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One open cell process-cooling tower manufactured by BAC located on the roof top, two floors above ground level. The cooling tower has a stainless steel basin with iron braces that contact tower water. The tower system is operated on softened city make-up water at 3.5 cycles of concentration. The chemical treatment program consisted of HS-4230 for scale and corrosion and M-30 for biological control. At the customerís request, on-site service was being performed on a weekly basis.
During a routine visual tower inspection, SRB nodules were seen on the iron braces in the cooling tower basin. No nodules were present on the stainless steel surfaces of the basin. A follow-up test using the Hach SRB BART was performed with results showing positive after 5 days.
The cooling tower basin was drained. The iron braces were scraped and brushed to remove the SRB nodules. The system was then shocked with AA-315 and a bromine based biocide. The biocide program was changed to include AA-315 and AA-6070T. HS-4230 remained for scale and corrosion control.
Because of the weekly on-site service and visual tower inspection, a major problem with SRB was averted. By quickly recognizing the telltale signs of SRB contamination and taking the proper corrective action, the tower system was protected against further damage.