Last fall, they were just four guys with an assignment to complete as part of their final year of chemical engineering studies at Toronto’s Ryerson University. This spring, they are the award-winning designers of a new process for treating waste water that could be used to remove a number of hazardous chemicals currently being flushed out of municipal facilities into lakes, rivers and streams.
The students, Pawel Kita, Charles Gilmour, Reuben Fernandes and Kirill Cheiko, were asked to design a waste-water treatment plant using commercially available technology. It was just one of a number of assignments their professor Manuel Alvarez Cuenca developed for his class of graduating students. In addition, their plant had to be located next to a seniors’ residence and had to be able to remove pharmaceuticals and endocrine-disrupting compounds from waste water.
“Municipal waste-water treatment plants in North America and elsewhere are not designed to eliminate these compounds,” says Fernandes. “Recent studies suggest that there is potential for human health effects when these substances enter our drinking water.”
The presence of these chemicals in tap water is an emerging issue with public health authorities. The students discovered ways to break them down with a three-step process using existing technology. “We combined these systems in a way that hasn’t been done before, as far as we can tell,” says Gilmour.
In the first stage, waste water would enter a plant and go through a series of screening and settling steps to allow gross solids such as oils, grease, grit and other materials to be removed. Next, the partly purified water would go through a series of reactors for biological treatment, which would remove phosphorus, nitrogen, organic content, along with some of the pharmaceuticals and endocrine-disrupting compounds.
A Canadian-developed membrane technology would then separate solids from the water. This filtration system uses thousands of hollow-fibre membranes that are suspended in a vessel. A suction mechanism draws water through billions of pores in the tube walls, filtering out parasites and mineral contaminants.
Once through the tubes, the water would be highly purified and ready for the third stage of treatment: an advanced oxidation process. Hydrogen peroxide would be added, and the water would be exposed to ultraviolet (UV) light, which would create highly reactive compounds to break down the non-conventional contaminants. Together, this unique process would remove 90 percent of the pharmaceuticals and endocrine disruptors.
The students won the annual Ryerson engineering competition for their work and received a social-awareness award in a province-wide engineering competition. But to date, the membrane bioreactor coupled with UV/hydrogen peroxide oxidation remains a concept on paper. They had neither the time nor the resources necessary to acquire equipment and build a prototype.
However, Cuenca is eager to land the research grants that would allow him and the four students to build it. He estimates that it would cost approximately $100,000 to assemble a small, lab-sized waste-water treatment system and to pay for research assistants.
The students are graduating this spring, and all four say they are uncertain what the immediate future holds for them. But their project certainly inspired them.
“We would very much like to continue working on this,” says Fernandes. “We genuinely feel it’s important. It’s easy to stay focused on something when you can see that it has a direct impact on the public. If we get the funding to move forward, most of us would like to commit to it.”