demand of environmentally benign technologies and found the way in the usage of
natural coagulants extracted from waste, being biodegradable, safer for human
health, and capable of causing flocculation in colloidal solutions on different concentrations (Moussas et al. 2011; Szyguła et al. 2009).
The main aim of coagulation-flocculation is the agglomeration of tiny colloids
into larger masses to reduce turbidity (Szyguła et al. 2009). Most of the natural
coagulants are polysaccharides in nature and are known as polymeric coagulants and
show two types of mechanisms, i.e., adsorption and charge cancellation and adsorption and interparticle bridging due to an interaction between π-electrons of dyes and
hydroxyl groups of polymeric coagulants (Renault et al. 2009; Verma et al. 2012).
Ferric chloride sludge was employed to remove Acid Red 119. Response surface
methodology revealed over 96% of the degradation was achieved at pH 3.5, ferric
chloride sludge dosage 236 mg L
À1 , and initial dye concentration of over 65 mg L
À1
(Moghaddam et al. 2010).
The generic behavior of the coagulation-flocculation technique was evaluated
using different coagulants against brilliant green and 6, respectively. However, the
addition of lime to magnesium chloride and ferrous sulfate improved decolorization
to 99% for both dyes (Mane and Babu 2011). In a similar study, coagulationflocculation process was evaluated for textile wastewater treatment before release,
which contains hydron blue dye using Al 2 (SO 4 ) 3 . The maximum dye removal of
64% was achieved under optimized conditions (Chenna et al. 2016).
Direct Red 23 azo dye was removed from textile effluents by Moringa
stenopetala seed extract, alum, and M. stenopetala-alum hybrid coagulant to evaluate and compare efficacy. All the three coagulants showed over 98% dye removal at
pH 7. However, the dosage of hybrid coagulant (80 mg L
À1 ) was lesser than seed
extract (240 mg L
À1 ) and alum (120 mg L
À1 ), thus proving the higher efficacy
(Dalvand et al. 2016). The potential of cationic polyelectrolyte based on lignin was
also evaluated by the removal of anionic dyes, namely, acid black, reactive red, and
direct red, from simulated dye effluent. A 100% dye removal was achieved with
5.4% sludge production. The obtained results showed the commercialization potential of the adsorbent (Fang et al. 2010).
The coagulation-flocculation potential of poly-aluminum chloride and bentonite
clay was evaluated for 3 and 7 removal considering various parameters. Bentonite
clay exhibited higher attraction to 7, resulting in over 99 and 98% removal of 7 and
3, respectively while poly-aluminum chloride showed an optimum removal efficiency of over 99% for 7 and 97% for 3 (Fosso-Kankeu et al. 2017). The efficiency
of natural polymer coagulants, Vigna unguiculata, Telfairia occidentalis,
Brachystegia eurycoma, Vigna subterranea, and Moringa oleifera, for decolorization
of crystal Ponceau 6R dye has been studied. Four variables of the coagulationflocculation process, namely, pH, coagulant dosage, dye concentration, and time,
were optimized using response surface methodology. The color removal efficiencies
obtained from the optimization analysis were in the range of 97–99% at pH 2,
coagulant dosage of 1000 mg L
À1 , and dye concentration of 20 mg L
À1 in 7 h
(Obiora-Okafo and Onukwuli 2015).
17 Methods for the Treatment of Wastewaters Containing Dyes and Pigments
625
natural coagulants extracted from waste, being biodegradable, safer for human
health, and capable of causing flocculation in colloidal solutions on different concentrations (Moussas et al. 2011; Szyguła et al. 2009).
The main aim of coagulation-flocculation is the agglomeration of tiny colloids
into larger masses to reduce turbidity (Szyguła et al. 2009). Most of the natural
coagulants are polysaccharides in nature and are known as polymeric coagulants and
show two types of mechanisms, i.e., adsorption and charge cancellation and adsorption and interparticle bridging due to an interaction between π-electrons of dyes and
hydroxyl groups of polymeric coagulants (Renault et al. 2009; Verma et al. 2012).
Ferric chloride sludge was employed to remove Acid Red 119. Response surface
methodology revealed over 96% of the degradation was achieved at pH 3.5, ferric
chloride sludge dosage 236 mg L
À1 , and initial dye concentration of over 65 mg L
À1
(Moghaddam et al. 2010).
The generic behavior of the coagulation-flocculation technique was evaluated
using different coagulants against brilliant green and 6, respectively. However, the
addition of lime to magnesium chloride and ferrous sulfate improved decolorization
to 99% for both dyes (Mane and Babu 2011). In a similar study, coagulationflocculation process was evaluated for textile wastewater treatment before release,
which contains hydron blue dye using Al 2 (SO 4 ) 3 . The maximum dye removal of
64% was achieved under optimized conditions (Chenna et al. 2016).
Direct Red 23 azo dye was removed from textile effluents by Moringa
stenopetala seed extract, alum, and M. stenopetala-alum hybrid coagulant to evaluate and compare efficacy. All the three coagulants showed over 98% dye removal at
pH 7. However, the dosage of hybrid coagulant (80 mg L
À1 ) was lesser than seed
extract (240 mg L
À1 ) and alum (120 mg L
À1 ), thus proving the higher efficacy
(Dalvand et al. 2016). The potential of cationic polyelectrolyte based on lignin was
also evaluated by the removal of anionic dyes, namely, acid black, reactive red, and
direct red, from simulated dye effluent. A 100% dye removal was achieved with
5.4% sludge production. The obtained results showed the commercialization potential of the adsorbent (Fang et al. 2010).
The coagulation-flocculation potential of poly-aluminum chloride and bentonite
clay was evaluated for 3 and 7 removal considering various parameters. Bentonite
clay exhibited higher attraction to 7, resulting in over 99 and 98% removal of 7 and
3, respectively while poly-aluminum chloride showed an optimum removal efficiency of over 99% for 7 and 97% for 3 (Fosso-Kankeu et al. 2017). The efficiency
of natural polymer coagulants, Vigna unguiculata, Telfairia occidentalis,
Brachystegia eurycoma, Vigna subterranea, and Moringa oleifera, for decolorization
of crystal Ponceau 6R dye has been studied. Four variables of the coagulationflocculation process, namely, pH, coagulant dosage, dye concentration, and time,
were optimized using response surface methodology. The color removal efficiencies
obtained from the optimization analysis were in the range of 97–99% at pH 2,
coagulant dosage of 1000 mg L
À1 , and dye concentration of 20 mg L
À1 in 7 h
(Obiora-Okafo and Onukwuli 2015).
17 Methods for the Treatment of Wastewaters Containing Dyes and Pigments
625