Simplified Model for the Class-I Settling Tanks Design

The purpose of this paper is to simplify the original one-dimensional mathematical model that is used to simulate the performance of nonuniform particle sizes in Class-I settling tanks. This paper shows that the modified model is both efficient and economical. The model is capable of providing such information as removal efficiency, particle size distributions in sludge and effluent suspension, and the thickness of bottom sludge. If the desired removal efficiency is provided, a simple equation from the simplified model can be used to calculate the length of the tank. Moreover, the model is quite straightforward and does not require a computer program to obtain results. It deals with only one parameter, the sediment coefficient α, which shows great advantages. Here α is taken as 1.2 for the Class-I settling tanks, however calibration is still recommended. Effluent information, which is important for further treatment units, can be calculated directly from the simplified model. The simplified model is qualitatively reasonable in comparison with other models.