Shrimp waste: From industrial garbage to offshore oil spill cleaner
Each year, approximately 100,000 tons of shrimp are landed by Newfoundland and Labrador’s fish harvesters.
With that comes approximately 40 per cent of unused byproduct.
Although much of the industrial waste is transformed into value-added products, a research team in the Faculty of Engineering and Applied Science is working to find the hidden value in the remainder.
“Shrimp wastes generally contain a significant percentage of protein and calcium,” said Dr. Helen Zhang, an associate professor in the faculty and the lead researcher on the project. “The relative abundance and high protein content make shrimp waste a promising resource for producing peptide-based dispersants.”
Dr. Zhang and her team acquire shrimp waste from local processing plants. They then treat the raw materials to generate an environmentally friendly dispersant – a dissipating, or scattering, agent, to combat offshore oil spills. A dispersant’s key component is surfactant molecules.
When used to clean up a spill, the dispersants start working immediately to break up the oil layers, or oil slicks, into small droplets, which increases the solubility of the oil into water.
Once oil hits the water, the natural bacteria, or other microorganisms, in the marine environment can degradate the oil, but it is difficult for the microorganisms to treat the layers of oil. That’s where the dispersant comes into play.
“We ‘disperse’ the oil layers into smaller droplets, which is easier for biodegradation,” said Dr. Zhang. “Eventually, the dissolved oil can be converted into carbon dioxide and water.
“The significantly less toxicity and effective dispersion demonstrated that this dispersant is an environmentally friendly alternative,” she continued. “It could achieve effective dispersion even at low salinity and under low temperature, which makes it applicable in harsh environments.”
Dr. Zhang says she and her team use enzyme-based hydrolysis, which is the chemical breakdown of a compound due to reaction with water. Essentially, that means they introduce enzymes to induce the extraction of proteins from the wastes. The hydrolysate liquids then go through further treatment to become dispersants.
Dr. Zhang came up with the idea to use shrimp waste as a green means of cleaning up oil spills when she was conducting biosurfactant work.
“In 2002, I was investigating the chemical structures of biosurfactant molecules and how they can be produced,” she said. “From there I started to think about how the green surfactants could be applied to solve real-life environmental problems.
At the time, Dr. Zhang was using the molecules for soil and groundwater remediation. When she arrived in St. John’s to take up her position at Memorial, she started to explore how the molecules might work to help clean up offshore oil spills. It was then that she adapted her existing studies to the development of green dispersants for use in the offshore oil industry.
“I attempt to not only treat the shrimp wastes, but to convert them into green products, into something useful.”