PVIA Lake Wister Treatment

The Poteau Valley Improvement Authority (PVIA) is looking for a solution to reduce the dissolved phosphorus level in Lake Wister. PVIA treats and distributes water to about 80% of LeFlore County in Oklahoma. The treatment system will be implemented in Quarry Island Cove, the location of the water intake station. The removal of phosphorus will reduce the amount of algae in the lake and therefore, reduce the disinfection by-products (DBPs), the result of organic matter reacting with chlorine, in the treated outflow. This system is designed to mix alum with lake water using a bubble curtain. The alum then reacts with phosphorus and creates a flocculant that will settle to the bottom of the lake. This bubble curtain will be produced by multiple diffusers or bubble tubing, placed across the length of the cove, so that as water enters the cove it is treated before being pumped to the water treatment plant. The aeration will be powered by the current compressor, located at the intake facility. Liquid alum will be distributed through pipes using chemical injectors and a variable speed pump to adjust the release rate. 

 

Alum chemistry analysis was completed to determine the amount of alum that should be used and how to adjust the amount based on cove pH and alkalinity. The aeration products were tested to determine which will provide better mixing with the alum. Diffuser discs and bubble tubing were tested at various pressures in a pool 8 ft deep. Testing showed that the bubble tubing provided better mixing throughout the pool. After cost analysis, the bubble tubing system was cheaper than the diffuser disc system. It is recommended to use two rows of bubble tubing with a single line of alum down the center.