This study was performed to investigate the seasonal removal rate of indicator microorganism, such as the Total Coliforms, the Heterotrophic bacteria, and the Fecal Coliforms, by chlorine disinfection. In this study, the samples were taken from the final sedimentation basin of the Daejeon Municipal ...
This study was performed to investigate the seasonal removal rate of indicator microorganism, such as the Total Coliforms, the Heterotrophic bacteria, and the Fecal Coliforms, by chlorine disinfection. In this study, the samples were taken from the final sedimentation basin of the Daejeon Municipal Wastewater Treatment Facility. Also, the optimum disinfection strategy was suggested to satisfy the disinfection standard that will be enforced from year 2003. 1. Typical concentrations of indicator microorganisms in the influent sewage was in the range of 30×10^(4)∼77×10^(4) CFU/㎖ for the Total Coliforms, 70×10^(5)-78×10^(5) CFU/㎖ for the Heterotrophic bacteria, and 24×10^(6)∼43×10^(6) CFU/㎖ for the Fecal Coliforms. 2. The level of microorganisms detected at the effluent from the final sedimentation basin was 195-4,200 CFU/㎖ for the Total Coliforms and 5,000 -79,400 CFU/㎖ for the Heterotrophic bacteria. The maximum concentration of the Fecal Coliforms was 46,000 MPN/100㎖, but sometimes the Fecal Coliforms was not detected. 3. When the chlorine dose was low, the removal rate of Total Coliforms during winter season was lower than those for other seasons. But, there was no temperature effect when the chlorine dose was high enough or the contact time was longer than a certain limit. In case of Total Coliforms, the disinfection time required to obtain more than 99% of averaged removal rate was 1 min at 2.0 mg/ℓ, 5 min at 1.0 mg/ℓ, and 10 min at 0.8 mg/㎖, respectively. 4. During spring and summer, the disinfection time required to remove the Heterotrophic bacteria more than 90% was 10min at 1.0mg/ℓ chlorine concentration and lmin at 2.Omg/ℓ, respectively. And during winter season, the required disinfection time was 20min at 1.0mg/ℓ and 5min at 2.0mg/ℓ. But, the removal rate was more than 90% when 30 min was allowed for the contact time, regardless of the chlorine dose between 1.0 and 2.0mg/ℓ. Thus, the effects of both temperature and chlorine dose decreased with increasing disinfection time. Also, it was found that the contact time required to inactivate the Heterotrophic bacteria more than 95% was 20 min at 2.0mg/ℓ, 30min at 1.0mg/ℓ, and longer than 30min at 0.8 mg/ℓ, respectively. 5. Comparison of required disinfection conditions revealed that the Heterotrophic bacteria needed a longer contact time than the Total Colifonns when the chlorine dose was same. 6. The disinfection reaction constant(K') for both the Total Coliforms and Heterotrophic bacteria was proportionate to the concentration of chlorine. The disinfection reaction constant(K') for the Total Coliforms was higher than that of the Heterotrophic bacteria. 7. It was not required to disinfect the treated wastewater because averaged value of Total Coliforms was less than 3,000 CFU/㎖, which is the proposed discharge standard for the existing model plant, for all seasons. However, if the clean area standard for Total Coliforms(> 1,000 CFU/㎖) is applied to the model plant, it is required to add 0.8mg/ℓ of chlorine during spring and 0.3mg/ℓ during summer and autumn, respectively, under the present T_(10) value of baffled chlorine contactor in the model plant. But, in case of winter, it was not needed to disinfect because the averaged value of Total Coliforms was merely about 900 CFU/㎖.
This study was performed to investigate the seasonal removal rate of indicator microorganism, such as the Total Coliforms, the Heterotrophic bacteria, and the Fecal Coliforms, by chlorine disinfection. In this study, the samples were taken from the final sedimentation basin of the Daejeon Municipal Wastewater Treatment Facility. Also, the optimum disinfection strategy was suggested to satisfy the disinfection standard that will be enforced from year 2003. 1. Typical concentrations of indicator microorganisms in the influent sewage was in the range of 30×10^(4)∼77×10^(4) CFU/㎖ for the Total Coliforms, 70×10^(5)-78×10^(5) CFU/㎖ for the Heterotrophic bacteria, and 24×10^(6)∼43×10^(6) CFU/㎖ for the Fecal Coliforms. 2. The level of microorganisms detected at the effluent from the final sedimentation basin was 195-4,200 CFU/㎖ for the Total Coliforms and 5,000 -79,400 CFU/㎖ for the Heterotrophic bacteria. The maximum concentration of the Fecal Coliforms was 46,000 MPN/100㎖, but sometimes the Fecal Coliforms was not detected. 3. When the chlorine dose was low, the removal rate of Total Coliforms during winter season was lower than those for other seasons. But, there was no temperature effect when the chlorine dose was high enough or the contact time was longer than a certain limit. In case of Total Coliforms, the disinfection time required to obtain more than 99% of averaged removal rate was 1 min at 2.0 mg/ℓ, 5 min at 1.0 mg/ℓ, and 10 min at 0.8 mg/㎖, respectively. 4. During spring and summer, the disinfection time required to remove the Heterotrophic bacteria more than 90% was 10min at 1.0mg/ℓ chlorine concentration and lmin at 2.Omg/ℓ, respectively. And during winter season, the required disinfection time was 20min at 1.0mg/ℓ and 5min at 2.0mg/ℓ. But, the removal rate was more than 90% when 30 min was allowed for the contact time, regardless of the chlorine dose between 1.0 and 2.0mg/ℓ. Thus, the effects of both temperature and chlorine dose decreased with increasing disinfection time. Also, it was found that the contact time required to inactivate the Heterotrophic bacteria more than 95% was 20 min at 2.0mg/ℓ, 30min at 1.0mg/ℓ, and longer than 30min at 0.8 mg/ℓ, respectively. 5. Comparison of required disinfection conditions revealed that the Heterotrophic bacteria needed a longer contact time than the Total Colifonns when the chlorine dose was same. 6. The disinfection reaction constant(K') for both the Total Coliforms and Heterotrophic bacteria was proportionate to the concentration of chlorine. The disinfection reaction constant(K') for the Total Coliforms was higher than that of the Heterotrophic bacteria. 7. It was not required to disinfect the treated wastewater because averaged value of Total Coliforms was less than 3,000 CFU/㎖, which is the proposed discharge standard for the existing model plant, for all seasons. However, if the clean area standard for Total Coliforms(> 1,000 CFU/㎖) is applied to the model plant, it is required to add 0.8mg/ℓ of chlorine during spring and 0.3mg/ℓ during summer and autumn, respectively, under the present T_(10) value of baffled chlorine contactor in the model plant. But, in case of winter, it was not needed to disinfect because the averaged value of Total Coliforms was merely about 900 CFU/㎖.
주제어
#하수처리장방류수 지표미생물 염소소독 환경공학
※ AI-Helper는 부적절한 답변을 할 수 있습니다.