A Theory of Diatomite Filtration

Abstract

This article discusses an equation that expresses the filtration of an iron‐bearing water under normal conditions of body feed, iron concentration, and filtration rate. The equation has been verified in the laboratory in the removal of 2 to 8 ppm of iron from water at a filtration rate of 1 gpm/sq ft. Runs to evaluate applicability of the equation at higher flow rates are now being made.

Hydraulic and Particle Size Characteristics of Some Diatomite Filter Aids

“…coefficients in the recently developed diatomite filtration equation 1, 2 : H = K3QW, + K.CDQ 2 t x 8i~~ (1) in which H is the total head loss through the filter cake in feet ; CD is the concentration of body feed in parts per million; K; is the impermeability coefficient for clean precoat in min-ftf/lb-gal : K4 is the impermeability coefficient for the body feed layer in min-It" jIb-gal; Q is the rate of flow in gallons per minute per square foot; t is the time of filtration in minutes; and W1 is the weight of precoat in pounds per square foot. When clean water is passed through a precoat layer of filter aid with no body feed layer present, the equation is:…”

Constant‐Rate and Constant‐Pressure Filtration Look Similar—But Are They?

“…For constant-pressure filtration, From Eq (2), and also for constantpressure filtration, dt/dV V + nRf/AP (3) where R' = specific resistance of the cake on the basis of the unit weight of the filter aid in the cake [LF-1 (length/ force)] A = area of the filter cake [L2] t = time of filtration P = pressure loss across the cake or the total driving force if the septum and the…”

Modified Form of Diatomite Filtration Equation

“…In Ruth's equation, IS A(1-ms) equal to W/s. If Eq 2 is rewritten in the terms of the diatomite filtration equation, and if viscosity is represented by f.k in centipoises, then H _ (2.10 X 10-5 ) tux _ -(60) (7.48)' gd QW -6.26 X 10....~QW (3). …”