Environment
Karnataka / Environment
These artificial floating platforms have nutrient-absorbing saplings that grow by absorbing pollutants from water.
Arundhati Sarkar| Sunday, December 4, 2016 - 19:16

Residents of JP Nagar are leaving no stones unturned to restore the polluted Puttenahalli lake to its pristine form. To sustain the ecology of the lake, which attracts migratory birds and is home to several aquatic creatures, the Puttenahalli Neighbourhood Lake Improvement Trust (PNLIT) has set out on another mission.

The trustees have launched artificial floating platforms (AFI) with nutrient-absorbing saplings that grow by absorbing pollutants from water, and in the process clean the lake.

How it all began

PNLIT explored alternate sources of water since rain water was insufficient. From May 2015, they began feeding the lake with treated water from the sewage treatment plant (STP). Earlier in 2016, Deloitte Shared Services India Pvt Ltd became their CSR partner to clean the lake of weeds. In June, they introduced the AFIs and also tied up with BMS College of Engineering to test the water for quality.

After filling the dry lake, the members then began looking at various options such as installing an aerator to circulate the water below the surface of the lake, or a fountain that would be aesthetically appealing.

However, since both the options were expensive and required maintenance, Usha Rajagopalan, a trustee of the citizen-driven Puttenahalli Neighbourhood Lake, recounts, “We decided to look for inexpensive and easier options.”

This is when, the idea of  AFIs occurred to them. Usha states that the concept of the AFI was captivating, simple, and had a visual appeal.

Once the first prototypes were installed, Eurasian Coot, a species of bird that lives on freshwater lakes and ponds, promptly built its nest on them. “This way, the biodiversity of the place is sustained”, Usha says.

Usha says overall there has been a steady improvement in the quality of water as the weeds are being removed.

The process of making Artificial Floating Islands

Nupur Jain, a social worker by profession and a trustee, says the islands have been made by her along with her husband Pranshu Jain and their gardener Jayanna.

Speaking about the design and the process, Nupur explains that the square base of the floating islands have been made using PVC pipes.

After the frames were ready, it was placed on ultra violet stabilised net. Following this, saplings were inserted into the net; in some cases saplings were put in small pots made from old bottles to see which ones would grow better.

On each island, around 20-25 saplings were planted, and then a finer mesh was placed on top for the plants to grow. Once ready, the islands were ready into the lake.

“The platforms were made in a way, that it floats, is stable in all the weather conditions, and does no harm to the water life,” Nupur says.

Benefiting the ecosystem

Plants like “Canna, Vetiver, Colocasia were selected as they are natural bio filters”, and absorb the organic nutrients from water, thereby purifying it.

Each plant has an advantage- Colocasias are said to be good biofilters, and the roots of the Vetiver are very long which helps in absorbing pollutants from the depths.

“The plants are all growing, and are also acting as perches and nesting places for birds,” Usha says.

The gardener removes unwanted vegetation and aquatic weeds to expose the water to the sun, and also replaces the plants in the platform whenever needed.    

Currently, there are seven islands on the lake and the trustees plan to assess the quality of the water and then make more such islands with other kinds of plants.

The outcome

Puttenahalli lake today is beaming with life. The trustees are delighted to see steady improvement, and feel “the trends are very encouraging.”

With the water quality good enough for aquatic lives to thrive, the Fisheries Department has released fingerlings in the lake which will be harvested soon.

Ducks, birds, fishes of various species, and butterflies, are all making their way to the lake once again.  

All images courtesy: Nupur Jain