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