Not all ballast water treatment systems are the same system design limitations can have a big impact on the efficiency of the system
One of the first lessons learnt by shipowners now operating ballast water treatment systems (BWMS) on newbuildings, or recently retrofitted systems on older ships, is that IMO and/or US Coast Guard (USCG) type-approval is not guarantee of 100% performance. Why is that?
DHI business development and project manager Gitte Ingelise Petersen explained some of the misconceptions. DHI is a Danish-based firm which has a 50-year track record in developing and implementing solutions that meet real-life challenges in water environments worldwide. This includes being an approved independent laboratory (IL) for the testing of ballast water treatment systems (BWTS). DHI is accredited to ISO standards, for IMO and USCG standards and for class societies like DNV, ABS, as well as being involved in the development of BWMS for manufacturers, too.
“Over the last 10 years we have done testing for more than 25 ballast water (system) manufacturers and more than 50% of the current type-approval testing has been done or part done with us here in in Denmark,” said Ms Petersen.
Ms Petersen was speaking at the Riviera Maritime Media What shipowners want and need from the BWMS industry and its regulators in 2022 webinar, held in January 2022. The webinar was sponsored by Ecochlor, DHI and Headway. Ms Petersen explained that the core issue as to why a type-approved BWMS fails to meet expectations in real life is that prior to the introduction of the D-2 standard, there was no rule on system design limitations and monitoring testing.
Ms Petersen referred to paragraph USCG Ballast Water FAQs 18.3, which states: “What operational parameters must be considered for type approval testing? The Coast Guard has not identified a set of specific parameters applicable to particular types of treatment technologies that must be addressed in the testing. The manufacturer must identify any operational parameters or design limitations (e.g., minimum UV transmittance or intensity, water temperature, etc.) for the proper operation of the system. These manufacturer claims will be taken into consideration by the IL during test plan development.”
“Shipowners must look closely at the system design limitations listed on the certificates”
“When selecting an approved BWMS, shipowners can be certain that the system was tested to comply with the biological discharge standard D-2. However, prior to the IMO BWM code, the regulations had little or no reference to design limitations,” said Ms Petersen, “and a reliable description of the system design limitations is essential for choosing the right BWMS.”
Ms Petersen said that shipowners must look closely at the system design limitations listed on the certificates and be aware of the limitations inherent in testing. For instance, she noted that salinity and temperature are listed; UV systems are not impacted by salinity and temperature, but electrochlorination systems are. However, it is not possible to realistically organise testing at different water temperatures – it is dependent on the season and where the testing is taking place.
A more complex issue is the relationship between system design limitations, filter or no filter, TRO consumption and the quality of water in different ports and harbours. Ms Petersen had prepared a table based on the System Design Limitations (SDLs) listed in USCG type-approval certificates.
System Design Limitation for BWMS with or without filter | |||||||
BWMS | Filter | TRO set point | Hold Time | ||||
(mg/l) | Fresh | Brackish | Marine | ||||
1 | Yes | 5 | > 3 hours | ||||
1 | No | 7.5-7.8 | 48 hours | Not applicable | |||
2 | Yes | >1.7* | >24 hours | ||||
3 | Yes | 7.5 | >24 hours | ||||
4 | Yes | 6 | Not applicable | ||||
5 | Yes | 2.5-3 | >24 hours | Not applicable | |||
6 | Yes | 10 | 24 hours | ||||
7 | Yes | 8 | 24 hours | ||||
7 | No | 8 | 48 hours | ||||
8 | Yes | 2 | 2 hours | ||||
9 | Yes | 7-15 | 24 hours | ||||
10 | Yes | 6-10 | Not applicable | ||||
11 | No | 12 | >24 hours | ||||
12 | Yes | 8 | >24 hours | ||||
13 | Yes | 6 | >24 hours | >2 hours | >24 hours | ||
*Apply dose dependent on ambient oxygen demand | |||||||
Source: DHI |
The table “System Design Limitation for BWMS with or without filter” shows the results of an examination of the limitations set out in USCG certifications by DHI. The particular BWMS are unnamed. The table shows the difference between filter and non-filter (BWMS 1). Ms Petersen noted several conclusions: one is that the main reason for a filter in an EC or any chemical treatment BWMS is to filter out organisms larger than 50 mu. There is a risk that these will not be killed. Another is that if the Type-Approval has been performed in water that is too low challenging related to ambient oxidant demand, there is a risk that the BWMS will not be able to perform when entering global harbours with natural high oxidant demands. Ms Petersen highlighted Spoorhaven in Amsterdam and the port of Melbourne in Australia as examples.
