A fed batch process is running at quasi-steady state with respect to substrate and biomass concentration. At $2 \mathrm{~h}$, the culture volume is $500 \mathrm{~L}$ with a constant sterile inlet feed at $50 \mathrm{~L} \mathrm{~h}^{-1}$ of glucose. The culture kinetic parameters $\mu_m$ and $K_S$ are $0.2 \mathrm{~h}^{-1}$ and $0.1 \mathrm{~g} \mathrm{~L}^{-1}$, respectively.
The substrate concentration in the reactor will be $\_\_\_\_\_\_\_\_$ $\mathrm{g} \mathrm{L}^{-1}$ (rounded off to one decimal place).