Since the Ballast Water Management (BWM) Convention came into force on September 8, 2017, it’s now imperative that shipowners and operators obtain and implement their own ballast water management plan. This plan will record how the ballast water has been stored on board the vessel, i.e. temperature, salinity, and volume – as well as information on how ballasting and deballasting take place. As the new standards are phased in over time, most ships will eventually need to install an on-board ballast water treatment system (BWTS). But with numerous technologies available, there are some important considerations to bear in mind before making a decision.
Size isn’t everything
Regulation D-2 of the IMO’s BWM Convention defines the ballast water performance standard. This is the required level of performance that a BWMS must achieve. As part of the convention, any vessel built after September 2017 must be fitted with a BWMS to meet the D-2 standard, and older vessels will require retrofitting. There are, however, a multitude of factors for shipping companies to consider before the most suitable technology can be installed. The process, from ordering to commissioning, can take up to one year to complete. BWMSs that are relatively quick and easy to install are favorable amongst shipping companies.
Furthermore, the original construction of most vessels doesn’t account for a BWMS or even have the space required for one to be fitted. This means installation needs to be adapted to suit the existing on-board circumstances. Manufacturers have found a way around this by producing scalable BWMSs or offering systems in a range of sizes that can fit on board any vessel. Some suppliers now offer services that can help when installing a system in limited space.
There is not one solution for everyone. Owners must do their homework. They have to select the ballast water treatment technology that is appropriate for their operation.
Compliance: Costly, but it pays off
Shipping companies are having to contend with hefty installation costs, but this figure could be dwarfed by operational costs throughout the system’s lifecycle. It’s vital that this is taken into consideration when selecting the appropriate system.
Back in 2010, the Maritime Environmental Resource Center (MERC) evaluated the cost of purchase, installation, and operation of various treatment system types, including:
- UV irradiation (after filtration)
- Electrolysis
- Chemical injection (after filtration)
To portray a fair examination, the assessment was carried out on different vessel types. Results found that UV irradiation and electrolysis appeared as the most reasonable solution for many ship types and sizes. A full report of their findings is available here.
Systems in the spotlight
As shipping companies look to install and retrofit BWMSs, UV technology to treat ballast water has become the most popular option, making up almost 50% of global sales. These kinds of treatment systems offer an environmentally friendly solution, and due their compact footprint, they can be easily installed into most vessels. They are versatile and can be used on most sizes of vessels, although they are more commonly installed on ships with low ballasting requirements, such as passenger ships and smaller container ships. However, a potential drawback is that current United States Coast Guard (USCG) regulations stipulate that organisms must be killed before being discharged. Low UV irradiation will only inactivate the invasive species, simply preventing any future reproduction. If a higher dose is administered, or the treated ballast water endures longer holding times, affected organisms will be killed. However, it is expected that USCG regulations will soon be harmonized with IMO standards.
According to the MERC study, the treatment of ballast water by electrochlorination is also a common choice. Electrochlorination is efficient in larger water quantities and flows. This process involves the generation of hypochlorite from salt and water molecules to eliminate invading organisms. However, potentially harmful hydrogen gas and chlorine are generated during the electrolytic process. Some manufacturers combat these risks by developing hydrogen traps that can be added or installed at the same time as the BWMS.
Some BWMSs inject chemicals into the ballast water as a means of sterilization. They are an easy installation option as they require less space on board. However, harmful chemicals can only be handled by qualified staff, meaning that ship operators may have to implement additional training and store certain safety equipment. The total cost of energy is minimized but a constant stock of chemicals is mandatory.
In both electrolytic systems and chemical injection systems, by-products may arise when the active substances react with water compounds. Neutralising agents may be injected to neutralise residual oxidants, therefore reducing risk but at the same time increasing the amount of added chemicals.
Preparation is key as deadlines near
It is important for companies to be aware of the limitations of different BWMSs. General factors in the decision-making process include holding time, water salinity, and water temperature. But ensuring system compliance, operational reliability, and lifecycle costs are the main priorities for shipping companies. Installation must be planned under supervision from experienced consultants, BWMS manufacturer representatives, and class surveyors. A well-revised, collaborative installation will cost time and money.
In most cases, crew will need to be trained in order to operate the machinery or to handle certain chemicals or substances. Maintenance costs, ease of use, and system complexity are all things for shipping companies to think about when selecting a BWMS that is right for their fleet. And with compliance deadlines just around the corner, companies are being urged to implement their plans.
Ballast water will remain a key talking point for the foreseeable future. SKF has created a website dedicated to the topic, with regular news updates covering the latest in ballast water Management.