CCA 3100
20
Procedure:
1.
Add 2000 mls of raw water to a 2 L beaker.
2.
Place the beaker under the CCA. Turn on the stirrer, the CCA and allow the unit to
stabilize. Slow changes in the hundredths decimal place are acceptable.
3.
Add pH control chemicals to the normal dosage rate used by the plant. Theoretically, a
final pH of 6.5 to 6.8 is optimum for alum coagulation.
4.
If the plant feeds polymer for pretreatment, add polymer to the beaker at the plant’s
normal dosage.
5.
Add coagulant dropwise using a pipette or syringe with 0.1 accuracy and watch the
streaming current value. When the streaming current value reaches zero, stop adding
coagulant. The coagulant must be added away from the piston opening in the probe.
Otherwise the coagulant will saturate the probe and drive the reading positive very
quickly.
6.
Record the number of mls used in the titration. Each ml is equal to 5 ppm.
7.
Discard the first sample.
The first sample is used to condition the probe and piston. It
also informs the operator with the approximate endpoint for the titration.
8.
Repeat steps 1-6 (do not wash the probe and piston) and record the mls of coagulant used.
9.
To calculate the ppm of coagulant, multiple the number of mls in step 8 by 5.
10.
Steps 1-6 should take less than 2 minutes to perform. Immediately place the beaker under
the gang mixer at 40 rpms for 3 minutes. Then allow it to mix at 10 rpms for 10 minutes.
Notes all parameters that you would record for jar testing including floc size, formation,
settling, pH, and turbidity.
Compare your results to the actual chemical dosage being used by the plant. If your results are
greater than +/- 10 percent, you may wish to proceed with the following steps.
Summary of Contents for CCA3100
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