• 상하수도학회지
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• 제9권3호
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• pp.116-126
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• 1995

The purpose of this study was to investigate the removal of ammonium nitrogen by biological nitrification in raw water containing LAS using BAC. At batch teats, LAS removal by ozone followed the first order reaction, and the rate constants(k) by ozone dose 1, 3mg/min.L were $0.040min^{-1}$, $0.062min^{-1}$ respectively. Therefore, the more ozone was dosed, the higher LAS was removed The reaction between ozone and ammonium nitrogen also followed the first order, and rate constants(k) at pH7,8 and 9 were $8.9{\times}10^{-4}min-1$, $3.8{\times}10^{-3}min^{-1}$, and $2.9{\times}10^{-2}min^{-1}$ respectively at ozone dose of 3mg/min.L . Therefore, ammonium nitrogen was little removed by ozone under neutral pH of 7. The continuous flow apparatus had four sets composed of a ozone contacter and a GAC column. Through continuous filtration test for 50days, the following conclusions were derived; (1) LAS was removed 23%, 30% respectively by ozone dose 1, 3mg/L, and was not detected in all column effluents during the period of experiment. Therefore, it appeared that adsorption capacities of each column still remained. (2) Ammonium nitrogen concentration after ozone contact varied little in raw Water because pH of raw water was from 6 to 7, and was transfered to nitrite and nitrate within GAC columns as the result of staged nitrification. After 30days, nitrite was not detected in all column effluents due to biological equilbrium between nitro semonas and nitrobacter Average removals of ammonium nitrogen in each column after the lapse of 30days were the following; ${\cdot}$ column A (ozone dose 3mg/L, EBCT 9.5min): about 100% ${\cdot}$ column B (ozone dose 1mg/L, EBCT 9.5min): 91% ${\cdot}$ column C (ozone dose 3mg/L, EBCT 14.2min): about 100% ${\cdot}$ column D (ozone dose 0mg/L, EBCT 9.5min): 53% Though column A and C reached nitrification of about 100%, column C (longer EBCT than column A) was more stable than column A. (3) After backwash, nitrification reached steady state within 5 to 8 hours. Therefore, nitrification was not greatly affected by backwash. (4) According to the nitrification capacity in depth of column A, C, where 100% nitrification occured. LAS was removed within 20cm, while ammonium nitrogen required more depth to be removed by nitrification.

• 한국환경보건학회지
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• 제29권1호
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• pp.74-83
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• 2003

Microcystin, stable compounds with circular heptapeptides, is presented inside cyanobacterial cell. So far, over 30 types have been known to exist and microcystin-LR, RR among them are the most potent toxin compound. By this reason, a strong oxidant, ozone was used in this study to remove the microcystins produced by cyanobacteria. Removal efficiency of microcystin at M water treatment plant was also evaluated. Microcystin concentration was determined by protein phosphatase inhibition assay. The results showed that dissolved microcystin in raw water detected in the range of 0.011-0.028 ㎍ Microcystin-RR equivalent/l. Above 98% of microcystin was removed through overall treatment system. Therefore, the water treatability of M treatment plant seemed to be excellent. Removal efficiency of microcystin according to unit process varied as characteristics of raw water such as DOC, UV/sub 254/ and turbidity. Removal efficiency of microcystin by ozonation was investigated in laboratory according to contact time and ozone dose. Dissolved microcystin was increased by twice fold according to ozone contact time, but increased by fifth fold according to ozone dose. So, changing of ozone dose more affected microcystin release than changing of ozone contact time. Behavior of microcystin by ozonation was similar to that of DOC, and residual ozone concentration gave influence to removal ratio of microcystin. In conclusion, single ozone treatment wasn't effective on microcystin removal in case of water containing a lot of cells. Therefore, it's more effective to use ozonation process after the removal of cyanobacterial cells in advance.

