerobic filter. The efforts of increasing the microbial concentration to overcome the low temperature effects to the microbial metabolisms were the reasons for two compartments of anaerobic reactor. The synthetic feed, containing glucose, beef extract and peptone as the carbon and nitrogen sources was used for influent with nutrients and trace metals. The volumes of the upflow anaerobic sluge blanket and the downflow anaerobic filter compartment were 1.1ℓ and 1.5ℓ, respectively. The SCOD removal efficiencies were above 80% upto 30㎏ COD/㎥/d at 25℃. The hydraulic retention times were reduced from 32 hrs to 4hrs at 10㎏ COD/㎥/d. More than 8 hrs hydraulic retention time, the SCOD removal efficiencies were 90% at 25℃. The SCOD removal efficiencies decreased with temperature drop. The SCOD removal efficiencies were 90%, 81% and 66% at 25℃, 20℃ and 10℃, respectively with about 5㎏ COD/ ㎥/d. volatile acid increased with increasing the organic loading rates and decreasing the temperature. The temperature was more effective than the organic loading rate to volatile acid variation. The clogging of the downflow anaerobic filter was found at high organic loading rate. Anaerobic protozoa was seen throughout the experiment.

양병수 , 안희숙 , 이재관 Byung Soo Yang , Hee Sook An , Jae Kwan Lee

DOI: Vol.8(No.1) 22-30, 1992

A parallel study of an-hybrid reactors with total media volume/total reactor volume ratio of 0.2, 0.5 and 0.8 was carried out under unsteady state start-up conditions. The results show that 20 to 50% media packings in an-hybrid reactors was evaluated to be sufficient to prevent the biological solids from escaping through effluent. It was also found that the hydraulic dead space and plug flow regime in the reactors trended to increase with the increase of packed media volume.

이인선 , 정동일 , 신상철 , 문현생 , 김원덕 , 이길철 In Seon Lee , Dong Il Jung , Sang Chul Shin , Hyun Seng Mun , Won Deok Kim , Kil Chul Lee

DOI: Vol.8(No.1) 31-38, 1992

The study was focused on the investigation of the existing secondary treatment facilities to develop a nutrient removal technology that can be applied to the existing activated sludge treatment facilities with minimum modification of the system. 12 sewage and industrial wastewater treatment plants were investigated to examine the status of the facilities, operation, and the characteristics of both influent and effluent. The nitrogen and phosphorus removal efficiencies from primary treatment in the existing facilities were 14∼42% and 27∼52% respectively, depending upon the overflow rate. The nitrification rate in secondary treatment varied from 4 to 67%, depending upon the SRT. The BOD/TN and BOD/TP ratios in the influent of the sewage treatment plants were 1.0∼3.2 and 10.7∼37.8 respectively. The values are mostly lower than those literatrue values from the biological treatment processes. Nitrification rates were in the range of 4 to 80%. It varied with the STR and little nitrification occurred at the SRT of lower than 3.5 days. The relationship between nitrification rate(Y) and SRT(X) was linearly expressed as Y=6.955 X-24.078(r=0.929). Nitrification was also affected by the F/M ratio. A F/M ratio less than 0.23 was required to have nitrification, and it should to be maintained below 0.08 for an efficiency of more than 40%. The nitrogen and phosphorus removal efficiencies in the aeration tank were 10.5∼21.1 % and 8.0∼33.0% respectively. The values were similar to the theoretical removal efficiencies in a conventional activated sludge process. The TN and TP contents of MLSS were 2.3∼6.6% and 0.9∼1.9% respectively. The removal efficiency(Y) increased with the increase of TP content of sludge(X), and the relationship between the two was Y=21.901X-14.100(r=0.883).

송준상 , 이길철 , 이장훈 , 김원덕 , 이인선 Jun Sang Song , Kil Chul Lee , Jang Whun Lee , Won Deok Kim , In Seon Lee

DOI: Vol.8(No.1) 39-45, 1992

In order to isolate and identify the microbiological strains, which can remove nitrogen, from samples of soil, return sludge of wastewater treatment plants, river water and river sediments and to determine their nitrogen removal activities, this research was performed. The results are summarized as follows: 16 strains which could have denitrification activities were isloated from 36 samples. According to morphological and biochemical results, 14 strains were identified to Pseudomnas sp., and 1 strain to Bacillus sp. and 1 strain to Micrococcus sp.. The strains indentified as Pseudomonas sp., have the high activities of denitrification and degradation of organic compounds, can be used in wastewater treatment plants for the purpose of upgrading the treatment rate. The strians, isloated from this study, grew well at the anoxic state and the average growth rates of cell dry weight per a day were 6.0㎎/ℓ (1st day), 7.0㎎/ℓ (2nd day), l0.0㎎/ℓ (3rd day). Denitrification rates according to incubation day were 40% at Ist day, 60-90% at 2nd day and more than 90% at 3rd day. Removed nitrate nitrogen per cell dry weight was 1.7988gNO₃-N/gMLVSS/day at 1st day, 0.852gNO₃-N/gMLVSS/day at 2nd day, 0.224gNO₃-N/gMLVSS/day at 3rd day. Nitrogen removal activity at 1st and 2nd day was high, but at 3rd day was decreased because of high cell dry weight and low NO₃-N concentration in culture vessel.

전상호 , 홍석균 Sang Ho Jun , Seog Kyun Hong

DOI: Vol.8(No.1) 46-50, 1992

Small scale water purification plants in rural and mountainous areas of Kangweon Province are surveyed in a special reference to the water quality management and safety control. Among the 87 working plants in Kangweon Province, 44 plants have the daily production of less than 1000 ton per plant. They are suffered from the lack of trained persons and equipments for the water quality monitoring and safety control for plant personnel. To establish efficient management system for water quality monitoring and safety control, it is recommended to designate a plant with trained persons and equipments as county water laboratory to support small sized-plants. Water Supply Protection Area across the Province desinated by downstream county to protect the upstream area of the water intake is not so effective in current situation because of short of manpower to manage them and inconvenience of residents of Protection Area.

박중찬 , 안태영 , 하영칠 Joong Chan Park , Tae Young Ahn , Young Chil Hah

DOI: Vol.8(No.1) 51-57, 1992

The effect of salts added to the natural esturine water from the estuary of Naktong river on the glucose turnover rate, respiration rate, and the total populations of the microorganisms were determined. At station 1, the turnover rate for glucose of the microorganisms has decreased up to two days after salt addition. The added salt lost its effect in four days. However, at station 2 and 3, the turnover rates for glucose of the microorganisms were less decreased or even increased with increasing salt concentrations. Again, no differences were noticed in four and seven days at stations 2 and 3, each respectively. The respiration rates showed increasing tendency with increasing salt concentrations at there stations. Added salts caused no noticeable changes in total bacterial numbers and viable counts during the testing period.