New Delhi, May 4 – Researchers at the Indian Institute of Technology (IIT), Guwahati, have made significant strides in sustainable energy solutions by developing innovative microalgal biorefinery models that convert wastewater into clean energy. This groundbreaking project integrates large-scale reactor systems, advanced sustainable thermochemical conversion processes, and green chemistry to produce biofuels while simultaneously treating both domestic and industrial wastewater.

The research team has successfully identified and genetically sequenced over 10 native microalgal strains capable of removing up to 85 percent of pollutants from wastewater. According to Kaustubha Mohanty, a professor in the Department of Chemical Engineering, the team constructed large-scale photobioreactors designed to maximize algal growth. They also created a waste-to-energy system that utilizes both harvested algae and sewage sludge to generate biocrude oil, a petroleum-like fuel.

“This proof-of-concept work demonstrates how microalgae can bioremediate wastewater and produce biofuels within a biorefinery and circular bio-economy framework,” Mohanty stated. He emphasized that the project incorporates processes that recycle, reuse, and valorize all solid and liquid wastes generated during the biorefinery operations. The team is now focused on scaling up their findings.

Sanjeev Mishra, a former PhD scholar at IIT Guwahati and current scientist at SSS-NIBE in Kapurthala, highlighted the pressing need for efficient wastewater treatment solutions due to urbanization, which has led to increased domestic sewage containing various organic and inorganic contaminants. “Developing a process that addresses energy security while treating wastewater effectively is crucial. Microalgal wastewater treatment offers a clean, green, and sustainable approach that aligns with biofuel production under the algal biorefinery model,” Mishra noted.

The research, published in the journal “Energy Conversion and Management,” reported an impressive yield of 40 percent biocrude, which includes petrol, kerosene, diesel, and industrial fuel. The team further advanced their approach by identifying methods to reuse leftover solids and liquids from the process, transforming them into valuable byproducts such as biodiesel and hydrochar.

Based on theoretical mass balance calculations, when scaled up to process 1 million liters of domestic sewage, the biorefinery could produce over 2,400 kg of algal biomass, along with 622 kg of sludge, 99 kg of petrol, 266 kg of diesel, and 234 kg of kerosene, among other products. Mishra added that the team is committed to enhancing sustainability by developing methods to extract high-value co-products and working towards the implementation of pilot-scale biorefineries.