Environmental Engineering Reference
In-Depth Information
2 Marine Biofouling of Polymers
Anju V. Nair and Mukesh Doble
Introduction
Biofouling is the undesirable accumulation of microbes (both prokaryotes and
eukaryotes), plants and marine animals on surfaces immersed in water. Attachment
to surfaces by living organisms is a serious problem faced worldwide by all users of
major water-based equipment including ships, loating buoys, pipelines and process
equipment such as heat exchangers. Biofouling occurs in fresh water lakes, ponds,
oceans and rivers. The major fouling community is algae, bacteria, barnacles, bryozoa,
hydroids, molluscs, polychaetes, seaweeds, and tunicates. The extent of fouling is
a function of several parameters, which include type of material, environmental
conditions, immersion time and nature of the biofouling community.
Biofouling leads to an increase in surface roughness of the hulls of ships. This leads
to a high hydrodynamic frictional resistance leading to increased fuel consumption.
The world leet of ships consumes 300 million tonnes of fuel annually, which can nearly
double with heavy hull fouling. The annual extra costs connected with biofouling
for the USA navy alone, is estimated to be 1 billion US$ [1]. Biofouling also leads
to an increase in the frequency of dry-docking operations, which involves downtime
for the vessels. Dry-docking involves bringing the ship to the port and removing the
biofoulants attached to the hull using physical/chemical methods, which may include
chipping, scraping or cleaning the surface with chemicals. A large amount of toxic
waste is generated during this process leading to the destruction of lora and fauna
near these ports. Deterioration and corrosion of coatings, release of chemicals and
introduction of invasive or non-native marine species to new environments are other
issues that are associated with biofouling [2]. Every year a large expense is incurred
in the removal of these biofoulers. Worldwide, marine industries spend £10 billion
a year to combat the problems associated with biofouling.
More than 4,000 marine species have been documented as biofoulers [3]. Many of
these can adapt themselves to changing environments. The irst step in the biofouling
 
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