A water treatment plant in Middle Tennessee had a current carbon feed rate of 0.5 to 1.0 ppm. This was considered low as most water plants normally feed between 3.0 and 5.0 ppm of activated carbon. Aulick was asked to provide a detailed comparison of this plant’s current carbon to that of Aulick’s carbon to gauge the better carbon for TOC removal.
Jar Testing Process Flow
The water plant provided a sample of their current carbon and coagulant for the trial. The coagulant was made down to a 0.2% solution for the jar testing. A gram of Aulick’s carbon and the current supplier’s carbon were added to 500 milliliters of finished water on a gang stirrer at medium speed that provided a carbon slurry of 1 ml = 1 ppm carbon in a 2 liter jar sample. Carbons were added first, followed by the coagulant at the beginning of the 1 minute rapid mix.
Gang Stirrer Mixing
- Rapid mix: 1 minute @ 100 rpm, flocculation 1: 20 minutes @ 20 rpm
- Flocculation 2: 10 minutes @ 15 rpm, sedimentation: 30 minutes @ 0.0 rpm
Raw Water Sample Before Chemical Addition
Jar Testing Results for TOC Removal
| Jar | Current Carbon | Aulick Carbon | Coagulant | TOC | Comments |
| 1 | 1 ppm | 20 ppm | |||
| 2 | 1 ppm | 20 ppm |
Flocculation 2
| Jar | Current Carbon | Aulick Carbon | Coagulant | TOC | Comments |
| 1 | 1 ppm | 20 ppm | |||
| 2 | 1 ppm | 20 ppm |
Settled
| Jar | Current Carbon | Aulick Carbon | Coagulant | TOC | Comments |
| 1 | 1 ppm | 20 ppm | 1.892 ppm | removal rate of 33.2% | |
| 2 | 1 ppm | 20 ppm | 1.938 ppm | removal rate of 34.8% |
Jar Testing Executive Summary
The current raw water tested at a 2.90 ppm TOC. Aulick’s carbon tested at a mean of 1.892 ppm TOC, a removal rate of 34.8%. The current supplier’s carbon tested at a mean of 1.938 ppm TOC, a removal rate of 33.2%.
