[학위논문]Evaluation on the inhibitory effect of silica nanoparticle on the oxygen uptake rate of activated sludge : 실리카 나노입자에 의한 활성슬러지 산소 호흡률 변화 관측 및 위해성 평가원문보기
Most sewage and waste water treatment processes use biological processes based on activated sludge. With the growing production of nanomaterials recently, it is highly likely that nanomaterials are flown into waste water treatment process by being included in general sewage and waste water. Thus, th...
Most sewage and waste water treatment processes use biological processes based on activated sludge. With the growing production of nanomaterials recently, it is highly likely that nanomaterials are flown into waste water treatment process by being included in general sewage and waste water. Thus, there is a growing interest in the impact of nanoparticles on the biological behavior of general activated sludge and many of related studies are being conducted. Previous studies mainly focused on the inhibition on the metabolic activity of microorganism when nanoparticles such as TiO2, Al2O3 and ZnO are dissociated into ionic materials in water. Meanwhile, there are not many studies on the impact of nanoparticles that exist in particulate form not ionic form like silica particles. Therefore, this study measured Oxygen Uptake Rate (OUR) of activated sludge to examine the effect of SiO2 nanoparticles (SNPs) on the biological activity of activated sludge. In other words, this study aimed to observe the change of OUR by concentration and size of SNPs and calculate inhibition based on the this. In batch experiment, the size of SNPs was set as 10-15nm, 45-50nm and 70-100nm whereas the concentration was set as 100, 500 and 1,000ppm. In general, SNPs exerted less effect on the OUR of activated sludge compared to silver nanoparticles, CuSO4 and 3,5-DCP. However, only 70-100nm SNPs showed the same tendency about inhibition whereas 10-15nm and 45-50nm SNPs only confirmed that they have an inhibition effect. That is, the study confirmed that SNPs have an inhibition effect on activated sludge but it was not discovered quantitatively. In continuous experiment, the size of SNPs was set as 10-15nm and 70-100nm and the concentration was set as 100ppm. MBR reactor was operated by classifying filamentous into 2 cases of dominant species and non-dominant species. In addition, control reactor was operated to measure OUR experiment result in comparison with reactors with the injection of 10-15nm and 70-100nm SNPs. In both cases where filamentous were dominant species and not so, inhibition effect was higher in 70-100nm SNPs than in 10-15nm SNPs. Moreover, in 70-100nm SNPs, inhibition effect was higher when filamentous were non-dominant species. All of 10-15nm SNPs escaped through separation membrane after HRT 6 hours whereas 70-100nm SNPs could not escape through separation membrane. Instead, the latter was gradually accumulated in reactor for 20 days according to SRT 20 days and the concentration of nanoparticles in reactor increased, which supposedly increased inhibition effect gradually. This experiment is believed to be essential in the future as well since the efficiency of water treatment technology can be influenced by the inhibition effect of SNPs on activated sludge.
Most sewage and waste water treatment processes use biological processes based on activated sludge. With the growing production of nanomaterials recently, it is highly likely that nanomaterials are flown into waste water treatment process by being included in general sewage and waste water. Thus, there is a growing interest in the impact of nanoparticles on the biological behavior of general activated sludge and many of related studies are being conducted. Previous studies mainly focused on the inhibition on the metabolic activity of microorganism when nanoparticles such as TiO2, Al2O3 and ZnO are dissociated into ionic materials in water. Meanwhile, there are not many studies on the impact of nanoparticles that exist in particulate form not ionic form like silica particles. Therefore, this study measured Oxygen Uptake Rate (OUR) of activated sludge to examine the effect of SiO2 nanoparticles (SNPs) on the biological activity of activated sludge. In other words, this study aimed to observe the change of OUR by concentration and size of SNPs and calculate inhibition based on the this. In batch experiment, the size of SNPs was set as 10-15nm, 45-50nm and 70-100nm whereas the concentration was set as 100, 500 and 1,000ppm. In general, SNPs exerted less effect on the OUR of activated sludge compared to silver nanoparticles, CuSO4 and 3,5-DCP. However, only 70-100nm SNPs showed the same tendency about inhibition whereas 10-15nm and 45-50nm SNPs only confirmed that they have an inhibition effect. That is, the study confirmed that SNPs have an inhibition effect on activated sludge but it was not discovered quantitatively. In continuous experiment, the size of SNPs was set as 10-15nm and 70-100nm and the concentration was set as 100ppm. MBR reactor was operated by classifying filamentous into 2 cases of dominant species and non-dominant species. In addition, control reactor was operated to measure OUR experiment result in comparison with reactors with the injection of 10-15nm and 70-100nm SNPs. In both cases where filamentous were dominant species and not so, inhibition effect was higher in 70-100nm SNPs than in 10-15nm SNPs. Moreover, in 70-100nm SNPs, inhibition effect was higher when filamentous were non-dominant species. All of 10-15nm SNPs escaped through separation membrane after HRT 6 hours whereas 70-100nm SNPs could not escape through separation membrane. Instead, the latter was gradually accumulated in reactor for 20 days according to SRT 20 days and the concentration of nanoparticles in reactor increased, which supposedly increased inhibition effect gradually. This experiment is believed to be essential in the future as well since the efficiency of water treatment technology can be influenced by the inhibition effect of SNPs on activated sludge.
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