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Contents of Ballast Water Management Plan
- Reduce the harmful effects on the marine environment spread by invasive aquatic microorganisms transferred from one area to another through ballasting operations.
- (IMO) adopted a convention in order to control and manage ships ballast and sediments on on 13th February 2004.
The ballast water management plan includes the following:
- International rules and regulations for different port state controls all over the world.
- Location of ports providing shore discharge facility of sediments and ballast water.
- Duties of the personnel on board for carrying out ballast operation.
- Operational procedure along with the method to be used for ballasting.
- Sampling point and treatment method should be given in the ballast water management plan.
- D1 standard concerns ballast water exchange, which must be undertaken within open ocean areas, >200nm from land and in seas >200m deep. The D2 standard covers approved ballast water treatment systems.
The simplest and most practical method is by ballast water exchange. Either by sequential method or by overflow method.
Record of the ballast water exchange with all the following data to be noted:
- Date of the operation
- Which ballast tank used in the operation.
- Temperature of the ballast water.
- Salinity of the ballast water in PPM (salt content in parts per million).
- Position of the ship (latitude and longitude).
- Amount of ballast water involved in operation.
- All the records entered must be signed by a responsible officer (normally chief officer).
- Master is overall in-charge of the operation and he will also acknowledge the ballast/ de-ballast operation by signing the BMP log.
- Date and identification of the tank last cleaned.
- If there is accidental discharge of ballast exchange it must be entered and signed. Same information is to be given to concerned port state authority.
Type of ballast water treatment onboard
Imagine the the different possible ways to kill a invasive species, like a torture chamber.
The main types of ballast water treatment technologies available in the market are:
- Filtration Systems (physical)
- Chemical Disinfection ( oxidizing and non-oxidizing biocides)
- Ultra-violet treatment
- Deoxygenation treatment
- Heat (thermal treatment)
- Acoustic (cavitation treatment)
- Electric pulse/pulse plasma systems
- Magnetic Field Treatment
A typical ballast water treatment system on board ships use two or more technologies together to ensure that the treated ballast water is of IMO standards.
Physical Separation/ Filtration Systems Ballast Water Treatments
The filtered solids and waste through backwashing from the filtration process is either discharged in the area from where the ballast is taken or further treated on board ships before discharging.
The following equipment are mainly used for ballast water filtration:
Screens/Discs: Screens (fixed or movable) or discs are used to effectively remove suspended solid particles from the ballast water with automatic backwashing.
Hydrocyclone: High velocity centrifugal force is used to rotate the water to separate solids. As hydrocyclone doesn’t have a moving part
Coagulation : coagulation is used prior to the filtration process to join smaller particles together to increase their size. As the size of the particles increase, the efficiency during the above mentioned filtration processes increases. Such treatment involving coagulation of smaller particles into small flocs is known as flocculation. The flocs settle more quickly and can be removed easily.
Magnetic Field Treatment
Magnetic powder is mixed with the coagulants and added to the ballast water. This leads to the formation of magnetic flocs which includes marine organisms. Magnetic Discs are used to separate these magnetic flocks from the water. (Refer the figure above)
Chemical Disinfection (Oxidizing and non-oxidizing biocides) Ballast Water Treatments
Biocides (Oxidizing and non-oxidizing) are disinfectants remove invasive organisms from ballast water. Must be readily degradable or removable to prevent discharge water from becoming toxic in nature.
On the basis of their functions, biocides are mainly divided into two types:
- Oxidizing
- Non-Oxidizing
Oxidizing biocides : This type of disinfectants act by destroying organic structures of the microorganisms such as cell membrane or nucleic acids. “Example of how rusts are formed, oxygen being the oxidizing agent”
Non-oxidizing biocides : Non-oxidizing biocides are a type of disinfectants which when used interfere with reproductive, neural or metabolic functions of the organisms.
Oxidizing Biocides
Some of the processes utilizing oxidizing biocides used on board ships are:
Chlorination – Chlorine is diluted in water to destroy the micro-organisms.
Ozonation – Ozone gas is bubbled into the ballast water using an ozone generator . The ozone gas decomposes and reacts with other chemicals to kill organisms in the water.
Non-Oxidizing Biocides
only a few such as Menadione/ Vitamin K are used in ballast water treatment system as they tend to produce toxic by-products.
Ultra-Violet Treatment Method
Ultraviolet ballast water treatment method consists of UV lamps which surround a chamber through which the ballast water is allowed to pass. The UV lamps (Amalgam lamps) produce ultraviolet rays which acts on the DNA of the organisms and make them harmless and prevent their reproduction.
“Personally experienced Ballast water treatment plant, Panesia, korea” These UV lamps are fragile and break easily. due to vibration caused by the system thus requiring high maintenance.”
Deoxygenation
As the name suggests, the deoxygenation ballast treatment method involves purging/removing of oxygen from the ballast water tanks to make the organisms asphyxiated. This is usually done by injecting nitrogen or any other inert gas in the space above the water level in the ballast tanks.
Heat Treatment
This treatment involves heating the ballast water to reach a temperature that will kill the organisms.
Ultrasonic Treatment
Ultrasonic energy is used to produce high energy ultrasound to kill the cells of the organisms in ballast water. Such high pressure ballast water cavitation techniques are generally used in combination with other systems.
Electric Pulse Treatment
The electric pulse /plasma for ballast water treatment is still in the development stage. In this system, short bursts of energy are used to kill the organisms in ballast water.
In the pulse electric field technology, two metal electrodes are used to produce energy pulse in the ballast water at very high power density and pressure. This energy kills the organisms in the water.
A Typical Ballast Treatment Treatment System on Ships
Most of the ballast water treatment system use 2-3 disinfectant methods together, divided into different stages. A general ballast water treatment plant comprises of two stages with one stage using physical separation while the second stage employing some disinfectant technology. The choice of treatment system used in combination depends on a variety of factors such as type of ship, space available on the ship, and cost limitations as mentioned before.
quote: https://www.marineinsight.com/tech/how-ballast-water-treatment-system-works/
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