Harmful algae blooms like the massive one that afflicted Lake Erie in 2011 are a serious threat to our waterways, but a chemistry researcher and his industrial partners are testing a new method of filtering agricultural wastewater with the help of an unexpected material: ground up shrimp and lobster shells.
Chitosan is a material made by treating crushed shellfish with sodium hydroxide, and professor Bulent Mutus is discovering that various forms are effective in lab tests at removing micronutrients, phosphates and metals like copper, zinc, and iron from greenhouse wastewater.
“There’s an inexpensive and plentiful supply of these materials, and we’ve been able to prove in concept that this can work,” said Dr. Mutus. “Now we’re just trying to scale it up in to an actual working filter that we can test in the field.”
Algal blooms are the result of an excess of nutrients, including nitrates and phosphates from household products and fertilizer used in agricultural and recreational settings, running off land into streams and rivers that drain in to warmer lakes. A large bloom could remove the water of oxygen fish and other aquatic wildlife need to survive.
According to a report released February 26 by the Canada-U.S. International Joint Commission, Lake Erie is getting choked up again with the single cell organisms that can form massive soupy blooms. The one that formed in Lake Erie in 2011 extended more than 5,000 square kilometres and was the largest ever recorded in that lake.
The IJC report says to eliminate blooms, authorities need to reduce the amount of phosphorus flowing in to lakes by 40 to 78 percent.
Mutus has tested a variety of chitosan-based solutions in his lab. One involved converting chitosan to beads that were then chemically stabilized and dried in a vacuum oven. Another involved simply coating chitosan flakes with metal ions that enhance the phosphate binding ability of the chitosan flakes. Filters were made by simply placing the chitosan in nylon and then running greenhouse wastewater through them.
Both solutions proved effective at removing phosphates, but the chitosan flakes were more cost-effective. Making the beads requires multiple steps, adding to the cost of production and hampering their potential for commercialization, according to a progress report Mutus recently sent to Farm and Food Care Ontario.
A non-governmental organization that increases awareness about farming and food in the province, Farm and Food Care Ontario funded the research through its Water Resource Adaptation Management Initiative. Bruce Kelly, the organization’s environmental program lead, said he’s optimistic about the project’s initial results.
“We’re delighted to help a project progress from an idea on a lab bench to a possible commercial venture,” he said. “This has the potential to address the agricultural waste water streams at greenhouses and vegetable washing facilities.”
Mutus is also working with Windsor-based PPG Chemfil Canada Ltd. to develop a working filter that can be tested this summer. Andrew Conway, the company’s vice president and chief operating officer, said his company is typically focused on the automotive industry, but this project offers a chance to expand into the agricultural and food processing sectors.
“I'm quite optimistic with this product's potential,” he said. “Based on what Bulent has shown us, we can see a potential product that can take us in a whole different market direction. That's very exciting.”