Biocatalytic Membrane Reactors

Abstract

Biocatalytic membrane reactors are biohybrid artificial systems where a biochemical conversion is combined with a membrane separation process. The term may indicate either that the membrane itself is biocatalytic, that is participates directly in the reaction forming the reactor's core system, or that a bioconversion step is combined with a catalytically inert membrane operation. In the latter case, the term “membrane bioreactor” is more appropriate. With reference to the more general term “membrane reactors”, membrane bioreactors are distinguished by the fact that the chemical conversion is catalyzed by chemical catalysts of biological origin, such as enzymes and cells, instead of ordinary chemical catalysts. Membrane science and chemical and biochemical engineering contribute to the development of these systems by designing compact, flexible, and efficient apparatuses, in which conversion and product separation from the reaction site occur simultaneously, thus enhancing yield according to Le Chatelier's principle. Biocatalytic membrane reactors allow to carry out concentration and separation without the use of heat; they permit innovative formulation strategies; the equipments need less space, are flexible and easy to scale-up (they are enabling technologies and respond well to the process intensification strategy); operating costs are low; energy consumed is low; products and coproducts are of high quality (which is very important for by-product valorization, waste prevention, and minimization). Due to the abilities of both, membrane processes and biocatalysts, to work with high selectivity and without additives, biocatalytic membrane reactors are particularly suitable for processing in the food and beverage, biotechnological, biomedical, and pharmaceutical fields, as well as in wastewater treatment. In this work, their basic aspects and main applications in topics of current industrial interest are be discussed. Keywords: biocatalytic membrane; membrane bioreactor; immobilized biocatalyst kinetics; membrane; biocatalyst; submerged membrane bioreactor; enantioselective bioconversion; membrane bioseparation