On 13th April 2004 IMO adopted the International Convention for the Control and Management of Ships’ Ballast Water and Sediments (in short BMW Convention). Most experts are of the opinion that MWM Convention will enter into force beginning of 2012 because at this stage access of one large shipping country would make the break even. It results from the schedule below that after a short transitory period lasting till 2016, when existing ships serving in international trade will be allowed to have WB exchange procedures, all ships sailing under the flag of signatory countries and calling to their ports shall have permanently installed BWT systems. It is expected that US will follow with their own, more stringent requirements soon after.

There are abt. 57 000 merchant ships in the world to be equipped with BWT systems. Forecasts indicate that within 5 years from enforcement of the Convention abt.10 000 ships will be affected per year with peaks of more than 16 000 ships in 2017 and 14000 in years 2018 and 2019. This shows that an important congestion can be expected both as to repair yards as well as producers of BWT systems.

In August 2011 there were 20 companies having final IMO approval of their BWT systems only. Further 51 companies have systems in different stages of approval.
There are two generic types of usually combined technologies for ballast treatment: solid – liquid separation and disinfection. The main disinfection priciples applied are:

• UV,
• electrolysis,
• cavitation,
• chemical injection,
• ozonation,
• deoxygenation.
 

The key questions to be answered when choosing WBT system are:

• availability of electric energy,
• type and parameters of existing ballast pumps,
• available space in machinery room,
• approvals
• track record.

WBT suppliers are strongly marketing their own products. They seldom mention any by-costs to be borne by shipowner. The most efficient and commonly applied system is a combination of mechanical filtering and UV disinfection. However even this system is not ideal for all ships because it has high electric power consumption, does not work in high sediment waters, increases the required ballast pump head, has high installation cost. This means that the total cost to be considered by Shipowner is not only the cost of BWT system but also of the cost of related conversion. For example in some cases to avoid the need for installation of additional generating set other types of systems may be considered as alternatives although they also have their own drawbacks. This shows the need for tight cooperation between shipowner and shipyard.

Remontowa Marine Design & Consulting (RMDC) has many years of experience in providing designs for newbuildings and conversions. It already has a track record in installation of WBT systems of different suppliers on newbuildings and existing ships. RMDC can give valuable advise to shipowners when type of WBT system is to be chosen. This can be done in form of feasibility studies. Later on RMDC can prepare specifications for repair yard, provide documentation for class approval as well as detail engineering for chosen yards.