environment
BWT system suppliers stake market claims
Ratification of the IMO’s Ballast Water Management Convention is widely anticipated this year, stimulating ship operators to evaluate which treatment technology is best suited to their existing and planned tonnage
by Doug Woodyard
ome 31 flag states (minimum of 30 required) and 26.44 per cent of the world tonnage (minimum 35 per cent required) had ratified the IMO Ballast Water Management Convention by December last year, with other large nations primed to sign. It is estimated that some 50,000-70,000 vessels will need to install approved ballast water treatment (BWT) systems in the years up to 2019. The basic requirements of the convention’s D2 standard are applicable to newbuildings and eventually to all relevant existing tonnage under a rolling programme. Type-approved BWT systems must be installed with the capability to meet a cleaning standard that results in fewer than 10 viable organisms/m3 if the organisms are 50 micron or larger, or 10 viable organisms/ ml if they are smaller than 50 microns. The USA has a stricter requirement requiring adherence to 1 viable organism/100ml. No single BWT solution is suitable for all ship types, according to UK-based Hamworthy, which has developed two different treatment solutions to offer flexibility and choice from its Aquarius product range. “We are currently the only OEM offering a choice to both the newbuilding and retrofit markets,” claims Dr Joe Thomas, managing director, Hamworthy Ballast Water Systems. The company’s Aquarius-UV system is a two-
S
stage approach featuring filtration followed by disinfection using ultraviolet light, thus avoiding the use of any active substance. As there is no detrimental effect on water quality, the ballast water can be safely discharged from the tank at any time; furthermore, maximum disinfection is ensured by exploiting UV treatment during the discharge cycle as well as on ballasting. In developing
the solution, Hamworthy
formed a strategic partnership with UK-based Hanovia, a specialist in UV system design
104 I Marine Propulsion I February/March 2012
RWO’s CleanBallast disc filter system
and production. Hamworthy assumed overall responsibility for performance compliance with the regulatory standards. Also marketed by Hamworthy, the Aquarius-
EC system similarly adopts a two-stage approach but with disinfection using an active substance generated by side stream electro-chlorination. The company collaborates with Magneto Special Anodes in developing the advanced electrolysis technology. When de-ballasting, the system neutralises any remaining active substance using sodium bisulphite, ensuring that the ballast water can be safely discharged to the sea. “Both systems provide a robust solution
for treating ballast water across a range of challenging ship operating and environmental conditions, exceeding the required IMO standards,” says Dr Thomas. “We have also adopted a modular approach to system design in both cases so that the equipment can be flexibly
arranged to suit the conditions on
board. Furthermore, both Aquarius systems are designed and supplied to treat ballast water across a full range of ballast pump sizes.” Filtration
is
control system to achieve complete ballast water management.
Land-based testing of both Aquarius systems was completed in early 2011 at the Royal Netherlands Institute for Sea Research. Sea trials are under way, the first official trial sampling resulting in a full pass against the requirements of the IMO D2 standard. Specific corrosion and paint coating tests on the Aquarius-EC system are also being conducted to MEPC requirements. With all testing completed, Hamworthy expects to secure IMO type approval for the Aquarius programme during 2012.
effected by the systems
using automatic back-washing screen filter technology; the filter is designed specifically for ballast water applications and filters particulates down to 40 microns. Automatic back-washing ensures efficient removal of particles that are discharged back to the environment of origin, the systems PLC-controlled with user-friendly touch screen operation.
All relevant data is stored by the PLC in accordance with IMO requirements and the system can be fully integrated into the main
A Sumitomo Ecomarine ultraviolet ballast water management system was due to be installed on NYK Cruises’ Asuka II for demonstration testing in January this year. The system developer, Sumitomo Electric, and the Japanese shipowner will co-operate in onboard testing to meet the requirements of the international convention on BWM. The Ecomarine system incorporates filter units originally developed by Sumitomo Electric to separate large plankton and other aquatic organisms. Any remaining small organisms are then eliminated by a high-powered medium pressure UV process. Overall, the system is designed to save power and reliably remove organisms, while offering ease of use and low maintenance. Tested on land in an arrangement comparable to
actual onboard conditions with a water treatment rate of 200 m3/h, Sumitomo reports, the Ecomarine system demonstrated the anticipated reduction in power consumption and high organism removal. Basic approval from IMO is expected in March 2012, as specified in the G9 approval procedure;
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