Ballast Water Management – Guarding the Bio-invasion

Ballast water is filled into the ballast tanks of the ships to maintain stability and improve the handling and manoeuvrability of the ship. Ballasting maintains a safe operating condition throughout the voyage by reducing hull stress, improving propulsion and, in the meantime, also compensating for any weight change in various scenarios of fuel and water consumption. Pumping in the sea water to be used as ballast is the most economical practice with the above mentioned advantages but it comes at a cost.

Ballast Water Management

 The worldwide tonnage of the shipping sector rose sharply with the introduction of steel hulled ship. The ships improved in size and technology and this opened more shipping routes across the globe. Ships were now traversing the length and breadth of the globe. The use of ballast water has been ever so evident since the introduction of steel hulled ships. In 1903, scientists found increased presence of Asian phytoplankton algae Odontella in the North Sea. The vast migration of alien species from Asian waters to North Sea was never clearly understood until late 1970 when improved R&D prompted the scientific community to review the problem in detail. By now major countries, especially, the one with rich aquatic resources viz. Australia and Canada reported invasion of foreign organisms in their aquatic ecosystems. By this time it was well established the fact that ship’s ballast water carrying with it vast multitude of aquatic organisms transfer the foreign species to newer ecosystems where they thrive to pest proportion, causing the so called Bio-Invasion.

When ships navigate diverse areas of the world, the aquatic organisms contained in the ballast water also travel the world along the ship’s navigational path, before being discharged into a completely new Environment in the host environment. While ballast water is essential for safe operation of modern shipping, it also poses serious ecological, economic and health problems. The ballast water taken in a ship is somewhere in the range of 5000 m3 for a small Handymax carrier and may go upto 30000 m3 for a VLCC. With such large quantities in discussion; the bacteria, cyst, larvae, eggs, small invertebrates of various species gets transferred to an entirely new ecosystem by the ship ballast. The transferred species may survive to reproductive population in the host environment becoming invasive with the native population and causing serious ecological imbalance. The concern was brought to the notice of IMO’s Marine Environment and Protection Committee. As the volume of sea trade is still on the rise, the problem may not have reached its peak. Quantitative data suggests that the rate of bio invasion is increasing at an alarming rate.

In 1991, MEPC adopted International guidelines for preventing the introduction of unwanted aquatic organisms and pathogens from ship’s ballast water and sediment discharges.  In November 1997, IMO adopted guidelines for control and management of ships’ ballast water to minimize the transfer of harmful aquatic organisms and pathogens.   It was only in 13 February 2004, when, International Convention for the Control and Management of Ship’s Ballast Water and Sediments was adopted by consensus in London.

Since its adoption in 2004 the convention was further expanded and guidelines revised. On 8^th September, 2017 the BWM Convention entered into force. Yet, before the effective date of BWM Convention, it was realised that the financial and technical burden on ship owners and charterers for installing Ballast Water treatment systems need more time to meet. As a result, though the convention came into effect on 8^th September 2017, yet, the installation period was rescheduled. As per the new guidelines, for vessels undergoing regular inspections between September 2012 and September 2014, the BWM’s mandatory installation period is to be postponed from 2022 to September 2024 for two years. The time limit for installation on new vessels has been postponed to after 8^th September 2019.

Highlights of Ballast Water Management (BWM) Convention

•  The BWM Convention targets all vessels those inject and discharge ballast water for international voyages. Non-commercial vessels operated by the state, such as warships, and ships not designed and constructed to carry ballast water are excluded from the scope of the convention.

•    The new convention required all member states to implement a Ballast Water Management plan.

•     All ships have to carry a Ballast Water Record Book, Ballast Water Management Plan, International Ballast Water management Certificates depending on the ship size.

•     Ships require a ballast water management procedure upto a given standard.

•     The BWM Convention forces all merchant vessels engaged in international trade to release the ballast water only after removing the potentially harmful organisms and which are rendered harmless, upto a given standard, by mechanical, physical, chemical and biological processes.

The following article will focus more on the technical aspects of the BWM Convention and the various requirements to be met for approval of Ballast water Treatment plants.

IMO has drafted GUIDELINES FOR BALLAST WATER MANAGEMENT AND THE DEVELOPMENT OF BALLAST WATER MANAGEMENT PLANS (G4) for easy implementation of BWM Convention. These guidelines are broadly divided into:

•     Part A : Ballast Water Management Convention and Ballast Water Treatment Solutions

•     Part B – Type Approval of BWMS

Part A focuses on the general guidelines for the BWM plan and its content. Part B deals with the various steps and standard for approval of a BWM treatment systems. For seafaring community and on-board officers it is vital to understand the part A for a fool proof execution on-board their ships.