• 상하수도학회지
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• 제31권4호
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• pp.273-279
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• 2017

Optimal processes to remove chromaticity at E water treatment plant(WTP) mainly caused by algae of E lake in Jeju island were investigated based on lab-tests of chlorine and ozone oxidation. 42.9% of chromaticity of filtered water was removed by chlorine oxidation under pH 7.0~8.0, dose of 1.0 mg/L with contact time of 30~60 min. On the other hand, chromaticity removal was 71.4% when post-ozone dose of 0.9~1.9 mg/L and pH 9.0, while it was increased to 86.7% under post-ozone dose of 3.1~7.3 mg/L and pH 9.0. However, there was no significant chromaticity removal efficiency increase when ozone doses were higher than 5.0 mg/L regardless of feeding point(i.e., pre-ozonation and post-ozonation) and pHs(i.e., 7.0 and 9.0.) under the experimental conditions. Based on the results, chlorine oxidation using existing chlorination facilities at the WTP is recommended for lower chromaticity while ozone oxidation is recommended for higher chromaticity by installing new ozone feeding facilities.

• 한국물환경학회지
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• 제20권2호
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• pp.145-150
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• 2004

This study investigated the effect of chlorine dose and chlorine reaction time for the formation of haloacetic acids (HAAs). According to the results, HAA formation was highly affected by chlorine dose and chlorine reaction time. HAA formation reached a plateau value at 30 mg/L of chlorine dose and 24 hr of chlorine reaction time. For the speciation of formed HAAs in the test water, the concentration of brominated-HAAs was significantly lower than that of chlorinated-HAAs because of low level of bromide ion concentration in the test water. It also investigated the removal efficiency of HAA precursors by several unit processes, such as ozone alone, UV alone, and combined ozone/UV system. Of them, ozone/UV system was proved as the best process to control the HAAs formation. The increase of the brominated-HAAs was observed during ozonation with and without UV irradiation showing the slight increase of total HAA concentrations.

• 상하수도학회지
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• 제18권1호
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• pp.59-65
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• 2004

The change of the microbial community structure in excess sludge of different sewage treatment plants by ozone treatment was investigated by quinone profiles. The resulting ozone dosage ranged from 0.1 to $0.4gO_3/gTS$. In terms of overall sludge reduction, more than 50% reduction of the total sludge mass could be achieved by ozone treatment at $0.4gO_3/gTS$. Quinone concentration and type in sludge of different treatment plants were remarkably decreases with increasing ozone dose. Ubiquinones(UQs)-8, -10 and MK-8 were still remained in the ozonized sludge at $0.4gO_3/gTS$. The results of this study showed that the remaining microorganisms belong to UQs-8, -10 and MK-8 were difficult to destruct cell membrane or wall by ozonation. Fecal Streptococci and Salmonella were not detected at ozone dose of $0.2gO_3/gTS$, but Fecal Coliform was not detected at ozone dose of $0.4gO_3/gTS$.

• The Korean Journal of Ecology
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• 제24권2호
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• pp.117-119
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• 2001

Solar ultraviolet-B (UV-B) irradiances incident on a horizontal surface at Taegu, Korea during 1996-1998 were calculated with 5 minute averages of measurements taken every 30 seconds by a broadband UV-B sensor. The average, maximum and minimum of daily UV-B dose were 11.31, 22.04 and 3.20kJ m$^{-2}$ day$^{-1}$ , respectively, for the measuring period. Variations in stratospheric ozone concentration measured from space explain 85% of changes in the daily UV-B dose. It was expected that decrease of 50 Du in stratospheric ozone cause increase of 24.1% in daily UV-B dose in this study.

• Fisheries and Aquatic Sciences
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• 제21권1호
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• pp.2.1-2.8
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• 2018

This study evaluated hemato-histological changes of black porgy in recirculating aquaculture systems (RAS) with three different ozone doses (no ozone, 20 g, and $40g\;ozone/kg\;feed\;day^{-1}$). During the 44-day study, black porgy did not show significant behavior changes or mortalities in both the ozonated systems displaying average total residual oxidants concentrations of 0.12 and 0.25 mg/L. There were no differences in growth and blood parameters among the systems. However, histological alterations on gills and livers were observed in both the treatment systems. In the higher ozone dose, signs of cellular damage were more apparent. Although the ozone doses did not manifest a serious adverse effect on growth and hematological observations in this short-term study, an ozone dose should not exceed $20g\;ozone/kg\;feed\;day^{-1}$ for black porgy based on the histological result. In order to use ozone in a seawater RAS, further studies will be needed to evaluate long-term effects of total residual oxidants.

