BHUBANESWAR: For years, the smoke from the burning paddy stubble has been catching large parts of North India in its toxic choke, and the government floundering for a way out. The answer seems to have been found, with scientists striking value in the farm waste by converting them into bio-bitumen, which can be used for road construction and various other purposes.
The idea of agricultural waste replacing conventional bitumen in road construction may sound futuristic, but thanks to the pioneering research led by the CSIR-Central Road Research Institute (CRRI) in collaboration with the Indian Institute of Petroleum (IIP), the bio-bitumen produced from paddy straws has successfully undergone field trials in Guwahati and Nagpur-Mansar bypass on NH-44.
A very enthused Union minister for Road Transport and Highways Nitin Gadkari announced at the recently held 84th Indian Roads Congress in Bhubaneswar that farmers could soon become not just ‘annadata’ (food-providers) and ‘indhan data’ (fuel producers) but also ‘bitumen data’ (bitumen producers).
India generates around 157 million tonne of grains annually and nearly 600 million tonne of crop residue, much of which is burned in the open and is the root cause of the serious pollution in North India. Since India boasts the world’s largest road network and nearly 90 per cent of roads use a bituminous top layer, bitumen consumption that stood at 88 lakh tonne in 2023-24 is projected to touch 100 lakh tonne this year. The country spends nearly Rs 30,000 crore on bitumen imports as half of the requirement is met through imports.
“This is where bio-bitumen produced from wastes offers a dual solution. With a blending capacity of up to 30 per cent, the bio-bitumen can significantly cut dependence on petroleum-based bitumen. The product has immense environmental benefits as it can reduce greenhouse gas emissions by nearly 70 per cent compared to conventional bitumen ,” said director of CRRI Prof Manoranjan Parida.
As the combustion of crop residue contributes massively to global warming, smog formation and serious health hazards, Prof Parida said, the bio-bitumen could be a sustainable and scalable solution that will support both farmers and the environment. “After a series of successful field trials, a patent for the technology has been filed. Several companies have evinced interest in producing the bio-bitumen from straw. We will soon transfer the technology. Farmers can now sell their farm residues instead of burning it,” he said.
CSIR- CRRI has developed two types of bio-bitumen - one by its own scientists in collaboration with CSIR-IIP ( Indian institute of Petroleum) and another in collaboration with Pune-based Praj Industries. Behind the innovative products are three brains - senior principal scientist of CRRI Ambika Behl, principal scientist G Bharath and scientist Rajiv Kumar. According to them, one tonne of paddy straw can produce 30 per cent biochar, 35 per cent bio-oil and 35 per cent biogas. The bio-oil is then refined through multiple chemical processes to create bio-binder (bitumen) suitable for road construction.
Behl said the idea of bio-bitumen struck while finding the solution for New Delhi’s toxic smog during winter, caused largely due to stubble burning. “Our research shows that agricultural biomass contains aromatics similar to those found in petroleum bitumen. Through pyrolysis, we could convert paddy straw into bio-bitumen, which can be an eco-friendly substitute to conventional bitumen,” she said.
In laboratory mix design, CRRI prepared bio-bitumen using lignin and CRMB-60 (crumb rubber modified bitumen). The bio-binder was lab tested for strength, durability and moisture resistance besides its overall performance before being commercially produced by Praj Industries. While the petroleum-based bitumen costs Rs 50 per kg, bio-bitumen from biomass can be available at Rs 40 a kilo.
“The performance of the bio-bitumen mix is almost identical to conventional bitumen. In fact, the tensile strength ratio and resilient modulus at 35 degree Celsius were found to be superior to fossil-based bitumen mixes. The field trials so far have successfully demonstrated up to 30 per cent replacement of industrial-grade bitumen with lignin-based bio-bitumen,” Behl said.
CRRI in a joint venture with Bharat Petroleum Corporation Limited (BPCL) has also developed an innovative technical textile product - geocell from municipal wastes, mostly plastics.
As part of its mission to create wealth from waste, the institute has come up with new geocells in accordance with civil engineering parameters so that it can be used in road constructions.
Along with Behl, principal scientist of CRRI Gagandeep Singh and chief manager (research and development) of BPCL Mahesh Kasture are part of the research team. The geocells developed by the team are five times more cost effective than the conventional ones. The product, which is expecting a patent soon, has also received all the mandatory approvals and is ready for commercialisation.
“Once a useful material, plastic has emerged as a threat to the environment with civic authorities finding it difficult to dispose of. The geocells derived from the plastic waste have undergone field testing in extreme hot and cold conditions. After the lab trials, it has been used on the Garhmukteshwar-Meerut Expressway. Once produced commercially, the geocells will address environmental challenges posed by waste plastics,” said Singh.