A continuous-flow, completely mixed without biomass recycle, biological treatment process with a flow rate of 1,000 m3/day and an influent…

A continuous-flow, completely mixed without biomass recycle, biological treatment process with a flow rate of 1,000 m3/day and an influent substrate concentration (So) of 1,000 mg/L achieves 99% substrate removal. The observed yield coefficient (Yobs) is 0.20 g biomass/g substrate and the hydraulic (θ) and solids retention
time (θc) is 20 days.
a) For the above-listed conditions, calculate the bioreactor biomass concentration (mg/L) and the bioreactor volume (L).
b) An equivalent biological process, but with biomass recycle, achieves the same substrate removal and observed yield coefficient as stated above, has a solids retention time (θc) equal to the retention time calculated in (a) above, and a bioreactor biomass concentration equal to 7,920 mg/L. Calculate the bioreactor
volume (L) for this system and compare it with the volume of the system without biomass recycle calculated in (a) above.