A fine aqueous suspension containing $1 \mathrm{lb}_{\mathrm{m}}$ of solids per $\mathrm{ft}^{3}$ of suspension is to be filtered in a constant pressure filter. It is desired to filter at an average rate of $100 \mathrm{gpm}$, and the filter cake must be removed when it gets $2 \mathrm{in}$. thick. What filter area is required? Data: $\Delta P=10 \mathrm{psi}$, $ho($ wet cake $)=85 \mathrm{lb}_{\mathrm{m}} / \mathrm{ft}^{3}, K$ (permeability) $=0.118$ darcies, $a=2 \times 10^{9} \mathrm{ft}^{-1}$