Modeling for Class‐I Sedimentation

Abstract

The design of class‐I (discrete particles) settling tanks would be more rational and economical if designed for overall particle removal rather than for an overflow rate based on the smallest particle to be removed. The overall percentage removals of discrete particles corresponding to different overflow rates were evaluated for several sets of samples having different sieve‐analysis parameters (different combinations of the effective size and the nonuniformity coefficients). A predictive model has been developed for evaluating the overall percentage removal from sieve‐analysis parameters, such as the effective size and the nonuniformity coefficient of the discrete particles present in the influent. Such a model can be used for a rational fixing of the design overflow rate to provide the desired overall percentage removal of the particles of a given size distribution. The experimentally observed data of several other researchers are found to be in total agreement with the values predicted from the writer's model. This justifies the robustness of the presented model.