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2009 Nalco Company
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Technical Help
(630) 305-CHEM
3D TRASAR
5500 - Installation & Operation Manual
34. Can I trim-feed oxidizing biocide with a separate pump at low level to
continuously maintain a halogen residual while on 3D TRASAR Bio-Control? (con’t)
Continuous addition of Oxidizing biocide and bio-reporter into the system can result in the Ratio
staying artificially low (below set point) and no true measure of microbial activity (Nalco Bio-Index)
will be obtained.
Nalco Bio-Index can only work by applying mini slugs of oxidizing biocide. The extent and timing of
the slug has to be controlled by the controller.
35. Can you make 3D TRASAR Bio-Control feed more oxidant into the system?
No
. The amount of oxidizing biocide added depends upon the measured microbial activity in the
system. This cannot be externally modulated or adjusted.
However
, the scheduled slug option
can be used to periodically supplement 3D TRASAR Bio-Control.
3D TRASAR Bio-Shock mode, an all slug mode of Biocide feed is an alternative method of applying
oxidizing biocide to the system. The bio-reporter monitors the microbial activity and when it reaches
a preset value, an Ox slug is triggered. By setting the duration and ORP level of the slug, the user
can modify the amount of biocide entering the system.
36. Can you make 3D TRASAR Bio-Control feed less oxidant into the system?
No
. The amount of oxidizing biocide added depends upon the measured microbial activity in the
system. This cannot be externally modulated or adjusted.
37. How responsive is 3D TRASAR Bio-Control to changes in the bio-population?
3D TRASAR Bio-Control monitors the fluorescence signal from the reacted and unreacted bio-
reporter every 5 seconds. It assesses the data-stream every 20 minutes and makes a decision
regarding whether to turn the oxidizing pump on or not.
If there is a process leak into the system that either increases the amount of nutrient available to
the microbial populations or decreases the efficacy of the biocide (sour leak, ammonia etc) 3D
TRASAR Bio-Control will respond with increased biocide feed within 20 minutes of the measured
event. There may be a delay in response in systems with long recirculation times. The Nalco Bio-
Index will take longer to show an increase because it is a 6 hour average measurement.
Typically process leaks affecting the microbiological population have been responded to at or
before the time that other effects have been observed in the system such as pH changes, turbidity
changes, conductivity changes or ORP changes.
