Weeding out a green fuel from Dal Lake

The obnoxious weeds choking the picturesque Dal Lake could soon turn out to be a money-spinner, as their rich methane content makes them ideal for biogas production and by-products such as bio-fertilisers.

The Dal Lake, which has been besieged by pollution, encroachment and weed growth, is a major tourist attraction and the Jammu and Kashmir Government has for long been involved in efforts to clean it up. Now, at least one part of the problem seems within sight of resolution. The State's Lakes and Waterways Development Authority is promoting the massive amounts of weed collected from Dal Lake as a valuable raw material for biogas production.

“The weed is rich in methane and we have learnt that there are a number of plants outside India that convert the weed into biogas, thus driving a million-dollar industry,” said Irfan Yaseen, Vice-Chairman of the waterways authority. “Even the by-product is rich in minerals, making it a high-grade bio-fertiliser.”

He says the waterways authority has floated an expression of interest and written to various business bodies in India, describing the project and calling for investment.

Rich haul of weeds

According to preliminary estimates by the authority, the plant will require an initial investment of about Rs 10-12 crore. Sections of the lake would be leased out to the investing company to ensure uninterrupted supply of raw material, says Yaseen.

Every year, more than 100,000 cubic metres of weed are removed, both manually and using machines, from the lake and thrown away as waste. “If commercial exploitation starts then we can take out many more times than the present quantity,” says Saba-u-Saalim, Chief Scientist at the waterways authority.

Currently, the cleared weeds are dumped in a landfill where they rot, and minerals and other matter from the rotting mass leak into the lake via the underground water system.

Waterways development officers are hopeful of turning the menace into an eco-friendly industry. “We can even earn carbon credits for such an industry,” says Saalim

The technology for such a plant is readily available. Sulabh International, too, has explored prospects for biogas generation from weeds. It has successfully demonstrated that biogas can be produced round the year from water hyacinth after harvesting, drying and pulverising it. The pulverised weed can be conveniently transported anywhere for biogas generation.

Weeds can primarily be used to produce biogas (methane), solid and liquid fertiliser and carbon dioxide. Aquatic fern such as Azolla, found in Dal waters, can produce biogas as well as biodiesel, thanks to its high oil content. Azolla can also be used as a sustainable substitute for livestock feed.

The shrinking lake

Over the past four decades, the once splendid Dal Lake has shrunk from 25 sq km to 12 sq km. Drawing flak from the people as well as environmental groups for its poor response to the crisis facing the lake, the Government embarked on a multipronged approach to restore the Dal to its former glory. In 2009, the Union Government approved a Rs 1,100-crore rejuvenation project for the lake. A major chunk of the money is going towards resettling and rehabilitating nearly 70,000 people living close to the waters to a new colony on the fringes of Srinagar city.

Adding to the lake's pollution are the floating vegetable gardens, sewage from numerous hotels, encroachments, declining water inflow, weed infestation and global warming. The waste generated multiplies during the tourist season. Explaining the measures taken to stem the flow of untreated sewage into the lake, Saalim says, “We are laying a network of 27 km of sewerage pipelines, which are connected to three treatment plants that can handle 15.2 million litres of sewage a day.”

Wetlands — a natural filter

Around 40,000-50,000 tonnes of material, including silt and nutrients, are added annually to the lake, greatly reducing its depth and boosting the growth of weeds.

The waterways authority is working on a plan to create artificial wetlands in and around the lake to act as a bio-filter.

“We are reviving the old wetlands in the hinterland, and we want to develop certain wetlands that can treat the nutrients that come from the upper catchments,” says Saalim.

To ensure transparency and stave off corruption in such a major project, the Union Ministry of Environment has approved the State Government's request for a monitoring authority. A panel of experts and consultants drawn from across the country will monitor the Dal Conservation project as a third party.

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