Phenolic wastewater discharged from an industry was treated with Pseudomonas $sp$. in an aerobic bioreactor. The influent and effluent concentrations of phenol were $10,000$ and $10\:ppm$, respectively. The inlet feed rate of wastewater was $80\:L\:h^{-1}$. The kinetic properties of the organism are as follows:

Maximum specific growth rate $\left ( \mu _{m} \right )=1\:h^{-1}$

Saturation constant $\left ( K_{S} \right )=100\:mg\:L^{-1}$

Cell death rate $\left ( k_{d} \right )=0.01\:h^{-1}$

Assuming that the bioreactor operates under 'chemostat' mode, the working volume require for this process is _____________ $L$ (rounded off to the nearest integer).