Understanding Biofilm in Water Systems

One of the first forms of life, bacteria are collectively essential to the continuation of life on this planet. Like all terrestrial lifeforms, they require the presence of water to survive and they can be found anywhere where moisture is present, including on – and in – higher lifeforms, including humans.

One of bacteria’s most successful evolutionary tricks to ensuring its survival is its ability to form biofilm. Some bacteria secrete natural polymers made up of polysaccharides, proteins, DNA, lipids and other organic compounds into its environment. Also known as extracellular polymeric substance (EPS), this hydrogel remains attached to the bacterium’s cellular wall, capturing and concentrating nutrients, protecting the cell itself, and allowing it to adhere to surfaces. It was this last trait which led pioneering Dutch microbiologist, Antonie van Leeuwenhoek to discover the existence of microbes in the mid-1600s as one of the subjects he examined with his breakthrough microscope was the bacterial film that forms on one’s teeth.

Biofilm’s Duo Role: Microbial Haven and Industrial Challenge

The same thing that has made biofilm such a winning strategy for microorganisms has made it a challenge for operators of water systems. Not only does a biofilm protect and feed an individual bacterium, it allows multiple microorganisms to colonize a surface. In fact, the presence of a surface allows bacteria to multiply when compared to a similar volume of uncontained water, as was first discovered in 1936 by Zobell and Anderson, and further quantified by Heukelekian and Heller in 1940.

 

biofilm life cycle

Biofilm LifeCycle

This blog has reported numerous times upon the challenges bioburden poses to water systems: jeopardizing the delivery ultra-pure water or steam as well as the physical risk to those systems caused by microbially influenced corrosion.

It isn’t just systems requiring high levels of purity which are at risk, any system where water will be used for human or animal consumption is at risk. When in contact with water, any surface can be colonized by biofilm. Anyone who has had a fish tank has had that unpleasant experience of coming into contact with biofilm. In water systems, reverse osmosis membranes, deionization resins, storage tanks, filters and piping systems can all provide anchorages. Low flowing water, stagnation during maintenance, dead legs in piping, or rough surfaces all provide increased likelihood that bioburden will affect a system.

Microbial Trend Analysis

Reintroduction

Reintroduction of bacteria due to a defect in the process or equipment.

Regrowth biocleaning

Regrowth of bacteria due to ineffective treatment.

Biocleaning: Strategies for Effective Water System Management

Bacteria and biofilms are the result of several billion years of evolution, making them difficult to remove. Different materials of construction and water quality requirements for water systems prevent a “one size fits all” solution from being developed. Unlike the fish tank, physical scrubbing with soap and water is often not an option. The most basic anti-bacterial method of using chlorine to kill any microbes is unacceptable because of its corrosive effect on both copper and stainless steel materials, in addition to potentially contaminating the system.

The best way to reduce the risk of biofilm formation in the first place is proper design. Copper has been traditionally used in municipal and other water systems because of the metal’s natural anti-bacterial properties. However, the use of stainless steel has become more commonplace for cost and logistical reasons. Common rules of thumb for water system design, such as ensuring constant and turbulent flow of water, limiting the amount of dead legs within a system, and reducing potential entry points for bacteria, should always be considered. Additionally, having a smooth, polished surface that has been cleaned, pickled and passivated (in the case of stainless steel) further denies bacteria a potential anchorage. Astro Pak’s are available for pre-construction design consultation services to help avoid such built-in pitfalls.

Designing Water Systems to Thwart Biofilm Build-Up

However, preparation and planning won’t completely eliminate the possibility of biofilm formation. Best practices recommend that a system be cleaned regularly. Flushing the system with 80°C water will only be sufficient to kill or remove free-floating bacteria (planktonic) contamination. The core of a well-established colony will be protected by its biofilm and will simply regrow. Further, if microbially influenced corrosion is taking place, the bacteria will be further protected by the pitting it has created within the metal itself.

As a colony grows, its composition will change as diverse species join. As a result, it is important to consider all of the present bacterial species when remediating the biofilm. Using proper testing protocol to determine what bacteria is inhabiting the system and the extent to which it is spread throughout will help determine steps to remove it. Mere testing of water samples will only return results for the planktonic bacteria. Instead, ongoing monitoring of plate-based cultures is critical to detecting the presence of a biofilm while also providing data regarding the timeframe for a build-up to occur. In this regard, not only will the system operator know what is contaminating their system, but also they will be better informed about how frequently it will require cleaning.

Once bioburden has been detected, it’s time to call in the experts in sanitization and biofilm removal. Astro Pak has been the precision cleaning industry leader for over six decades and the TSG’s team of experts build on that deep institutional knowledge to find the most optimal solution to degrade and eliminate bioburdens from a variety of systems and surfaces.

Plan Ahead

The formation of biofilm is not inevitable, but even the best-designed systems can be at risk due to mechanical issues or other unexpected occurrences.  Clients working with Astro Pak’s TSG can establish a science-based testing and cleaning regimen that complies with their specific industry standards. Regularly scheduled cleaning and servicing protocols tailored to each system’s specific needs greatly reduce the likelihood of contamination by microorganisms, protecting the system and the consumer as well as the operator’s bottom line.

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Chad Clements

Chad Clements works as the Chemical Engineer for Astro Pak’s Technical Services Group, providing technical guidance to field, shop, and cleanroom locations across the United States. He has a background in precision cleaning, oxygen cleaning, process engineering, chemistry, and bacterial remediation. Chad holds a bachelor’s degree in Chemical Engineering from the University of Florida. Prior to working under the Technical Services Group, he worked as a Process Engineer for Astro Pak’s Florida Cleanroom facility.

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