By Sara Jerome,
Water operators in Wichita Falls, TX, are using a three-pronged chemical treatment to tackle an odor problem that has stirred up complaints from customers.
Daniel Nix, utilities operation manager for the city, said the water is safe to drink even though it smells bad, according to the Times Record News.
Chlorine dioxide, powder-activated carbon, and potassium permanganate can each be used to treat odor, he said. The city is using all three at its Cypress and Jasper water treatment plants.
"Because of the severity of the odor we've had coming in from the lakes, we're actually using all three of them at doses we've never used before," he said. "We are throwing everything we've got at it."
Here’s how the plant is applying the chemicals:
The chemicals are added at different stages of the water treatment process. The chlorine dioxide is introduced into the system at the holding lagoons, and then a powder-activated carbon slurry is added at the Parshall Flume, a chemical mixing chamber and flow monitor. The potassium permanganate is then added as the water exits the traditional cleaning stage at a clarifier. The chemicals have to be added separately because one can cancel out the other if added together.
The saga has meant lots of lab work for water operators in the city.
"We've been in the lab doing studies to make sure the optimum dose of our chemicals is correct to combat these odors," Nix said, per the report. "It's not flip the switch and now you're producing odor-free water. It's a gradual process."
The utility also has workers testing the supply on their own noses.
Mark Southard, water source purification superintendent, noted that “a panel of four to five employees is used to literally see if the water coming out of the plants pass the sniff test. He said samples are heated to 60 degrees Celsius, or 140 degrees Fahrenheit, and the employees assess the smell between it and a couple other samples, including a blank, which is water that has no smell, nutrients or compounds,” the report said.
Algae is the cause of odor problems in the system, Nix said. The utility is no longer drawing water from Lake Arrowhead, where algae is severe.
“The combination of vegetation build up at the lake, which has provided the algae with food and nutrients to feed off, and 100-degree temperatures making the lake hot has resulted in the smelly water. An algicide has been put on Lake Arrowhead to kill the algae,” according to the report.
The smell has sparked fears among residents that their water is not safe. The utility has fielded four to five calls a day about the “dirt and must” odor problem, according to KAUZ.
Wichita Falls is known for its forward-thinking water treatment practices. The city was among the first to apply direct potable reuse, which it used as an emergency measure during the Texas drought, which is now over.
To read more about repressing foul smells at a wastewater treatment plant visit Water Online’s Odor Control Solutions Center.