Laccases, mannanases, peroxidases, and xylanases are applied in pulping process
to delignify the pulp and boost the bleaching. Although cellulases are primarily
applied in papermaking, there has been a growing interest of using these enzymes in
the pulping process as well. The refining and grinding of wood in conventional
mechanical pulping result in pulp rich in fines and bulk and higher stiffness; hence,
in the subsequent steps, the energy consumption is high. On the other hand, the use
of cellulases in a mechanical pulping process known as biomechanical pulping
substantially reduces the energy consumption (up to 40%) during the subsequent
refining process and enhances the strength properties [100–102].
In paper mills, there are some fines, peel off fibrils, and other dissolved and
colloidal substances which often cause drainage problems. Alleviating this problem
can improve the process productivity. The use of cellulases and hemicellulases, in
addition to enhancing pulp beatability, helps to solubilize drain plugging constituents and considerably improve the drainage [103]. These effects of enzymatic
treatment are accompanied by an overall improvement in the mill performance
[101]. Moreover, cellulase treatment is known to decrease defibrillation which
concomitantly reduces fiber coarseness [104]. Manufacturing of easily degradable
cardboard and soft paper such as sanitary paper and paper towels utilizes such
enzymes.
Application of laccases in pulp and paper industry is versatile. Application of
laccases, as aforementioned, delignifies and brightens pulp. Like lipases, laccases are
also capable of removing lipophilic substances which are responsible for pitch
deposition on papermaking machines [105]. Since laccases generate reactive radicals
with lignin and functionalize lignocellulosic fibers, in addition to delignification, it
can also improve the chemical and physical properties of the pulp [106, 107]. Moreover, laccases which mediate polymerization and depolymerization reactions can
remove colored and toxic compounds from mill effluent and, hence, render bioremediation purpose.
Kraft pulping is the major pulping process which involves alkaline treatment.
Therefore, the enzymes intended for pulp and paper application preferably should be
alkaline active to avoid or reduce the time-consuming and cost-incurring pH adjustments. Hence, alkaliphiles which are major sources of alkaline active enzymes are
vital in these multibillion-dollar processes.
4.1.4 Paper Recycling
Paper recycling is a flourishing business with great economic and environmental
impact. It has become mandatory for most pulp and paper industries and believed
playing a remarkable role in the fight against deforestation. In addition to saving
trees, paper recycling significantly cuts down the water and energy consumption and
hence contributes toward greener environment. However, regeneration of highquality secondary fibers from old papers is not a simple task. Deinking and removal
of adhering materials are among the most important challenges in paper recycling.
Alkaliphiles: The Versatile Tools in Biotechnology
17
to delignify the pulp and boost the bleaching. Although cellulases are primarily
applied in papermaking, there has been a growing interest of using these enzymes in
the pulping process as well. The refining and grinding of wood in conventional
mechanical pulping result in pulp rich in fines and bulk and higher stiffness; hence,
in the subsequent steps, the energy consumption is high. On the other hand, the use
of cellulases in a mechanical pulping process known as biomechanical pulping
substantially reduces the energy consumption (up to 40%) during the subsequent
refining process and enhances the strength properties [100–102].
In paper mills, there are some fines, peel off fibrils, and other dissolved and
colloidal substances which often cause drainage problems. Alleviating this problem
can improve the process productivity. The use of cellulases and hemicellulases, in
addition to enhancing pulp beatability, helps to solubilize drain plugging constituents and considerably improve the drainage [103]. These effects of enzymatic
treatment are accompanied by an overall improvement in the mill performance
[101]. Moreover, cellulase treatment is known to decrease defibrillation which
concomitantly reduces fiber coarseness [104]. Manufacturing of easily degradable
cardboard and soft paper such as sanitary paper and paper towels utilizes such
enzymes.
Application of laccases in pulp and paper industry is versatile. Application of
laccases, as aforementioned, delignifies and brightens pulp. Like lipases, laccases are
also capable of removing lipophilic substances which are responsible for pitch
deposition on papermaking machines [105]. Since laccases generate reactive radicals
with lignin and functionalize lignocellulosic fibers, in addition to delignification, it
can also improve the chemical and physical properties of the pulp [106, 107]. Moreover, laccases which mediate polymerization and depolymerization reactions can
remove colored and toxic compounds from mill effluent and, hence, render bioremediation purpose.
Kraft pulping is the major pulping process which involves alkaline treatment.
Therefore, the enzymes intended for pulp and paper application preferably should be
alkaline active to avoid or reduce the time-consuming and cost-incurring pH adjustments. Hence, alkaliphiles which are major sources of alkaline active enzymes are
vital in these multibillion-dollar processes.
4.1.4 Paper Recycling
Paper recycling is a flourishing business with great economic and environmental
impact. It has become mandatory for most pulp and paper industries and believed
playing a remarkable role in the fight against deforestation. In addition to saving
trees, paper recycling significantly cuts down the water and energy consumption and
hence contributes toward greener environment. However, regeneration of highquality secondary fibers from old papers is not a simple task. Deinking and removal
of adhering materials are among the most important challenges in paper recycling.
Alkaliphiles: The Versatile Tools in Biotechnology
17