To determine the optimum dose of chlorine that is required to remove all ammonia from a water sample.
There were (5) 200 mL beakers that were set up and were labeled WDR 0, WDR 3.04, WDR 6.09, WDR 7.61 and WDR 12.2.
B. Fifteen minutes were allowed for reaction time for each beaker.
C. The residual ammonia concentration was determined using the Nessler Method that uses HACH program #2500 on the .
HACH DR/4000 Spectrophotometer and the following steps were required.
1. Filled a 25 mL graduated cylinder to the mark with the sample.
2. Filled a graduated cylinder to the mare with the distilled water.
3. Added three drops of Mineral Stabilizer to each cylinder.
4. Stirred each cylinder and inverted several times to mix.
5. Pipet 1.0 mL of Nessler reagent into each cylinder.
6. Touch the soft key on the HACH DR/4000 Spectrophotometer under timer (1 minute reaction period will begin).
7. Poured the solutions of each of the 25 mL graduated cylinder into separate 25 mL sample cells.
8. When timer finished, the cell containing the water, the blank was wiped and placed into the cell holder.
9. The softkey under zero was touched displaying 0.0 mg/L NH3-N).
10. The cell containing the sample was wiped and placed into the cell holder.
11. The results in mg/L NH3-N were recorded.
Results.
Chlorine/Ammonia WDR.
(mg Cl2/ mg NH3-N) Residual Ammonia.
(mg/L as N) Comments.
0 0.176 .
3.04 0.162 .
6.09 0.138 .
7.61 0.132 Breaking point.
12.2 0.176 .
The ammonia residual was 0.176 when the WDR was at 0. The ammonia residual was 0.162 when the WDR 3.04. The ammonia residual was 0.138 when the WDR was at 6.09. The ammonia residual was 0.132, which was the breaking point, when the WDR was at 7.61. The ammonia residual was 0.176 when the WDR was at 12.2.
.
Discussion.
The ammonia residual for the Chlorine WDR 0.00 was of 0.176 mg/L which was just as high as the ammonia residual for the Chlorine WDR 12.2. This seemed strange to me because the higher amount of Chlorine WDR should mean that the lower amount of ammonia residual.
