Evaluation of a Semi-Continuous Disk-Stack Centrifuge for the Harvest of Tsukamurella Paurometabola C-924 Bacterium

The disk stack centrifuge is an equipment widely used in the current biotechnological industry because of the multiple advantages it offers, the most important being its high operational flexibility, robustness, and processing speed. The objective of this research was to evaluate whether a semi-continuous disk stack centrifuge can be used to harvest Tsukamurella paurometabola strain C-924 cells, the active ingredient of the ecological bionematicide HeberNem®, to replace the tubular centrifuges currently used. The methodology used consisted of the development of a type 23 factorial statistical design, in which three input parameters were considered: feed rate [Qalim], wet weight of the diluted cell suspension to be centrifuged [PHalim], and time between discharges [tdesc]. The output parameters considered were wet weight of concentrated biomass [PHbio] and recovery percentage [ %Rec], which must have values greater than 600 g/L and 95 %, respectively, to obtain a corresponding final yield with the quality standards established for this biotechnological product. The results obtained were that the average values for PHbio and %Rec were 657.28 g/L and 97.43 %, respectively, which met the quality standards for this stage. The experimental design was optimized to determine the optimal values for the three input parameters, thus obtaining the following values: 64 L/h for Qalim, 176 g/L for PHalim, and a tdesc of 5 min. The semi-continuous disk stack centrifuge evaluated can be successfully implemented in the harvest step of the HeberNemÒ production process, thus replacing the tubular centrifuges currently employed. The statistical-mathematical programs Statgraphics Centurion® XV.II, Microsoft Excel®, and MATLAB® v7.0.1 were used for data and results processing.