The Annex to the BWM Convention consists of 24 regulations as follows:

 

Fig. 1 Annexes to BWM Convention

From the 8^th September, 2017 those ships to which the BWM Convention applies are required to:

1. Have on board and implement an approved BWM Plan (BWMP) that complies with Regulation B-1. The BWMP is required to be ship specific.

2. Record as per Regulation B-2 all ballast water operations in a BWM Record Book (BWRB).

3. Be subject to BWM surveys in accordance with Regulation E-1 and have on board a valid International Ballast Water Management Certificate (IBWMC) if the ship is equal to or above 400 GT.

4. Comply with the required ballast water management standard in accordance with the implementation schedule defined in Regulation B-3.

Ballast Water Management Plan (BWMP)

Each ship is to have on board and implement a Ballast Water Management Plan (BWMP). Such a plan is to be approved by the Administration taking into account Guidelines developed by IMO. The BWMP is to be specific to each ship and is to at least: 

• ·   detail safety procedures for the ship and the crew associated with BWM as required by the Convention;

• ·    provide a detailed description of the actions to be taken to implement the BWM requirements and supplemental BWM practices as set forth in the Convention;

• ·    detail the procedures for the disposal of sediments at sea; and to shore

• ·     include the procedures for coordinating shipboard BWM that involves discharge to the sea with the authorities of the State into whose waters such discharge will take place;

• ·     designate the officer on board in charge of ensuring that the plan is properly implemented and list his duties;

• ·     contain the reporting requirements for ships provided for under the Convention; and

• ·     be written in the working language of the ship. If this language is not English, French or Spanish a translation into one of these languages must be included.

• ·     The BWMP is to include training and education for ship’s crew on BWM practices and the systems and procedures used on board the ship.

• ·    Regular review of the Plan by the owner, operator, or master is to be conducted to ensure that the information contained is accurate and updated. A feedback system is to be employed which will allow quick capture of changing information and incorporation of it into the Plan.

• Changes to the provisions of the BWMP will need approval of the Administration.  

BWM Convention introduces two standards (reg. D1 and D2) for the handling of discharged ballast water:

D-1 standard covering ballast water exchange requires ships to conduct the exchange at least 95% of their ballast water by volume such that at least 95% of water by volume is exchanged far away from the coast where it will be released. The Ballast Water Exchange can be either of the Sequential, Overflow or dilution method, but for a particular ship, only the method stated in BWM certificate is to be done.

D-2 standard covering ballast water treatment which requires ballast water management to restrict to a specified maximum the amount of viable organisms allowed to be discharged and to limit the discharge of specified indicator microbes harmful to human health. Reg. D2 sets the standard for the Ballast Water Treatment plants that require fitting of an approved ballast water management system.

Effective from 8^th September, 2017 all ships to which BWM convention applies, need to carry out BWE in accordance with reg. D1 and BWM plan of the particular ship. Regulation D2 i.e. the installation of approved ballast water treatment system becomes mandatory at a later date as explained under.

  Ship Category - A ship constructed on or after 8th September 2017.
The Ship must follow regulation D-2 (treatment) from the date of delivery of the ship.

Ship Category - A ship constructed prior to 8th September 2017 which has completed IOPP renewal survey on or after 8 September 2014 but prior to 8 September 2017.
1). The Ship must follow regulation D-2from the date of 1st IOPP renewal survey after 8 September 2017.
2). From 8 September 2017 until the date of 1st IOPP renewal survey the ship must either conduct Ballast Water Exchange (BWE) and comply with regulation D-1 or alternatively comply with regulation D-2.

Ship Category - A ship constructed prior to 8th September 2017 which has  not completed it's IOPP renewal survey on or after 8 September 2014 but prior to 8 September 2017 and which has it's first IOPP survey due in the period 8 September 2017 to 8 September 2019.
1). The Ship must follow regulation D-2 from the date of 2nd IOPP renewal survey after 8 September 2017.
2).  From 8 September 2017 until the date of 2nd IOPP renewal survey the ship must either conduct Ballast Water Exchange (BWE) and comply with regulation D-1 or alternatively comply with regulation D-2.

Ship Category - A ship constructed prior to 8 September 2017 for which an IOPP renewal survey is not required.
1). The ship follow regualtion D-2 from the date decided by the administration but not later than 8 September 2024.
2). From 8 September 2017 until the 8 September 2024 the ship must either conduct Ballast Water Exchange (BWE) and comply with Regulation D-1 or alternatively comply with Regulation D-2.

Fig. 2 Compliance to Reg. D-2 of BWM Convention

Regulation D2 detailed overview

 Technologies developed for ballast water treatment are subject to approval through specific IMO processes and testing guidelines. These are designed to ensure that such technologies meet the relevant IMO standards, are sufficiently robust, have minimal adverse environmental impact and are suitable for use in the specific shipboard environment. Ballast water treatment systems are required to be tested against the IMO guidelines. Approval consists of both shore-based testing of a production model, to confirm that the D-2 discharge standards are met; and shipboard testing, to confirm that the system works in service.

