As many as 21 dyeing units, which were operating illegally in Dharmapuri district for the past one week, were closed by the revenue authorities in association with the District Environment Office, official sources said. A revenue official told The Hindu on Sunday that the illegal units were functioning in and around Jarugu, Palacode, Easalpatti, Thenmarudu and Dharmapuri town. The giant-sized cauldron with rings and generators for extracting groundwater were seized. R. Kamalanathan, Tahsildhar, Dharmapuri, said that on the basis of the directions given by Collector R. Lilly, a team of officials inspected some of the illegal units on Friday. It was alleged that dyeing units, which were facing effluent discharge problem in Tirupur, Erode and Pallipalayam had shifted their base to Dharmapuri district. Meanwhile, the Communist Party of India thanked the Collector for her prompt action on its demand to remove illegal dyeing industries.