detoxification. However, complete removal of pollutants has not been achieved
(Orrego et al. 2010).
7.1 Physicochemical Methods
Physicochemical processes based on sedimentation and floatation, coagulation and
precipitation, filtration, reverse osmosis, adsorption, ozonation, and other advanced
oxidation have been well reported for the effective removal of pollutants as well as
variety of suspended and floating matters from the paper industry wastewaters.
Application of sedimentation and floatation processes, used for separation of
solids from effluent, has been evaluated in paper industry effluent as an effective
decolorization process (Pokhrel and Viraraghavan 2004; Thompson et al. 2001).
However, practical viability of such systems at large scale is not feasible due to its
high cost and generation of large amount of sludge which pose disposal problem.
Coagulation and precipitation methods using metal salts to generate larger flocs
from small particles have been also used for the treatment of paper industry effluent.
Aluminum chloride as coagulant and modified natural polymer (starch-g-PAM-gPDMC) as a flocculant for treatment of wastewaters from primary sedimentation
tank have been studied by Wang et al. (2011), and result suggested that at the optimal
condition (coagulant dosage of 871 mg L
À1 , flocculants dosage of 22.3 mg L
À1 , and
pH 8.35), turbidity and lignin removals and water recovery efficiency were 95.7%,
83.4%, and 72.7%, respectively.
Membrane technologies have also been applied for pulp and paper mill wastewater treatment. Membrane treatment technology in pulp and paper industry is
performed to optimize loop closure and therefore helps to reduce freshwater intake
as well as wastewater treatment. The other purposes of membrane treatment processes are to improved product quality because of minimizing pollution of wastewaters reuse of treated effluent and recovery of valuable substances and reduction of
environmental pollution because of improved effluent quality. Ultrafiltration
(UF) and reverse osmosis are some examples of membrane filtration technology
for color removal of effluent. Usually, they have been applied for the removal of high
molecular weight dissolved organic components from paper mills effluent. The
filtration techniques are now being used for the removal of color and for further
reuse of process wastewaters from paper mill industry (Joensson et al. 1996; Katkar
and Sasidharan 2000; Laitinen et al. 2001). Membrane techniques usually represent
a large capital investment. This process requires pretreatment in order to prevent
problems of fouling.
The technique of adsorption has been found to be an efficient and cost-effective
method to remove pigments, dyes, and other colorants of industrial effluents and to
control the BOD and COD. Activated carbons, inorganic oxides, and natural adsorbents (such as clays and clay minerals, cellulose materials, chitin, and chitosan) have
been extensively used as adsorbents by many workers to treat wastewaters
(Al-Asheh et al. 2003; Naseem and Ve Tahir 2001). It is an advantageous technique
14 Pulp and Paper Mill Wastewater: Ecotoxicological Effects and. . .
347
(Orrego et al. 2010).
7.1 Physicochemical Methods
Physicochemical processes based on sedimentation and floatation, coagulation and
precipitation, filtration, reverse osmosis, adsorption, ozonation, and other advanced
oxidation have been well reported for the effective removal of pollutants as well as
variety of suspended and floating matters from the paper industry wastewaters.
Application of sedimentation and floatation processes, used for separation of
solids from effluent, has been evaluated in paper industry effluent as an effective
decolorization process (Pokhrel and Viraraghavan 2004; Thompson et al. 2001).
However, practical viability of such systems at large scale is not feasible due to its
high cost and generation of large amount of sludge which pose disposal problem.
Coagulation and precipitation methods using metal salts to generate larger flocs
from small particles have been also used for the treatment of paper industry effluent.
Aluminum chloride as coagulant and modified natural polymer (starch-g-PAM-gPDMC) as a flocculant for treatment of wastewaters from primary sedimentation
tank have been studied by Wang et al. (2011), and result suggested that at the optimal
condition (coagulant dosage of 871 mg L
À1 , flocculants dosage of 22.3 mg L
À1 , and
pH 8.35), turbidity and lignin removals and water recovery efficiency were 95.7%,
83.4%, and 72.7%, respectively.
Membrane technologies have also been applied for pulp and paper mill wastewater treatment. Membrane treatment technology in pulp and paper industry is
performed to optimize loop closure and therefore helps to reduce freshwater intake
as well as wastewater treatment. The other purposes of membrane treatment processes are to improved product quality because of minimizing pollution of wastewaters reuse of treated effluent and recovery of valuable substances and reduction of
environmental pollution because of improved effluent quality. Ultrafiltration
(UF) and reverse osmosis are some examples of membrane filtration technology
for color removal of effluent. Usually, they have been applied for the removal of high
molecular weight dissolved organic components from paper mills effluent. The
filtration techniques are now being used for the removal of color and for further
reuse of process wastewaters from paper mill industry (Joensson et al. 1996; Katkar
and Sasidharan 2000; Laitinen et al. 2001). Membrane techniques usually represent
a large capital investment. This process requires pretreatment in order to prevent
problems of fouling.
The technique of adsorption has been found to be an efficient and cost-effective
method to remove pigments, dyes, and other colorants of industrial effluents and to
control the BOD and COD. Activated carbons, inorganic oxides, and natural adsorbents (such as clays and clay minerals, cellulose materials, chitin, and chitosan) have
been extensively used as adsorbents by many workers to treat wastewaters
(Al-Asheh et al. 2003; Naseem and Ve Tahir 2001). It is an advantageous technique
14 Pulp and Paper Mill Wastewater: Ecotoxicological Effects and. . .
347