ballast water treatment
out that the capacity of the system is well matched to vessels in this segment. “Most relevant systems in the passenger industry will only require one UV lamp, [for] up to 167m3 per hour, while some will have two UV lamps in two chambers [for] up to 334m3 per hour.” Optimarin
continues to improve its OBS
technology and over the past year has updated the software that regulates the power consumption of the UV lamps. Based on the UV intensity, which is measured and fed back to a control panel, Optimarin can automatically regulate power consumption. In particular the new approach can reduce power when the vessel is in clear water conditions and increase it to maximum when water conditions are poor. Experience to date has demonstrated that the software has reduced power consumption by up to 50 per cent. Optimarin
has no recent experience of
installations in the passenger ship sector, although it is interested in this market. Mr Nilsen said, “We have in the past year installed our system on board a large number of platform support and other offshore vessels that have comparable ballast pump capacities, but less available space and power. This experience demonstrates its suitability for passenger ships, as it can be configured in a number of different ways.” There are a number of other manufacturers
offering UV-based ballast water treatment systems, including US company Hyde Marine, whose Hyde Guardian is a totally chemical-free process, based on an automatic backflushing disk filter and medium pressure UV treatment. The system has successfully been installed on two cruise vessels, Coral Princess and Celebrity Mercury, as well as vessels of other types. Finland’s Wärtsilä has joined forces with US-based Trojan Technologies to develop a new ballast water treatment system. This technology, currently under development, promises to combine filtration and UV disinfection techniques into a single unit, making this compact and easy to install. Not all manufacturers are confident that UV is
best for the passenger shipping industry. Severn Trent De Nora’s Ms Teng said, for instance, “Ballast water treatment systems using UV-based technology seem to be meeting the needs of passenger vessels, and the combination of higher power consumption but irregular use appears to be acceptable in this
94 I Passenger Ship Technology I Spring 2012
A 334m3 Optimarin system during installation
market segment. However there may be a false sense of security with UV-based systems as, if they prove not to work well at sea, this may only manifest itself once the Convention is ratified and when system performance inspections are performed by port state control authorities.” She said that there are currently no guidelines for such inspections, although these are expected to be issued in draft during the IMO MEPC 63 meeting in March 2012. One established player that believes non-UV systems can still have success in the passenger market is Veolia Water’s RWO division, which is continuing to focus on its tried and tested CleanBallast technology, combining a mechanical disk filter and electrolytic disinfection. “With over 20 CleanBallast units already commissioned, this is one of the few ballast water treatment systems that has operational experience including sea trials in very difficult environments. It is suitable for use on passenger vessels and we are in discussions with both shipyards and owners to install CleanBallast on passenger vessels,” said spokeswoman Saskia Skovdal. During the past 12 months RWO has refined the design to reduce the footprint of the CleanBallast system by as much as 50 per cent and has cut capital expenditure costs by 30 per cent – improvements which should make it more attractive to passenger vessel operators. Ms Skovdal added, “CleanBallast is a system which is already in use, exceeds IMO test requirements and has very low power consumption.” PST
www.passengership.info
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