The biomass pulse-response method was established and the biomass transmission index was introduced as a quantitative parameter for evaluating the biomass-adsorbent interactions in the expanded bed.With baker’s yeast intact cells and cell debris as the model biomass and anion exchanger Streamline DEAE as the model adsorbent, a series of factors were investigated to optimize the evaluation method.The appropriate operation conditions were chosen as the OD 600 of biomass pulse at the range of 0.5—0.6, and pulse loading at 80% volume of sedimented bed, expansion factor at 2.5.The method was then used to study the influence of ionic strength of fluid phase on the biomass-adsorbent interactions.The consistent results and slight measurement errors demonstrated that the biomass pulse-response method established in the present work is feasible, reliable and effective for quantitative evaluation of biomass-adsorbent interactions in the expanded bed.
Expanded bed adsorption (EBA) has been widely used in industrial downstream bioprocessing. Solid matrix is the principal pillar supporting the successful application of EBA. A novel spherical cellulose-titanium dioxide composite matrix was prepared through the method of water-in-oil suspension thermal regeneration. Its typical physical properties were wet density 1.18g.cm-3, diameters in the range of 100-300um, porosity 85.5%, and water content 72.3%. Expansion characteristics and liquid mixing performance of the matrix in expanded bed were investigated using water and 10% (by mass) glycerol solution as mobile phases. The results indicate that the custom-assembled matrix has a stable flow hydrodynamics and exhibits the same degree of liquid-phase mixing or column efficiency as the commercially available Streamline adsorbent.
