Eco green evaporator for dyeing units

The Green Textile Movement, a division of the NIFT-TEA Knitwear Fashion Institute, Tirupur, has come up with an 'eco green industrial evaporator' to treat textile effluents based on a similar German technology.

As per the Tamil Nadu Pollution Control Board's (TNPCB) advice, the project is being studied further at IIT Madras. The minister has also promised to take the project to the notice of the Chief Minister.

According to the promoters of the project, effluents are initially treated through biological or chemical methods under the present system. Following this, as much as 80 to 90 per cent of the effluents are treated using the Reverse Osmosis system. However, owing to technical reasons, handling the remaining 10 to 20 per cent through evaporators is a major problem. Hence, they are unable to fully adhere to the HC order in 2006, which directed them to use the Zero Liquid Method (ZLM). The final evaporation requires more power or firewood and the machines could also become useless due to the sedimentation of salt on them. Finally, on January 28 this year, the HC ordered the closure of 700 units at Tirupur even thought they spent crores of rupees trying to achieve ZLM. Now, the institute, on the basis of Gradierwerk, a biological method to treat seawater followed in Germany, established a model plant in a unit at SIPCOT in January. The plant has been effectively treating effluents for the past three months. Under this concept, a plant could be established using 30 ft high wooden frames. Then velikathan (thorny shrubs or prosopis juliflora) is sprayed onto its various wooden compartments. The effluents are then sprayed on the overhead of the wooden frame using motors. Following this, the effluents would percolate through the velikathan and evaporate. As much as 1 lakh litres of water with 30,000 TDS ppm of salt treated in such a manner would give an output of 10,000 litres with 20,000 TDS ppm salt. The remaining 10,000 litres could then be converted into solid waste using a crystaliser in a chilling unit, thus attaining ZLM. In comparison to the existing RO system, this new method is more cost effective, environment friendly and could also improve rainfall.