improper disposal of dyes especially azo dyes to water bodies is of great concern
since the ecosystem can be disturbed by inappropriate disposal and, due to their
and carcinogenicity and toxicity, constitutes a potential health and environmental
problem. For the treatment of azo dye wastewater, chemical, physical, and biological approaches have been used. Biological technique has been renowned as
environmentally friendly, inexpensive, and having viable properties. Decolorization is the method in which the azo bond is being broken down, and it is the first
step for the degradation of azo dye. Several types of bacteria and fungi have the
capability of decolorization; however, limited of them have been accepted by the
textile industries. The lack of implementation is primarily accredited to the low
efficiency of the technique, for the growth and activity of microorganisms are
inhibited owing to the toxicity and salinity of azo dye wastewater. In recent years,
the plant’s ability for stimulation of bio-decolorization of azo dye has received
much attention.
A constructed wetland model for synthetic reactive dye wastewater treatment by
narrow-leaved cattails (Typha angustifolia Linn): Wastewater of textile industry is
contaminated by reactive dye that results in unattractive levels of wastewater color,
high salt content, and high pH when discharged into public water systems. A sustainable and alternative method for decolorization of textile wastewater by plant is
phytoremediation which is suitable for long-term operation. For this purpose,
narrow-leaved cattails are used which is one of the species of wetland plant with
efficiency for decolorizing and remediating textile wastewater. Furthermore, chemical
oxygen demand (COD) can be controlled or lowered, and residue of dye can be
removed. The narrow-leaved plants are salt tolerant and also performed a good salt
tolerance, even after being exposed to a salt solution for 15 days. In a constructed
wetland model with a vertical flow system, the narrow-leaved cattails were set up,
operating from bottom to top for synthetic reactive dye wastewater (SRDW) removal.
The removal of SRDW can be achieved by narrow-leaved cattail at approximately
0.8 g (SRDW) m(-2) day
-1
. Approximately 60% DE colorization of SRDW was done
by this plant. The reason for the selection of this method in textile industry is that it is
suitable for textile wastewater management and wetland’s improvement. The COD
can be lowered or controlled by these plants, and also it can remove dye, sodium, and
total dissolved solids (TDS), but in contrast, other biological and chemical methods
could not remove TDS and dye at the same time. According to the results of this
research, the cell structure of this plant which is spongy in nature has the ability to
absorb large amounts of nutrients and water. Physicochemical analysis revealed
increasing amounts of sulfur, silicon, iron, and calcium in the plant leaves and roots
after exposure to wastewater. The amide group or protein in the hydrophytes might
help in the textile dye removal. During the process of decolorization, this plant
accumulates dye in the intercellular space and still grows in this SRDW condition.
Hence, it is proven here that for textile dye wastewater treatment, narrow-leaved
cattails are efficient (Nilratnisakorn et al. 2009).
Plant-water-soil-microorganism and their interaction in CWs: The system of
constructed wetland is a complex man-made system that serves as filter for wastewater that can mimic the natural wetland structure. The treatment of wastewater by
6 Constructed Wetlands: A Clean-Green Technology for Degradation and. . .
149
since the ecosystem can be disturbed by inappropriate disposal and, due to their
and carcinogenicity and toxicity, constitutes a potential health and environmental
problem. For the treatment of azo dye wastewater, chemical, physical, and biological approaches have been used. Biological technique has been renowned as
environmentally friendly, inexpensive, and having viable properties. Decolorization is the method in which the azo bond is being broken down, and it is the first
step for the degradation of azo dye. Several types of bacteria and fungi have the
capability of decolorization; however, limited of them have been accepted by the
textile industries. The lack of implementation is primarily accredited to the low
efficiency of the technique, for the growth and activity of microorganisms are
inhibited owing to the toxicity and salinity of azo dye wastewater. In recent years,
the plant’s ability for stimulation of bio-decolorization of azo dye has received
much attention.
A constructed wetland model for synthetic reactive dye wastewater treatment by
narrow-leaved cattails (Typha angustifolia Linn): Wastewater of textile industry is
contaminated by reactive dye that results in unattractive levels of wastewater color,
high salt content, and high pH when discharged into public water systems. A sustainable and alternative method for decolorization of textile wastewater by plant is
phytoremediation which is suitable for long-term operation. For this purpose,
narrow-leaved cattails are used which is one of the species of wetland plant with
efficiency for decolorizing and remediating textile wastewater. Furthermore, chemical
oxygen demand (COD) can be controlled or lowered, and residue of dye can be
removed. The narrow-leaved plants are salt tolerant and also performed a good salt
tolerance, even after being exposed to a salt solution for 15 days. In a constructed
wetland model with a vertical flow system, the narrow-leaved cattails were set up,
operating from bottom to top for synthetic reactive dye wastewater (SRDW) removal.
The removal of SRDW can be achieved by narrow-leaved cattail at approximately
0.8 g (SRDW) m(-2) day
-1
. Approximately 60% DE colorization of SRDW was done
by this plant. The reason for the selection of this method in textile industry is that it is
suitable for textile wastewater management and wetland’s improvement. The COD
can be lowered or controlled by these plants, and also it can remove dye, sodium, and
total dissolved solids (TDS), but in contrast, other biological and chemical methods
could not remove TDS and dye at the same time. According to the results of this
research, the cell structure of this plant which is spongy in nature has the ability to
absorb large amounts of nutrients and water. Physicochemical analysis revealed
increasing amounts of sulfur, silicon, iron, and calcium in the plant leaves and roots
after exposure to wastewater. The amide group or protein in the hydrophytes might
help in the textile dye removal. During the process of decolorization, this plant
accumulates dye in the intercellular space and still grows in this SRDW condition.
Hence, it is proven here that for textile dye wastewater treatment, narrow-leaved
cattails are efficient (Nilratnisakorn et al. 2009).
Plant-water-soil-microorganism and their interaction in CWs: The system of
constructed wetland is a complex man-made system that serves as filter for wastewater that can mimic the natural wetland structure. The treatment of wastewater by
6 Constructed Wetlands: A Clean-Green Technology for Degradation and. . .
149