The shipping industry faces a huge problem of aquatic species invasion in ship’s ballast water. This poses a significant threat to the marine ecosystem. Moreover, this bio invasion can cause an alarming situation if not controlled within time.
That’s why the International Convention for the Control and Management of Ship’s Ballast Water and Sediments has implemented the ballast water management protocols. According to IMO’s orders, each boarding ship should have a ballast water management plan with a ballast water treatment system to preserve the marine ecosystem.
In this article, we will tell you what ship ballasting is, what ballast water treatment system is, what ballast water treatment filters and other techniques are used to filter the ballast water.
What is ship ballasting?
Ship ballasting is the process in which water is pumped into ships’ ballast tanks while in transit or at a port. The water is pumped using a commercial vessel. The process is mainly used in ships for safety purposes. When the ship is carrying a heavy load in one hold, and a lighter load in the other, ballasting will help the sailor balance the ship. Moreover, ship ballasting is also beneficial to balance the ship when you are facing the rough sea.
Many aquatic animals seep into ballast water and disturb the marine ecosystem. That’s why IMO sets rules and regulations regarding ballast water management. Many shipping operators are now starting to get proper ballast water treatment systems on their ships.
What is a ballast water treatment system?
Previously, the ballast water treatment system referred to the process of asphyxiating the organisms by injecting an inert gas like nitrogen into the ballast tank. This process is effective in preserving the marine ecosystem. But it takes almost 2 to 4 days to remove the organisms completely. Moreover, the tank should also be sealed from atmospheric oxygen. That’s why this technology is not popular now. With the introduction of the latest technologies and ballast water treatment filters, people nowadays prefer other more efficient methods.
Ballast water treatment technologies
Various technologies can be applied to filter microorganisms during ballast water treatment. These are:
- Physical filtration system
- Chemical disinfection (by oxidizing and non-oxidizing biocides)
- Ultraviolet or UV treatment
- Deoxygenation method
- Thermal treatment (use of heat to purify the ballast water)
- Ultrasonic treatment (cavitation treatment)
- Pulse plasma system or electric pulse method
- Magnetic field treatment
However, the technology you should choose depends upon several following factors:
- Space available
- Implementation cost
- Level of environmental friendliness
- Effectiveness of the ballast water filter system on the organisms present in the water
- Cost efficiency
- Safety of crew
- Process and ease of installation and operation
Generally, most ships use two or more technologies for ballast water treatment to ensure their treated ballast water is up to the standards of IMO.
Physical separation or filtration of ballast water
The ballast water filtration system is a widely used system to separate marine organisms and the suspended solid materials or sediments in the ballast water. This system uses sedimentation or surface filtration to separate the suspended solid materials. The filtered particles and wastewater will be discharged to the area where the ballast is taken. Some ship owners have water treatment systems on their ships. They further treat the wastewater and discharge it to the sea.
No doubt, ballast water is necessary for safe and efficient shipping, but it can also cause serious ecological, economic, and human health-related issues. Because marine life is carried with this water, humans can also get seriously ill. These marine organisms include bacteria, microbes, eggs, and larva to small animals. These animals may reproduce in ballast water, establish a large population, invade human life, and cause more problems.
That’s why ballast water filtration and separation are necessary. The ballast water filtration system filters can successfully eliminate all types of organisms along with other sediments. Moreover, in the ballast water filtration system, all of this will be done prior to the main disinfection treatment.
Benefits of ballast water filtration system
The ballast water filtration system effectively achieves the rules and regulations of IMO. Aside from this, the physical separation of ballast water filtration has the following benefits:
- There is no need to dispose of and change the media paper frequently.
- The system is completely automatic, requiring minimal human invasion, mainly for supervision.
- The ballast water filtration system is the most low-maintenance system in the entire industry.
- Minimal operating cost is needed.
- Provide maximum effectiveness.
- The wastewater can be further treated and discharged into the area where the ballast water was taken.
- Ballast water filtration reduces environmental pollution and has a positive impact on the health of humans.
