Ballast Water Management in Ships | Ballast Water Exchange Methods | SHIPMATE

History of ballast water discharge regulations

The year was 1988. Australia and Canada were the first two counties that questioned highly toxic ballast water treatment. They were the first to question the relevance of non-native species invading the water at ports. The International Marine Organization took cognizance of the issue. It took a decade and a half for the organization to negotiate with member states and agree on ballast water management standards. 

In 2004, on the 13th of February, the standards were adopted at the BWM Convention named the International Convention for the Control and Management of Ships’ Ballast Water and Sediments. It took another thirteen years for the BWM Convention to get enforced in 2017.

What is the Purpose of Ship Ballast Water Management?

The objective is to reduce or eliminate invasive or non-indigenous species in the water. Before we proceed, let’s look at some key information:

• 80% of international trade happens via sea.
• Every year, 10 billion tonnes of blast water is transported.
• This volume of water can fill up 4 million pools used in Olympic Games.
• One new invasion occurs every nine weeks.

When non-indigenous species are introduced in the port water, there could be damaging effects. The European Maritime Safety Agency says that invasive species in the aquatic waters can result in:

• Diminishing the habitat quality of the port-of-call since deep-water species cannot survive in coastal waters and vice versa;
• Can harm the protected and endangered regional marine species;
• Increase vulnerability with microbial exposure;
• Harm the local fishing industry.

Steps To Reduce Hazards Associated with Ballast Water

Section D of Ballast Water Management mentions methods of treating ballast water. There are two main regulations:

1. D1 deals with Ballast Water Exchange Standards. It is about replacing the ballast water with seawater. At least 95% of the ballast water must be exchanged per the standards. The Convention has defined three ballast water exchange methods.
2. D2 standard is about ballast water performance standards. It mentions the number of microorganisms that can be discharged into the water.

The Ballast Water Exchange Methods

1. The sequential method of ballast water exchange – this method involves deballasting about ninety-five percent of the entire ballast water volume in the tank and then replacing it by refilling. It is also called the pump-out method or pump-in. The five percent that is not deballasted is permitted for unpumpable ballast.
2. The Flow-through method involves replacing ballast water by overflowing the ballast tank to a minimum of three times the capacity of the tank.
3. Dilution method ballast water – in this case, the water is filled in from the top while there is a discharge from the bottom simultaneously. The flow rate should be equal so that the water level is constant in the tank throughout the exchange operation.  

Guidelines for the control and management of ships ballast water.

• It is mandatory for all ships to have a Ballast Water Management Plan and the Ballast Water Record Book.
• The ballast water exchange should take place mid-sea.
• The ballast water exchange areas, as per the Convention, is 200 Nautical miles from the nearest port. The minimum depth of water should be 200 meters.
• If the above is not possible, the distance should be as far away from the land as possible. The minimum distance should be 50 Nautical Miles, and the water depth should be at least 200 meters.
• Ships, however, need not deviate from their original route to meet ballast water discharge criteria.

The Ballast Water Management Plan

The plan should contain: 

• Shore location where the facility to discharge ballast water is available.
• The duties of the ballast water management officer and the team.
• Procedure for ballasting.
• Locations for ballast exchange in different coastal water.
• Treatment method of the water.
• Sampling point.
• Ship Safety Management System
• A ballast water handling log detailing operation date, temperature, salinity, ship position, date of last cleaning, identifying the tank, and more.

Duties of the ballast water management officer

The ballast water management officer is accountable for the Planned Maintenance System of the ship, ensuring that the ballast water treatment, be it sequential method ballast exchange or dilution method ballast water exchange, is followed as per plan. The officer should assist the port state control with sampling and meeting all ballast water requirements. Prepare the declaration, maintain the ballast water handling log, and more.

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