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Treatment of textile dyes using biological and physiochemical techniques

Aim of the project
This project is focused on degradation of textile dyes using white-rot fungi and combining anaerobic-aerobic bacterial processes. Part of the effort is also on photocatalysis, though being a physico-chemical process it has many advantages. First a laboratory scale treatment process for synthetic wastewater will be developed. Once this is achieved the next step will be to build a pilot plant at a textile factory in India. The final goal is to be able to reuse the treated wastewater within the factory.

Why are textile waste waters problematic?
In textile industries, considerable amounts of water and chemicals are used. During the dyeing process about 20% of dye is lost to the wastewater and wastewaters from textile industries usually contain large amounts of dyes as well as organic matter, salts and other substances.

Cloth has been dyed for centuries, but the environmental problems arose first after industrialization replaced traditional natural dyes by the synthetic dyes used today. Since synthetic dyes are designed to resist bleaching by UV-light and chemicals to improve the quality of the textiles, they are also persistent in the environment and some dyes can be biologically modified into carcinogenic compounds. The release of untreated wastewater poses a threat to the environment and the most serious problems are ground water and surface water pollution. Further, the discharge of colored effluents into water bodies affects the sunlight penetration which in turn decreases both the photosynthetic activity and dissolved oxygen levels.

The removal of dyes from textile wastewater is one of the major environmental challenges. Since the majority of dyes are recalcitrant to conventional biological methods the most common techniques used today are physico-chemical. However, many of these methods suffer from limitations. They are usually not cost-efficient and most of them lead to generation of hazardous waste that needs to be dealt with separately. There is thus a need for new treatment options. Promising alternatives are biological treatment methods such as white-rot fungi or sequential anaerobic-aerobic treatment, which offer inexpensive and environmentally friendly ways to treat dye containing wastewater.