Fig. 3 Ballast Water Treatment Standards as per IMO Guidelines (cfu refers to the Colony Forming Unit)

Ballast Water Treatment Systems

The Treatment system for Ballast Water Management can be broadly classified into 2 types: Physical and Disinfection.

• ·         Physical methods include systems like Filtration, Coagulation, Hydrocyclone and alike.

• ·         Disinfection methods include chemical treatment, UV radiation, Electrolysis, Ultrasonic treatment, Deoxygenation or Gas Injection.

 

Fig. 4 Ballast Water Treatment Methods

All these methods named here have their own set of advantages and disadvantages. A combination of two or more methods, usually one from Physical and one from Disinfection method forms an ideal Ballast treatment system. Many commercially available treatment systems available features the combination of even three methods to achieve the set standards of IMO guidelines and at same time prove their easy reliability and retrofitting onboard ships.

Filtration method as name suggests include filters and strainers to remove the particles or organisms greater than the size of pores of filtering media. The filters are usually self-cleaning type as in the self backflushing filters using either discs or mesh screens. The filter is installed at the uptake of the Ballast Water and the backflushed sediments are discharged back to the sea.  Maintaining the flow normally requires that the filter is regularly cleaned, and it is the balance between flow, operating pressure and cleaning frequency that determines the efficacy of the filtration process. In principle, surface filtration can remove sub-micron (i.e. less than 1μm in size) micro-organisms. However, such processes are not viable for ballast water treatment due to the relatively low permeability of the membrane material.. The limitation to this method is obviously the size of filtering media and the backpressure against the filter. 

Fig. 5 Filtration Method

Hydrocyclone method utilizes he centrifugal force and difference in the specific gravity of sea water and the particle or organisms to be separated. The Ballast water is passed through a hydrocyclone unit which imparts a circulatory motion to the incoming liquid, the centrifugal force and the difference in the sp. Gravity of the liquid and the particles causes the heavier particles to move outward where they settle down and can be separated. The limitation to this system is that only particles with sp. Gravity greater than that of water can only be removed.

Fig 6. Hydrocyclone Method

Coagulation Method involves adding a suitable coagulant or flocculants that can enhance the flocculation of particles or organisms and hence increases the size and their specific gravity. The flocculated particles are heavier and of larger size and can be easily separated either by sedimentation, magnetic separation, filtration or by a hydrocyclone. However, because flocculation is time dependent, the required residence time for the process to be effective demands a relatively large tank. The processes can be advanced, however, by dosing with an ancillary powder of high density (such magnetite or sand) along with the coagulant to generate flocs which settle more rapidly. This is sometimes referred to as ‘ballasted flocculation’

Chemical Treatment involves using various Active Substances to chemically treat the ballast water and kill the living organisms before being discharged into the sea. Pre prepared or packaged disinfectants are used as chemical poisons or oxidisers. Commonly used biocides include chlorine, chloride ions, chloride di oxide, sodium hypochlorite or peracetic acid. The efficacy of these processes varies according to the conditions of the water such as pH, temperature and, most significantly, the type of organism. Chlorine, whilst relatively inexpensive is virtually ineffective against cysts unless concentrations of at least 2 mg/l are used. Chlorine also leads to undesirable chlorinated byproducts, particularly chlorinated hydrocarbons and trihalomethanes. Chlorine dioxide is normally produced in situ, although this presents a hazard since the reagents used are chemically hazardous. Prior to discharge of the treated ballast water it is mandatory to neutralize the ballast water to safe levels. Usually sodium sulphite is used to reduce the residual chlorine to zero. The limitation to this method is the maximum amount of chemical that can be added as increase in conc. Of chemicals escalates corrosion in the tanks.

UV Radiation involves the use of ultraviolet light to alter the genomes of the oraganisms and render the mincapable to reproduce. The UV light is produced by amalgam lamps surrounded by quartz sleeve which can produce UV lights at different wavelengths and intensities thus catering to vast range of microorganisms. The process is however limited to the transmission of UV light in case the water is turbid or dirty. Usually this method is combined with physical separation such as filtration at the intake to remove any turbidity in water and improve the effectiveness of the UV light.

Fig 7. UV Radiation Method

Ultrasonic Treatment involves high frequency agitation of Ballast water inside the tanks produces high frequency ultrasound waves which is capable to rupture the cell walls of the organisms rendering them harmless. The large scale bubbles produced owing to agitation also improves this method as continuous formation and collapse of bubbles causes hydrodynamic forces and high frequency noise, adding to the effectiveness of this method. However the large scale ultrasound generator onboard ships is a costly affair, which is where this method find its limitation.

