KATHMANDU, JANUARY 22
Even as our traditional water sources and recreational areas are polluted as a result of human activity and other pollutants produced in the city, the Floating Treatment Wetland System (FTWS) has been there to restore the endangered heritage.
Lakes and other wetlands provide water to communities as well as a recreational area and habitat for a variety of plants and animals; however, ponds and wetlands are constantly deteriorating due to polluted water.
Urban water bodies like Nagdaha in Dhapakhel, Lalitpur, get contaminated water from nearby settlements and agricultural and grazing lands through seepage and runoff.
"These bodies of water become saturated with excessive nutrients such as ammonia, nitrate, and orthophosphate, resulting in eutrophication," said Ayashwori Byanju, research assistant at the Small Earth Nepal, adding.
"It harms the aquatic ecosystem, reduces scenic beauty, and degrades water quality, rendering it unsuitable for human use."
A nature-based solution known as the Floating Treatment Wetland System (FTWS) has been recently implemented in Dhanmondi and Gulshan lakes in Bangladesh, Naya Goan Talai in India, and Nagdaha in Nepal by Small Earth Nepal (SEN), with support from the Asia-Pacific Network for Global Change Research (APN) and collaboration with various national, international, governmental, and non-governmental organizations from five countries (Bangladesh, India, Japan, Nepal, and the United States of America).
"This serves as an eco-technological means of lowering the pollution level of these water bodies, according to Byanju," she told THT.
She also emphasized that FTWS employs phytoremediation plants that float freely on a synthetic buoyant mat, supporting shallow-rooted plants with roots that hang freely in the water column.
"The hanging roots, with the help of associated pollutant-degrading microbes, absorb pollutants from water bodies, thereby controlling lake water pollution," she added.
Similarly, Dr. Dhiraj Pradhananga, UNESCO Chair in Mountain Water Sustainability, stated that the project was successful in carrying out the microcosm study and field prototype study of FTWS by providing a common platform for scientists, researchers, students, local stakeholders, and policymakers.
"In Nepal, a microcosm study was conducted on the grounds of the Kathmandu Valley Water Supply Management Board (KVWSMB), Bhaisipati, Lalitpur, using locally available indigenous flowering plants," he said.
Meanwhile, research assistant Byanju emphasized that, within the two months of the study, the major pollutants, nitrate, ammonia, and biological oxygen demand (BOD), had been reduced by 99%, 56%, and 41%, respectively, in comparison to the initial concentration, according to the microcosm study's results.
The study used two plant species: Tradescantia pallida and Canna indica, also known as Indian shot and Purple Heart, respectively.
"We found that while Tradescantia pallida was better at reducing the concentrations of ammonia and nitrate in the water, the Indian shot was effective in reducing nitrate, ortho-phosphate, and BOD," she claimed.
According to her, they created field prototypes of the floating rafts and installed them in Nagdaha in collaboration with youth clubs, volunteers, communities, and local stakeholders.
"The lake's floating rafts provided a platform for local governments and communities to monitor and learn more about the FTWS as a pollution remediation technology," she said.
Likewise, Dr. Dhiraj Pradhnanga said that the FTWS technology has shown to be a successful phytoremediation method in eliminating too many nutrients from
contaminated lake water, improving its quality.
"As a consequence, the quality of the lake's water has improved, which helps manage the growth of invasive plants and enhances aquatic ecosystems, resulting in safe drinking water for people," he said.
"This technology may offer communities and local governments a way to improve the water quality of urban lakes that face comparable water pollution issues."
