Tertiary Treatment Processes
It is worthwhile to mention that the textile waste contains significant quantities of non-biodegradable chemical polymers. Since the conventional treatment methods are inadequate, there is the need for efficient tertiary treatment process.
Oxidation techniques: A variety of oxidizing agents can be used to decolorize wastes. Sodium hypochlorite decolourizes dye bath efficiently. Though it is a low cost technique, but it forms absorbable toxic organic halides (AOX) [4]. Ozone on decomposition generates oxygen and free radicals and the later combines with colouring agents of effluent resulting in the destruction of colours [5]. Arslan et al. investigated the treatment of synthetic dye house effluent by ozonisation, and hydrogen peroxide in combination with Ultraviolet light [6]. The main disadvantage of these techniques is it requires an effective sludge producing pretreatment.
Electrolytic precipitation & Foam fractionation: Electrolytic precipitation of concentrated dye wastes by reduction in the cathode space of an electrolytic bath been reported although extremely long contact times were required. Foam fractionation is experimental method based on the phenomena that surface-active solutes collect at gas-liquid interfaces. However, the chemical costs make this treatment method too expensive [7].
Membrane technologies: Reverse osmosis and electrodialysis are the important examples of membrane process.