Environmental Engineering Reference
In-Depth Information
The biggest operating cost for most systems is power and for large power con-
sumers (electrolytic, advanced oxidation processes and UV) the availability of
shipboard power will be a factor which may limit its installation and operation.
For chemical dosing systems, power consumption is very low and chemical costs
are the major factor. For these reasons chemical addition may be better suited to
treat small ballast capacities.
Although the BWMS operate at generally low pressure and thus do not require
additional ballast water pumping pressure, those employing Venturi devices (for
exerting shear forces and proper mixing of chemicals) incur pressure losses of up to
2 bar.
For most systems it is recommended that the installation takes place in the
engine/machine room near the existing ballast water pumps, although installation
on deck may also be possible if appropriate precautions are taken. If the location is
in an explosion zone, then the installation will need explosion proofi ng. Some of the
technologies can be provided as explosion-proof products, but there is a cost factor
for this. The generation of hydrogen by the electrolytic technologies is not consid-
ered an issue, provided the gas is vented and diluted with air to safe levels.
Whilst disinfection by-products are an issue, and central to the approval of bal-
last water management systems that make use of active substances, suppliers are
confi dent that the levels of active substances and by-products generated are unlikely
to be problematic. There is a large amount of scientifi c and technical information
on disinfection by-products formation that is likely to support this. However, all
systems using active substances will be reviewed by an independent expert group
of GESAMP to assess the environmental acceptability of the treated water at
discharge.
Ballast Water Management Systems Testing and Approvals
All systems need to be type approved by a Flag state before being sold to a client.
Systems that use Active Substances by the defi nition in the BWM Convention have
to undergo a more thorough certifi cation process and obtain Basic and Final
Approvals by IMO MEPC. This process was initiated to proof the environmental
acceptability of treated ballast water when discharged from a vessel.
All systems are tested in a land-based setting with challenging water conditions
(different water parameters and high organism numbers) to show that the D-2 stan-
dard is met. Ten test cycles need to be carried out in minimum. In addition, at least
three test cycles need to be undertaken over a period of at least 6 months on board
of commercial vessels to document that they meet the D-2 standard and are seawor-
thy. These tests are addressed in the IMO Guidelines G8. Currently a harmonization
of sampling methods and sample analysis options is ongoing with all test facilities
and shipboard sampling teams being involved (GloBalTestNet) and in October 2013
a Memorandum of Understanding of these was signed to achieve these goals. Test
facilities are located in China, Denmark, Germany (Stephan Gollasch for shipboard
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