This study was very complex, and included high turbidity spiking of the Lake Waco water with local clay sediments. This involved pumping and mixing. The DAF process, previously tested at a standard rate of 6 gpm/sf of aeration basin, was tested at the high rate of 12 gpm during this pilot plant study.

Also tested was the use of chlorine dioxide as a clarified water disinfectant. This high strength, short term residual disinfectant is known for improving the taste of water while providing initial disinfection.

Pipeline travel time from the new proposed DAF site to the existing treatment plant, which will continue to be used for filtration and pumping, was modeled. The use of both new and depleted granular activated carbon filters were used.

The scale model test unit provided excellent clarification at the high 12 gpm rate with water at a high turbidity level of 70 NTU and more. Geosmin (a taste and odor compound) was significantly removed by the chlorine dioxide and new granular activated carbon. Total organic carbon was reduced by the new carbon. Depleted carbon was less effective.

Using the high rate process at 12 gpm will provide a construction savings of at least $5 million for the City of Waco.

Author: Webmaster