Strategy for selection of methods for separation of bioparticles from particle mixtures

Abstract

The desired product of bioprocesses is often produced in particulate form, either as an inclusion body (IB) or as a crystal. Particle harvesting is then a crucial and attractive form of product recovery. Because the liquid phase often contains other bioparticles, such as cell debris, whole cells, particulate biocatalysts or particulate by-products, the recovery of product particles is a complex process. In most cases, the particulate product is purified using selective solubilization or extraction. However, if selective particle recovery is possible, the already high purity of the particles makes this downstream process more favorable. This work gives an overview of typical bioparticle mixtures that are encountered in industrial biotechnology and the various driving forces that may be used for particle-particle separation, such as the centrifugal force, the magnetic force, the electric force, and forces related to interfaces. By coupling these driving forces to the resisting forces, the limitations of using these driving forces with respect to particle size are calculated. It shows that centrifugation is not a general solution for particle-particle separation in biotechnology because the particle sizes of product and contaminating particles are often very small, thus, causing their settling velocities to be too low for efficient separation by centrifugation. Examples of such separation problems are the recovery of IBs or virus-like particles (VLPs) from (microbial) cell debris. In these cases, separation processes that use electrical forces or fluid-fluid interfaces show to have a large potential for particle-particle separation. These methods are not yet commonly applied for large-scale particle-particle separation in biotechnology and more research is required on the separation techniques and on particle characterization to facilitate successful application of these methods in industry.

Formation and Separation of Particles fromEmiliania huxleyi

“…By‐products, salts, and cell fragments set the recovery of bioproducts from biological systems to be a challenging process. For each system, various driving forces must be overcome before the product could be isolated . After cell disruption, the biological broth was characterized to identify the initial suspension conditions.…”

Interfacial displacement of nanoparticles by surfactant molecules in emulsions

“…Particle-stabilised emulsions that form during the extraction of bitumen from oil sands reduce the volume of oil recovered and generate waste problems [14]. Strategies for recovering bioparticles selectively separated at liquid-liquid interfaces [15] may be limited by the stability of the particle-drop aggregates. The efficient use of particles for the encapsulation and removal of non-aqueous phase contaminants from soils [16] requires displacement of the particles from the interface so they can be recycled.…”

Controlling Pickering Emulsion Destabilisation: A Route to Fabricating New Materials by Phase Inversion

“…They hinder separation of the products from the reaction mixture and recycling of the catalyst [14,15]. Particle separations using biphasic extractions are also hindered by particles becoming trapped at the liquid interface [16,17]. …”