News

After Fuel, its plastic from Food

The environmentalists are concerned that the Plastic is dangerous for the environment. It is the reason for pollution in the Sea, land and also is the reason of dangerous gases when burnt. The need of the bio-degradable plastic with the microns within the limited grade which can be dissolved in the soil. The plastic is un-dissolvable, hence creating environmental problems.

The animals like cattle, buffalo are also swallowing the plastic bags, which results in the death of the animal. 

Extending the hunt for sustainable materials as an alternative to fossil fuel-derived plastics, scientists at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) are working with the humble drylands crop plant sorghum (jowar) and a bunch of microbial minions to help shape a biobased plastic future.

Commonly used bioplastic feedstock (raw materials) are cellulose, starch, glucose and vegetable oil. "We need a good amount of feedstock. Sorghum is a rich source of starch like corn and potato. Starch-based edible cutlery is popular across the world," A Ashok Kumar, sorghum breeder at ICRISAT, said.

In the early 1940s, Henry Ford experimented with making plastic parts for automobiles. He came up with what was called the "plastic car made from soybeans". Since that decade, when mass plastic production began from oil-based materials, its use surged dramatically, becoming a big part of our daily lives. The resulting plastic pollution crisis and awareness of depleting fossil fuel reserves drove research towards alternative, sustainable materials.

For example, Bakeys, a Hyderabad-based company produces edible spoons made by baking a dough consisting primarily of sorghum (Sorghum bicolor), with some additional wheat and rice flour. A startup in the Czech Republic is experimenting with edible coffee cup composed of a cereal based crisp waffle. "People are using sugarcane bagasse as source material for bioplastic but here we developed a sorghum that is far more effective for biomass based plastic and will be much cheaper and more sustainable," Kumar said.

High biomass sorghum hybrids, grown in a hectare, churn out 20 tonnes of dry mass in four months that is double that of normal sorghum and four times when compared to paddy.

Specific techniques are employed to convert these feedstocks into thermoplastic starch, poly-lactic acid, polyhydroxylalkanoates, poly-3-hydroxybutyrate, polyamide 11 and biopolyethylene, which can be processed into biodegradable polymers.

Sorghum biomass specifically, is transformed into polylactic acid which is further processed into bioplastic. In the transformation process, sorghum bagasse has to go through sacharification, fermentation and polymerisation. Bacterial fermentation of sugars derived from sorghum biomass produce lactic acid which is then synthesised by polymerisation to produce polylactic acid.

Ashok Kumar explained when starch is used as feedstock it is put through a sacharification process using enzymes to produce liquid glucose. Special bacteria or fungi can produce lactic acid monomers from liquid glucose. The monomer is then polymerised to produce polylactic acid, a biodegradable polymer.

"Whatever chemicals  are used for generating normal plastic from oil, the same are used here. The major difference is that you are tapping into plant-based raw material. So it is biodegradable but you make it synthetically," Kumar said.

A single search online is indicative of the slowly changing narrative, in favour of bioplastics. Carry bags for shopping, packing material for food items and meats, bin liners for hotels, cutlery, nursery plant pots and trays, wet waste compost bag, plant seed bag, cling wrap, food wrapper and a plethora of products made from plant-based materials vie for attention.

Do-it-yourself (DIY) "plastic from starch" videos are also part of the throng on sustainable solutions.The production and use of bioplastics is considered as a sustainable solution due to low emission of greenhouse gasses.But there are challenges too at both ends of the production cycle. It takes a significant amount of energy to manufacture these plastics and there are question marks on their biodegradability.

Can bioplastic fit in within the current industry infrastructure and does it put pressure on forests (to convert into land for growing feedstock plants)? For starters, the ICRISAT Microbiology Team has in hand three microbial strains that can speed up the break down of the used bioplastic mass (64 percent degradation in 60 days).

"We identified certain microbes (Myceliophthora thermophila ATCC-48104, Aspergillus awamori and Bacillus subtilis) that will degrade the bioplastic very quickly. They are also biodegradable by themselves but you can hasten up the degradation with any of the microbes," he said.

Although, at this stage bioplastics are slightly costlier than normal petrochemical-derived plastics and can't be molded into a variety of things, Ashok Kumar asserts it is worth the effort and expense.

Currently, bioplastics represent about one percent of the about 320 million tons of plastic produced annually.

But with rising demand and with more sophisticated materials, applications and products emerging, the market is already growing by about 20 to 100 percent each year.

"It is worth the effort of making bio-plastics, as it is partly or wholly made from sustainable plant sources and it will blend in with the mainstream plastic supply chain except the usage of raw material and the production process. Going forward it is the era of 'green technologies' and irrespective of the cost considerations we need to embrace them for sustenance of life on earth," Ashok Kumar added.

A report by UN Environment that assesses the potential of replacing certain conventional plastics applications with alternative materials states that is neither possible nor desirable to remove all plastics from society, but alternatives can have a significant role in reducing our dependence.

It further adds that the "purposeful agricultural production of biomass to supply the biopolymer industry has to be balanced against the need to support food production and preserve biodiversity."

"The use of alternatives must be part of a broader strategy towards more sustainable production patterns, particularly for packaging and other single-use items, including the principles of redesign, reduce, reduce and facilitating recycling," the report said.



Share your comments