Bengaluru: The floating islands that clean Agara, Madiwala lakes

Bengaluru: Continuous pollution of lakes across the city has been one of the major environmental concerns for citizens, who want to revive lakes to their pristine glory. To reduce pollution and cut down level of heavy metals in waterbodies across the city, the Karnataka Lake Conservation and Development Authority (KLCDA) has introduced artificial floating islands (AFI) at Madiwala and Agara lakes on a pilot basis. 

These islands are low platforms on which plants with large root surface are planted. The roots react with pollutants and improve the quality of water. The KLCDA is using vetiver and typha grasses on these platforms to reduce the level of ammonia and nitrogen in lakes.

“The size of the platform is 6x8 sqft and it costs Rs 6,000-8,000 per island, which is cost effective. Also, our staffers are preparing it inhouse,” said Ms Seema Garg, CEO, KLCDA.

The AFI was first introduced at Puttenahalli Lake in 2016 and regular testing proved that the water quality had improved considerably. The water samples were tested every month for pH levels, nitrates and sulphates which showed that pollutants had reduced. 

“These islands are easy to maintain and can be shifted anywhere. The roots flow freely in the water purifying the water,” said Ms Usha Rajagopalan, chairperson, Puttenahalli Neighbourhood Lake Development Trust.

But one should be wary of the number of floating islands as they can choke a lake, warned IISC scientist T.V. Ramachandra, adding that constructed wetlands serve a better purpose than floating islands.

“Plants on islands should be regularly harvested, otherwise photosynthesis comes down. Moreover, any plant can absorb heavy metals. I prefer constructed wetlands, because they are easier to harvest,” he said.