Redesign and start up operation a bioreactor at pilot plant scale for solid-state fermentation processes

A stainless steel bioreactor was redesigned in order to facilitate the production of microbial protein by solid-state fermentation. A double-helix stirrer was built to replace a blade-stirrer. Mixing time was set at 12 min every two hours. An air-manifold was built and installed at the bottom of the reactor. It allowed uniform bubbling in the water reservoir, providing a continuous flow of saturated air through the biomass. The intermittent mixing provided it a uniform substrate with minimum damage to the mycelial biomass. Along with the saturated air, allowed removal of the metabolic heat produced and prevented formation of dead zones in the biomass. A fermentation with Trichoderma reesei QM 9414 on water-treated sugar cane bagasse was carried out to test the operation of the bioreactor. The fermented product reached 7% crude protein at 48 h. A maximum of 10.96% was reached at 96h. This value was much higher than the laboratory value, confirming that the design allows a more efficient fermentation process.