Optimal Operating Points for SCP Production in the U-Loop Reactor

The microorganism Methylococcus capsulatus can grow on cheap carbon sources such as methane and methanol. M. capsulatus has a protein content of approximately 70% and can be used for production of so-called Single Cell Protein (SCP). Static simulations of SCP production using Methylococcus capsulatus in an U-loop reactor have been used to determine the optimal operation. The optimal operating point is located close to both washout and oxygen limitation. With oxygen being the most expensive reactant, the U-Loop reactor is operated in the oxygen limited mode and substrate feed is controlled according to the oxygen feed. The maximum oxygen feed is determined by the maximum biomass concentration that can be tolerated in the reactor. Higher biomass concentration is believed to give a more viscous fluid that requires more pumping energy for circulation in the U-loop and has a lower gas-liquid oxygen transfer rate. The optimal dilution rate is relative constant around 0.2 1/hr. This operating strategy gives the highest SCP productivity.