BALLAST WATER MANAGEMENT

• The main relevance of the ballast water convention is to control the pollution caused by ballast water when discharged from one location into a different ecology
• This convention is intended to stop the transfer of unnecessary aquatic organisms and pathogens through the discharge of ballast water 
• The intention is to preserve ecology in biologically rich coastal water and similarly in deep oceanic water
• The intention is achieved by doing ballast water exchange during the vessel’s voyage
• By doing so, the pollution caused by ballast water can be controlled
• Because, the aquatic organisms and/or pathogens that are taken in coastal water are less likely to survive in deep oceanic water & similarly, those taken in deep oceanic water are less likely to survive in deep coastal water due to changes in water chemistry, temperature & salinity.

Ballast water exchange cannot be carried out anywhere at sea. Certain requirements must be complied with to perform ballast water exchange at sea

• Conduct ballast water exchange at least 200 nautical miles from the nearest land and in water of at least 200 meters in depth.
• When a ship cannot meet the above criteria due to short voyages or enclosed water, the exchange is to be conducted as far from the nearest land as possible, but at least 50 NM from the nearest land and in water of at least 200 meters depth.

Regulation D1 (Ballast water exchange standards)

• The standard is to replace the ballast water in mid-sea
• This method is based on the fact that species from coastal water cannot survive in deep water and species from deep water cannot survive in coastal water
• When replacing the ballast water at sea, BWM convention regulation D1 requires that at least 95% of the ballast water needs to be exchanged
• It can be achieved in two ways:      (I) Either deballast at least 95% of the volume of ballast water and then refill it (5% is allowed for unpumpable ballast)                                                                                                                          (II) Or Keep ballasting the ballast tank & keep overflowing it through air pipe or any other openings. BWM convention regulation D1 requires to pump in 3 times the tank capacity to achieve 95% of ballast exchange 

Regulation D2 (Ballast water performance standards)

• Regulation D1 is temporary & ultimately all ships need to arrive at Regulation D2
• It aims to control the number of species that can be discharged
• Ballast water needs to have less than 10 viable organisms per cubic meter
• This can be achieved by the Ballast Water Treatment System
• This system is fitted before the ballast overboard and treats the ballast water to the required standard before the ballast water goes overboard

(a) Sequential Method

• In this process, the ballast tank is first emptied and then refilled with new ballast water to achieve 95% of ballast exchange
• All of the ballast water in each tank is deballasted until the suction of the ballast pump is lost & eduction should be done to avoid a situation where organisms are left in the bottom
•  The tanks are then refilled with new water
• 5% is allowed for unpumpable ballast water
• Exchange can be carried out individually or in pairs

(b) Flow-through Method

• In this process, the replacement ballast water is pumped into a ballast tank & keep allowing water to overflow through the air pipe or any other opening to achieve 95% of the ballast exchange
• Regulation D1 requires to pump in ballast water 3 times the tank capacity to achieve 95% of ballast exchange

(c) Dilution Method

• In this process, the replacement ballast water is filled from the top of the ballast tank & simultaneously discharged from the bottom at the same rate
• The tank level should be maintained throughout the ballast exchange operation
• At least 3 times of tank capacity is to be pumped through the tank
• Two ballast pumps are used, one is acting as a  filling pump and other as a suction pump

Phytoplankton species

Every ship shall have a BWMP approved by the administration, which is the ship’s specific and shall have at least:

• Designate the officer-in-charge
• Procedure for disposal of ballast water
• Safety procedure for ship and crew
• Be written in the working language of the ship
• Reporting requirements for ships

a) Ultra-voilet treatment method:

• It consists of UV lamps that surround the chamber from which ballast water is passed.
• It produces the UV rays that sterilize micro-organisms, act on DNA, and make them harmless.
• It also prevents its reproduction.

b) Gas Treatment method:

• When filling ballast water, Inert gas is blown into the ballast water using a Venturi tube, the oxygen concentration of water is reduced, and ballast water is sterilized.
• The oxygen concentration of inert gas is lower than 0.1%, and this is lower than inert gas used for oil tankers (lower than 5%).
• In addition, some system uses ozone which has strong disinfection.
• These treatment methods may need a neutralization process or water quality adjustment during the discharge of ballast water.

c)Electrolysis method:

• The uptake ballast water is passed through filters and large aquatic organisms and dirt more than 50 microns are removed.
• Cavitation damages the cell membranes of organisms, and nitrogen gas purified onboard and hydroxyl ions generated by electrolysis are added to sterilize and to kill aquatic organisms and fungi.
• There are no active substances that are brought into the ship from outside the ship.

d) Magnetic Separation method:

• This is a treatment system for aquatic organisms, micro-organisms, and microbes in which magnetic powder is fed to the ballast water during its filling, water is agitated, and magnetic separation is performed.
• No chemicals for sterilization are used.
• The aqueous ingredients in ballast water are also unchanged, and re-treatment of discharged water, neutralization, etc., are not necessary.