IEA Solar Heating and Cooling Programm - NachhaltigWirtschaften.at

IEA SHC Task 38 Solar Air Conditioning and Refrigeration Subtask C Report, Date: 13.01.2009
• Regular maintenance and cleaning should be scheduled.
• The open Cooling device should be located as far as possible from the fresh air
intakes of a building the areas with organic intake, like kitchen exhaust fan.
• As far as possible remote from out door public areas.
• Reduction of the water droplet rate by high performed separator without a hindrance
for inspection and maintenance
Additional to the design active measure are necessary like injection of biocide. A possible
alternative could be the installation of UV-C disinfection facility including the necessary
control measures and the installation of suitable metal ion electrolysis, e.g. silver-copper ion
method which is discussed hereafter.
The above mentioned measures together with a regular maintenance will avoid the growth of
virulent bacteria like Legionella pneumophila.
5.3 Water Treatment with Disinfectants
In wet cooling towers different water treatment chemicals are used for scale and corrosion
inhibition, anti-foaming, cleaning, biofilm control and disinfection. Many different commercial
products are on the market which uses different chemical substances. Within this section
only a very short overview on the used biocides for Legionella control should be given. Good
information on commercially available products can e.g. be found on the web pages of the
companies
• Lenntech (http://www.lenntech.com/water-treatment-chemicals.htm) and
• Accepta (http://www.accepta.com/water_treatment_chemicals/biocides.asp)
In principle the biocides for Legionella control can be divided up into oxidising biocides and
non-oxidising biocides.
The commonly used oxidising agents are:
• Chlorine
• Chlorine dioxide
• Ozone
• Hypochlorite
Every disinfection technique has its specific advantages and its own application area. The
company Lenntech assigns the following advantages and disadvantages to different
technologies (compare: Table 5-1)
page 30