**5.10 Papermaking and pulp industry**

With the biotechnology advancement increased dependence of pulp and paper industries. Many enzymes are used almost in papermaking for bio-bleaching and papermaking, such as pectinases, mannanase, and α- galactosidase [131]. Pectinase can degrade the galacturonic acid polymer, lowering the cationic demand of pectin solutions and the filtrate from peroxide bleaching of thermomechanical pulp [132]. Bio-bleaching of eucalyptus kraft pulp obtained by a mixture of alkaline pectinase and xylanases from Streptomyces sp. QG-11–3 [133], *Bacillus subtilis, Bacillus pumilus* [134], and *S. cerevisiae* [135]. Bio-bleaching results in less requirement of chemical-bleaching, giving the same pulp brightness, enhance the physical properties of the paper sheet, and reduce the organochlorine compounds in the effluent. Liu *et al.*, lowering the used pectin concentration in bio-bleaching by using crosslinked chitosan beads, leading to a sharp decrease in pectin molecular weight and cationic demand of pectin solution [136].

#### **5.11 Wastepaper recycling**

The major problem in wastepaper recycling is deinking process that needs a large amount of environmentally damaging chemicals. Bio-deinking using enzymes is less polluting, gives better quality, and is energy-saving. Pectinases, cellulases, hemicellulases, and ligninolytic enzymes are used for bio-deinking. These enzymes alter bonds near the ink particle, removing the ink from the fiber surface. Then, the resulting ink is removed by washing or floatation [137, 138]. A combination of pectinase and xylanase has been used for bio-deinking of school wastepaper [139]. Hence, bio-deinking lowers the values of biological and chemical oxygen demand in the effluent, reducing the treatment cost for wastewater to be environment friendly [140].

#### **5.12 Wastewater treatment**

The wastewater of the vegetable food industries contains pectic substrates. The typical treatment of its wastewater involves multiple steps that are high in cost, have longer times, and pollutes the environment [141]. Thus, using alkaline pectinases to remove the pectic substrate is a good alternative, cost-effective, and eco-friendly method, easing the decomposition by activated sludge treatment [142, 143].
