machine such as printers, rejects, etc. The post-consumer waste is usually old
wastepaper collected from consumers. The requirements of raw material are sourced
both indigenously and through imports.
2.4 Chemicals
Paper manufacturing from wood is a chemical-intensive process. Large amount of
various chemicals used during papermaking process, viz., optical brightening agent,
pigments, retention agent, caustic soda, sizing agent, wet strength additive, dry
strength additive, mineral fillers, coating binders, pulping chemicals, and bleaching
chemicals, are summarized in Table 14.1.
In kraft and sulfite pulping, the cooked wood chips are dipped in a chemical
solution to dissolve the lignin that binds the fibers together. Caustic soda (NaOH)
solution was used for processing of recovered fibers. Pulp and paper mills also use
combinations of chlorine and oxygen-based chemicals to bleach or brighten the pulp.
At the time of papermaking process, various coatings, fillers, and also many other
additives are added to the pulp to assist the manufacturing and encounter the
functional requirements of various types of paper.
2.5 Water
In papermaking process, water plays an important role because it carries fibers
through each step of paper manufacturing process and chemical treatment and
separates spent pulping chemicals and the complex combination of organic matter
from the pulp. Water is the basic process medium of pulp and paper manufacturing;
it carries the fibers through each manufacturing step and chemical treatment and
separates spent pulping chemicals and the complex mixture of organic residues from
the pulp. Huge amount of water is used during the paper manufacturing process.
3 Steps in Pulp and Paper Production
The pulp and paper production process involved mainly four steps: wood handling
and debarking, pulping, bleaching, and papermaking. The flow diagram for paper
manufacturing process employing wood and/or agro-residues as raw material is
shown in Fig. 14.1.
14 Pulp and Paper Mill Wastewater: Ecotoxicological Effects and. . .
337
wastepaper collected from consumers. The requirements of raw material are sourced
both indigenously and through imports.
2.4 Chemicals
Paper manufacturing from wood is a chemical-intensive process. Large amount of
various chemicals used during papermaking process, viz., optical brightening agent,
pigments, retention agent, caustic soda, sizing agent, wet strength additive, dry
strength additive, mineral fillers, coating binders, pulping chemicals, and bleaching
chemicals, are summarized in Table 14.1.
In kraft and sulfite pulping, the cooked wood chips are dipped in a chemical
solution to dissolve the lignin that binds the fibers together. Caustic soda (NaOH)
solution was used for processing of recovered fibers. Pulp and paper mills also use
combinations of chlorine and oxygen-based chemicals to bleach or brighten the pulp.
At the time of papermaking process, various coatings, fillers, and also many other
additives are added to the pulp to assist the manufacturing and encounter the
functional requirements of various types of paper.
2.5 Water
In papermaking process, water plays an important role because it carries fibers
through each step of paper manufacturing process and chemical treatment and
separates spent pulping chemicals and the complex combination of organic matter
from the pulp. Water is the basic process medium of pulp and paper manufacturing;
it carries the fibers through each manufacturing step and chemical treatment and
separates spent pulping chemicals and the complex mixture of organic residues from
the pulp. Huge amount of water is used during the paper manufacturing process.
3 Steps in Pulp and Paper Production
The pulp and paper production process involved mainly four steps: wood handling
and debarking, pulping, bleaching, and papermaking. The flow diagram for paper
manufacturing process employing wood and/or agro-residues as raw material is
shown in Fig. 14.1.
14 Pulp and Paper Mill Wastewater: Ecotoxicological Effects and. . .
337