:max_bytes(150000):strip_icc():format(webp)/GettyImages-83994452-57896b1e3df78c09e928bcd1.jpg)
..........................................................................................................................................................
Ballast Water Systems
How Ballast Water Systems Work
by Paul
Bruno
A ballast water
system is essential for the safe operation of a ship, but the operation of
these systems causes significant threats to the environment and local economy.
What Is a Ballast
Water System?
A ballast water
system allows a ship to pump water in and out of very large tanks to compensate
for a change in cargo load, shallow draft conditions, or weather.
The capacity of
ballast water tanks might be millions of gallons on a large vessel.
This allows vessels
to carry a light or heavy load while maintaining ideal buoyancy and handling
conditions in all situations.
A ship might
discharge all ballast water tanks to pass a shallow area or forward tanks only
to raise the bow in rough open seas.
Physical components
of the system include; raw water intakes, large and small strainers, pumps,
distribution pipes, ballast water tanks, treatment system, discharge system,
and all the valves, sensors, and controls to run the equipment.
Invasive Species in
Ballast Water
Invasive species are
a significant threat to ecosystems and the economies of the affected areas.
Researchers think
that about one-third of all documented invasive plants and animals are able to
travel in the ballast water tanks of ships.
Zebra Mussels were
introduced into Lake Saint Clair in 1988 when a ship emptied ballast water into
the Great Lakes System.
The Great Lakes hold
nearly twenty percent of the earth’s fresh surface water in a watershed system.
The non-native
mussels eliminated native varieties once used by industry and have caused an
estimated 7 billion dollars (US) in damage by encrusting or clogging underwater
equipment essential to industrial and recreational activities.
Sea Lamprey and Spiny Water Fleas are
organisms which feed off of host fish or compete with young fish for food.
Many species of fish
impacted by these invasive species have significant commercial or sporting
value. These animals and others can live in fresh or salt water and may spread
into inland waterways from saline ports and harbors.
Plants can also
travel long distances in ballast water.
Eurasian Milfoil is a
surface plant which can clog equipment and deter recreation where it forms
thick mats. Eurasian Milfoil was introduced to the United States in the 1940s.
Because the plant can
produce large colonies from only one small fragment it is likely the plant was
introduced in the ballast water of a ship.
Resolving Ballast
Water Issues
For years amateurs
and professional researchers have experimented with a huge array of weapons to
combat invasive species in a ship’s ballast water.
Most of the
difficulty is due to the fact that huge volumes of water must be treated in a
reasonably short period of time.
Many land-based
systems for treating public supplies takes many hours or days to pass water
through their treatment systems.
A ship, on the other
hand, must be able to discharge ballast water as quickly as cargo is loaded.
In emergency
situations, ballast tanks need to empty as quickly as possible. A quick pass
through most ballast water treatment systems is not enough to kill all the
organisms that may be present.
Ballast Water
Treatment Solutions and Shortcomings
No Discharge or
Ballast Exchange Rules: International, National, and Local law govern ballast
water discharge.
Some areas require
ballast tanks to be sealed while others allow ballast to be exchanged. Ballast
exchange allows tanks to be filled with local waters.
Sealed ballast tanks
may need to be emptied in an emergency situation and exchange is hindered by
the fact that foreign waters must be discharged in close proximity to the sensitive area
for vessels to operate safely.
Mechanical Filters:
Filters which are fine enough to remove the small immature young and eggs of
invasive species clog quickly and require constant maintenance.
Thermal Treatment:
The idea is to heat ballast water to kill any unwanted organisms. Unfortunately
heating such a huge volume of water is impractical due to time and energy
constraints.
Other Energy
Treatments: Ultraviolet, sonic, and other radiation have all been tried but
have similar problems to a thermal treatment; limits on time and energy.
Chemical Treatments:
One of the earliest and most dangerous of all the methods used to control
invasive species in ballast water. Chlorine bleach and other toxic chemicals
will kill existing organisms but the release of these chemicals on the scale
necessary to treat every ship would reach toxic levels for all aquatic life
near the discharge points.
The Future of Ballast
Water Treatment
Researchers are
pursuing this difficult and financially lucrative goal at institutions around
the world.
In 2011, a team
announced their successful small-scale test of a two-phase ballast treatment
system which eliminates unwanted organisms and produces sodium bicarbonate as a
byproduct.
The system is
undergoing full-size tests in the Great Lakes. The test for a scalable system
is expected to perform well.
It is not clear how
regulatory agencies around the world will respond to the potential discharge of
industrial amounts of sodium bicarbonate into their waters.
Sodium bicarbonate is
a common and safe chemical in small amounts, but studies must be conducted to
assure this method is safe for long term use.
Paul
Bruno
Introduction
United
States Coast Guard licensed Ship Master with Passenger Certification.
A marine
contractor familiar with all ship systems who has worked in the industry for
more than 20 years.
Has a
USCG Master's License and a degree in Creative Nonfiction and Technical
Writing, from the University of Wisconsin.
Experience
Paul
Bruno is a former writer for ThoughtCo who contributed work for over five years
on the maritime industry. He has worked with a variety of vessels throughout
his maritime career, including various commercial ships as well as the Great
Lakes schooner reproduction "Dennis Sullivan." As a marine
contractor, Paul is familiar with all ship systems, and his lifelong passion
for electronics has led to a focus on marine hardware and software development.
When he is not working, Paul's favorite hobby is knot work, keeping busy with
the nearly 4,000 documented knots, splices, and eyes.
Education
USCG
Master's License, 1993
Creative
Nonfiction and Technical Writing, University of Wisconsin, Milwaukee and
University of Waikato, Hamilton NZ
A
Message from Paul Bruno
ThoughtCo
and Dotdash
ThoughtCo
is a premier reference site focusing on expert-created education content. We
are one of the top-10 information sites in the world as rated by comScore, a
leading Internet measurement company. Every month, more than 13 million readers
seek answers to their questions on ThoughtCo.
For more
than 20 years, Dotdash brands have been helping people find answers, solve
problems, and get inspired. We are one of the top-20 largest content publishers
on the Internet according to comScore, and reach more than 30% of the U.S.
population monthly. Our brands collectively have won more than 20 industry
awards in the last year alone, and recently Dotdash was named Publisher of the
Year by Digiday, a leading industry publication.
No comments:
Post a Comment