Growth of an organism on glucose in a chemostat is characterized by Monod model with specific growth rate = $0.45 \:h^{-1}$ and $K_{s}= 0.5 \:g/L$. Biomass from the substrate is generated as $Y_{XS}=0.4 \:g/g$. The chemostat volume is $0.9\:L$ and media is fed at $1\:L/h$ and contains $20 \:g/L$ of glucose. At steady state, the concentration of biomass in the chemostat is _________________ $g/L$.