Answer
The D-2 Standard is a performance-based requirement under the International Convention for the Control and Management of Ships' Ballast Water and Sediments (BWM Convention). Unlike the D-1 standard (which focuses on ballast water exchange), the D-2 standard requires ships to install a type-approved Ballast Water Management System (BWMS) to treat ballast water, ensuring that the number of viable organisms discharged meets specific safety thresholds.
D-2 Discharge Standards
Ships must ensure their treated ballast water discharge complies with the following concentration limits for viable organisms:
The 3 Specific Target Indicator Pathogens (Mandatory Exam Answer)
The D-2 standard mandates that the discharge of the following indicator microbes must not exceed these specific safety concentrations:
| Pathogen Name | Mandatory Maximum Allowable Discharge Concentration |
|---|---|
| 1. Vibrio cholerae (Serotypes O1 and O139) | Less than 1 cfu (colony forming unit) per 100 ml or less than 1 cfu per 1 gram (wet weight) of zooplankton samples. |
| 2. Escherichia coli (E. coli) | Less than 250 cfu per 100 ml. |
| 3. Intestinal Enterococci | Less than 100 cfu per 100 ml. |