Arijit Nath

Immobilized biocatalytic process development and potential application in membrane separation: a review

Abstract Biocatalytic membrane reactors have been widely used in different industries including food, fine chemicals, biological, biomedical, pharmaceuticals, environmental treatment and so on. This article gives an overview of the different immobilized enzymatic processes and their advantages over the conventional chemical catalysts. The application of a membrane bioreactor (MBR) reduces the energy consumption, and system size, in line with process intensification. The performances of MBR are considerably influenced by substrate concentration, immobilized matrix material, types of immobilization and the type of reactor. Advantages of a membrane associated bioreactor over a free-enzyme biochemical reaction, and a packed bed reactor are, large surface area of immobilization matrix, reuse of enzymes, better product recovery along with heterogeneous reactions, and continuous operation of the reactor. The present research work highlights immobilization techniques, reactor setup, enzyme stability under immobilized conditions, the hydrodynamics of MBR, and its application, particularly, in the field of sugar, starch, drinks, milk, pharmaceutical industries and energy generation.

Bioadsorbtion of industrial dyes from aqueous solution onto water hyacinth (Eichornia crassipes): equilibrium, kinetic, and sorption mechanism study

AbstractIn the present investigation, bioadsorbtion of different industrial dyes, such as, methylene blue, Congo red, crystal violet, and malachite green from aqueous solution have been performed by water hyacinth using lab-scale batch bioreactor. Maximum removal of different dyes, such as, methylene blue, Congo red, crystal violet, and malachite green were found at pH 7.0, 6.0, 8.0, and 8.0, respectively. Optimum doses of adsorbent were found to be 6.5, 7.5, 6.0, and 7.0 g L−1 for methylene blue, Congo red, crystal violet, and malachite green, respectively. Optimum initial dyes concentration were found to be 65, 75, 70, and 75 mg L−1 for methylene blue, Congo red, crystal violet, and malachite green, respectively. Optimum contact time for adsorbtion was found to be 5 days for all the dyes. The maximum percentages of removals were found to be 90, 88, 92, and 90% for methylene blue, Congo red, crystal violet, and malachite green, respectively. The adsorption kinetic data are adequately fitted to the pseudo...

Studies on the separation of proteins and lactose from casein whey by cross-flow ultrafiltration

AbstractA novel strategy has been developed for separation of individual whey protein fractions and lactose from casein whey by a cascade of different molecular weight cut-off (MWCO) cross-flow ultrafiltration (UF) membranes. Centrifugation (166.67 r.p.s., 277 K, 1800 s) followed by microfiltration (MWCO: 0.45 × 10−6 m) were employed for separation of fat molecules and suspended solids from casein whey. Immunoglobulins, such as IgG, IgA, and IgM were separated as retentate of 100 kg mol−1 UF membrane; bovin serum albumin, lactoperoxidase, and lactoferrin were separated as retentate of 50 kg mol−1 UF membrane; lactose were separated by 5 kg mol−1 UF membrane as permeate, and major proteins like β-lactoglobulin (molecular weight 18.3 kg mol−1) and α-lactalbumin (molecular weight 14.2 kg mol−1) were separated by proper control of pH. At pH 5.4 the most dominant whey protein, β-lactoglobulin (isoelectric point 5.2–5.4), formed dimer which was found to have immense effect on the separation characteristics. Hyd...

Bioreactor and Enzymatic Reactions in Bioremediation

Intellectual revolution with new visions and hopes is responsible for the development of membrane-associated bioreactor with specific emphasis on waste valorization. Generally, an enzyme or microorganism is immobilized in the matrix and is used in a membrane bioreactor. Conversely, a membrane separation unit is associated with a bioreactor to separate out a reaction product, known as catalytic membrane reactor. The performance of membrane-associated bioreactors is considerably influenced by the operating conditions, such as substrate concentration, immobilized matrix material, types of immobilization, and characteristics of the membrane module. The advantages of membrane-associated bioreactors over free-enzyme biochemical reactions and packed bed reactors are the large surface area of the immobilization matrix and better product recovery, along with heterogeneous reactions, reuse of enzymes, and continuous operation of the reactor. Moreover, due to possible separation of products and reactants, reversible reactions are always facilitated in this type of reactor. In the present chapter, the characteristics of membrane-associated bioreactors, more particularly membrane bioreactors with special interest of immobilization technology of enzyme and microorganism, hydrodynamic study associated with chemical reactions, and its application is described. Furthermore the application of membrane bioreactor with respect to synthesis of prebiotic galactooligosaccharide, and lactic acid have been elucidated.

Conventional macro- and micromolecules separation

The second step for the recovery of valuable compounds from food wastes is macro- and micromolecules separation. The objective of the current chapter is to present different technologies (e.g. alcohol precipitation, ultrafiltration, isoelectric solubilization/precipitation, and extrusion), which have been implemented for this purpose. For instance, solutes are precipitated in the presence of an antisolvent agent, even if they exist in very low concentrations within the feedstock. In addition, the solubility of proteins or lipids could be reduced when pH value turns to their isoelectric point, causing their precipitation. On the other hand, ultrafiltration is a pressure-driven membrane separation technology, which is basically used to separate macro- and micromolecules based on their size. Extrusion is a process using shear energy and heating in order to modify (physically or chemically) the physicochemical properties of macromolecules (polysaccharides, dietary fibers, or proteins) and micromolecules (sugars, polyphenols, vitamins, or minerals). This ability has also been used in particular applications for compound recovery from food wastes.

Emerging purification and isolation

Abstract Being the fourth step of the 5-Stage Universal Recovery Process, isolation and purification of target compounds become more compact, environmental friendly, and cost effective, producing pure end-products. This chapter presents some emerging purification and isolation techniques, such as, magnetic fishing, aqueous two-phase system, and ion-exchange membrane chromatography. In the presence of magnetic particles, solutes are separated due to their selective affinity and recovered by suitable buffer. On the other hand, the aqueous two-phase system is a liquid/liquid partitioning technique, comprising two types of phase-forming components. Finally, Ion-exchange membrane chromatography is a technique where biomolecules (mostly protein) are separated due to their ionic charge (adsorbtion and elusion by pH of buffer). The features of these technologies are dsecribed in detail in this chapter.

Packed-Bed Bioreactor and Its Application in Dairy, Food, and Beverage Industry

Abstract Packed-bed bioreactors are tubular types of reactors which are packed with immobilized enzyme or microbial cells as biocatalysts. Different techniques such as encapsulation, cross-linking, covalent bonding, and adsorption are generally used for immobilization purposes. Because reactions carried out in packed-bed bioreactors are heterogeneous, catalytic biochemical reactions and mass transfer resistance may have a predominant role in determining the reaction kinetics. Thus reactions carried out in these bioreactors may occur in either a mass transfer-controlled or reaction-controlled regime. Important factors for the design such a reactor are reactor to catalyst particle diameter ratio, reactor length to diameter ratio and void fraction. The advantages of packed bed bioreactor over other bioreactors are reuse of enzymes, continuous mode of operations, low substrate and product inhibition, high yield of desired product. These bioreactors are widely applied for valorization of food, beverage, nutraceutical synthesis, as well as waste treatment.