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Ballast Water Management

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BWM type approval

Type approval

The IMO BWM Convention was ratified in September 2016 and applies to all ships and offshore structures that carry ballast water and are engaged in international voyages. Furthermore, the revised USCG BWM regulations came into force in 2012. Both will require ships to treat ballast water to ensure compliance with the D-2 standard (IMO) and the discharge standard (USCG). With our extensive knowledge of BWM and treatment technologies, we are ready to assist with type approval of BWM systems according to the latest requirements.

DNV GL is the worldwide leading body in type approval of ballast water management systems (BWMS) according to   the IMO Guidelines . Furthermore, we are the first classification society accepted by the United States Coast Guard (USCG ) as an independent laboratory (IL) to evaluate and test technologies designed to treat ballast water on ships according to USCG regulations. We have developed a type approval programme for assessing BWMS during type approval according to  the IMO and USCG regime. More than 25 systems are currently being tested and/or approved for USCG/IMO type approval at different locations around the world. 

In addition to type approval of BWMS, DNV GL also performs approval of test facilities engaged in environmental, land-based and shipboard testing of BWMS. We are leading a partnership with several biological and environmental test facilities worldwide to test and evaluate BWMS to the USCG regulations. More test facilities are in the pipeline to be added to our network of sub-contractors worldwide. For further details, please contact us or visit our FAQ  page. 

Overview of different technologies

There are a variety of treatment options for ballast water. DNV GL has done a survey of the number of systems sold by various BWMS vendors. The survey demonstrated that systems using UV and electrolysis technologies have the largest market share today. This is the state of the market today and may possibly change when more experience comes to light for the different technology types.

Some of these technologies are described below :

Filter and UV

Technology
Short description
Technology
Filter and UV
Short description
These systems filter the particulates and bigger organisms before UV disinfection. Usually, filters automatically back flush when a certain differential pressure is exceeded. The UV light kills or inactivates the organisms by disrupting their DNA, leaving them unable to perform vital cellular functions. During ballasting, the seawater is filtered and UV-treated, only to then be UV-treated a second time during de-ballasting.
These systems do not produce any harmful by-products and they are mostly independent of temperature and salinity. Different UV transmittance in the seawater will imply higher energy demand.

Filter and electrolysis

Technology
Short description
Technology
Filter and electrolysis
Short description
These systems filter the particulates and the bigger organisms before active substances generated from the electrolysis are injected into the ballast water. The electrolysis can be installed inline or in a side stream, where the disinfectant breaks down the cell membranes of the organism.
The active substances are produced through oxidation of seawater in the electrolysis chamber. Electrolysis also produces hydrogen gas which shall be correctly handled for safety of the ship. During ballasting, the seawater is filtered and active substances are injected. During de-ballasting, the active substance is neutralized prior to discharge overboard.

Ozone

Technology
Short description
Technology
Ozone
Short description
These systems disinfect by injecting O3 generated from ambient air. The O3 oxidizes and neutralizes aquatic species by reacting with seawater to produce effective disinfectants. Salinity and temperature are not obvious factors affecting the efficiency of these BWMS, however longer holding time may be required.
Residual by-products are required to be neutralized prior discharge. Since ozone is toxic, additional safety measures and crew training are necessary.

Chemical injection

Technology
Short description
Technology
Chemical injection
Short description

These systems are often used in combination with filtration. A chemical solution is injected into the ballast water to ensure disinfection. The disinfectant may be liquid or granular and will require neutralization prior to discharge overboard.

Chemicals used are trademarked, and supply might be limited to specific ports. The chemicals must be stored on board in closed containers and may be hazardous. The use of chemicals requires implementation of strict safety provisions and crew training. These BWMS have a higher operational cost than other ballast water technologies.

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