Abstract

AbstractOxygen transfer capacity has greatest influence on activated sludge performance. Inthis study, experimental procedure is carried out to determine the effect of airflow rate and thelevel of diffusers submergence, on the oxygen transfer rate of diffused air systems. In addition,a number of readings were also collected from published papers. The data were selected tocover various scales of plants and operating conditions. After sorting out, all data were treatedand then combined to the experimental readings in order to expand the applicability of theresults. Individual mathematical models to describe the effect of each parameter were alsoderived. The results of the study showed that, increasing the airflow rate at fixed water depthand diffusers submergence enlarge the oxygenation capacity of the system. The equation, whichcontrols this relationship, is linear. At diffusers submergence of 4.6 m, the slope of the equationwas 11.8. With reduce the depth of diffusers to about 0.4 m; the slope of equation was decreaseto 2.3. At constant airflow rate, the depth of diffusers has a significant effect on both of theoxygenation capacity and oxygen transfer efficiency of the system. Exponentional form ofequation is shown to be efficient in expressing the relationship between the submergence andthe oxygenation capacity. At 0.4 m, diffusers submergence, the oxygen transfer efficiency was1.8 whereas; this value is rising to about 11.5 at 4.6m submergence.Keywords :Oxygen transfer capacity, diffused aeration, airflow rate, diffusers submergence, KLa

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The article was added to IASJ on 2012-06-24

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