An aqueous acetic acid solution flows at the rate of $1000 \mathrm{~kg} / \mathrm{h}$. The solution is $1.1 \mathrm{wt} \%$ acetic acid. It is desired to reduce the concentration of this solution to $0.037 \mathrm{wt} \%$ acetic acid by extraction with 3 -heptanol at $298 \mathrm{~K}$. For practical purposes, water and 3-heptanol are immiscible. The inlet 3-heptanol contains $0.02 \mathrm{wt} \%$ acetic acid. An extraction column is available which is equivalent to a countercurrent cascade of 35 equilibrium stages. What solvent flow rate is required? Calculate the composition of the solvent phase leaving the column. For this system and range of concentrations, equilibrium is given by (Wankat, 1988): wt ratio acetic acid in solvent $=0.828 \times$ wt ratio acetic acid in water.