The Four Way Special Utility District (SUD) operates multiple potable water plants, serving both urban and rural customers.
The problem
Well Number 3 flows at 750 GPM and serves over 2,000 rural customers. The Utility District faced aesthetic issues with Hydrogen Sulfide (H2S) and color due to the presence of tannic acids in the source water. While the presence of these contaminants is not uncommon, the conventional treatment methods being utilized — aeration and chlorine injection — were ineffective at color, taste and odor control and held the potential for exceeding regulated disinfection by-products, Trihalomethanes (THMs) and Haloacetic Acids (HAA5), formation.
The Solution
The Four Way SUD contacted Mike Walker, PE, of Goodwin-Lasiter Inc. in Lufkin, Texas, to evaluate the water concerns. Goodwin-Lasiter proposed ozone treatment as the solution and consulted with Jerry Clark of Clark Water Treatment in Nacogdoches, Texas, a manufacturer’s representative.
Working together, the team submitted a design proposal to the Texas Commission on Environmental Quality (TCEQ) which detailed solutions to the problems facing the SUD. After a few months of technical data exchange with the Commission, little progress had been made. Engineers traveled to Texas to support the consultant’s efforts to answer the Commission’s questions and concerns on the benefits of ozone to meet the application needs and protect public health. The packaged ozone system design presented incorporating a highly efficient ozone contacting system that was shown to allow tight control of the dissolved ozone levels to reduce color, taste and odor concerns while avoiding the formation of regulated disinfection by-products, including THMs, HAA5 and bromate. The process design presentation was supported by laboratory testing which confirmed no excessive disinfection by-product formation resulting in the Commission’s approval.
In addition to color, taste and odor control that ozone treatment provides, the treatment process enhancement allowed for reduced chlorine dosage and discontinuation of the current high energy demand air stripping process. The ozone system installed included on-site oxygen and ozone generation, side stream ozone transfer skid and dissolved ozone measurement and control by a PLC PID loop.
The Results
The ozone system, with the highly efficient contacting element, is now in operation at Plant Number 3. The Four Way SUD follows stringent water monitoring and laboratory testing to meet TCEQ permitting requirements and is pleased with the results which were slightly better than projected. The utility, their customers and the Texas Water Commission are very pleased that the negative well water quality parameters could be addressed so effectively by ozone treatment.
___________________________________________________________________________________________________
Paul Overbeck is from Mazzei Injector Company, LLC. For more information about the company, please visit www.mazzei.net.
