Ballasting and Deballasting is the term used to stabilize ships in the water, especially when ship is discharged from all heavy load, it becomes light in weight hence unbalanced to float smoothly on the surface. So ballasting is taking water into the tanks of the ship to meet the standard load for balancing and same manner when the ship needs loading, deballasting is required or may be this process required in certain circumstances as well when the ship sails.
As per International Maritime Organization (IMO) there are two standards for ballast water management:
D1 Standard – Ballast Water Exchange (BWE)
First standard is the D1 standard which refers to Ballast Water Exchange (BWE). For BWE, efficiency of at least 95% volumetric exchange of ballast water is required. Efficiency is considered as 95% standard when the ship uses to have pumping-through method and where it pumps three times. This entire operation has to be done while ship conducts 200 nautical miles operations from the shore/land, and the water should meet the standard of min 200 meters deep. It is better to go as far as from the land to undertake BWE operation however, minimum 50 nautical miles could also be considered however, under no conditions water depth should not be less than 200 meters. One more thing to remember is, to contact the port state administrators to confirm Ballast Water Exchange requirements within local waters.
D2 Standard – Ballast Water Performance
D2 standard refers to performance of the ballast water and this is all about chemistry and the laboratory testing where we need to get report for D2- Ballast Water Performance Testing from accredited lab. Purpose of D2 standard is to stipulate the level of acceptance of organism that could be found in the discharge ballast water.
- The viable organisms fewer than 10 greater than or equal to 50 micrometers in minimum dimension per cubic meter;
- The viable organisms fewer than 10 less than 50 micrometers in minimum dimension and greater than or equal to ten micrometers in minimum dimension per milliliter.
Additionally, a ballast water discharge of indicator microbes, as a health standard, shall not exceed the following specified concentrations:
- Toxicogenic Vibrio cholerae (O1 and O139) with less than one colony-forming unit (cfu) per 100 milliliters or less than 1 cfu per 1 gram (wet weight) zooplankton samples;
- Escherichia coli less than 250 cfu per 100 milliliters;
- Intestinal Enterococci less than 100 cfu per 100 milliliters
You might also be interested in our Ballast Water Analysis as per IMO D2 Standards Services.