Answer
The IMO International Convention for the Control and Management of Ships' Ballast Water and Sediments (BWM Convention) sets specific regulatory standards under Section D to prevent the transfer of harmful aquatic organisms and pathogens.
D-1 Standard: Ballast Water Exchange (BWE)
The D-1 standard regulates operational ballast water exchange in open sea during transit:
- Efficiency: Ships performing ballast water exchange must achieve an efficiency of at least 95% volumetric exchange of ballast water.
- Exchange Methods: Pumping through 3 times the tank volume (Flow-through or Dilution methods) or sequential emptying and refilling.
- Location Requirements:
- At least 200 nautical miles from the nearest land and in water at least 200 meters deep.
- If unable, at least 50 nautical miles from land and in water at least 200 meters deep (or in designated BWE areas).
D-2 Standard: Ballast Water Performance Standard
The D-2 standard specifies maximum discharge concentration limits for viable organisms and indicator microbes. Compliance requires installing an approved Ballast Water Management System (BWMS) on board.
Organism Category | D-2 Discharge Limit |
|---|---|
Organisms ≥ 50µ m (e.g., zooplankton) | Less than 10 viable organisms per cubic meter (m3) of ballast water. |
Organisms 10 µm to 50µm (e.g., phytoplankton) | Less than 10 viable organisms per milliliter (mL) of ballast water. |
Toxic Vibrio cholerae (Indicator Microbe) | Less than 1 colony-forming unit (cfu) per 100 mL (or 1 cfu per gram wet weight). |
Escherichia coli (Indicator Microbe) | Less than 250 cfu per 100 mL. |
Intestinal Enterococci (Indicator Microbe) | Less than 100 cfu per 100 mL. |
D-3 Standard: Approval Requirements for BWMS
Regulation D-3 mandates that Ballast Water Management Systems used to comply with the D-2 standard must be approved by the Flag State Administration:
- BWMS Code / G8 Guidelines: Type approval standards ensuring the equipment operates safely and effectively under various operational conditions (e.g., salinity, turbidity, temperature).
- G9 Guidelines (Active Substances): If the BWMS uses chemical disinfectants or generates Active Substances on board (such as electrochlorination / ozone / chlorine dioxide), it must undergo a two-tier approval process by the IMO GESAMP (Group of Experts on the Scientific Aspects of Marine Environmental Protection) for Basic Approval and Final Approval.
D-4 Standard: Prototype Ballast Water Treatment Technologies
Regulation D-4 provides a framework for testing innovative treatment technologies:
- Application: Applies to ships participating in Flag State-approved research programs to test and evaluate prototype ballast water treatment technologies.
- Exemption Period: A ship participating in an approved prototype program is granted a 5-year allowance from the date the ship would otherwise be required to comply with the D-2 standard before needing to install a fully type-approved system.