Chemicals produced using biotechnological methods like fermentation processes are obtained as complex diluted aqueous mixture, which still contains the production organism. Centrifugation is a commonly used technology for biomass separation. By flocculation, the settling velocity of microorganisms can be increased. Here, a laboratory flocculant screening method tailored for the separation of flocculated biomass in a fully hermetic disc stack centrifuge is described. The specific requirements of this process, namely, floc formation, floc stability, sliding behavior in the disc stack, and flowability of the sludge, were transferred to lab scale and validated in pilot tests. The qualitative results of the laboratory screening were in agreement with the processes at industrial scale.

Rheological characterization of the solids phase in bio‐industry disc‐stack centrifuges is considered. Three discriminatory properties of the solids phase are investigated, namely, the particle settling velocity, the angle of repose, and the solids phase viscosity. The solids phase produced in disc‐stack centrifuges in the food or biopharmaceutical industry possesses both liquid‐like and solid‐like properties which can be quantified by means of these test methods. The resulting rheological characterization can be used for diagnostic purposes in the selection process of industrial centrifuges and for optimization of centrifuge solids handling in biomass processing of suspension systems.

No abstract