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3 Immobilized Enzymes for Bioconversion of Waste to Wealth

Waste

Biodegradable

wastes

Non-biodegradable

wastes

Recyclable

Non-recyclable

Product

Wealth

Figure 3.1

Schematic representation of waste to wealth.

Wastes are produced in agricultural, household, and industrial sectors includ-

ing food processing activities. Agricultural activities will produce several types

of wastes in the daily operations, such as hazardous wastes, solid wastes, and

wastewater. There are several advantages of recycling wastes like reduction in the

amount of waste disposals, saving natural resources including nonrenewable ones

like petroleum, reduction in the amount of energy desirable to manufacture new

products, reducing pollution, and several more [1]. During the industrial treatments

of agricultural products, agro-industrial wastes can be generated. These can also be

considered as most abundant renewable resources on the earth. Large amounts of

such wastes can be generated throughout the year. Solid wastes like garbage, sewage

sludge, ashes, discharged wastes, and trash of any solid or semi-solid materials have

become another major concern, since humans started living in large permanent

settlements [2]. Myriads of the organic wastes including the agro-waste can be

exploited as a substrate in the production of sustainable energy or other desirable

products at a fraction of the standard cost using enzyme technologies. Immobilized

enzymes are advantageous economically and performance wise. In this chapter,

immobilization methods of enzymes and how immobilized enzymes are used for

the conversion of waste into useful products are discussed. In addition, applications

of nanotechnology for the immobilization of enzymes and bioconversion are

brought in.

3.2

Enzymes as Biocatalysts

Enzymes are versatile biocatalytic proteins, which have applications in many areas

including organic synthesis [3]. The main benefits of using enzymes at industrial

scale are generally the high reaction rates and the specificity of the reactions they

catalyze. The major advantages of using enzymes in biocatalyst transformation are

their region-, chemo-, and steriospecificity as well as the mild reaction conditions

those can be used.

For the usage at industrial level, the free enzymes will pose several disadvan-

tages such as low stability, low activity, non-native activity, and so on. In the last

few decades, applications of enzymes have been rapidly increased in several fields

like food modification, biofuel production, biomedical, agro-industrial waste trans-

formation, pharmacy, laundry, etc. [3]. Enzymes are also applied in paper, leather,

and textile industries which effects a significant cost reduction. As a substitute of

traditional chemical catalysts, the demand for new biocatalysts is greatly increasing.