Anti-Fouling Solution for Seawater Cooling System on Ships in The Arctic

Relevance of the Topic

Biological fouling by living organisms in recirculating water supply systems leads to clogging of sea chest inlets, critical narrowing of the internal pipeline space, reduced heat exchanger efficiency, and ultimately, inevitably results in the failure of general ship systems and the shutdown of machinery.

At the same time, cleaning the internal cavities of pipelines or box coolers is practically impossible using mechanical, chemical, or acoustic methods. Unprotected equipment, once it reaches a critical level of biofouling, typically requires disassembly and replacement. Therefore, the issue of biofouling prevention is well-known and highly relevant.

Cleaning of the seawater supply pipes of a ship requires disassembly and replacement, which increases maintenance costs.

It should be noted that most research on the fouling of marine structures has been conducted for temperate and warm climate zones. There has been an unacceptably low level of scientific studies on this issue in the seas of northern latitudes. As a result, some experts still hold the belief that the biological activity of microorganisms in high latitudes is reduced to a near-zero level due to the effects of low temperatures on microflora.

Samples of benthic microflora, collected at various times from the White Sea and the Kara Sea, indicate that in recent decades, with the expansion of human industrial activity in the Arctic, there has been a sharp increase in bioflora capable of forming microbial substrates on structures submerged in seawater. Additionally, the number of macro-organism species capable of colonizing both internal and external surfaces of marine structures has increased significantly.

Classification of Biofouling and its Stages

Biofouling in pipeline systems that operate with seawater consists of accumulations of microorganisms, plants, algae, and small marine animals concentrated on the inner surfaces of pipelines that supply seawater to shipboard systems, including box coolers in propulsion cooling systems. The biofouling process is characterized by the rate and volume of organism attachment to surfaces.

Bio-organisms that contribute to pipeline fouling are classified into two main groups:

• Calcareous organisms: mollusks, worms, barnacles
• Non-calcareous organisms: seagrass, algae, biofilm slime

Due to the high nutrient content of seawater, the reproduction rate of microorganisms is extremely high. The settlement of bio-organisms inside pipelines occurs in three distinct stages:

Stage 1. At this initial stage, molecules of proteins, lipids, and polysaccharides present in the water form a molecular base layer on pipeline surfaces.

• This layer serves as a substrate for further biofilm development
• The formation process occurs within seconds after contact with water
• If no protective action is taken, this layer immediately appears upon the first exposure to seawater

Stage 2. The next phase of biofouling is bacterial adhesion, during which microorganisms begin to attach to the macromolecular layer.

• This stage develops within hours to several days
• Microorganisms secrete extracellular polymers, which create a strong bond between the biofilm and the pipeline surface
• At this stage, if there is no counteracting treatment to prevent biofilm attachment, biofouling becomes irreversible

Stage 3. The final phase of biofouling involves the colonization of the biofilm-covered surface by calcareous and non-calcareous macro-organisms.

• This process takes from one week to a month
• Once colonization is complete, biofouling can no longer be prevented or reversed—only mechanical removal of biomass is possible

Proactive protection measures must be implemented as early as possible to prevent irreversible colonization and ensure optimal operation of shipboard seawater systems.

Electrolytic System as a Method of Biofouling Counteraction

Several practical methods have been developed to combat biofouling in cooling systems and seawater intake pipelines on ships. These methods include:

• Mechanical removal
• Electrochemical treatment
• Ultraviolet (UV) exposure
• Ultrasonic treatment

Each method has its advantages and limitations, but the most universal and effective solution, in our opinion, is the electrolytic method, which works at the earliest stage of biofouling, while the process is still reversible.

The electrolytic method consists of the negative impact of free metal ions on the ability of microorganisms to attach to pipeline walls, as well as the suppression of microflora growth and reproduction. A wide range of scientific studies has established that copper ions, even in the smallest concentrations, can suppress the viability of marine microorganisms.

At the same time, aluminum hydroxide ions, formed as a result of flocculation, create copper-aluminum flocs, which are evenly distributed along the pipeline walls and prevent microorganisms from attaching to their surfaces. Additionally, the formed gel-like film of copper and aluminum ions protects pipeline surfaces from corrosion.

The electrolytic treatment not only prevents fouling but also creates a protective layer.

This method is implemented using two anodes—one copper and one aluminum, located in the seawater pump filter, near the intake opening of the pipeline in the kingston box or in the box cooler of the cooling system.

A direct current is applied to the anodes, leading to the release of copper ions and aluminum hydroxide, which negatively affect microorganisms. Simultaneously, all pairs of anodes from all kingston boxes are connected to a single multi-channel control panel.

Such biofouling prevention equipment and protection of internal surfaces of seawater pipelines is installed both on large-tonnage vessels and on small craft.

Key Conclusion

Calculations and experience in using anti-fouling systems show that the application of such equipment significantly reduces dry-docking costs by several times.

Implementing biofouling prevention systems on ships ensures economic effectiveness

MGPS/ICAF biofouling protection systems are already being supplied to several shipbuilding enterprises and are being installed on vessels of various classes.

PSS Corporation — a manufacturer and supplier of comprehensive cathodic protection solutions — has extensive experience in producing biofouling prevention systems for seawater supply pipes on vessels of all classes.
The company conducts monitoring of individual system components and accumulates detailed performance statistics on system operation. This contributes to the rapid restoration of systems during maintenance and repair operations.

The manufacturing cycle of such equipment, including testing and preparation for shipment to the customer, takes from 6 to 12 weeks, depending on the number of anodes and the specifications of seawater pumps. The higher the pump’s capacity, the larger the required anode units.