Feature 3 | Ballast water & waste water treatMent
Growing array of solutions to meet new
rules
Motivated by growing concerns over the ecological and economical problems
associated with invasive species transported in vessels’ ballast, the use of
shipboard treatment systems for ballast water will become a mandatory
requirement. David Tinsley investigates.
U
nder the International Convention the BalPure system
for the Control and Management of from severn trent
Ships’ Ballast Water and Sediments, De nora (Credit:
systems of the requisite standard will have severn trent de
to be installed in vessels constructed after a nora llC).
certain date, originally foreseen from 2009
onwards. Transitional arrangements depend
on the keel laying date and the vessel’s ballast
water capacity. The timetable provides for the
retrofitting of existing ships up to 2016.
However, the slow pace of ratification
has meant that the convention has still
to enter force. Nonetheless, the level of
interest displayed by vessel owners and
operators in the growing array of solutions
offered by equipment makers, and often
translated into orders, clearly demonstrates
an acknowledgement of the fact that the new advanced oxidation technology (AOT), even where the suspended solid content
regulations will take effect before too long. a process similar to that used in many of is more than 400mg/l. The emphasis on
Ships with smaller volumes of ballast water today’s self-cleaning products, whereby the capability to handle and remove high
will be the first that will have to comply with organism growth is prevented through an sediment loads is in consideration of the fact
the new regulations. AOT reaction which occurs when sunlight that shipboard ballasting operations often
Unilateral action on the part of various strikes titanium dioxide. take place in harbour and estuarial waters.
countries and states suggests the advisability The PureBallast version of this technology, Severn Trent De Nora offers the patented
of committing to a shipboard system sooner Wallenius AOT, was developed by Alfa BalPure system, which generates biocides,
rather than later. Existing vessels dating Laval in cooperation with Wallenius Water. and meters and analyses the residual level
from before the newbuild keel-laying trigger A PureBallast system is sized according to of both biocides and neutralising agents. It
date will have to perform time-consuming the ship’s ballast volume, and involves one logs overall system performance to provide
and sometimes risk-prone ballast water or more Wallenius AOT units, which treat a record for both the authorities and the
exchange up until such time as a treatment the water during ballasting and deballasting operator. Standard models can treat up to
plant is installed. operations. These units contain the titanium 10,000m³/h of ballast water, but custom-
The wide choice and variety in the dioxide catalysts, generating radicals when designed units can accommodate larger
solutions brought to market is indicative of hit by light. Since the creation of radicals in flow rates. BalPure is utilised during both
the nature of the impending International the AOT units is not dependent on the water ballasting, to disinfect incoming seawater,
Maritime Organization (IMO) regulations, in type, PureBallast is not sensitive to water and in de-ballasting operations, to neutralise
that the emphasis has been placed on criteria turbidity or salinity levels. the residual oxidant in the discharged
as to the amount of living organisms in the Mechanical separation followed by seawater using sodium sulphite.
discharged ballast water, rather than on the electrolysis-based disinfection are the two Relatively few of the approximately 30
specific nature of the shipboard system. stages embodied in RWO’s CleanBallast systems announced worldwide have as yet
Alfa Laval’s PureBallast system was one system, which is suited to all vessel types gained type approval. One of those to recently
of the first to have received type approval, and pump capacities, and distinguished by have type approval conferred is OptiMarin’s
and is claimed as the first chemical- a suitability to operations in high sediment Ballast System (OBS). Unlike many of
free ballast water treatment system to conditions. the other systems in which chemicals,
have gone on the market. It is based on CleanBallast has been shown as effective electrochemical generators or biocides are
34 Ship & Boat International March/April 2010
SBI_MarApr10_p34-35.indd 34 26/02/2010 12:23:02
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