Stopping the transfer of invasive species and harmful organisms is at the heart of ballast water treatment. However, the organisms are mostly microscopic and not visible to the naked eye. More to the point, ballast water systems are not meant to make observation easy but to move very large quantities of water in quite short spans of time.
Crew can monitor and measure the flow rate of ballast and will know if a filter is blocked but not if it is worn to the point where it allows larger organisms through the screens. Crew can also check the salinity of the water so would likely know if the water is outside the parameters the electrochlorination or electrolysis type system is able to operate with. Similarly, they might be able to determine if the water is too turbid for a UV system to work effectively.
Unlike monitoring exhaust systems where gas detecting sensors can measure very small changes in the make-up of the exhaust or treating bilge water through a separator equipped with a 15ppm alarm, determining if ballast water meets the convention requirements is not possible on a continuous basis. In fact it is almost impossible to even know if a system is operating as it is meant to.
The new IMO G8 guidelines for system approval adopted in 2016 should tighten up the type-approval process but even here it is recognised that not all systems will work under all circumstances. In the introduction section of the 2016 guidelines, point 1.5 says:
The requirements of regulation D-3 stipulate that ballast water management systems used to comply with the Convention must be approved by the Administration, taking into account these Guidelines. In addition to such ballast water management system approval, as set forth in regulation A-2 and regulation B-3, the Convention requires that discharges of ballast water from ships must meet the regulation D-2 performance standard on an on-going basis. Approval of a system is intended to screen-out management systems that would fail to meet the standards prescribed in regulation D-2 of the Convention. Approval of a system, however, does not ensure that a given system will work on all ships or in all situations. To satisfy the Convention, a discharge must comply with the D-2 standard throughout the life of the ship.
Under the new G8 process, system makers are expected to set out the circumstances under which a system may not or cannot effectively treat the ballast in its operating manual. That is well and good, but it offers no assistance to crews as to what to do under the circumstances.
So it is clear that, while the IMO recognises that systems may sometimes not be capable of meeting the discharge standard, the ship is not excused from doing so. For their part, ships’ crews should generally be capable of operating the equipment on board and to understand when it is not working correctly as regards pumping or flow of the water.
However, with ballast water treatment regulations laying down allowed levels of micro-organisms that are permitted to be viable, seafarers who are not expected to be trained microbiologists will have great difficulty determining if the treatment process has been effective. For all practical purposes treated ballast is indistinguishable from the water that passed through the initial filter when taken on board whether the treatment was effective or not.
Almost nobody expects that when ships are obliged to use a treatment system there will be no PSC inspections of the system operation and its ability to meet the discharge standard. Sampling by PSC inspectors will usually involve laboratory testing with the results known only after what may be a considerable delay. This all leaves shipowners open to penalties if the treatment system is defective for any reason.
Despite assurances to the contrary, there are many experts who argue that a 100% kill rate is an impossible target for any system. That should be a worry for owners as PSC authorities are not known for their leniency and, in certain cases, failure to meet requirements is seen as a revenue stream for governments and regulatory bodies as many owners who have fallen foul of ISM inspections can testify. The IMO may talk about contingency arrangements, but it has no control over the action of governments that do not wish to fall in with those arrangements.