Students Design Automated, Cost-Effective Water Treatment System

July 2, 1998

GAINESVILLE — An automated water treatment system designed by University of Florida engineering students reduces the cost of treating drinking water while boosting its quality.

The system is expected to result in substantial savings at Gainesville Regional Utilities, which is installing it at the utility’s Murphree Water Treatment Plant this summer, said Jeff Harmon, a GRU contract engineer who helped oversee the project.

It may also change the way other water plants treat water, he said.

“I think the big thing that evolved out of this project was it showed it is worthwhile to automate these types of plants, and you can get money out of it,” Harmon said. “People involved with the industry don’t even think it’s worth worrying about.”

In Florida, untreated drinking water often has unacceptably high levels of hydrogen sulfide and calcium, said Paul Chadik, assistant professor of environmental engineering sciences. Hydrogen sulfide causes an odor reminiscent of rotten eggs, while high levels of calcium in so-called “hard” water encrusts pipes in water heaters and plumbing, Chadik said.

For years, water treatment managers have dealt with the problem by adding chlorine to the water to oxidize the hydrogen and lime to remove the calcium. But at the Murphree plant and other plants around the state, the process is not always efficient: Operators adjust the amount of chemicals added based on hourly or periodic manual tests, meaning doses don’t always match levels of calcium or hydrogen sulfide in the water. Also, operators tend to err on the safe side by adding more lime or chlorine than necessary, Chadik said.

Even if operators’ doses are only slightly high, costs add up quickly due to the large volume of water treated. In 1996, GRU spent $621,000 for chlorine and lime, Chadik said.

Last school year, six undergraduates designed a system that varies the amount of chlorine or lime added automatically using data from real-time measurements. They came up with the design — and built a working model at the Murphree plant — as part of the College of Engineering’s Integrated Product and Process Design Program, which pairs students with corporate or government sponsors for yearlong design projects.

Gary Rubenstein, a senior in environmental engineering and one of the students, said the system uses probes to measure the electrochemical potential of the water — an indicator of sulfide levels — and the water’s acidity. The data is fed to a controller, which relays information to a computer. The computer then adjusts dosages of lime and chlorine to proper treatment levels. Contrasting the GRU operators’ hourly measurements and dosage changes, the process repeats itself once every second.

“You get better control over your chemicals, which translates into two things: saving money on chemicals and more consistent water quality,” Rubenstein said.

Conservative estimates show the system is expected to reduce the chemical doses by more than 10 percent, resulting in a savings to GRU of about $60,000 annually, Rubenstein said. The utility may also save money on the disposal costs of calcium carbonate waste created when the lime is added to the water, he said.

Last school year, 180 students participated in the Product and Process Design program, completing at least 29 projects for industry and government sponsors including Energizer, Lockheed Martin, and Motorola. In addition to gaining real world experience, they earn six hours of credit in the program.