Flocculant Screening Method at Lab Scale for Application in Disc Stack Centrifuges with Hermetic Design

Abstract

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 Solids Phase in Biomass Processes of Disc‐Stack Centrifuges

“…If the particles are shear‐sensitive and if high shear forces act in the centrifuge inlet, solids may break, causing smaller particles, lower settling speeds, and reduced centrifuge capacity. The effect of shear forces, mimicking the inlet of a high‐speed centrifuge, may thus be investigated in a spinning disc device, further described by Merkel et al …”

“…Measurement of settling speed and angle of repose of bacteria γ ‐amino butyric acid (GABA) together with coagulants and polyelectrolytes for increasing of agglomerate size is already described in Merkel et al . In this paper, some other biological solids from food and life science sectors have been compared to GABA and GABA flocculated with the polyelectrolyte Zetag 7587.…”

Turbulent Shear and Breakup of Flocculated Biomaterial in Centrifuge Inlets

“…demonstrates the laser diffraction measurements of the flocculated bacteria suspension processed through the SDD at various shear rates. Details on these measurements can be found in . The median diameter of the distributions treated at 5000 and 10 000 rpm were used together with the ε avg in Eq.…”

“…Laser diffraction measurements of bacteria flocs subjected to shear in the SDD at disc speeds of 0, 5000, and 10 000 rpm. Data from .…”

“…Particle size distributions before and after the SDD were measured by laser diffraction with an inline Malvern Mastersizer 3000 (Malvern Instruments Ltd, UK). For further details on the experiments see Merkel et al .…”