Tech By BlueInGreen Betters Water, Wildlife

Every year, low oxygen levels threaten the trout population at the North Fork River, one of the country’s premier trout fishing destinations.

BlueInGreen, a Fayetteville-based company, has developed a unit that could solve the river’s oxygen problem and protect the trout, a significant contributor to the state’s economy. The 4.2 miles of North Fork River provide a direct economic benifit of $6 million annually.

The company has developed a mobile unit called the Supersaturated Dissolved Oxygen Delivery System, or SDOX, to inject the gas into the river.

Anna McCain, a technical writer with BlueInGreen, said oxygen levels fall naturally in bodies of water during the summer and fall months when the temperature changes and stratification occurs. Warm water rises to the surface and cold water drops to the bottom. The two layers don’t mix, she said, so there is no source of oxygen at the bottom.

Because trout live in cold water and require more oxygen than most other fish, the low oxygen levels are harmful to the trout population and have caused the North Fork River to be placed on the Arkansas Department of Environmental Quality’s list of impaired water bodies.

When the oxygen is low, the trout become dormant.

“They don’t swim, they don’t eat, they don’t grow or reproduce,” said Scott Osborn, chief technology officer of BlueInGreen. “They become more susceptible to disease and a lot of them die.”

BlueInGreen received a $500,000 grant from the National Science Foundation to conduct tests in November at the North Fork River and Norfork National Fish Hatchery to determine if the systems would be effective in oxygenating water in hydroelectric reservoirs and tailrace rivers.

One study was conducted in the water flowing from the Norfork dam into the fish hatchery. The second study was conducted directly below the dam during conditions of low flow, when oxygen levels are at their lowest.

The goal was to maintain a dissolved oxygen concentration of six milligrams per liter, ADEQ’s minimum standard for oxygen levels in Arkansas waters.

Osborn said the objective of the study was to improve the water quality and health of the fish in the hatchery and determine the cost of operating the system compared to traditional technologies.

While the data collected is still being analyzed, Osborn said anecdotal evidence showed an improvement in the health of the fish when the oxygen was injected into the water.

“It definitely made a difference in the hatchery,” he said. “The fish were swimming around better.”

McCain said the trout fishermen that were on the river during the test noticed a major difference.

“All of a sudden they were able to catch fish,” she said. “They could tell when the system was turned off and were asking for it to be turned back on.”

Osborn said one of the advantages of using the SDOX system over existing technologies is that the system is mobile and can be applied at the exact location where oxygen is needed.

The system, which is about the size of a horse trailer, uses a gas-powered generator to deliver a stream of oxygenated water through a hose. The hose can be placed at any depth and the flow of oxygen can be controlled, allowing only the required amount to be added at a specific location.

The SDOX system can also be used to treat wastewater effluent in municipal and industrial treatment plants.

Oxygen is needed in the treatment process for bacteria to break down organic waste. McCain said traditional methods use bubbles to add dissolved oxygen to wastewater. Most of the bubbles rise out of the water into the atmosphere, however, and the gas is wasted.

With the SDOX system, McCain said, no oxygen is wasted, making it about 80 percent more cost effective.

The City of Fayetteville purchased a SDOX system for its Paul R. Noland Wastewater Treatment Facility after comparing it to an existing system.

In a side-by-side comparison of the two systems, the SDOX increased the effluent dissolved oxygen by almost 50 percent above the existing system and used 79 percent less power than the existing system.

BlueInGreen has another sale pending to a golf course in the northern part of the country.

Ponds in developments such as subdivisions or golf courses have to be aerated to keep the water circulating.

Typically, Osborn said, a fountain is used to aerate the pond. In colder regions, the fountain keeps the pond from freezing over in the winter. Birds see the water and decided to land there, rather than migrating south. The birds can leave behind a mess, Osborn said, and be a nuisance for development owners.

The SDOX can aerate a pond under a layer of ice, making the unit an attractive alternative to fountains.

The cost of the systems varies according to size. A system used to treat a pond can cost about $30,000 to $40,000, while a system used to treat an entire river can cost about $7 million.

The HyDOZ

BlueInGreen is developing another product that uses hyper ozonation technology to disinfect water.

The hyperconcentrated dissolved ozone unit, also called HyDOZ, can be used to remove microbes and chemical components from wastewater.

It works like chlorine but without a lot of the dangerous side effects, Osborn said.

There is some concern about the use of chlorine in treating drinking water in part because it doesn’t treat drug residuals.

BlueInGreen received a two-year, $750,000 grant from the National Institute of Environmental Health Sciences, a division of the National Institutes of Health, to study the removal of pharmaceutical residuals from wastewater using the HyDOZ.

The test will be conducted at the City of Springdale’s wastewater treatment plant this spring, Osborn said.

The test will determine if antibiotic residuals can be removed from wastewater and if the method is cost effective.

The technology has been around for more than 100 years but it’s been cost prohibitive, Osborn said.

The hope is that the HyDoz can reduce the capital and operating costs of disinfecting water and be a practical treatment option, he said.