The wastewater inflow to an activated sludge plant is $0.5\ \text{m^3/\text{s}$, and the plant is to be operated with a food to microorganism ratio of $0.2\ \text{mg/mg-d}$. The concentration of influent biodegradable organic matter (after primary settling) is $150\ \text{mg/L}$, and the mixed liquor volatile suspended solids (MLVSS) to be maintained is $2000\ \text{mg/L}$. Assuming complete removal of biodegradable organics in the tank, the volume of aeration tank (in m$^3$, integer) required is \underline{\hspace{2cm}}.}