• 대한환경공학회지
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• 제27권6호
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• pp.663-669
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• 2005

본 연구에서는 정수처리 공정에서 오존을 보다 효율적으로 적용하기 위하여 수중의 오존소비특성을 파악하고자 하였다. 오존의 소비특성을 측정하기 위하여 흐름주입분석법(FIA: Flow injection analysis)의 원리를 이용하여 오존분해속도 측정 자동화장치를 제작하였다. 수중의 오존농도를 연속적으로 측정함으로써 오존의 소비 경향은 순간적으로 오존이 소모되는 구간(I.D: instantaneous ozone demand)과 의사 1차 반응($k_c$: pseudo first-order rate constant)으로 소모되는 두 구간으로 나누어지며, 각 구간에서 오존 주입량에 의하여 영향을 받는 것으로 나타났다. 또한 I.D와 $k_c$값을 이용하여 구한 모델식으로부터 시간에 따른 오존 잔류농도를 예측할 수 있었으며, 예측된 모델간은 실험값과 비교하였을 때 거의 일치하는 것을 알 수 있었다. OH 라디칼의 농도 및 $R_{ct}$는 OH 라디칼 probe compound를 이용하여 간접적으로 계산하였다. I.D와 $k_c$ 구간에서 OH 라디칼 생성 경향을 파악할 수 있었으며, OH 라디칼 생성 또한 오존 주입량에 의하여 영향을 받는다는 것을 확인하였다. 마지막으로 정수처리 공정 및 계절에 따른 수질 차이에 의해서 오존소비인자가 변화하는 것을 확인하였으며, 이에 따라 오존공정의 적절한 도입위치 및 주입량을 효과적으로 결정해야 할 것으로 판단되었다.

• 한국물환경학회지
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• 제34권2호
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• pp.149-156
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• 2018

Oxidation of Ciprofloxacin, Trimethoprim, and Enrofloxacin by ozone was experimentally investigated to observe the effects of background water quality (such as ultrapure water, humic acid, and biologically treated wastewater) and water temperature on the removal rate of these antibiotics, and, thereby, to be able to provide design information when the ozone treatment process is adopted. Initial concentrations of the antibiotics spiked to $10{\mu}g/L$, and the ozone dose was 1, 2, 3, 5, and 8 mg/L. While the removal rate of Ciprofloxacin under ultrapure water background by ozone oxidation was over 99%, the removal rate under humic acid and biologically treated wastewater background was markedly lower, in the range of 49.3% ~ 99% and 19.8 % ~ 99 %, respectively. When water temperature is decreased from $20^{\circ}C$ to $4^{\circ}C$, the removal rate is reduced from the range of 19.8% ~ 99 % to the range of 7.5 % ~ 99 % under a biologically treated wastewater background. The effects of background and temperature on the removal rate of Trimethoprim and Enrofloxacin were similar to that of Ciprofloxacin, but the degree was different. Therefore, it is concluded that the background of water to be treated, as well as water temperature, should be taken into consideration when the design factor, such as ozone dose, is determined, so that the treatment objective of the ozone treatment process can be most effectively met.

• 상하수도학회지
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• 제31권4호
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• pp.347-356
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• 2017

Oxidation of erythromycin, sulfamethazine and sulfathiazole by ozone was experimentally investigated to see the effects of background water quality such as ultrapure water, humic acid and biologically treated wastewater and water temperature on the removal rate, consequently to provide design information when the ozone treatment process is adopted. Initial concentration of the antibiotics was spiked to $10{\mu}g/l$ and ozone dose was 1, 2, 3, 5, 8 mg/l. While the removal rate of erythromycin under ultrapure water background by ozone oxidation was over 99%, that under humic acid and biologically treated wastewater background was markedly reduced to the range of 59.8%~99% and 17.0%~99%, respectively. When water temperature is decreased from $20^{\circ}C$ to $4^{\circ}C$, the removal rate is reduced from the range of 17.0%~99% to the range of 9.4%~97.4% under biologically treated wastewater background. The effects of background and temperature on the removal rate of sulfamethazine and sulfathiazole were similar to erythromycin, but the degree was different. Therefore, it is concluded that the background of water to be treated as well as water temperature should be taken into consideration when the design factor such as ozone dose is determined to meet the treatment objective in the ozone treatment process.