Biofouling describes the accumulation of microorganisms, plants, algae, and animals on submerged structures like ship hulls. It is a major problem for shipping and industrial processes. Biofouling occurs in four stages - formation of a conditioning film, accumulation of microorganisms, growth of bacteria and diatoms, and overgrowth by algae and invertebrates. It increases drag on ships and maintenance costs. Traditional antifouling methods using chemicals like TBT have been banned due to environmental effects. Newer non-toxic methods use natural substances from marine organisms or physical removal, but these are less effective or more costly. Corrosion is also a major issue for ships and needs ongoing prevention

1. Biofouling, Antifouling and Treatments
Institute of Marine Sciences, University of Chittagong

2. Biofouling :
Bio means “Life” and Fouling comes
“Pollute”
Biofouling describes a wide range
of organisms attached to surfaces
immersed in the ocean which effect
the surface or substratum of any
objects.
Fouling phenomena are common
diverse, ranging from fouling of ship
hulls and marine infrastructures.

3. Biofouling Effects & Impacts

4. •Biofouling is the undesirable
accumulation of microorganisms, plants,
algae, and/or animals on wetted
structures.
•Marine and freshwater biofouling is one
of the major unsolved problems currently
affecting the shipping industry and
industrial aquatic processes.
•Marine biofouling commonly refers to
the adverse growth of marine organisms
on immersed artificial structures such as
ship hulls, jetty pilings, navigational
instruments, aquaculture net cages and
seawater in taking pipes.
Biofouling

5. How Biofouling occurs?
The establishment of the fouling community is composed of four stages (Fig. 1; Abarzua and
Jakubowski, 1995) and some of these stages can overlap or occur in parallel.
Figure 1.Process of fouling: The 4 main stages of marine biofouling (NERC News 1995)

6. Biofouling is not as simple a process as it sounds. Organisms do not usually simply suck onto
a substrate like a suction cup. The complex process often begins with the production of
a ”Bioflim”.
Formation of biofouling
Formation of Microfouling
• In the aquatic environment, any submerged solid surface gets coated by a complex layer,
initially consisting of an organic conditioning film.
• Formation of this film is immediately followed by an accumulation of microorganisms (eg.
bacteria, fungi, diatoms, and other micro-organisms) and the secretion at their cell surface of
extra cellular polymeric substances (EPS) during attachment, colonization, and
population growth.
• A biofilm is a film made of bacteria, such as Thiobacilli or other microorganisms, that forms
on a material when conditions are right. (Gehrke, T; Sand, W. 2003).

7. Bacteria Growth Spread
•Nutrient availability is an important factor;
•Bacteria are not the only organisms that can create this initial site of
attachment diatoms, seaweed, and their secretions are also culprits.
Formation of macrofouling
• A macrofouling community consisting of either 'soft fouling' or
'hard fouling’ may develop and overgrow the microfouling.
• Soft fouling comprises algae and invertebrates, such as soft
corals, sponges, anemones, tunicates and hydroids.
• Hard fouling comprises invertebrates such as barnacles,
mussels and tubeworms, bryazons and seaweeds.

8. Biofouling Agents

9. Biofouling processes

10. Effects of biofouling
• Both micro- and macrofouling in the world’s oceans cause huge material and economic
losses in maintenance of mariculture facilities, shipping facilities, vessels, and seawater
pipelines (Wahl, 1997; Clare, 1998;Fusetani, 2004; Yebra et al., 2004).
• Biofouling increases weight and frictional resistance of the ship, thus affecting its
hydrodynamics, speed and maneuverability (Rolland and DeSimone 2003).
• Biofouling is everywhere. Parts of a ship other than the hull are affected as well: heat
exchangers, water-cooling pipes, propellers, even the ballast water. (Brizzolara, RA. 2002).
• biofouling on ship hulls is a powerful way of spreading species to new parts of the world
oceans leading to bioinvasion, which is now recognised as a major threat to biodiversity
(Anil et al., 2002).

12. Biofouling
formation
and
remedial
measures

13. Remedial measures of Biofouling
• Physical method
• Chemical method
• Biological method
Physical method
• The simplest method for treatment of fouling is simply to remove by
mechanical cleaning eg, by treatment of the fouled surface with high-pressure
water jets (Granhag et al., 2004).
• scraping

14. Disadvantages
• Costly
• Time consuming
• Less effective
• Not easily applicable to everywhere

15. Chemical method
• TBT(Tributyltin)
• Copper
• UV irritation
• Chlorination
• Titanium alloys
• Silicone elastomers

16. DISADVANTAGES
• Evidence of adverse effects of TBT prompted
the International Marine Organization to call
for a ban on the application of TBT based
antifouling paints from 2003 and the
presence of such paints on the surface of
ships from the year 2008.
• some want to eliminate copper-based
coatings, claiming they are responsible for
the same negative effects as TBT.
• These are not organism specific.

17. Biological method
• There may be no greater way to fight nature than
with nature itself.
• The disadvantages of physical and chemical methods
we need the help of natural source for producing
ecofriendly antifouling compounds.
• Several kinds of natural antifouling agents that
inhibit growth of fouling orgonisms have been
isolated from marine organisms like bacteria
(Holrnstrom et al., 1996), marine algae (Abarzua et al., 1999, de Nys et
al., 1996, Eng-Wilmot et al., 1979, Gross et al., 1991, Hellio et al., 2002, Ishida 2000,
Murakami et al.)

18. Ship & Structure Corrosion
Ship corrosion is a major hazard for the
industry. The deterioration of these
structures causes higher maintenance
costs, early system failures, or an overall
shortened service life.
Corrosion is a natural process which as
a result, reduces metallic elements back
to their original state. All metals have
different levels of risk for example gold
is the least corrosive while magnesium
is the most corrosive.

19. Galvanic corrosion is the most common form of corrosion and therefore the most dangerous. This occurs
when two or more metals are in contact with each other, while submerged in an electrolyte solution like saltwater.
As a result, the more reactive metal begins to deteriorate at a faster pace which is never a good sign in regards to
personal safety. Physical signs of corrosion are flaking and blistering of paint and eventually lead to pitting of the
metal.
Therefore, Crevice corrosion involves the interaction of one metal part with two
connected environments such as a tight, confined space, where elements like oxygen are
limited. In conclusion, depending on the environments involved, pitting or cracking may
occur, causing some serious damage
Flow-accelerated corrosion this type of ship corrosion occurs from the constant flow of
water against a metals surface which can be particularly harmful and may rapidly
breakdown a vessels protected layers.
When a metal is affected by corrosion, an oxide layer is formed which in turn protects a
metals lower layers from further harm. Removing oxidation begins when salt water flows
over this layer.

20. conclusion
• Bio fouling remedial measures move towards nontoxic antifoulants.
• Marine lives such as corals, sponges, marine plants, and dolphins, etc.,
prevent the surface of their bodies with antifouling substances without
causing serious environmental problems.
• Therefore, these substances may be expected to be used, as new
environmental friendly antifouling agents, especially those having highly
anesthetic, repellent, and settlement inhibitory properties, etc., without
showing biocidal properties, are desirable.

21. Thank you All
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