278
The chemical methods of dyes removal are advanced oxidation processes, Fenton
reaction, oxidation, ozonation, photochemical and ultraviolet irradiation, and electrochemical decomposition. Most of the above mentioned methods are costly due to
high energy consumption and formation of secondary pollution. The most dangerous, however, is the apparent decolorization, which, despite the color removal, does
not lead to detoxification of substances present in wastewaters. As a consequence,
colorless decolorization products are still found in the aquatic environment. This
effect occurs during decolorization, e.g., by chlorination, brown lignin-rich wastewaters generated during pulping of wood in the pulp and paper industry. It leads to
the formation of colorless but toxic, mutagenic, and carcinogenic by products of
cleavage, i.e., chlorolignins and dioxins (Crini 2006). Other undesirable drawbacks
are additional chemicals usage in macroscale and specific equipment. The color
reduction yield by chemical treatment ranged from 88% to 99% (Katheresan
et al. 2018).
Physical dye removal methods such as coagulation and flocculation, membrane
filtration, nano-filtration or ultra-filtration, reverse osmosis, adsorption, and ion
exchange are usually straightforward methods. These techniques are often chosen
because of its simplicity and 86–99% effectiveness (Katheresan et al. 2018).
Physical methods consume a lot less chemicals compared to the biological and
chemical ones.
Although many dye removal methods are known and extensively researched,
only several of them could be implemented by industries due to their drawbacks and
limitations (Bhatia et al. 2017; Gupta and Suhas 2009; Katheresan et al. 2018; Raval
et al. 2017; Yagub et al. 2014).
Fig. 11.4 Methods of textile wastewater treatment
A. Wołowicz and M. Wawrzkiewicz
The chemical methods of dyes removal are advanced oxidation processes, Fenton
reaction, oxidation, ozonation, photochemical and ultraviolet irradiation, and electrochemical decomposition. Most of the above mentioned methods are costly due to
high energy consumption and formation of secondary pollution. The most dangerous, however, is the apparent decolorization, which, despite the color removal, does
not lead to detoxification of substances present in wastewaters. As a consequence,
colorless decolorization products are still found in the aquatic environment. This
effect occurs during decolorization, e.g., by chlorination, brown lignin-rich wastewaters generated during pulping of wood in the pulp and paper industry. It leads to
the formation of colorless but toxic, mutagenic, and carcinogenic by products of
cleavage, i.e., chlorolignins and dioxins (Crini 2006). Other undesirable drawbacks
are additional chemicals usage in macroscale and specific equipment. The color
reduction yield by chemical treatment ranged from 88% to 99% (Katheresan
et al. 2018).
Physical dye removal methods such as coagulation and flocculation, membrane
filtration, nano-filtration or ultra-filtration, reverse osmosis, adsorption, and ion
exchange are usually straightforward methods. These techniques are often chosen
because of its simplicity and 86–99% effectiveness (Katheresan et al. 2018).
Physical methods consume a lot less chemicals compared to the biological and
chemical ones.
Although many dye removal methods are known and extensively researched,
only several of them could be implemented by industries due to their drawbacks and
limitations (Bhatia et al. 2017; Gupta and Suhas 2009; Katheresan et al. 2018; Raval
et al. 2017; Yagub et al. 2014).
Fig. 11.4 Methods of textile wastewater treatment
A. Wołowicz and M. Wawrzkiewicz