Eco India Eco India: The East Kolkata Wetlands face an existential threat from property developers This mosaic of salt marshes, settling basins and farmlands is said to be the world's largest natural, biological sewage treatment system. Scroll Staff May 16, 2021 · 08:55 am Play Supervising Producer: Nooshin Mowla | Director of Photography: Prabal Bose | Video Editor: Sujit Lad | Script & Field Producer: Shruti Shrivastava | Script & Associate Producer: Rhea Arora | Executive Producer: Sannuta Raghu We welcome your comments at letters@scroll.in. Eco India Kolkata West Bengal Environment