How to stop biofilms and biofouling with ultrasound?

  • Within the water environment, biofilms are commonly comprised of algae
  • Chemicals used to treat biofilms can be detrimental to wildlife and the wider environment
  • Untreated biofilms are harmful to human health and business operations

In business, time is money. Any interruption to business-as-usual can trigger an enormous financial burden that reduces profits, and the effects of that can be hard to recover from.

Across the water industry, there is a lurking challenge that many encounter, but only a select few know how to deal with effectively – biofouling and biofilms. This microscopic problem can quickly transform into a monstrous nightmare for industry, slowing flow rate, clogging up pipes and heat exchanges, and reducing efficiency.

But it doesn’t need to be this way. No longer do water companies need to live in fear of expensive biocides and management decisions that don’t deliver the results they need to operate smoothly. Wasting precious time and money on solutions that never really solve the problem can now be a thing of the past for forward-thinking businesses in the know. Science and innovation have uncovered a modern solution to this age-old problem – ultrasound.

Research and real-world results have indicated that ultrasound is an environmentally friendly and cost-effective solution to problems caused by biofilms and biofouling. First, let’s look in more detail at biofilms and why they are so problematic for the industry before delving into the solutions to their management. By the end of this article, you will have a comprehensive overview of biofilms and biofouling across water industries and why ultrasound is the leading effective and eco-friendly solution on the market for sustainable management.

What are biofilms and biofouling?

Biofilms are a type of biofouling – the accumulation of microorganisms, plants, algae or small animals, typically on underwater surfaces and structures that can cause degradation and disrupt the structure’s efficiency. You may know biofilms as the typically slimy or gelatinous substances that cover surfaces – especially around water. These sticky layers are a community of one or more types of microorganisms, including bacteria, fungi or protists. They are one of the most successful lifeforms on Earth and have established themselves for millions of years. Biofilms are everywhere. From microscopic single-cell organisms living together that escape the naked human eye to algae inches thick on rocks. In order to grow, biofilms require water and a source of nutrients which are both easy to find in many natural and artificial environments. While biofilms are naturally occurring and play an essential role in many ecological systems, they can pose many issues if left unchecked when growing in the wrong place.

How do biofilms grow? Biofilms can be comprised of many types of microorganisms, but within the water environment, they are more commonly made up of algae. As they are plants, in order to grow, algae require sunlight and nutrients such as phosphorus and nitrogen. Due to nutrient runoff, many water bodies are experiencing a surge in nutrients within their systems. Many of these nutrients originate from fertilisers and pesticides from agricultural land. Over time this exponential increase in nutrient availability, alongside a generally warmer climate, enables algae to grow at an eye-watering pace. The water industry must have a solution at its fingertips to stop this growth in its tracks – especially for harmful algae like cyanobacteria.

Cyanobacteria, or blue-green algae, is particularly problematic for managers. Although it depends on the environmental conditions, which will vary with each body of water, cyanobacteria can proliferate to produce expansive harmful algal blooms if left undetected and unmanaged. Cyanobacteria are often disastrous for the water industry. Its presence often leads to poor water quality, which poses a risk to human health and livestock, pets and other water-dependent industries. Thankfully there are measures you can put in place to ensure cyanobacteria, and other biofilms, do not expand into harmful algal blooms.

Over recent years the study of biofilms has increased dramatically. Due to their success, biofilms have evolved to repel certain biocides, making them difficult to manage. According to researchers in Montana, the management of biofilms in the U.S. alone costs the water sector billions of dollars in energy losses, equipment damage and product contamination. The latest science suggests that an integrated approach is paramount in achieving a sustainable anti-fouling strategy, including analysing the fouling situation, selecting suitable components from anti-fouling management, and effectively monitoring biofilm development. It is no longer enough to throw a few chemicals at the problem and hope for the best.

Biofouling in water systems: a recipe for disaster

If they’re naturally occurring, why are biofilms such a problem for the water sector? Simply put, biofilms usually grow in areas that are inaccessible or hard to penetrate by water treatment biocides that may already be circulating throughout a system. If left untreated, biofilms can rapidly grow out of hand and quickly develop into larger deposits that can cause structural damage to the system as well as creating a perfect breeding ground for bacteria that are harmful to human health, such as legionella, pseudomonas, E. coli and other waterborne diseases. Biofilms also drive up sanitiser and oxidiser demand, fueling the formation of disinfection byproducts, corroding metal plumbing and components, and, when neglected, can grow so thick it restricts plumbing flow. They can cause enormous problems for your business that can cost time, money, and even lives.

Another term you may have come across in the industry for the damage inflicted by biofilms is Microbially Influenced Corrosion (MIC). Many industries are affected by MIC, ranging from chemical processing industries, nuclear power generation, water treatment and more.

Maintaining water’s hygienic and aesthetic quality during transport in the distribution systems still challenges drinking-water technology. The presence of biofilms in drinking water pipe networks is particularly problematic and can be responsible for various water quality and operational problems. These include but are not limited to: loss of distribution system disinfectant residuals, increased bacterial levels, reduced dissolved oxygen, taste and odour changes, red or black water problems due to iron or sulfate-reducing bacteria, microbial-influenced corrosion, hydraulic roughness, and reduced materials life.

