What Causes Fouling? Five Types of Fouling Explained

Many processes and types of equipment struggle with fouling issues caused by various substances, each with unique qualities. At Altum Technologies, we have experience in removing and preventing a wide range of fouling types.

In this article we will introduce five common types of fouling and discuss how Altum’s solution efficiently solves issues caused by them.

Carbonates

Different carbonates, such as potassium, sodium, and calcium, play a significant role in scaling issues within process industries. You might already be very familiar with carbonate buildup, as it is very common in households. The annoying lime buildup that gathers on our coffee makers and flat irons while also clogging our shower heads, requiring us to regularly remove the persistent substance, is a form of calcium carbonate fouling. Lime is an ordinary, annoying problem in many households – and an even bigger issue within process industries.

The cause for calcium carbonate buildup is “inverse solubility”: as temperatures rise, calcium carbonate’s solubility decreases, leading to the formation of insoluble crystals. This can be seen in practise as the white buildup on our coffee makers and showerheads, and as buildup on industrial equipment.

A similar process applies to other carbonates as well. Evaporation caused by higher temperatures increases the concentration of solvents containing carbonaes. As concentration increases due to a rise in temperature, crystals form and scaling is more likely to happen. When these crystals attach to heated surfaces, they can obstruct heat transfer, reduce equipment efficiency, and increase maintenance requirements.

Calcium carbonate-based fouling is a common issue in multiple industries and processes, and Altum’s high-power ZPD ultrasonic solution with multiple applications removes and prevents it in an energy efficient way to ensure production and cost efficiency in addition to increasing operation uptime. Altum’s solution works by controlling the crystallization effect to prevent scale from adhering to surfaces.

Read more about one of our carbonate prevention cases here.

Sulfates

Crystals formed by sulfates like calcium, nickel, or lithium sulfate as part of different processes, can easily gather in the wrong places and clog vital pumps and pipes, thus disturbing or even stopping whole processes altogether.

One example of how Altum’s solution can be utilized to minimize issues with sulfate fouling is its use in a crystallizer. In crystallizers, Altum’s solution works by sonicating the location prone to fouling with ultrasound. Altum’s solution affects scaling locally by preventing it with microscopic vibrations at the inner surface of the equipment to detach the foulant. With Altum’s solution, this vibration is precise and software-guided to ensure the best possible results.

With our high-power ZPD Ultrasonic solution, we have achieved great results in solving fouling issues related to the nickel sulfate crystallization process to enhance production output and increase production days in a year. By removing and preventing sulfate-related fouling issues and restoring optimal performance with ultrasound, we can help you achieve seamless, stable and predictable operations and extended equipment lifespans.

Read more about one of our nickel sulfate cases here.

Biofilm

Biofilm, a slimy layer of microorganisms, can wreak havoc on your process industry systems: examples of biofilm include film of water microorganisms and cellulose-based film born from cellulose processing. These biofilms lead to contamination, reduced efficiency, and increased maintenance needs.

Biofilm fouling is a significant concern in the pulp and paper industry, especially when seawater is employed for cooling purposes in industrial equipment. The combination of organic matter from the pulp and paper process and the microorganisms present in seawater (e.g. algae, fungi and even shells) creates an optimal environment for biofilm formation. As seawater flows through the equipment, microorganisms start to settle on the surfaces, eventually forming an insulation layer on the inner surfaces of the equipment.

Biofilm can have varied structures, compositions, and thicknesses across different equipment areas and can disturb efficient cooling, which can affect the overall performance of the equipment and raise operational costs. It can also cause obstructions, leading to reduced flow rates in cooling systems and speed up corrosion in equipment.

Altum’s ZPD has been used to prevent biofilm built-up across multiple industries and equipment types by implementing ultrasonic waves in the cooling system to effectively prevent and disrupt biofilm growth. Our technology disrupts the buildup with precise and software-guided microscopic vibrations to ensure clean equipment.

Oxides

Oxides are formed when other elements, such as iron and magnesium, react with oxygen. Over time, oxide fouling can lead to decreased efficiency, disturbances in heating and cooling, and even equipment failure.

Iron is one of the most common sources of oxide formation and is thus a common cause of fouling. Rust, a familiar problem when dealing with iron or steel, is a specific type of iron oxide that occurs when iron reacts with oxygen in the catalytic presence of water. Because of the way rust forms, these iron oxides are often released into water within heated pipelines, especially as pressure increases. Subsequently, they can adhere to various surfaces within the system. It’s worth noting that the smaller the pipes, the quicker iron oxide buildup can lead to clogging.

With Altum’s high-power ZPD solution, we have gained great results in preventing iron oxide fouling, leading to lower pressure in pipes, substantial decrease in maintenance needs and increased efficiency of the process. Oxide fouling prevention and removal is done by increasing particle movement near surfaces. The ultrasound vibrates the structures, increasing particle movement and thus preventing the foulant particles from attaching. The same applies for oxides that form in the process, as the vibration detaches them before any substantial growth is accumulated. This way of fouling mitigation resembles how particles move on a Chladni Plate, but instead of nice patterns the particles can be removed entirely.

By effectively removing and preventing oxide deposits and restoring optimal functionality, we help you unlock the full potential of your process.

Struvite

Phosphate minerals are a large and diverse group, but only a few are somewhat common. Here we will concentrate on one common phosphate mineral, struvite. Struvite, or magnesium ammonium phosphate, is found in crystal form and is white to yellowish or brownish white in color. It forms in alkaline conditions when its constituent ions are present in a 1:1:1 ratio of magnesium, ammonium, and phosphate.

Struvite poses a significant challenge in wastewater and sewage treatment as well as biogas production due to the anaerobic conditions used in these processes, which release ammonium and phosphate from waste materials. This struvite can then scale various equipment, such as pipes, pumps, lines, belts, and centrifuges, significantly hindering operation efficiency by causing clogging issues.

Struvite fouling removal can be a challenging task. Traditional methods like using hydro-jetters or grinders often require expensive downtime and extensive manual labor. Fortunately, Altum’s ZPD ultrasound technology offers a non-disruptive solution. Simply attaching the transducers externally enables the treatment of struvite fouling. When removing and preventing struvite fouling, Altum’s solution works by creating microscopic vibrations at the inner surfaces of the equipment, which detach the foulant without harming the equipment.

As an industry specific example, we have achieved significant success in eliminating struvite buildup from pipes and pumps within a biogas manufacturing process. Altum’s innovative solution effectively eliminated this scaling, reducing maintenance requirements and enhancing overall process efficiency.