Due to their nature, cooling towers continuously scrub particles from the air. These accumulate in low flow areas, become nutrients for microbes and constitute the ideal condition for a biofilm formation. Biofilm is probably the most difficult challenge a cooling water system faces. Until recently, our knowledge of biofilm was extremely limited. However, new scientific evidence revealed their complex structure and opened new ways to tackle this hidden enemy as Dr. Simona Vasilescu from the Water Treatment Platform of NCH tells us in more detail.
Biofilms are all around us
From the helpful microbes that populate our intestines to the grime we battle to remove from our bathroom tiles. Biofilm is a community of micro-organisms attached to a surface, and held together by a slimy bacterial secretion.
The science behind biofilm
Major advances in biofilm research have only occurred in the past ten to fifteen years. Emerging techniques from microbiology and molecular biology have allowed the development of new laboratory and field assessments. With the knowledge and understanding of how complex and incredibly tenacious biofilms are, we are beginning to understand their significant impact on our everyday lives, from the biomedical field to the industry.
Specifically in industrial water systems, a biofilm is formed when slime encapsulates bacteria that have become attached to a surface. The biofilm is highly efficient in protecting the bacteria from any biocide treatment added to the water. Recent research shows that biofilms are very difficult to remove from a system, as the bacteria underneath live in highly sophisticated communities that are capable of constantly adapting to become resistant to chemical treatment.
Biofilms and their impact on cooling systems’ performances
Biofilms are much more insulating than calcium carbonate scale or iron oxide deposition, traditionally recognised as problematic, explains Dr. Vasilescu. For example, a mere 0.1mm layer of biofilm is four times more isolating than an equivalent coating of scale or iron oxide build-up, having a huge impact on your annual electricity bill.
System pipework and mission critical equipment in cooling systems like heat exchangers, chillers, etc. can be seriously damaged by the bacteria growing underneath and within the biofilm layer. The deterioration, called microbiological induced corrosion (MIC), is up to 1,000 times more aggressive than normal corrosion decay and is accountable for up to 50 per cent of the total costs of corrosion prevention and treatment to the worldwide economy.
Biofilms are also the perfect safe hold for pathogens, like deadly Legionella. These are protected by the biofilm and can thrive within, eventually being released through water droplets into the atmosphere.
Addressing the problem
Biofilms are very thin and difficult to detect, particularly since in any water system there are plenty of corners and low flow areas for the biofilm to develop. In many cases, the biofilm can evolve aggressively over a short amount of time. When biofilms become noticeable, it is often too late: at that stage, they become extremely difficult to manage.
We at NCH have invested in state-of-the-art research to develop chemical treatments capable of disrupting biofilms, making our water treatment programs more efficient and protecting the assets of our customers.
Our New Science and Technology Group, working in close partnership with leading R&D groups from universities, designed a new formulation able to unlock the complex matrix shield that gives the biofilm its incredible resistance. The new patented product called bioeXile is up to 1000 times more efficient in penetrating biofilms than biocide alone, and 100 times more efficient than biocides plus traditional biodispersants.
The fight against biofilm is a continuous battle. Therefore, involving a specialised water treatment company that understands how to tackle biofilms might be the easiest way to defuse this deadly, ticking time-bomb.