A non-aesthetic pollution and are serious health-risk factors.However,

A large variety of organic dyes are extensively used in many fields of up-to-date technology involving various branches of the textile industry , leather tanning industry , paper production , food technology , agricultural research , light-harvesting arrays , photoelectrochemical cells and in hair colorings .Important quantities of synthetic dyes are discharged in the environment from industrial effluents . A loss of 1–2% in production and 1–10% in use are a fair estimate. For reactive dyes in the textile industry, their loss can be about 4%. The presence of these pollutants in waters can change their appearance, e.g. 1 mg dm?3 of a dye is likely to cause visible colorization of the water or alter the clarity. Due to their large-scale production and extensive application, synthetic dyes can cause considerable non-aesthetic pollution and are serious health-risk factors.However, the growing impact of environmental protection on industrial development promotes eco-friendly technologies, reduced consumption of water and lower output of wastewater , the release of important amounts of synthetic dyes to the environment causes public concern and legislation problems are a serious challenge to environmental scientists. The impact and toxicity of these pollutants in the environment have been extensively studied . However, the knowledge concerning their carcinogenic, mutagenic and bactericide properties is still incomplete owing to the large variety of dyes produced.Since dyes usually present high stability under sunlight and resistance to microbial attack and temperature, the large majority of these compounds are not degradable in conventional wastewater treatment plants. The research of powerful and practical treatments to decolorize and degrade dyeing wastewaters to decrease their environmental impact has then attracted increasing interest over the past two decades1.In textile industries the wastewater that contains dyes are main source of acute pollution2. Application 7/105 metric ton dyes are produced worldwide annually. 100 tons or less are used in 90 % of textile products per annum3. During dyeing process 10-25% dye lost occurs. In various environmental components 2-20% dyes are released as effluents.A large quantity of water is used in processing (90-94%) during dyeing and less quantity for cooling (6-10%). It is recommended that the water must be recycled due to high contamination of water during finishing and dyeing process4Due to colored products of dyes world becomes more attractive. But many of these textile dyes are accounted as pollutants. Chemical finishing in textile are major cause of these pollutants5. For synthetic and natural dyes , origin and nature are considered as initial criteria for their classification. In past 2600 BC animal and vegetable resources are used to prepare dyes in China. Dyes for clothes of Egyptian mummies were also used for encasing and obtained from Rubia plants. Indigofera plants were used 3000 BC to synthesize indigo dyes. Crushed predatory sea snails were used to prepare Tyrian purple dye by old Phoenicians civilizations since 15th century