Determining the Optimum Position and Size of Lamella Packet in an Industrial Wastewater Sedimentation Tank: A Computational Fluid Dynamics Study

Hirom, Kirpa; Devi, Thiyam Tamphasana

Determining the Optimum Position and Size of Lamella Packet in an Industrial Wastewater Sedimentation Tank: A Computational Fluid Dynamics Study

2022

Hirom, Kirpa | Devi, Thiyam Tamphasana

A full-scale three-dimensional CFD study is done to determine the optimum position and size of lamella packet for an industrial wastewater sedimentation tank. The Euler–Lagrange method is adopted for this study by utilising the discrete phase model (DPM). Validation of the model is done by comparing the settling efficiency obtained from this study with that of the experimental settling efficiency from a published paper. A huge amount of wall-clock time for the study is saved without compromising on the final result by performing preliminary 2-D simulations before the actual 3-D study. Out of the three positions studied, namely inlet-biased, outlet-biased, and centre-biased, the outlet-biased position is found to be the most effective in improving the settling efficiency of the sedimentation tank. It is also observed that the settling efficiency increases with an increase in the number of inclined plates, but, only up to a certain extent after which there is a rapid fall in the settling efficiency. The total settling efficiency is found to be highest when only 39 inclined plates are installed with an outlet-biased position. Short-circuiting between inlet and outlet is found to be the most prominent problem deterring the complete filling up of the sedimentation tank with inclined plates. ARTICLE HIGHLIGHTS: • The first study about the optimum position of inclined plates. • A comprehensive study on the optimum number of inclined plates using the discrete phase model. • Key findings especially about the paradox of ‘increase in settling efficiency with increase in the settleable area due to addition of incline plates’.

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