more-inWeeds, plastic pipes and bottles, usually the bane of most waterbodies, have come to the rescue of Puttenahalli lake. Using polyvinyl chloride (PVC) pipes and discarded one-litre PET (polyethylene terephthalate) bottles, ‘floating islands’ have been created on which various types of weeds are grown (vetiver, canna, colocasia, and alligator grass, among others). Biological Oxygen Demand (BOD), which is an indicator of pollution, has decreased by over 67%, from 188 mg per litre to 62 mg per litre. “There is still a long way to go before we reach the ideal BOD limit of less than 20 mg per litre. We are experimenting with different types of platforms and weeds,” said Usha Rajagopalan, trustee of the citizen-driven Puttenahalli Neighbourhood Lake Improvement Trust (PNLIT), which conceived the project.

Source: The Hindu August 10, 2017 11:26 UTC