By Vishnupriya Hathwar
Phytoremediation (phytos – plant, remedy – cure) is a general term used when plants are used to “cure” water or soil and rid them of excess organic and inorganic materials. These materials can range from excess salts to nitrogenous wastes.
Phytoremediation is very common in the natural world. As examples we can consider areas like marshes, wetlands, lakes, streams, lagoons and even agricultural lands such as paddy fields. So what happens here?
Plants take up water and nutrients from the soil to grow and flourish. There are some plants however, which take up certain nutrients in larger quantities and grow faster. They are generally varieties of reeds, grasses, floating plants like hyacinth etc. They take up more of nitrogen, phosphorus, calcium, sulphur containing compounds that are harmful in large quantities to other living organisms. Using these compounds the plants grow and reproduce really fast. This decreases the harmful compounds in the water or soil very quickly and allows other varieties of plants to grow.
A natural system like this supports decontamination, recycling and reuse of resources, while allowing diversity and variety to thrive. Humans have observed this natural system and have put them to use in many places in their own lives. Many people use plants to keep their backyard fish pond clean and healthy, while others use plants to keep larger water bodies and land areas clean and healthy.
At Puttenahalli Lake, floating islands are used for phytoremediation. Vetiver grass is a local South Indian grass which is really good at phytoremediation. This grass also binds the soil and prevents soil erosion. At the lake we have planted clumps Vetiver grass on the sloping banks and planted a few on the floating islands as well. Along with Vetiver, Canna is also used and lotus or lily will soon be introduced.
Floating islands are simple structures containing PVC pipes covered with fishing net. The grass bulbs and crowns are inserted in the net spaces and the plants are allowed to grow. This type of growing plants in the absence of soil is known as Hydroponics. In hydroponics instead of the soil, the water will have the nutrients. Thus, the plants will grow faster and better too!
The PNLIT is striving to make the Puttenahalli Lake cleaner and greener by using native plants and natural methods.