3.1 Debarking
The wood materials for the paper production started with conversion of wood logs
into chips suitable for pulping in a series of steps which may include debarking,
sawing, chipping, and screening. Logs are debarked hydraulically with highpressure water jets, or mechanically by rubbing logs against each other or with
metal chippers. The plant bark is a useless material for paper industry as it contains
little fiber and high content of extractives; it is dark in color and often carries large
quantities of grit. The chips for pulping are then passed over a series of screens to
separate chips on the basis of length or thickness. The suitable chip sizes are
available to the pulping process (Ljungberg and Brannvall 2011).
3.2 Pulping
Pulping of wood chips is an important step in paper manufacturing. Pulping is
performed to obtain cellulose fibers from raw plant materials including hardwood,
agro-residues, and recycled fiber/waste paper. Pulping can be performed by chemical, mechanical, and chemo-mechanical processes. Chemical process such as “kraft
Fig. 14.1 Flow diagram of paper manufacturing process in paper industry
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339
The wood materials for the paper production started with conversion of wood logs
into chips suitable for pulping in a series of steps which may include debarking,
sawing, chipping, and screening. Logs are debarked hydraulically with highpressure water jets, or mechanically by rubbing logs against each other or with
metal chippers. The plant bark is a useless material for paper industry as it contains
little fiber and high content of extractives; it is dark in color and often carries large
quantities of grit. The chips for pulping are then passed over a series of screens to
separate chips on the basis of length or thickness. The suitable chip sizes are
available to the pulping process (Ljungberg and Brannvall 2011).
3.2 Pulping
Pulping of wood chips is an important step in paper manufacturing. Pulping is
performed to obtain cellulose fibers from raw plant materials including hardwood,
agro-residues, and recycled fiber/waste paper. Pulping can be performed by chemical, mechanical, and chemo-mechanical processes. Chemical process such as “kraft
Fig. 14.1 Flow diagram of paper manufacturing process in paper industry
14 Pulp and Paper Mill Wastewater: Ecotoxicological Effects and. . .
339