Each day, the Western Virginia Water Authority provides water service to more than 158,000 people through a system of reservoirs and treatment facilities.
Each day for more than 10 years, Virginia Tech scientists and students have used an environmentally friendly approach to help to make sure the water is safe.
Cayelan Carey is an assistant professor of biological sciences whose research interests reside in freshwater and ecosystem ecology. Carey, who received her bachelor’s degree from Dartmouth and her doctoral degree from Cornell, joined the biological sciences faculty in 2013 largely because of the strength of freshwater research at Virginia Tech, including a project at the Falling Creek Reservoir in Roanoke, Va.
In winter 2012, John Little, the Charles E. Via, Jr. Professor of Civil and Environmental Engineering, invited Carey to collaborate on a project to improve Falling Creek’s water quality. At that time, much of the project’s expertise was focused on the engineering necessary to install and operate of a new system to reduce algae. Carey said her research in controlling algae and the opportunity to use a cutting edge engineering system made joining the Falling Creek research team an easy decision, a year before she arrived at Virginia Tech.
Working with a team of students at the smallest of the Western Virginia Water Authority’s reservoirs, the group’s goal was to test the new system to keep algae out of the drinking water supply.
The location of the reservoir, while picturesque, presents a number of issues that make it an ideal candidate for algae blooms.
“The reservoir is small and shallow, it’s in a valley, and it has to contend with the effects of wind,” said Jamie Morris, water production manager with the water authority.
In short, it’s not the best place to be.
It’s also at the end of the line. Falling Creek is fed by streams from much larger reservoirs that bring with them phosphorus. This phosphorus can be stored in the lake sediments and is largely responsible for creating algal blooms.
To help with the issue, the team installed the new water oxygenation system in 2012. Carey and her team have been testing and modifying it throughout 2013. The side-stream saturation system was developed to maintain oxygen at the sediment level by removing water to a small, land-based facility and injecting it with oxygen under pressure before returning it to the same depth in the reservoir. The oxygen helps keep phosphorus locked in the sediments, preventing algal blooms.
The system has never been deployed successfully in a shallow lake, so the researchers are gathering water-quality data while testing new equipment that could provide major improvements to water quality in other lakes.
“The testing we did this summer seems to have gone very well,” Carey said. “We are completing our analysis this fall, but the preliminary results are extremely promising and indicate that the dissolved oxygen system at the reservoir is effective at preventing the release of iron and manganese from the lake sediments.”
The results are excellent news for those who receive the water from the reservoir as iron and manganese contribute to odor in drinking water and negatively affecting the taste and color.
The preliminary success of the system a saves the water authority from having to resort to other methods to ensure a safe supply of drinking water.
“It’s been a great experience working with Virginia Tech researchers and students for the last 10 plus years,” Morris said. “Because of their expertise we can limit the amount of chemicals we use to provide clean, safe drinking water, and we also limit the amount of treatment the water needs. From an environmental perspective this is an ideal partnership.”
“Being able to work with the water authority, and to learn water quality assessment techniques at an operational facility, is a fantastic experience,” Carey said. “It also exposes our students to environments and organizations they will likely work with in their careers after graduation, which is an enormous benefit to our students.”
Cayelan Carey and her research team pump oxygen into the water to control phosphorous concentrations. The team then monitors the effect the oxygen has on the water.