Pharmaceuticals in wastewater target of sewage treatment study
Studies show some pharmaceuticals can harm fish, but effects on humans still not clear
It looks a bit like something that was cobbled together with stuff found in the basement. Two small tanks, a hodgepodge of pipes and some dirty tubes that make up the membrane.
But scientists at Acadia University hope this bioreactor is the solution to an emerging question: how to stop traces of medications swallowed by Canadians and excreted into toilets from slipping through wastewater treatment plants and into streams, rivers and lakes.
"The municipal wastewater plant, they're not designed to treat the pharmaceuticals," says Anthony Tong, a professor of chemistry at the university. "That is the major concern here."
Tong and his team will soon begin testing the device and the special membrane that's been devised, an effort that throws traditional sewage treatment methods for a loop.
Rather than kill bacteria in sewage water, researchers are looking to pinpoint particular strains that can be effective in breaking down pharmaceuticals. The membrane will hold on to those bacteria, using what's already in the wastewater to clean out contaminants.
"It's doable," Tong says. "It's more of a how and when we are going to implement a new technology to improve the pharmaceutical treatment efficiency."
Pharmaceuticals end up in wastewater because drugs are not completely metabolised. In some cases, as much as 90 per cent passes through our bodies.
N.S. waste water tested
In recent years, Acadia researchers have sampled water leaving more than 20 sewage treatment plants across Nova Scotia, testing each for 13 commonly used pharmaceuticals and finding traces of all.
The list includes drugs to treat diabetes, inflammation and depression, and household staples like acetaminophen. Scientists also looked at caffeine and cotinine, which is found in tobacco.
The levels of pharmaceuticals in samples varied greatly, Tong said, depending in part on the level of treatment the water received. The chemist's aim is to improve on that, creating a system that can be easily added to sewage plants to specifically target pharmaceuticals.
The work adds to an emerging body of research examining pharmaceuticals that are going down household toilets and eventually emerging in the environment.
Tong says most of the samples he and his team tested revealed only trace amounts, not enough to have an "acute toxic effect."
The worry, he says, is bioaccumulation — pharmaceuticals building up in tissue over time and making their way up through the food chain.
The amounts detected in other studies are generally small and it's not clear what effect, if any at all, this might have on humans. But scientists have shown some pharmaceuticals can harm aquatic reproduction.
Last year, Environment Canada officials told a Senate committee hearing that more than 165 individual pharmaceuticals and personal care products have been identified in water samples.
The difficulty in determining wider implications is that wastewater treatment plants are all different and the "cocktail" of pharmaceuticals that come through them vary, says Wendy Krkosek, a research engineer with Dalhousie University's Centre for Water Resources Studies.
The ongoing research is being monitored by Halifax Water, which runs several wastewater treatment plants in the metro area.
Susheel Arora, director of waste water services, says sewage plants are generally not designed to remove pharmaceuticals, but some are still eliminated through regular treatment.
He says some ecotoxicity studies show changes in fish, but scientists are still looking at the effects of miniscule concentrations.
"That's where the research is going," Arora says. "What is the risk? That's the billion dollar question. What is the risk of these things at those certain low levels."
There are currently no national standards specifically governing the treatment of pharmaceuticals in wastewater. And Arora says he believes it will be a "long time" before sewage plants are required to filter out such contaminants.