Biofouling is one of the main problems faced by every type of ship at the sea. Marine growth such as barnacles and mussels have been the reason for problems such as decreased ship efficiency, corrosion etc. Biofouling not only sticks to the external surface of the ships but also gets into the water intakes and sticks to the surface of the pipes leading to problems such as blockage and corrosion.
In March 2017, the bulk carrier DL Marigold became the world’s first biofouling “casualty.” The vessel was ordered from both New Zealand and Fijian waters for being an invasive species threat, after divers discovered dense fouling of barnacles and tube worms on the ship’s hull. It was the first time an international ship had been ordered to leave a New Zealand port because of biofouling.
Bacteria especially Pseudomonas aeruginosa, that is found throughout the world’s oceans can cause ships to lose up to 40 millimetres per year even when built with duplex stainless steel, one of the hardest and most corrosion resistant materials used in the industry.
Though mechanical removing tools can be used to get rid of such marine growth, this is not always possible. For this reason, different types of marine growth prevent systems are used on board ships, along with anti-fouling paints. Advanced coating materials are used to prevent bio-fouling and corrosion, however “Most protective coatings need to be re-applied every few years.
Biofouling costs the aquaculture and shipping industries billions of dollars a year in maintenance and extra fuel usage. Scientists from the University of Sydney have developed nanowrinkled coatings that have the potential to avoid the build-up of damaging biological material and save up to $320 million annually spent by the Australian shipping industry because of biofouling.
The weight and drag caused by bacteria living on the surface of ships can also affect speed and maneuverability, the researchers said. They estimated that more than a third of fuel consumed by Chinese ships was wasted compensating for extra drag caused by bio-corrosion. US spends upwards of US$23 billion on the issue every year
Chinese scientists have developed a new material by combining copper with the widely used duplex stainless steel in the right formulation, which is corrosion and bacterial resistant while as strong as the steel.The new material could be a breakthrough in helping China become a new sea power, said Huang Weiping, a marine engineering professor with the Ocean University of China who was not involved in the research.
Scientists develop new coating to reduce biofouling costs
A team of chemistry researchers from the University of Sydney Nano Institute has created nanostructured surface coatings that have anti-fouling properties without using any toxic components. The new coating uses ‘nanowrinkles’ which are inspired by the carnivorous Nepenthespitcher plant. This plant traps a layer of water on the tiny structures around the rim of its opening.
The new materials were tested when they were tied to shark netting in Sydney’s Watson Bay, showing that they were efficient at resisting biofouling in a marine environment. Specifically, they resisted almost all fouling from a common species of marine bacteria, while control Teflon samples without the lubricating layer were completely fouled. Furthermore, test surfaces were placed to swimming nets at Watsons Bay baths in Sydney Harbour for seven weeks. Again, the slippery surfaces were still very efficient at resisting fouling.
Biofouling breakthrough to harness UV-LED Technology
AkzoNobel is to develop a fouling prevention technology using ultraviolet light-emitting diodes (UV-LED) to eliminate fouling growth on underwater surfaces.
The technology was developed by Royal Philips, and the anti-fouling solution will integrate UV light-emitting diodes in a protective coating scheme. This will allow for the UV light to be emitted from the coating surface, preventing biofouling accumulation on the protected area.
Klaas Kruithof, chief technology officer, AkzoNobel, said: “We actively look for complementary technologies and partners to innovate with. In this case, the combined capabilities and technology of Royal Philips and AkzoNobel will enable us to accelerate the realisation of this transformative innovation, which we intend to initially market ourselves and consider licensing out to third parties for large-scale adoption.”
Control of biofouling represents a substantial economic and environmental benefit for vessel owners and operators due to the improved fuel efficiency of clean hulls as well as maintenance savings. Initially, the focus for the biocide-free solution will be on applications for ships, yachts and offshore assets, but the project could potentially be extended to include other surfaces challenged by fouling issues.
China: New bacteria-fighting solution can lead to stronger, faster and long lasting ships
Chinese team, led by professor Yang Ke, have developed a new material by combining copper with the widely used duplex stainless steel in the right formulation, which is corrosion and bacterial resistant while as strong as the steel. To test the new material, the scientists cultured P. aeruginosa on it. The copper-steel amalgam killed nearly 97 per cent of the bacteria in a week, preventing corrosion and “effectively eradicating the biofilm”, according to the team’s paper in the journal Biofouling.
The researchers were inspired by Eighteenth century custom of British royal navy which covered the bottoms of its wooden ships with copper to prevent hulls from rotting, a crucial technology that helped the UK achieve maritime dominance in the late 18th century. Corrosion and Bacteria are the most dangerous enemies of warships. Hundreds of billions of yuan are lost in damage due to corrosion that stainless steel undergoes when exposed to seawater. In 2011, the USS Independence aircraft carrier was returned to dry-dock after less than a year in service due to severe corrosion found on steel components around its engines.
For underwater projects, repeated coatings cannot be applied because it is impossible to do the job in water,” Though still undergoing testing, the special material can be applied to critical components such as joints and shafts, where the traditional practice of coating with anti-corrosion materials is difficult or impossible, thus significantly increasing the performance and durability of a vessel, the scientists said.