Pilot plant improves drinking water quality

A pilot plant designed to be a miniature replica of a 60-mgd water plant is up and running, and it is establishing ways to improve drinking water quality for customers served by Knoxville, Tenn.’s, water treatment plant. To ensure the continued quality of its drinking water and to meet new federal drinking water regulations in the most cost-effective manner, the Knoxville Utility Board (KUB) commissioned Burns & McDonnell, Kansas City, Mo., to design a permanent pilot plant capable of performing real-time, on-site, state-of-the-art process evaluations.

The $500,000 pilot plant is proving to be a powerful research tool with the flexibility to explore more than 600 treatment configurations.

Using dual treatment trains, one 7-gpm pilot unit simulates existing plant operation and serves as a control while the other 7-gpm unit is used to evaluate process changes. This allows KUB’s technical staff to make comparisons and to visualize reactions that would actually take place in the full-size plant. A side benefit is that the pilot units serve as a good training tool for current and future plant operators.

The facility allows operators and laboratory staff to draw for testing six different water streams from different locations throughout the plant. By encompassing all unit processes in one location, testing can be completed on:

* alkalinity and pH changes on coagulation efficiency and corrosion potential;

* alternative disinfectants and disinfection by-products from chlorine, ozone, chlorine dioxide and chloramines;

* alternative chemicals and chemical dosages to determine effectiveness of coagulation, flocculation and sedimentation processes for turbidity and total organic carbon removal;

* optimization of filtration absorption with powdered and granular activated carbon; and

* removal of disease-causing microorganisms, such as Cryptosporidium, Giardia and viruses.

The state is watching KUB’s testing results for possible application to other utilities. In just a few months, the pilot plant has produced data that is helping KUB adjust process chemistry and chemical feed applications at the main water treatment plant.

“KUB and its customers will quickly see the benefits of this pilot plant, which is a showcase facility,” says Bill Elmore, KUB’s superintendent of water. “It helps our operators and engineers to better understand the complexities of water treatment and to provide the best water to our customers under increasingly stringent water quality and regulatory conditions. The pilot plant will allow us to move quickly into testing and data acquisition required by the forthcoming Information Collection Rule under the U.S. Environmental Protection Agency’s pending National Primary Drinking Water Regulations.”