Cooling tower microbiological clean-up

Cooling Tower Microbiological Clean-Up photo


Our client, an ethanol plant in northern Indiana, USA, experienced microbiologically-based fouling in their 28,000 gallon per minute cooling tower system. 

Due to the fouling, critical heat exchangers had to be cleaned on a regular basis due to reduced heat transfer efficiency, and the cooling tower fill had a thin layer of brown film. The current microbiological control program included an oxidizing biocide (bleach), non-oxidizing biocide (MBT) and a surfactant. Complicating matters was the fact that makeup water had 0.5 to 1.25 ppm total iron.


After a thorough review of the system, Veolia Water Technologies recommended an organic dispersant called Hydrex® 2252 to replace the non-oxidizing biocide and surfactant. Microbiologically-based organics are dispersed by the bio-dispersant, allowing for more effective biocide usage and the newly suspended solids to be blown down from the system. Approximately 40-50 ppm of Hydrex 2252 was intermittently fed to the 100,000 gallon cooling system.



As a result of using Hydrex 2252, the critical heat exchangers have not needed cleaning and the brown film on the cooling tower is gone. Corrosion results have improved from a range of 0.31-1.88 to a current average of 0.59. 

While costing the same as the previous program, Hydrex 2252 is easier to use and has reduced energy, manpower and maintenance requirements, resulting in savings for the client.


Hydrex 2252 is a multi-faceted product with exceptional performance in preventing organic
deposits and fouling in cooling water systems over a wide variety of operating conditions.
It also has advanced corrosion control capabilities and works synergistically with all biocides for excellent microbiological control. It is stable at all typical cooling water pH ranges and under stressed conditions, providing superior results for systems operating at higher cycles of concentration. Hydrex 2252 is a superior aid in the dispersion of hydrocarbon-based fouling as well.