One of the essential rituals of a ship during the voyage is loading and discharge of ballast water. Large vessels load thousands of tons of water to ensure safe operation and easy maneuverability of the ship while on sea. The ballast water may contain several species of organisms which when transferred to another ecosystem could thrive and endanger public health and may have an adverse effect on the ecosystem. The best way to protect the marine environment is to use ballast water treatment system.
Ballast water treatment refers to disinfecting the ballast water to keep it free from organisms before it is discharged into the sea. Although it is often used interchangeably with ballast water exchange, the process of water treatment is completely different from simply flushing out the ballast tanks.
When water from one eco zone is released onto another eco system, it can pose serious problems by spreading of aquatic organisms and can endanger the environment. That’s why, it is imperative that the ships use ballast water treatment before discharging the ballast water.
How ballast water treatment system works?
First, the ballast pumps pump up the ballast water on the ship, which is then filtered using fully automated back flushing filter. The filter comes with a 40 micrometer screen. Most of the organisms over and above 40 micrometer are removed in this filtering process. The filter could be either hydraulic or electronic.
Next, the water is disinfected through electrodialytic process. An inline disinfectant is produced and is then injected into the water. This process is called water activation. Only a small quantity of water undergoes the activation process.
After this, the activated water is made to flow into the total ballast water. The water activation unit can be placed away from the ballast line and can be connected with a small pipe and power cable. Best is, the water treatment leaves hardly any residue and therefore is ecofriendly. Also, since the elecrodialytic process needs low salinity levels, the power consumption is quite less. The process works even in case when the vessel is charting in river water. In such cases, sea water stored in storage tank is used for the process.
Many a times, the ballast water treatment system may use nitrogen super saturation to the treatment. While this is not a part of the treatment, it helps in keeping the vessel from rusting and corrosion, thereby increasing the life of the vessel.
At the discharge point, the ballast water is flushed out of the vessel. This facilitates de-ballasting in controlled environment.