Unfortunately, boiling water contaminated by biofilms and biofouling does not remove toxins but increases concentration levels, according to the National Resource Defense Council (NRDC). The NRDC also notes that the economic toll of biofilms in the US has yet to be fully assessed, with estimates suggesting the cost of managing freshwater blooms alone to be $4.6 billion annually. These events often negatively affect local economies as persistent algal blooms typically cost millions in lost tourism revenue while negatively impacting the residential water supply.

Once they have become established within a water system, biofilms can be challenging to remove. Organic matter, debris and dust can easily enter a system and provide food for the bacteria to grow, and it can be near impossible to restrict the flow of these nutrients within a water system. Instead of completely eliminating the biofilm, as this is an impractical task, the focus should be on reducing the biofilm’s impact on the efficiency and day-to-day operations of the plant.

How can you stop biofilm formation?

Traditionally, the most frequently used chemicals, known as biocides, to manage biofilms are chlorine and bromine. But these chemicals come with their own limitations and are not a one-size-fits-all or comprehensive solution to biofilm management. Bromine and chlorine can only penetrate the outermost layers of the biofilm. Managers should use them in concert with other chemicals, but even then, they are not completely effective at killing all bacteria and may stop working after some time. When continually bombarding microorganisms, such as bacteria, with chemicals, they can evolve to resist them, posing severe problems to efficiency and system safety.

Unfortunately, flushing chemicals through a system and hoping for the best is not a solution for biofilm management. Not only that, but after decades of research, we now understand that chemicals used to treat biofilms can be detrimental to wildlife and the wider environment. We are also becoming increasingly aware that not all bacteria are detrimental to human health. Some are beneficial to both the environment and humanity. How can managers ensure that only the harmful bacteria are targeted during treatments? Managing nutrient levels is essential in the short- and long-term reduction of harmful algae blooms and biofilms. This means regular testing of all influents and sections of the water body to determine the source, after which potential management solutions can be applied. But this can be costly for a business, with time, money and human resources invested in tackling the issue.

Yet left untreated, biofilms present infrastructural damage, health threats and diminishing profits to businesses. So, what is the solution? Luckily for those in the water industry who have endured this headache for decades, new and innovative technology is paving the way for an eco-friendly, sustainable solution to biofilm management that is cost-effective for businesses too. Believe it or not, you can prevent biofilms from forming by applying ultrasound. Although more frequently associated with hospital procedures, ultrasound is quickly becoming the go-to solution to biofouling and algal bloom management.

Ultrasonic technology is pioneering harmful algal bloom management. It is safe to use, requires little manual intervention, and has proven to be effective in killing algae. It, therefore, makes sense that the water industry can also use ultrasound to tackle other forms of biofouling and biofilms. While recognising that every biofilm provide is unique with its own set of challenges, it is becoming increasingly apparent that a holistic approach to management is the best solution to effectively resolving biofilm issues. Ultrasonic technology is one solution that can provide rapid, long-term relief to the problem. When paired with reducing nutrient levels, it is an optimal management measure to minimise algae levels rapidly.

A Modern and Innovative Solution to Biofilms: Ultrasound

Biofouling is a recurring issue throughout the industry, but newly-developed high-power ultrasound is a powerful enough technique to clean fouling in minutes. So how does it work?

Ultrasonic technology has two primary forms: sub-cavitation intensity and cavitation intensity. Both methods effectively prevent or inhibit biofouling caused by algae, but differences in their approach may harm the wider environment. Sub-cavitation creates high-frequency vibrations and is deemed more eco-friendly. In contrast, cavitation methods often cause destructive microscopic pressure changes that can damage the environment and associated infrastructure. During cavitation techniques, intense heat pressure generates hydrogen radicals that may kill bacteria and other organisms, cause oxidation reactions, and degrade anticorrosion layers.

Ultrasonic technology is a pioneer of sub-cavitation technology. Remarkably, ultrasound technology, when correctly used, can create turbulence that prevents bacteria from setting in. It does this by producing frequencies that cause algae to hit its natural resonant frequency: the speed at which it will vibrate. As biofilm formation starts with bacteria attaching to a surface, these specific ultrasound frequencies, waveforms and amplitudes can prevent biofouling formation by breaking up the bacteria in its tracks.

Ultrasound antifouling utilises high-frequency sound that can be used to reduce or prevent biofouling on aquatic structures and surfaces. It has been estimated that approximately 95% of the 70,000 species and two million sub-species of algae are affected by ultrasonic systems. As a result, the latest ultrasonic solutions are practical and offer a safer way to eliminate harmful algae. Ultrasonic treatment by LG Sonic can reduce algae growth by 70-90% and prevent biofouling growth.

One of the most attractive features of ultrasound technology is that it offers a holistic solution for monitoring and management for the water industry. Not only will it attack biofilms and biofouling at first sight, but it also features water sensors to continually monitor the surrounding water to identify changes in water chemistry before they become a problem. Many systems are also fitted with solar panels, which removes the requirement for land-based power sources while reducing the system’s total running cost.

While there are many different versions of this technology on the market, the ultrasonic sound waves of LG Sonic create industry-leading resonance around the solid surfaces within the water, thereby preventing bacteria from adhering to a surface. When you use ultrasonic technology, your mind can be put at ease, knowing that you have a round-the-clock monitoring system attacking biofilm formation at its source, leaving your business to get on with the important work without interruptions.