Electrolysis Treatment involve passing current through water which generates free chlorine, sodium hypochlorite and hydroxyl ions. Electrochemical oxidation follows due to creation of ozone and hydrogen peroxide. As already discussed, chlorine acts as a disinfectant and the ozone and hydrogen peroxide adds to the effectiveness of chemical disinfection. This method is limited in effectiveness to seawater having a certain level of dissolved salt and could also create unwanted residuals.

Deoxygenation/Gas Injection involves removing dissolved oxygen in the ballast water and replacing it with inactive gases like nitrogen or other inert gas.  Deoxygenation method can effectively kill the aerobic organisms and also prevents the corrosion of the tank. The method is limited in effectiveness by the time for which the ballast water remains deoxygenated and inerted. Deoxygenation takes a number of days to come into effect due to the length of time it takes the organisms to be asphyxiated. The tank requires a minimum time for which it has to maintained in inert condition for effectively killing the organisms. 

 

These processes discussed above can be summarized as follows:

•   For chemical dosing systems, power is very low and chemical costs are the major factor. For these reasons chemical addition may be better suited to small ballast capacities. Although the systems operate at generally low pressure and thus do not require additional ballast water pumping pressure, those employing venturi devices (for exerting shear) incur pressure losses of up to 2 bar.   
• Most chlorination systems are applying a dose in the region of 2 mg/l residual chlorine which has proven to be effective.

•  Systems in which chemicals are added normally need to be neutralised prior to discharge to avoid environmental damage in the area of discharge. Most ozone and chlorine systems are neutralised but some are not. Chlorine dioxide has a half-life in the region of 6-12 hours, according to the supplier, but at the concentrations at which it is employed it can be safely discharged after a maximum of 24 hours.

• Chemical dosing systems such as Peraclean, SeaKleen and chlorine dioxide have low capital costs because only a dosing pump is required but require chemical storage facilities and availability of chemicals in the ports visited.

•  Deoxygenation is the only technology specifically developed for ballast water treatment and is effective because the de-aerated water is stored in sealed ballast tanks. However the process takes between one and four days to take effect, and thus represents the only type of technology where voyage length is a factor in process efficacy. This type of technology is also the only one where, technically, a decrease in corrosion propensity would be expected (and, according to one supplier, has been recorded as being suppressed by 50-85%), since oxygen is a key component in the corrosion process. The water is reaerated on discharge.

•  Essentially most UV systems operate using the same type of medium pressure amalgam lamps. A critical aspect of UV effectiveness is the applied UV dose/power of the lamp. This information has not been given by all suppliers. Another aspect of UV effectiveness is the clarity of the water. In waters with a high turbidity or colloidal content, UV would not be expected to be as effective.

•  Most ozonation suppliers are using an ozone dose of 1-2 mg/l which has proven to be effective.

•  UV systems are the least complex treatment plants to operate. Electrolysis and electro chlorination plants are the most complex.

•  Deoxygenation plants are relatively simple devices if an inert gas generator is already installed on the ship and in the latter case would take up little additional space.

•  The biggest operating cost for most systems is power and for large power consumers (electrolytic and advanced oxidation processes) availability of shipboard power will be a factor.

•  For most systems it is recommended that installation takes place in the engine/machine room near the existing ballast water pumps, although installation on deck may also be possible if appropriate precautions are taken. If the location is in an explosion zone, then the installation will need explosion proofing. Some of the technologies can be provided as explosion-proof products, but there is a cost penalty for this. The generation of hydrogen by the electrolytic technologies is not considered an issue, since the gas is vented and diluted with air to safe levels. 

Treatment technologies can be combined and differ in rate of application, holding time, power consumption and effects on other ship equipment or structures. A combination of different treatments can reduce the limitations of an individual technology. Therefore, many ballast water management systems (BWMS) use a combination of two or more technologies, e.g. filtration combined with UV, filtration combined with chemical injection/ electro chlorination, etc. With continual advancement and R&D, new methods of ballast Water treatment will enter into market. Such new methods are required to be approved by Administration as per the regulation D-3 (figure 1) of the BWM Convention. With installation of Ballast Water treatment Plants onboard all ships by September 2024, it also becomes important for Officers to thorough themselves with the working principle of the system. The correct functioning of the Ballast treatment is even so evitable with the fact that sampling of a ships ballast water is permitted by authorities (PSC Inspection) as per the article 9 of the BWM Convention adding to the woes of the Seafarers after ODMCS and OWS.

The BWM Convention needs to be followed and improved not only professionally, but also as a moral obligation to us for the want of maintaining a balanced and sustainable environment of the planet earth. The Seafaring Community stands at the forefront of ensuring the effective adherence to the convention. Our duty to our children and their children cannot be overstated. We all would wish them to inherit a world with clean, productive and beautiful seas. This Convention is just a step in realizing this wish.