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Offshore Support Journal

Ballast Water Treatment Technology

New ballast water treatment methods get MEPC 70 approval

Mon 20 Mar 2017

New ballast water treatment methods get MEPC 70 approval
This ultra low frequency unit is a vital part of the Semb-Eco LUV 500 BWMS (credit: Ecospec)

New treatment technologies are still emerging in the crowded BWMS marketplace

After nearly two decades of developing technologies aimed at removing the threat of invasive species in ballast water, it should come as no surprise that finding a new method of treatment among the systems available is a rarity. That said, two systems discussed at the 70th meeting of IMO’s Marine Environment Protection Committee (MEPC 70) in October last year do make use of chemicals or systems not used in any other systems.

By far the majority of the systems available make use either of UV or some form of electrochemical treatment but there are systems employing physical treatment such as ultrasound, oxygen stripping, cavitation or heat to destroy organisms, while others use chemical dosing.

Systems that do not use active substances only need to achieve type-approval to enter into the commercial arena and, since many of the newer arrivals appear to be publicity shy, often the first that the wider world hears of them is when their type-approval is advised at an MEPC meeting. Any system that makes use of an active substance has a longer journey through the IMO approval process and is required to pass its basic and final approval tests of the active substance before being permitted to seek type-approval from a recognised organisation.

The number of new systems appearing each year has been gradually reducing as the entry into force date loomed closer but, even so, new systems are appearing on a regular basis. At MEPC 70, one active substance system was given basic approval, two received final approval and the meeting was advised of four other systems having achieved G8 type-approval. Not all of these were new systems: one had achieved type-approval two years previously, another was a variant of a previously approved system and two were new additions to the list of available systems.

The two newly announced systems are the Semb-Eco LUV 500 system developed by Ecospec and to be manufactured by Sembcorp Marine Repairs and Upgrades in Singapore. This system uses filtration and UV but also has a third feature described by Ecospec as ultra low frequency (ULF) wave treatment. The Semb-Eco BWMS comprises a self-cleaning filter, the main biofouling control (BFC) unit and a supplementary UV reactor. The intake ballast water passes through the filter and is then exposed to low intensity UV irradiation from low pressure UV lamps.

In the final stage, the ballast water passes the BFC unit emitting the ULF wave. Ecospec claims it is the combination of the ULF wave and the low intensity UV light exposure that disrupts the living cell metabolic activity and DNA of the microorganism cell and inhibits reproduction. It says that without the ULF wave treatment, its UV treatment would consume so much power that it would be practically prohibitive to use – something that many system makers would dispute.

The second new system is the LeesGreen Ballast Water Management System manufactured by Shanghai Lee’s FUDA Electromechanical Technology. It is another in the growing list of filtration and UV systems and the description of the system supplied to the IMO shows no evidence of other unique technology.

The system achieving active substance basic approval is the ClearBal developed by University of Strathclyde in the UK but notified to the meeting by Denmark. It had been previously presented for basic approval at MEPC 68 but was rejected for a number of reasons connected with its ability to ensure that the chemicals it uses would be adequately mixed in a ship’s ballast tanks, a potential risk to human health and some missing test results on toxicity to fish. The expert group tasked with evaluating systems suggested that more thought be given to the issues, which has clearly been done for it now to achieve basic approval.

ClearBal uses a solution of two active substances; brilliant green (BG) and cetyltrimethyl ammonium bromide (CTAB) in a 1:2 ratio to inactivate marine species in ships’ ballast water tanks in situ. The ClearBal solution is contained in a storage tank connected to the dosing unit, which delivers it via a dosing pump and a control unit that adjusts the amount of biocide injected into the ballast system suction pipeline based on the flow rate measurement recorded by a flow meter.

The ClearBal BWMS is an in-line system with a minimum 24 hours holding time in ballast tanks. Upon deballasting, the ballast water is detoxified using activated charcoal before it is discharged. The detoxification system consists of a unit for dosing activated charcoal to the ballast pipe, a mixing unit and a separation unit to retrieve residual ClearBal and activated charcoal from the ballast water.

For two systems to appear with new technologies is an unusual event these days but it may be that if ballast treatment is to work effectively and ships are to be safe from the threat of PSC detentions, new systems and new methods may be necessary for the future. As the type-approval process tightens, the shortcomings of older systems will become more obvious and although some protection has been promised, that can never be guaranteed.

A number of industry associations – including the International Chamber of Shipping, BIMCO and Intertanko – along with India co-sponsored a submission to MEPC 70 pointing out that since the G8 Guidelines covering procedures for type-approving BWMSs are currently under review, it would make sense for vessels whose first renewal survey falls within two years of the entry into force date to be granted an extension to the second renewal survey to ensure that they can obtain systems approved under the revised guidance.

The committee did not manage to achieve agreement on this and it was finally agreed that both sets of proposed amendments should be forwarded to MEPC 71 (scheduled to take place in July) for adoption.

The recent discussions at MEPC suggested that there are around 4,000 systems currently installed on ships although it is known that not all of these are in regular use. In terms of the total number of vessels that may need to fit treatment systems – the question of exemptions in similar risk areas has the potential to considerably reduce the total number – 4,000 is actually quite a high percentage. If those ships need to improve treatment efficiency they may be obliged either to upgrade systems where that is possible or to replace the installed system completely.

One answer for such ships could be supplied by port authorities or terminal operators providing a shore ballast treatment system or by one of the increasing number of containerised systems that are appearing. Damen of the Netherlands set that particular ball rolling but they are no longer alone. Some system makers have been looking at the concept and could produce versions themselves and other third party engineering concerns are following the Damen model.

One of those is Ballast Water Containers of the UK, which has developed a range of containerised treatment systems that in theory can be fitted with any maker’s treatment system. At present systems from Wärtsilä and Optimarin are planned. The containerised systems only require a flow and return connection to the ship’s ballast piping to be installed at a point where the container can be connected.

For a fleet operator, the flexibility offered by containerised systems with standard connections is that units could be switched between ships relatively easily. That could permit a ship operating in fresh and brackish waters to use a UV system but change to an electrochemical one when operating in saltwater and areas of high turbidity.

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