Determination of the hindered settling factor for flocculated suspensions

The determination of the settling velocity of particles in suspension is a difficult problem due to the complexity of the indirect particle–particle interactions. Formally, a function called the hindred settling factor r (ϕ), which is a function of the solids volume fraction ϕ, is introduced to take into account the increase in the drag forces. The current method for estimating this function is to measure the initial fall rate of the suspension in a batch sedimentation experiment. Here, we propose a steady‐state experiment for flocculated suspensions using vacuum filtration, where the fixed bed height is measured as a function of the liquid flow rate through a porous membrane. Recovering the function r (ϕ) or a related function D (ϕ) involves numerical differentiation of the data. This experiment will also yield the membrane permeability as a function of volume fraction (in cases where clogging or fouling of the membrane occurs). The results using numerically simulated data show good recovery of the assumed r (ϕ) function.