In a key step toward improving the feasibility of reusing wastewater as drinking water, the U.S. Environmental Protection Agency has granted University of Michigan researchers $1.2 million to study how well current treatment methods remove viruses from wastewater.
The team believes that existing techniques may already be effective at removing pathogens, potentially reducing the complexity of upgrading water treatment facilities in drought-prone areas seeking to reuse wastewater and storm runoff for drinking water.
“In areas where water scarcity is becoming a growing concern, they may be forced to look at methods like desalination or potable reuse for their drinking water,” said Krista Wigginton, associate professor of civil and environmental engineering, who will head a three-year study. “If we make reuse rules too stringent, and we’re not giving treatment systems the proper credit for what they’re already removing from the water, we’re going to create a much more expensive project for communities.”
A rising global population and increasingly strained water resources call for a hard look at how to effectively and safely reuse wastewater as drinking water. The World Health Organization estimated that by the year 2025, half of the world’s population will live in areas that qualify as “water-stressed.” Already in the United States, several regions are seeing increased and prolonged droughts that put water supplies in jeopardy.
As the EPA puts it: “The changing climate is challenging many communities to meet their long-term water needs. Reuse of treated wastewater and stormwater for agricultural, nonpotable or even potable uses provides an alternative source of water that can be more reliable than traditional water sources.”
Wigginton’s team will help identify what aspects of water quality can be monitored in real-time to validate that viruses are effectively removed in water treatment processes. They’ll start by evaluating three treatment techniques: ozone treatment, coagulation/flocculation/sedimentation and biological wastewater treatment.
These methods, Wigginton said, likely get less credit than they deserve for their ability to remove viruses. The reason? Viruses are too hard to measure.
In-lab reactors will mimic the various treatment processes, giving the team the opportunity to tweak variables like temperature and the presence of organic matter to discern how the measurable parameters are related to how well viruses are removed. Using this data, Wigginton and the team hope to produce predictive computer models capable of estimating the treatment outcomes.
Then, U-M’s team will work with two utilities — the Southern Nevada Water Authority in Las Vegas and Hampton Roads Sanitation District in Virginia Beach — to conduct pilot studies. Those will provide real-world conditions to verify U-M’s modeling on virus removal.
“We may actually be better at virus removal than we already know,” Wigginton said. “For some of these processes, like ultraviolet light, we already have robust models for predicting how they eliminate viruses. But for others that may not have been studied as much, we don’t have these models. We want to correct that.” EPA officials will be constant partners during the research. The program falls under the agency’s National Water Reuse Action Plan, launched in 2020.