Environmental Engineering Reference
In-Depth Information
Cause:
Flow proportioning control device not zeroed or spanned
correctly
Corrective action:
Re-zero and span the device in accordance
with the manufacturer's instructions.
•
symptom 12.
Chlorine residual cannot be obtained.
Cause:
High chemical demand
Corrective action:
Locate and correct the source of the high
demand.
Cause:
Test interference
Corrective action:
Add sulfuric acid to samples to reduce
interference.
•
symptom 13.
Chlorine residual analyzer, recorder, and controller
do not control chlorine residual properly.
Cause:
Fouled electrodes
Corrective action:
Clean electrodes.
Cause:
Loop time too long
Corrective action:
Reduce the control loop time by
:
(1) moving
the injector closer to the point of application, (2) increasing the
velocity in the sample line to the analyzer, (3) moving the cell
closer to the sample point, and (4) moving the sample point
closer to the point of application.
Cause:
Insufficient potassium iodide being added for the amount of
residual being measured
Corrective action:
Adjust the potassium iodide feed to corre-
spond with the chlorine residual being measured.
Cause:
Malfunctioning buffer additive system
Corrective action:
Repair buffer additive system.
Cause:
Malfunctioning analyzer cell
Corrective action:
Call authorized service personnel to repair
the electrical components.
Cause:
Poor mixing of chlorine at the point of application
Corrective action:
Install a mixing device to cause turbulence at
the point of application.
Cause:
Improperly set rotameter tube range
Corrective action:
Set a proper feed rate range.
9.2.6.5 Dechlorination
The purpose of dechlorination is to remove chlorine and reaction
products (chloramines) before the treated wastestream is discharged
into its receiving waters. Dechlorination follows chlorination—usually
