Application of computational fluid dynamics in an outer channel of orbal biological system
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Date
2019-06
Authors
Nurzulaikha Binti Mohd Kamal
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Abstract
Orbal Biological System (OBS) is one of the modified oxidation ditches which claimed
as the most energy efficient, safest and has the lowest maintenance. The OBS can be
easily modified to meet wide assortment of influent conditions and effluent requirements.
There are three channels in OBS, outer channel, middle channel and inner channel. The
outer channel of OBS has the largest volume among the three channels, which is about
50% of the total volume of the system. It is crucial to study the operating system of the
outer channel of OBS as it contribute to the highest energy consumption in the system.
This is because in the wastewater treatment system nowadays, the quality standards of
the effluent are not only the criteria to be focused on, but other aspects such as economic
also are taken as considerations. Therefore, the study was conducted to understand the
function and the effect of the number of aeration discs in the outer channel of the OBS.
The Computational Fluid Dynamics (CFD) model is developed to have a better picture
of the OBS. The simulation in CFD were used to study the behaviour of the influent in
the outer channel of OBS and the velocity distribution for different operating conditions
in the outer channel of OBS. The result of the CFD model were used to study the
relationship between the velocity and the number of aeration discs being used. Based on
the study, by turning off some shaft in the outer channel of OBS was contributing to less
energy consumption. From the research, the average deviation for the CFD model is 23%,
which need improvement in grid generation. The research provides a better
understanding of model flow behaviour of a biological treatment system using the
simulation tool. It can contribute to a better design of wastewater treatment process
models in the future.