Scientists in Manipur — which dominates the media discourse on insurgency — are on an aggressive hunt for bioenergy sourced from alien plant invaders of the iconic Loktak lake, aiming to showcase the “Jewel of India” as a top bio-entrepreneurship destination.
On the agenda is a proposal to set up a biorefinery, in the lake landscape, that churns carbohydrate-rich feedstock — derived from an invasive weed called paragrass — into alcohol and other value-added chemical products.
Spearheaded by a group of scientists at Institute of Bioresources and Sustainable Development (IBSD) here under the leadership of Director Dinabandhu Sahoo, the search for alternative energy from paragrass (pani wala ghaas or buffalo grass) — a fodder source — also offers a way to rein in the growth of these slow but steady invaders.
“Our study shows that this excessive growth of paragrass can tackled by using it sustainably as a biorefinery feedstock. Initially we will set up a 500 kg capacity as a pilot plant. Subsequently it will be upscaled to industrial scale,” Sahoo, told this correspondent.
The spurt in the growth of paragrass and other weeds, as also algal blooms, is enhanced by the unnatural enrichment of the water body by two plant nutrients, phosphorus and nitrogen (in a process called eutrophication), which ultimately leads to depleted oxygen levels and generally poor water quality.
“Only mechanical removal of the weeds and throwing them around the lake is not going to help. After decay and disintegration of these weeds the nutrients are coming back to the lake (leading to eutrophication). Therefore, we decided to start a bioenergy programme which can create wealth from the waste,” explained Sahoo.
Loktak, northeast India’s largest freshwater lake, is unique for a floating mass of intertwined and semi-anchored thick plant mats, locally known as phumdis.
In these phumdis, about 1.5 metre deep, one encounters fisherfolk (crouched within make-shift huts and shelters) going about their business surrounded by a multitude of plant and animal species, including some very rare ones.
The phumdis, which form a thick biomass or floating meadows, shelter the 206 critically endangered Sangai deer (brow antlered deer), ensconced in the southern corner of Loktak inside the Keibul Lamjao National Park — the only refuge of the animal whose dainty gait is said to have inspired Manipuri dance traditions.
To ensure its survival, an ecological balance must be struck in the wake of changes in the natural flora of the phumdis due to pollution and human interference.
A hour-and-a half drive from Imphal to Loktak throws up views of rotting phumdi biomass (including the alien weeds) along the roadside through Moirang. They have been dragged out by cranes and dumped on roadsides with locals padding them together with mud to farm vegetables.
Though invasive species now dominate the flora and “programmes to remove the invasive grasses have not met with success due to rapid re-growth”, these plants can become unlikely heroes in green energy discoveries, Sahoo believes.
Many parts of the Loktak lake have been taken over by paragrass.
The rest of the landscape is dominated by wild rice grass, phragmites (grass), different types of algae, water hyacinth and the like.
According to agricultural biotechnologist Rajiv Kangabam of the Department of Agricultural Biotechnology at Jorhat’s Assam Agricultural University, paragrass was introduced in Manipur during 1972-1973 to support the state’s dairy industry.
It was reported that cattle feeding on paragrass had enhanced milk production.
“This plant grows luxuriantly in the Loktak lake and prevents the growth of other native species, thereby threatening the indigenous plants,” Kangabam told this correspondent.
Swaying hairy leaves and hollow stems of paragrass floating above the water reach out to visitors as they canoe their way through the phumdis inside the park. One can also spot algal blooms in the water body.
The chemical make-up of these semi-aquatic weed lends itself to being excellent feedstock for bioethanol production.
“It constitutes of 42 per cent of cellulose and about 20 per cent hemicellulose, the hydrolysis of which can yield fermentable sugars which is an excellent feedstock for bioethanol production. For a low cost process, we used sodium hydroxide based pre-treatment,” Sahoo noted, referring to a study published in Bioresource Technology late last year.
One kilogram of biomass processing yields approximately 120 ml of ethanol depending on fermentation efficiency, co-author Sabeela Ummalyma said.
As of now, the focus is on improving the fermentation condition to get maximum ethanol production as well as better pre-treatment condition for getting more fermentable sugars, Ummalyma said.
Sahoo argued that the waste-to-wealth biorefinery approach can be applied to areas facing similar problems.
“Chilika Lake in Odisha is facing a huge problem due to extensive growth of Phragmitis (popularly called Nala) in Nalabana island. Our work on integrated biorefinery to produce mainly bioenergy and biofertiliser will not only solve the environmental problems but also boost the bioeconomy of the region,” Sahoo added.