IIT Guwahati researchers develop scalable microalgal biorefinery for green fuel, clean water

New Delhi: Researchers at Indian Institute of Technology (IIT), Guwahati have developed innovative microalgal biorefinery models that turn wastewater into clean energy, according to officials.

The innovative project combines large-scale reactor systems, advanced sustainable thermochemical conversion processes and green chemistry to produce biofuels while treating domestic and industrial wastewater.

The team identified and genetically sequenced over 10 native microalgal strains removing up to 85 percent of pollutants from wastewater.

"To make the process efficient and cost-effective, we built large-scale photobioreactors that maximise algal growth. The team also designed a waste-to-energy system that uses both harvested algae and sewage sludge to produce biocrude oil, a petroleum-like fuel," Kaustubha Mohanty, Professor, Department of Chemical Engineering told PTI.

"This is a proof-of-concept work, where we have demonstrated that how microalgae can bioremediate wastewater as well as produce biofuels under a biorefinery and circular bio-economy approach. We have also developed various processes where all the solid and liquid wastes that are generated under biorefinery get re-cycled, re-used and valorised to biofuels. Now, we are planning to scale-up the work," he added.

Sanjeev Mishra, who was a PhD scholar at IIT Guwahati and now a scientist at SSS-NIBE, Kapurthala, explained that urbanisation has led to a considerable amount of domestic sewage containing various organic and inorganic contaminants "Therefore, it is necessary to develop a process that can resolve the escalating issues of energy security along with simultaneous wastewater treatment in a simple and efficient way. In this context, microalgal wastewater treatment is one of the clean, green, and sustainable process that can integrate with biofuel production under algal biorefinery approach," he added.

The research published in journal Energy Conversion and Management yielded a remarkable 40 per cent biocrude, comprising petrol, kerosene, diesel, and industrial fuel.

"The team went a step further by finding ways to reuse leftover solids and liquids from the process, turning them into valuable byproducts like biodiesel and hydrochar. Based on the theoretical mass balance and scaled up using 1 million litres of domestic sewage, over 2400 kg algal biomass (along with 622 kg of sludge), 99 kg petrol, 266 kg diesel and 234 kg kerosene, besides other things can be obtained.

"To further enhance sustainability, the team developed methods to reuse solid residues and liquid by-products, extracting high-value co-products and working toward pilot-scale biorefinery implementation," Mishra added.