TP26-18 Combining Conventional and DNA- Based Monitoring to Optimize Microbiological Control in an Industrial Cooling Water System

A chemical processing facility in Western Canada has experienced persistent slime 
accumulation in heat exchangers along with elevated microbiological activity in the cooling 
tower system. The system consists of a cross-flow cooling tower with an approximate 
volume of 4,000 m³ (1.06 Million US Gallon), supplied with cold lime-softened river water 
(RW) as makeup (CTMU). The performance of two shock treatment strategies - oxidizing 
biocide (OX) and non-oxidizing biocide (NX) - was evaluated in response to persistent slime 
accumulation within the cooling tower system. OX shock treatments are implemented 
specifically to mitigate severe slime build-up and are triggered by defined microbiological 
indicators, such as elevated planktonic counts in the cooling tower return (CTR) or the 
detection of sulfate-reducing bacteria (SRB). During each OX shock event, bleach is applied 
as the primary oxidizing agent. NX shock treatments are also applied as needed; however, 
due to local effluent discharge limitations, NX dosage must remain well below the label 
maximum.