component are also found to be more lethal to specific forms of marine life.
Suspended particles released along with the dye wastewater can choke fish gills
and kill them (Wang et al. 2005). Dyes can also influence directly or indirectly
human life, causing various abnormalities in the form of tumours, cancers and
allergies (Carmen and Daniela 2012). The presence of these pollutants is also
aesthetically undesirable and consequently alters the self-purification ability of
streams and rivers. Hence, the decontamination of these dyes molecules from dye
wastewater effluent has become of utmost importance to protect both the aquatic and
terrestrial environment.
13.5 Characteristics of Dye Wastewater
The textile industries are one of the most growing sectors as industrialization and
modern fashion world proliferate. These industries are considered as one of the
biggest polluter industries demanding plenty of water and various complex
chemicals during the processing stages. The textile industries are classified as dry
processing mills and wet processing mills based on waste and effluent generation
(Verma et al. 2012). The dry processing unit generates dry fabric rejects, while wet
processing units generate a considerable amount of effluent because of different
processing stages that are required for the production of textile fibres. The wet
processing unit has been accomplished by various stages of sizing, de-sizing,
scouring, bleaching, mercerizing, drying, printing and finishing stages. All these
different stages generate distinct wastewater depending on the process and the
chemical used. Dye wastewater released during these operational units in textile
industries needs critical attention during coagulation because of the toxic/organic
nature of colloids present in dye wastewater. Table 13.1 represents the various stages
of wet processing unit and characteristics of effluents generated from them.
Consequently, the water discharge from the textile industries has a high environmental impact because of the tremendous amount of water requirement among other
industries, globally, and each subunit effluent is highly polluted (Sonal and Mishra
2019). An average-sized textile industry consumes approximately 200 L per kg of
fabric produced per day (Kant 2012). It has been estimated by the World Bank that
textile dyeing and finishing treatment given to a fabric generate around 17–20% of
total industrial wastewater (Kant 2012). In India, approximately 80% of the total
production of 1,30,000 tons of dyestuff are consumed by the textile industry, due to
high demand for cotton and polyester, globally (Naik et al. 2013).
On the whole, the dye wastewater released from textile and dyestuff industries is
very complex and arduous to treat (Fewson 1988). The effluent discharged from the
industry contains high biological and chemical oxygen demand, besides acids,
alkalis, dyes, hydrogen peroxide, starch, surfactants, dispersing agents and soaps
of metals (Paul et al. 2012). Still, the most notable consideration has been given to
the dyes. These dyes are released in high concentration and are persistent even in low
concentration. During manufacturing and textile dyeing-printing, complete
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S. Sonal and B. K. Mishra
Suspended particles released along with the dye wastewater can choke fish gills
and kill them (Wang et al. 2005). Dyes can also influence directly or indirectly
human life, causing various abnormalities in the form of tumours, cancers and
allergies (Carmen and Daniela 2012). The presence of these pollutants is also
aesthetically undesirable and consequently alters the self-purification ability of
streams and rivers. Hence, the decontamination of these dyes molecules from dye
wastewater effluent has become of utmost importance to protect both the aquatic and
terrestrial environment.
13.5 Characteristics of Dye Wastewater
The textile industries are one of the most growing sectors as industrialization and
modern fashion world proliferate. These industries are considered as one of the
biggest polluter industries demanding plenty of water and various complex
chemicals during the processing stages. The textile industries are classified as dry
processing mills and wet processing mills based on waste and effluent generation
(Verma et al. 2012). The dry processing unit generates dry fabric rejects, while wet
processing units generate a considerable amount of effluent because of different
processing stages that are required for the production of textile fibres. The wet
processing unit has been accomplished by various stages of sizing, de-sizing,
scouring, bleaching, mercerizing, drying, printing and finishing stages. All these
different stages generate distinct wastewater depending on the process and the
chemical used. Dye wastewater released during these operational units in textile
industries needs critical attention during coagulation because of the toxic/organic
nature of colloids present in dye wastewater. Table 13.1 represents the various stages
of wet processing unit and characteristics of effluents generated from them.
Consequently, the water discharge from the textile industries has a high environmental impact because of the tremendous amount of water requirement among other
industries, globally, and each subunit effluent is highly polluted (Sonal and Mishra
2019). An average-sized textile industry consumes approximately 200 L per kg of
fabric produced per day (Kant 2012). It has been estimated by the World Bank that
textile dyeing and finishing treatment given to a fabric generate around 17–20% of
total industrial wastewater (Kant 2012). In India, approximately 80% of the total
production of 1,30,000 tons of dyestuff are consumed by the textile industry, due to
high demand for cotton and polyester, globally (Naik et al. 2013).
On the whole, the dye wastewater released from textile and dyestuff industries is
very complex and arduous to treat (Fewson 1988). The effluent discharged from the
industry contains high biological and chemical oxygen demand, besides acids,
alkalis, dyes, hydrogen peroxide, starch, surfactants, dispersing agents and soaps
of metals (Paul et al. 2012). Still, the most notable consideration has been given to
the dyes. These dyes are released in high concentration and are persistent even in low
concentration. During manufacturing and textile dyeing-printing, complete
310
S. Sonal and B. K. Mishra