Anolyte circuits of cathodic dip painting systems are used to cool the anodes of the dialysis cells and to discharge the acid generated during the coating process. The anolyte’s temperature being approx. 30° C and the organic acid representing an ideal medium for microorganisms, this system can be easily contaminated.
These germs are often controlled with fungicides, bactericides, etc. unfortunately, however, there often is only short-term success with these pesticides because in general the germs tend to become resistent against them. The application rate is then sometimes increased,
yet, with little success.
The financial damages caused by these germs can be considerable. In practice, it is very
common to see a mucous
accumulation of the entire anolyte circuit. It takes much time and effort to do the mechanical cleaning in order to avoid a
production stop. Even after a successful cleaning, recontamination with germs normally cannot be avoided. There are germs remaining in the tubes, dialysis cells, pumps, etc. and so the process of recontamination starts within a few weeks.
You can certainly imagine that these cleaning processes,
especially with big cathodic dip painting systems in the automobile industry, often being
equipped with hundreds of
tubular dialysis cells or dozens
of flat cells, cause immense costs.
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Till recently, application engineers of the paint suppliers have sometimes recommended to install a copper rod or a split copper cable in the anolyte tank in order to avoid contamination with germs.
There is no doubt about the germicidal effect of copper. In practice, however, with the
unleaded paints used today the amount of copper released is
often not enough to avoid
contamination effectively. In our
water decontamination system
EKK WES-A we have taken
advantage of the germicidal
effectiveness of copper ions. The copper emission, however, is considerably increased by supplying direct current.
Wellknown automobile manufacturers are already among our customers.
This system emits copper into the waste water. Kindly check the regional conditions regarding waste water treatment and observe the maximum
permissible amount valid in your
community that may be discharged into the local canalisation. |