She also noted that measuring the “Ambient Oxygen Demand” during type-approval testing will provide useful information for shipowners and a reliable description of the SDL and Ambient Oxygen Demand is essential for the selection of a BWMS.
Picking up on the theme of challenging water, Headway’s, director of strategy and development department, Kechao Lu, said that the company’s OceanGuard had four main advantages: one is that the OceanGuard system is already installed on over 1,000 ships and a considerable body of knowledge has accumulated about operations in challenging waters.
The second advantage named by Mr Lu is that the Headway BWMS is approved across the range, for flow rates of 50 m3 to 4000 m3. “The third advantage is ultra-low power consumption, even in fresh water,” said Mr Lu. “This is very good for retrofit installations where the available power may be limited.”
The fourth advantage is that even during the pandemic, Headway has been able to deliver systems with lead times of just one month. “The pandemic has been a challenge for all suppliers, but we can supply a whole system in a month,” said Mr Lu.
“Referring to the topic of the webinar,” said Ecochlor’s vice president sales & marketing, Panos Smyroglou, “what shipowners want, what they need, is filter-less.” This is one of the first items Ecochlor was asked to address by its clients. The reason is that in challenging water the filter loses efficiency and slows down cargo handling. Other factors include lower capex and installation costs and time.
He added: “It has been delayed to the market due to legitimate concerns regarding the reliability or the efficacy of existing treatment technologies when used with or without a filter.”
The new Ecochlor systems without a filter, and the older systems, had already addressed one particular concern of shipowners – power consumption. The Ecochlor BWMS were designed with lower power consumption. Mr Smyroglou noted that the Ecochlor systems are cold ironing (shore power)-ready with a power demand of 6 Kw or lower. “You will not need a large electric load while in the port,” he said.
Regarding turbidity, he said the Ecochlor chemical process is not consumed by suspended sediment, which means it is not impacted by turbidity. The chlorine dioxide produced in the Ecochlor system is highly effective against lving organisms, and is, according to Mr Smyroglou, more effective than chlorine.
“Prior to the IMO BWM code, the regulations had little or no reference to design limitations”
The shipowners’ perspective was given by INTERTANKO, the global organisation that represents the views of independent tanker owners. INTERTANKO’s environment director, Tim Wilkins, said that what owners would like to see now is collaboration. The statistics from Port State Control point to deficiencies reported in the Ballast Water Record Book, and at a slightly lower level, errors reported in the Ballast Water Management Plan.
The Ballast Water Management Plan falls into the orbit of the BWMS manufacturers and Mr Wilkins, as a representative of owners, would like to see collaboration on updating this. It has been in place longer than most BWMS have been in use and needs to be updated in light of practical experience.
Mr Wilkins was also keen that there was collaboration from all stakeholders in BWMS to tackle to recognise the issue of challenging water. He noted that INTERTANKO has data from its members on the subject. “We have been surveying our members since April 2021 and we have over 450 reports from 174 different ports around the world,” he said.
He noted that BWMS stakeholders and IMO have been working on ballast water treatment regulation for 20 years and it seems that only now is challenging water being recognised as an issue. It is hoped that this issue and the other issues that are likely to arise in the run up to the introduction of the D-2 standard on 8 September 2024, and beyond, are properly addressed and resolved at the forthcoming MEPCs.
© 2023 Riviera Maritime Media Ltd.