A slurry is to be filtered with a rotary drum filter that is $5 \mathrm{ft}$ in diameter, $8 \mathrm{ft}$ long, rotates once every $10 \mathrm{~s}$ and has $20 %$ of its surface immersed in the slurry. The drum operates with a vacuum of $20 \mathrm{in}$. Hg. A lab test was run on a sample of the slurry using $1 / 4 \mathrm{ft}^{2}$ of the filter medium at a constant flow rate of $40 \mathrm{~cm}^{3} / \mathrm{s}$. After $20 \mathrm{~s}$, the pressure drop was $30 \mathrm{psi}$ across the lab filter, and after $40 \mathrm{~s}$, it was 35 psi. How many gallons of the filtrate can be filtered per day in the rotary drum?