EE&T was one of the first U.S. firms to investigate the use of DAF for treatment of spent filter backwash water (SFBW) intended for recycle. In studying this application, our personnel visited numerous U.S. and European installations using DAF for potable water clarification or DAF used for residuals thickening. EE&T has recently completed a bench and pilot testing program for AwwaRF to evaluate DAF for treatment of spent filter backwash water. We believe that we are one of the only firms to regularly utilize bench-scale DAF equipment for this application.

EE&T was the first group to demonstrate through pilot testing that DAF treatment conditions required for effective treatment of SFBW intended for recycle were very similar to those used for potable DAF treatment. Significant removals of iron and manganese were also achieved. The developed DAF setpoints were sufficient to attain clarified water quality superior to that of the raw water, thereby meeting recycle goals.

Another DAF application studied by EE&T targeted removal of arsenic for the Southern Nevada Water Authority (a large direct filtration facility). The project included a potential retrofit of the full-scale flocculation basins with DAF. Arsenic reductions of more than 50 percent were attained in bench and pilot tests.