The International maritime organization (IMO) in 1997 adopted
the guidelines for control and management of ship’s ballast water to minimize
transfer of harmful aquatic organisms and pathogens from one sea area to
another. Later, the Marine Environment Protection committee on February 2004
adopted the International Convention for the Control and Management of Ship’s
Ballast Water and Sediments.
According to this convention all ships should carry and
implement ballast water and sediments management plan, maintain ballast water
record book and carry out ballasting and de ballasting operations in accordance
with the convention.
Mentioned below are ten important points for complying with the
ballast water convention:
1. General Methods For Managing Ballast Water Whose Source Is
Anything Other Than The Deep Ocean Are As Follows:
1) Proceed to Port state approved offshore location to carry out
exchange
2) Seal tank against discharge while in port waters
3) Pump water to a shore reception facility
4) Prove by Laboratory analysis that the ballast Water in safe
and acceptable
5) Treat the Ballast in-Situ using an approved treatment method.
2. Important Points To Consider For Taking Ballast In
Port
To the greatest extent possible, the ship should be slightly
ballasted in port for departure using ballast tanks to allow for safe
Navigation. The master should ensure that the ship takes on ballast water that
is as clean as possible and care should be taken to minimize any sediment
uptake. Taking on Ballast under the following circumstances should be avoided
whenever possible:
1) In shallow water
2) In vicinity of sewage out-falls or dredging operations
3) Near, where there is a known outbreak of diseases
communicable through ballast water
4) In areas with toxic phytoplankton blooms (harmful algae
blooms such as Red tides)
5) At night when bottom- dwelling organisms may rise up in the
water column
6) Where the incoming or outgoing tide is known to be turbid
7) Where tidal flushing is poor
3. Important Methods Of Ballast Water Exchange
Ballast water exchange operations are to be carried out in the
deep water, open ocean as far as possible from the shore. The exchange should
be conducted when the vessel is sailing in clean ocean water, which can be
found more than 200 nautical miles from shore and in the water where the depth
is 200 meters or more.
Currently three methods are exists and the sequential method is
preferred.
Method 1:
Sequential method: The ballast tanks with water to be exchanged
are emptied and refilled with clean ocean water in order to achieve at least a
95 percentage volumetric exchange. In this method the ballast tanks are
emptied until the ballast pumps lose suction and then the tanks are further
stripped by eductor systems.
Method 2
Flow-through method: A process by which replacement ballast
water is pumped into a ballast, allowing the incoming water to overflow through
the air vent or dedicated overflow vents. In practice, this means that at
least three (3) tank volumes are to be pumped through each ballast tank to
achieve 95% of efficiency of exchange.
Method 3
Dilution method: A process in which the replacement ballast
water is filled through the top of ballast tank (e.g. Manhole) with simultaneous
discharge from the bottom of the tank at the same rate, while maintaining a
constant level in the tank during the operation.
4. Ballast Water Sampling Point
The sampling of ballast water may be required by the local
authorities such as a Quarantine officer. Normal ballast water sampling may be
done through the sounding pipe. Location of the sounding pipes’ heads are to be
marked and should be shown on the vessel plan.
5. Sediment Management
Routine cleaning to remove sediments from tanks which are used
to carry ballast should be regularly under taken:
1) Flushing with small quantity of clean water in an empty tank
and de-ballasting it again
2) Manual cleaning by making an entry in to a ballast tank or
tanks. The tank entry is an hazardous operation and safety procedures should be
followed before entry. Inform port authority and “Enclosed space entry permit”
to be made prior entry.
6. Chain Lockers and Sea Chests
Subjected to practical accessibility, all sources of sediment
retention such as anchors, cables, chain lockers, suction wells should be
cleaned out regularly as an additional precaution to further reduce the
possibility of spreading contamination.
7. Disposal of Sediments
During cleaning and De-slitting operations, the tank sediments
should be safely disposed of and should NOT be discharged in estuarine of
coastal waters. Safe disposal consists of removal to shore facilities or
designated landfill areas or discharge into deep ocean water in accordance with
the convention.
8. Record Keeping
All the data of ballasting and De-ballasting operations, ballast
water exchange etc. should be recorded with time and position in the
ballast water record book .When sediment is cleaned from ballast tanks or chain
lockers, this data should also be logged.
9. Ballast Water Management Officer
Usually, Chief Officer is the designated person for ballast
water management. He must ensure that the procedures laid out in the ballast
water management plan is implemented on board properly. It is important to plan
and carry out ballasting and De-ballasting operation taking in to account the
stability, trim factors of the vessel and advising other officers to carry out
the operation safely. Prepare the ballast water declaration from prior to
arrival in port. Assist port state control or quarantine officers for any
sampling that may need to be taken. Maintain the Ballast water record book
properly.
10. Crew Training and Familiarization
All officers and ratings should be trained and familiarized
regarding ship’s pumping plan, positions of air and sounding pipes, location of
tanks and manholes, compartment and tank suctions, pipe lines as well as remote
pump operation and sounding equipment. Also all crew should be made aware of
safety precautions and hazards involved. In addition, officers should be
familiarized with record –keeping and approved stability booklet, and ballast
water log should be cross checked everyday.
More researches are still under
progress to enhance ballast water management and to eradicate the transfer of
harmful aquatic organisms and pathogens, thus preventing change in marine
environment and marine lives. Plans for making ships without ballast tanks
are also underway which will further help in putting an end to
pollution caused by ballast water.
