How to manipulate this equation so that it suits a 2nd order equation

Amount of solid holdup ( Wcat) Wcat=koveralluflpQf(1mf)ubrln(CACA0) Wcat is the amount of catalyst or solid holdup p is the density of the catalyst or particle mf is the bed voidage at minimum fluidisation ubr is the bubble rise velocity koverall is the overall rate constant ufl is the velocity under fluidised conditions CA0,CA are the initial and final concentrations respectively Lfl is the depth of the bed under fluidised conditions ub is the bubble velocity Qf is the fluid flowrate