How to remove waste drugs from water supply

Tuesday, April 13, 2010 @ 10:04 PM gHale


There is now a solution that will increase safety and help reduce the rising levels of pharmaceuticals ending up in the water supply.

An advanced wastewater treatment system could remove 90% of pharmaceuticals and endocrine-disrupting compounds (EDCs) using commercially available technology, according to Toronto-based Ryerson University chemical engineering students. There is currently no such sewage treatment plant in North America.

With tap water now the environmentally responsible choice over bottled water, the amount of pharmaceutical medications making their way into the water supply through improper disposal and bodily elimination warrants some concern. So, as part of their final-year undergraduate project, Ryerson’s Kirill Cheiko, Reuben Fernandes, Charles Gilmour and Pawel Kita used research data from academic and industry sources to design a simulated wastewater treatment plant to deal with the potentially harmful waste.

“In Canada, the government doesn’t enforce the removal of pharmaceutical drugs and EDCs, including Bisphenol A, from wastewater. As a result, municipalities don’t currently pursue removal, since it would incur extra expense,” Cheiko said. “That said, it could also potentially reduce health-care costs.”

Quite a few prescription and over-the-counter drugs end up flushed down the toilet. Others do not fully metabolize after ingestion and eliminate from the body soon after administration. While the rate of elimination varies (at least five percent of acetaminophen and up to 80 percent of the antibiotic ciprofloxacin), the final result is the same: biologically resistant contaminants end up in municipal wastewater.

Eventually, those chemicals enter the environment and the drinking water supply. While there haven’t been any studies done to determine the long-term effects of these pharmaceuticals and EDCs on humans, there are concerns. It is not just over the counter prescriptions, even in trace amounts, chemotherapy drugs can inhibit normal cell function; and pain-relievers and blood-pressure diuretics can lead to liver damage.

The students’ design uses two processes in combination, both using commercially available technology. First, wastewater goes through membrane biological reactors. This activity increases the amount of bacteria already present in the treatment process and makes them “hungrier.” From there, sewage goes through an advanced oxidization process. Typically used to treat drinking water, this process works in the same way as an antioxidant does in the body: It destroys harmful toxins. But whereas most wastewater treatment plants use chlorine as a disinfectant the students proposed using ultraviolet light (UV) and hydrogen peroxide for the purposes of advanced oxidation and disinfection. Normally, UV light would be unable to penetrate murky wastewater, but after undergoing the membrane biological reactor, liquid waste in the students’ simulated wastewater treatment plants would be clear enough to permit the use of UV light. Afterward, the students concluded, the wastewater would be clean enough to go straight into lakes and rivers.

The students and faculty advisor Professor Manuel Alvarez Cuenca are seeking funding to test the proposal in Ryerson’s Laboratory of Water Treatment Technologies. They also recommend, however, that municipalities conduct their own research and set up pilot studies around the areas’ hospitals and long-term care facilities, where waste drugs are more abundant.

The price of not acting could be severe, warn the students. “The chronic effects on the human population are still unknown, but we are working with a cautionary principle,” Fernandes said. “It’s worth our time to work on this problem.”

The group’s project, Treating Pharmaceuticals and Endocrine Disruptors at the Source: An Advanced Wastewater Treatment Plant Design, placed 1st for Social Awareness and received an honorable mention for their innovative design of an advanced wastewater treatment plant at the 2010 Ontario Engineering Competition in Waterloo, Ontario.



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