Shipping companies have a degree of responsibility over whether they actually manage to remove organisms from ballast water before discharging. How can this be best done? Tanker Operator magazine spoke to Chelsea Technologies.
Just buying and installing a type approved ballast water system may not be enough to guarantee regulatory compliance, says Matt Kenney, head of marketing with Chelsea Technologies, a UK specialist in sensor design and manufacture.
Shipping companies have a degree of responsibility over whether the ballast water they discharge contains organisms above the allowed limit. In most maritime state legislatures, ship operators are deemed accountable for “knowing” that they discharged pollutants into territorial waters. In the US, ship operators can be prosecuted for non-compliant ballast water discharge even if they do have a type approved system, Mr Kenney says.
A May 2020 study by certification company SGS, “Commissioning Testing of Ballast Water Management Systems,” (available for free download), found that of 95 systems the company was asked to test between October 2019 and April 2020, 21 per cent failed to meet the “D-2” treatment standard enforced by the IMO. This may be because they had been installed incorrectly. In that case, the shipping companies have spent millions of dollars for equipment which doesn’t work. Before this study was produced, there was not much data available about how effective ballast water systems actually were, Mr Kenney says. Now testing ballast water systems is growing as an issue in IMO.
Some states, including Singapore and Panama, have required commissioning testing since 2018 – so all systems are tested after they are installed. Commissioning testing is likely to be required globally by 2021, if it is ratified in the MEPC 75 meeting (previously scheduled for March 30, 2020, currently postponed due to Covid). The commissioning testing may not involve actually testing the ballast water after being treated. It may be just testing that the equipment appears to be functioning correctly, on the basis that the equipment itself has already been tested in its type approval process. But it may also include an “indicative” test of the discharge water, for example using a device like FastBallast. A failure of the indicative test will mean that the installation itself fails, Mr Kenney says.
Deterioration over lifetime
Another unaddressed question is what processes should be used to monitor effectiveness of a system during the lifetime. Reasons for ballast water system performance to deteriorate can include blocked filters, fouling on a UV element, or the vessel handling a different kind of ballast water, such as from tropical waters, or with higher sediment levels, which means it is harder for UV light to penetrate. Or a different crew, or even a different vessel owner, may operate the system in a different way, or not know how to use it, or understand its limitations.
Mr Kenney envisages that ballast water testing may one day be like the testing for oil content in bilge water before it is discharged – where regulations require the water is continuously tested, and discharge is automatically shut off if oil concentration rises above the maximum allowed 15 ppm. This would be a logical regulation for authorities who really want to make sure no invasive organisms are able to enter their waters, although very difficult to achieve technically.
Chelsea Technologies has developed a small unit, “FastBallast”, which tanker companies can use onboard to analyse a sample of ballast water, get an indication of what the organism level is, and determine whether it is probably compliant before discharge. The unit costs “under £10,000” ($13k) which is expensive for a discretionary cost, but low compared to the $1.5m cost of a ballast water treatment system, or of course any penalties. The device is the same size, just slightly thicker, than a laptop. So it is feasible for shipping companies to employ staff to visit vessels in port to test their ballast water, carrying the device with them. It is a self-contained unit with a small sample chamber, where you add a sample of discharge water and then press ‘go’.
Complexities of compliance
The Ballast Water Convention states that inspectors can conduct a sampling of ships’ ballast water in accordance with “guidelines to be developed by the organisation” – but there is no standard methodology for how to sample a ship’s ballast water.
The IMO ballast water standard, “D2”, has multiple layers. The water you discharge must have under 10 organisms per m3 which are over 50 micrometres, fewer than 10 organisms per millilitre which are between 10 and 50 micrometres, plus some other limits of specific indicator microbes.
Knowing for sure if ballast water is compliant would require analysing very large volumes of ballast water, which would be impractical. For example, you would need a minimum of approximately 3m3 of ballast water to make a reasonable check for the “10 organisms per m3” rule. This would likely involve a water tanker driving up to the vessel to collect ballast water and take it to a laboratory.
But the FastBallast analysis can give a reasonable indication of compliance by looking for phytoplankton in the 10-50 micrometre range in a small sample of water – because these are often the toughest organisms to treat, Mr Kenney says.
Phytoplankton typically have a high resilience to ballast water treatments compared to indicator microbes or some zooplankton in the >50 µm category. In other words, if you’ve killed the phytoplankton, you’ve probably killed everything else too, he says.
The technical challenge is finding a way to measure living organisms in ballast water post treatment but not dead ones. Dead or non-viable organisms are not a concern in ballast water because they cannot reproduce when they are discharged.
FastBallast uses a method known as ‘active fluorometry’ to analyse the number of living phytoplankton cells in the sample. Phytoplankton display inherent fluorescence from chlorophyll; if the phytoplankton are living, the intensity of this fluorescence increases as they are exposed to a pulse of high-intensity light.
In FastBallast, a 20ml sample is stirred continuously, within which 0.5ml is probed with a 400µs pulse of light. Large phytoplankton typically contain more chlorophyll, so they produce a stronger fluorescence signal than small phytoplankton as they pass through the 0.5ml analysis region. By analysing the intensity and variation of the fluorescence signal, FastBallast can accurately calculate the number of phytoplankton within the sample.
FastBallast can detect down to 1 cell per ml, well below the IMO D-2 standard of 10 cells per ml. The reading takes only 2-10 minutes. It can be used for over 2 years between services, and needs minimum consumables, no laboratory testing or costly reagents. Normally it works with 20 ml sample volumes, so a little smaller than a standard whisky shot (25 – 35 ml). It can also be set up to provide continuous measurement, but this is not usually necessary for most operators.