Abstract
A cooling tower is a heat removal device, which extracts waste heat to the atmosphere through the cooling of a water stream to a lower temperature. Cooling towers are frequently associated with biofilm problems and Legionnaires disease outbreaks. Where biofilms can cause clogging and corrosion, reduction of biofilms is important for operational reasons and public health. Therefore, effective anti-biofilm strategies are needed in practice. The aim of the present study was to reduce biofilm formation using a nano-hydrophobic coating on cooling tower fill materials - polypropylene cooling tower fill material was coated with nano-silica. The effectiveness of the hydrophobic coating was investigated for a 6-month test period in a model cooling tower system, by monthly counting of the surface-associated bacteria using an epifluorescence microscope. A significant reduction (up to 4 log) in surface-associated bacteria was observed on coated test samples in comparison to uncoated control coupons. This study is the first report regarding the use of nano-silica coatings on cooling tower fills. The coating can be easily fabricated and the range of possible applications can be expanded to include a variety of conditions.
Highlights
Biofilm is a dynamic structure adhering to solid surfaces that are generally in contact with water, and consists of colonies of bacteria and usually other microorganisms that secrete a polysaccharide-based protective coating in which they are encased (Costerton, 1999)
The efficacy of the hydrophobic coating on fill material over a 6-month period was evaluated to determine the effectiveness in controlling biofilm formation in a model recirculating water system simulating cooling tower water system conditions
The results of the present study clearly showed that total bacterial counts on nano-silica coated test surfaces, determined by epifluorescence microscopy, were significantly lower (P< 0.05) than that of uncoated polypropylene samples
Summary
Biofilm is a dynamic structure adhering to solid surfaces that are generally in contact with water, and consists of colonies of bacteria and usually other microorganisms that secrete a polysaccharide-based protective coating in which they are encased (Costerton, 1999). Fill is composed of thin sheets of plastic polymer material to create an increased surface area upon which the water flows. It is a natural tendency of microorganisms to attach to wet surfaces, multiply and embed themselves in a slimy matrix composed of extracellular polymeric substances that they produce, forming a biofilm. Biofilm formation in cooling tower water systems is undesirable for operational and public health reasons. These systems provide an ideal environment for bacteria to grow and multiply (Torvinen et al, 2014; Türetgen et al, 2005). Bacterial biofilms in cooling towers develop most frequently on heat transfer surfaces as temperatures there favour the rapid growth of L. pneumophila (Harris, 2000)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
