A finite velocity simulation of sedimentation behaviour of flocculating particles – A real-time model evaluation

Abstract

A mechanistic velocity model is developed to simulate the behaviour of flocculating colloidal particles in turbid water. The current model is based on one-dimensional mass transport in the vertical direction as an integrated form of the model derived by Ramatsoma and Chirwa. The percentile removal model achieved more accurate simulation of physical experimental data than known models such as the Ozer's model and San's model. In this study, an integrated velocity form was used to estimate flocculent settling velocity of fine suspended particles under near quiescent conditions. Model closeness to experimental measurements was determined as a function of the sum of squares error (SSE) between model data and experimental data. The proposed velocity model offers a distinctive advantage over the interpolated-isopercentile based models which are prone to numerical errors during interpolation. The results contribute towards the ultimate goal of achieving full automation of the design of gravitational particle separation devices for water and wastewater treatment.

Analysis of the goodness of fit of the San model for the calculation of the removal percentage of flocculent particles with low initial turbidity values in the problem water

“…In the first case: [10] present an integrated velocity form to estimate flocculent settling velocity of fine suspend particles, the proposed velocity models offer an advantage over other interpolated-isopercentile models which are prone to numerical errors during interpolation. [22] present a simple approach for estimating the flocculent settling velocity of fine suspended particles, the empirical flocculating equation is expressed as a function of time, depth and others constants.…”

“…This method has been adapted and modified by different authors, until a graphical integration methodology is obtained, which contemplates the experimental data to calculate the total removal [4]. If it is taken into account that the construction of isoconcentration curves is a tedious, inaccurate process, susceptible to human error and that it may have problems when reproducing them [5], different authors have developed mathematical equations in order to eliminate these problems: [6][7][8][9][10], and others have used two-dimensions transport models and computational fluid dynamics (CFD) for simulate the settling process and improve tank efficiency [11][12][13].…”

“…Previous studies on this topic, coincide in using for their experiments, initial turbidity values in the problem water above 100 NTU [4,5,[10][11][12]. Turbidity values in these ranges are characteristic of waters with medium and high levels of turbidity.…”