Reuse of Salt-Containing Dyeing Effluents by Means …
15
Although the values presented in Table 2 are indicative and should be adapted to
each particular situation, this table can be used as a guide to determine the current
density value required to carry out the EC-UV treatment.
7.2 Results of Wastewater Colour Removal
The treatment of high conductivity liquor baths with the EC-UV system enables
to reach a fast and complete removal of colour of effluents, even in cases of deep
colouration, as can be seen in Fig. 9.
During the EC-UV treatment, the dye molecules are broken down into smaller
ones, which are also soluble but uncoloured or slightly coloured. Thus, the effluents
are decoloured with the advantage that no sludge or solid waste are generated.
As it has been specified before, the effluents must only to meet some characteristics
in order to ensure the proper functioning of the EC-UV system:
• pH between 9 and 12
• Conductivity > 30 mS/cm.
When they accomplish these characteristics (or these parameters are adjusted to
meet them), the effluents could be directly treated with the EC-UV system. The
addition of chemicals is not required as the electrons supplied by the electricity are
the only reagent. The salts already contained in the effluents act as an electrolyte to
transport the electrons through the solution.
As an example, Fig. 10 shows the results of decolourisation after the application
of EC-UV treatment to three residual dyebaths with a wide range of conductivity
Fig. 9 Reactive dye effluents treated to 100% colour removal (pH 10.6–10.7, conductivity 60–120
mS/cm)
15
Although the values presented in Table 2 are indicative and should be adapted to
each particular situation, this table can be used as a guide to determine the current
density value required to carry out the EC-UV treatment.
7.2 Results of Wastewater Colour Removal
The treatment of high conductivity liquor baths with the EC-UV system enables
to reach a fast and complete removal of colour of effluents, even in cases of deep
colouration, as can be seen in Fig. 9.
During the EC-UV treatment, the dye molecules are broken down into smaller
ones, which are also soluble but uncoloured or slightly coloured. Thus, the effluents
are decoloured with the advantage that no sludge or solid waste are generated.
As it has been specified before, the effluents must only to meet some characteristics
in order to ensure the proper functioning of the EC-UV system:
• pH between 9 and 12
• Conductivity > 30 mS/cm.
When they accomplish these characteristics (or these parameters are adjusted to
meet them), the effluents could be directly treated with the EC-UV system. The
addition of chemicals is not required as the electrons supplied by the electricity are
the only reagent. The salts already contained in the effluents act as an electrolyte to
transport the electrons through the solution.
As an example, Fig. 10 shows the results of decolourisation after the application
of EC-UV treatment to three residual dyebaths with a wide range of conductivity
Fig. 9 Reactive dye effluents treated to 100% colour removal (pH 10.6–10.7, conductivity 60–120
mS/cm)