• Membrane and Water Treatment
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• 제10권6호
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• pp.395-404
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• 2019

The influence of chlorine on marine bacterial communities was examined in this study. A non-chlorine-adapted marine bacterial community (NCAM) and a chlorine-adapted bacterial community (CAM, bacterial community treated with $0.2mg-Cl_2/L$ chlorine) were cultivated for 1 month. A distinct difference was observed between the NCAM and CAM, which shared only eight operational taxonomic units (OTUs), corresponding to 13.1% of the total number of identified OTUs. This result suggested that chlorine was responsible for the changes in the marine bacterial communities. Kordiimonas aquimaris was found to be a chlorine-resistant marine bacterium. The effect of intermittent chlorination on the two marine biofilm communities formed on the reverse osmosis (RO) membrane surface was investigated using various chlorine concentrations (0, 0.2, 0.4, 0.6 and 0.8 mg $Cl_2/L$). Although the average number of adherent marine bacteria on the RO membrane over a period of 7 weeks decreased with increasing chlorine concentration, disinfection efficiencies showed substantial fluctuations throughout the experiment. This is due to chlorine depletion that occurs during intermittent chlorination. These results suggest that intermittent chlorination is not an effective disinfection strategy to control biofilm formation.

• 한국물환경학회지
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• 제16권4호
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• pp.513-521
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• 2000

Intermittently aerated activated sludge process was applied as a water reuse process of $70m^3/day$ for the upgrade of organic, nitrogen and phosphorus removal efficiency and clarifier performance. After application of the intermittently aeration, removal efficiency of BOD, SS, T-N and T-P were achieved 95%, 90%, 80% and 60%, respectively. Removal efficiencies in intermittently aerated process were considerably increased. comparing to those of continuously aerated activated sludge process. Also sludge rising problem in clarifier was improved. Average concentration of supplied reusing water were BOD 5 mg/L, turbidity 4 NTU and after chlorination, residual chlorine 0.4 mg/L, coliform 0 MPN/100mL. Intermittently aerated activated sludge process could be one of the best alternative process for the retrofit of conventional activated sludge process for the removal of nutrient in water reuse system.

• 한국어병학회지
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• 제16권2호
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• pp.91-102
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• 2003

The present study was investigated the effects of chlorine dioxide ($CIO_2$) on the rcspimtory metabolism of olive flounder (Parolichlhys olivaceus) imtermittently exposed to seawater chlorinated by $CIO_2$:. Oxygen consumption of flounder before and after once or twice $CIO_2$-treatment with 12 hr- or/and 24 hr-interval were serially measured with automatic intenniteent-flow respirometer system (AIRS). The oxygen consumption rates of flowKier exposed to 0.10 and 0.20 ppm$CIO_2$, were not different from the control fish prior to the once or twice chlorinations . On the other hand, the respiratory metabolic rates of flounder exposed to 0.30 ppm$CIO_2$ were significantly increased 15% and 22 - 23% after the once and twice chlorinations compared to the control fish. respectively. The flounder exposed In 0.40 and 0.50 ppm$CIO_2$: died within 4 hr and I hr. respectively. The elevation( respiratory metabolism in flounder exposed toO.30 ppm$CIO_2$ and above is considered due to physiological stress caused by $CIO_2$ exposure.