Please tell us about yourself

Shrikalaa Kannan started her PhD in the field of Bioresource Engineering at McGill under the supervision of Dr. Vijaya Raghavan in January 2013. She is a native of India where she completed her undergraduate degree in Biotechnology. During the course of her undergraduate study, she became passionate about bioengineering and technology that drove her to pursue graduate studies in the field of Bioresource Engineering.  Her Master’s thesis at McGill focused on food safety where she employed radiofrequency heating to pasteurize in-shell eggs. Her thesis was awarded “The best graduate thesis – MSc category” by the Canadian society for Bioengineering. She is also the recipient of the Schulich doctoral scholarship for the year 2013, a highly prestigious award of excellence from the Schulich foundation.  She is greatly inspired by her supervisor Dr. Raghavan as he specializes in inventing new post-harvest technologies that helps protect the food produce thereby reducing the wastage from inadequate post-harvest practises.  She is a strong believer of translational research, where the benefit of the scientific research reaches the society immediately. Food research is one such field where scientific intervention and advancements have had huge impact on the quality of life of the people. Her research interests include food waste reduction and utilization.

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What do you do?

Before that beautiful salmon filet lands on your plate, a lot of less appetizing stuff gets stripped away: By one estimate, the global seafood industry produces 64 million metric tons of waste each year. A new study suggests a potentially sweeter fate for all those heads and guts: They can be turned into a coal-like substance called hydrochar, which could be used as fuel or added to soil to improve fertility and sequester carbon.

A few years ago, McGill University graduate student Shrikalaa Kannan learned that the city of Gaspé, Quebec, which has a large fishing industry, prohibited local shrimp processing plants from disposing of seafood waste in municipal landfills. Although solid seafood waste can also be processed into fish meal for fertilizer and feeding livestock, such factories often generate complaints because of their fishy odor. Meanwhile, liquid seafood waste often ends up in the sewage system or in water bodies, where its high nutrient content can stimulate harmful algal blooms. The industry in Gaspé was looking for environmentally friendlier alternatives. Kannan, who was researching technologies to turn waste into biofuel, wondered if she could find a solution that could be used not only in Gaspé, but all over the world.

Previous studies had applied a process called hydrothermal carbonization to transform products including wood and plant residue, sewage, and food waste into hydrochar. During this process, waste is heated with water under pressure and at temperatures of 150–300 °C, generating a series of reactions that produce a carbon-rich solid. The solid can be burned as fuel or added to soil to improve water and nutrient retention while sequestering carbon. But all these previously studied waste streams contain cellulose, which breaks down easily with acid or base treatment, easing carbonization. Kannan wanted to adapt the method for seafood waste, which contains more complex carbohydrates, proteins, and fats.

So she and her colleagues ground up samples of fish and shrimp waste from a local market, and heated them by microwaving the waste in quartz vessels at high pressure and 150 °C for an hour. But they obtained no hydrochar, not even when they treated the waste with acid first. So Kannan tried again, first treating the waste for 16 hours with three commercially available enzyme products used in a previous study that made hydrochar from food waste .

The enzymes, including lipase and protease, hydrolyze complex macromolecules in the food waste into simpler compounds such as glucose. This time, it worked: The team recovered 29% of the dry weight of the fish waste as char, and 36% of the shrimp waste. The char smelled like coffee, Kannan says; she suspects this may be a sign of the Maillard reaction, the reaction between amino acids and carbohydrates that takes place when food is browned.

Next, Kannan plans to determine the carbon content and calorific value of the char to evaluate its potential as fuel. She also wants to test whether treating the waste at higher temperatures could increase the yield.

S. Kent Hoekman, an environmental scientist at the Desert Research Institute in Reno, Nev., says he is impressed with the researchers’ application of an existing technology to a new problem, and the use of enzymes to help carbonize the seafood waste. However, he notes it would be physically and economically challenging to scale up the process for real waste streams, especially because the required enzyme treatment would be expensive and slow. There’s no significant market in the U.S. for biocoal products like hydrochar, but that could change with policies like a potential carbon tax, he says.

How does your work benefit the community?

Seafood processing operations generate enormous quantities of waste in the form of solid residues and liquid effluents. Currently there is an increasing demand for attractive seafood waste utilization strategies that could minimize environmental pollution while recovering products that are of commercial interest. Hydrothermal carbonization (HTC) is a technique that utilizes wet biomass to produce a solid product called hydrochar that has potential for wide applications in the field of energy, agriculture, and material science. Hydrothermal carbonization has been in use mainly to treat lignocellulosic biomass such as wood or agricultural waste. Recently, the Hydrothermal carbonization process has been gaining attention as an efficient waste management tool that can utilize high-moisture-containing complex waste streams, a mixture of lignocellulosic and nonlignocellulosic biomass, such as sewage and municipal waste. However, there is limited knowledge on the effectiveness of Hydrothermal carbonization on purely nonlignocellulosic industrial wastes such as seafood waste.

Shrikalaa Kannan’s research combines two global challenges – increasing sustainability in the current energy technologies and reducing environmental pollution from bio-waste. Her work focuses on the generation of biofuels from bio-waste.