Why ships carry ballast water
When a cargo vessel offloads its freight, it becomes too light to sail safely. Ships compensate by pumping seawater into dedicated ballast tanks to maintain stability, trim, and propeller immersion. This water — taken on at the origin port — contains microorganisms, bacteria, algae, and larvae native to that location. When the ship arrives at the destination port and pumps the ballast water out, those organisms are released into a foreign marine environment. Without natural predators or competition, invasive species can dominate local ecosystems, causing irreversible ecological and economic damage.The treatment cycle
A BWTS treats water twice:
Both operation types appear as
operation_type values in the telemetry data. The system must be actively treating (lamps on, flow within limits) during both operations to be compliant.
UV treatment method
This system uses ultraviolet light to disinfect ballast water. UV-C radiation at the correct intensity disrupts the DNA of microorganisms, rendering them unable to reproduce — even if they survive passage through the UV reactor. The critical metric is UV intensity, measured in W/m² at the reactor sensor. The higher the intensity, the more effective the treatment:- Below 252 W/m² → non-compliant with IMO D-2
- 252–530 W/m² → IMO D-2 compliant, not USCG compliant
- Above 530 W/m² → compliant with both IMO D-2 and USCG standards
The 16-lamp diamond array
This installation uses 16 UV lamps arranged in a diamond pattern across the reactor cross-section. The arrangement ensures full coverage of water flow with no untreated channels. Having 16 lamps provides two key advantages:- Redundancy — The system remains operational even if several lamps fail or degrade, as long as aggregate intensity stays above compliance thresholds.
- Progressive replacement — Lamps can be replaced individually during port calls without taking the entire system offline.
System components referenced in telemetry
Where operations happen
Thelocation field in telemetry records the port name where each operation takes place. Ballasting and deballasting always occur during port calls — treatment is not active at sea.