Disinfection of Cooling Water
The disinfection of cooling water plays a very important role in a cooling tower, because the most important and, at the same time, most critical part of a cooling water circulation system is the heat exchanger. Microorganisms find optimal growth conditions on its warm and large surface and develop close and slimy coatings of living and dead matter. These coatings are called “biofilm”. Due to the thermal isolating effect of the biofilm, the heat exchanger’s efficiency is decreased. Furthermore, biofilm are often colonized by Legionella that proliferate in this coating. Legionella causes the so-called Legionella's disease and find optimal growth conditions between 30 and 37 °C, and develop to a serious problem.
In addition, microorganisms excrete corrosive metabolisms causing increased wear of materials. Using untreated sea- and river-water as cooling water permits shellfish growth that can block heat exchangers within weeks. For this reason, biocides must be used for disinfection of cooling water.
Diverse demands are placed on a biocide in cooling water treatment:
- high effectiveness against bacteria, algae, viruses and fungi
- fast disinfection of the cooling water and sufficient residual effect at the lowest concentration possible
- cost effective and easy to use
- ecologically safe
- easy to determine the concentration - if possible online
The following technologies are used for the disinfection of cooling water:
- Chlorination by means of chlorine gas or sodium hypochlorite (bleach)
- Chlorine dioxide disinfection
- Bromine technique: uses sodium hypochlorite together with sodium bromide, forming hypobromite as active compound in the cooling water. Advantage over chlorine: can be used at higher pH values
- Ozonation
Each of these disinfection technologies for cooling water treatment has its specific advantages and disadvantages. Which technology best is suited for a specific application depends on many factors. Our specialists with years of experience in cooling water treatment are at your disposal to select the optimal technology or optimal combination of technologies. This is possible, only because we have nearly the complete portfolio of disinfection technologies for cooling water treatment on hand. You won't find this anywhere else!