- The filters used in the ballast water filtration system require no media paper.
- By using a good quality filter in your ballast water filtration system, you can filter everything ranging from larger solid particles to single sub-micron size organisms.
Equipment needed in ballast water filtration
Physical separation or filtration is the most reliable way of treating ballast water. This is also the most efficient way of protecting marine creatures and the ecosystem. But the whole physical separation system requires some equipment. Here is that equipment.
1. Screens or discs
The screen can be fixed or removable, or discs are the main element of the filtration system. The screen or disc is responsible for effectively removing the suspended solid particles from the ballast water. Remove the sediment and solid particles during automatic backwashing, screen, or disc.
A screen or disc in the filtration system is widely used because it is environmentally friendly. It does not need the use of toxic chemicals to treat the ballast water. Screen or disc filtration is effective in removing large size particles. This technology is not very effective against smaller size particles and tiny organisms. That’s why this method alone is not sufficient to treat the ballast water according to IMO standards.
Hydrocyclone is useful in separating suspended solid particles from the ballast water. It involves the usage of high-velocity centrifugal force to rotate the water and separate solid particles vigorously.
Another advantage of using hydro cyclone is its easy installation and operation. It has no moving parts, so installing and maintaining onboard ships is easy. However, the efficiency of hydrocyclone varies with the mass and density of the particles and sediment. Like screen filtration, this method also successfully removes small-sized particles.
I have already told you some physical filtration methods in the previous section. And as you can see, both of them cannot filter smaller particles from the ballast water. That’s why many ship boarders coagulate ballast water before filtration.
Coagulation of ballast water will join the small size particles together to increase their size. These larger particles can be easily filtered now using any of the above-mentioned methods. Thus coagulation increases the efficiency of ballast water filtration. To convert them into small flocs, you can also perform flocculation and coagulation of smaller particles. Flocs are easier to filter and can be removed rapidly.
However, remember that some ballast water treatment systems use ancillary powder, like sand, magnetite etc., or coarse filters for the purpose of coagulation and flocculation. In this situation, an additional tank is required to treat ballast water before filtering them, and thus more space is needed on boarding the ship.
4. Media filters
Lastly, some sailors also use media filters in their physical ballast water treatment system to filter small sizes particles. But media filters require extra maintenance. It is also observed that compressible (crumb rubber) media filters are more efficient than conventional granular filters in physical ballast water treatment systems due to their compact size and low density.
Other methods used for ball ballast water treatment
Mainly physical filtration is used to treat ballast water, but some sailors also use some other methods. Here are those other methods with their brief descriptions.
1. Magnetic field treatment
This treatment is based on coagulation technology. Magnetic powder with coagulants is added to the ballast water to create magnetic flocs of smaller particles and marine organisms. Magnetic discs are installed in this ballast water treatment system which will separate these flocs.
2. Chemical disinfection of ballast water
The chemical disinfection method involves the addition of biocides in the ballast water. Biocides are actually disinfectants that can remove invasive organisms from the ballast water. However, your biocides should only remove or inactivate the marine organisms and should not be toxic to water. The only purpose of biocide is to degrade marine organisms.
3. UV treatment of ballast water
In this method, the ballast water will flow through the chamber surrounded by UV lamps. The UV rays will be discharged from these lamps. These rays will act on the DNA of marine organisms to make them harmless and infertile. This method is slightly costly but still the widely used one for ballast water filtration purposes.
Deoxygenation, as the name suggests, involves removing oxygen from ballast water to asphyxiate marine organisms. This is usually done by adding nitrogen to the water and sealing the tank afterward. However, this technology requires 2 to 4 days to asphyxiate the organisms.
5. Heat Treatment
Heat treatment of ballast water requires a separate heat system on ships. The ballast water will be treated at a high temperature until all of the organisms are killed. Heat treatment is not much used because it takes a lot of time to kill the organisms. Moreover, heat treatment can also cause corrosion in the tanks.
6. Ultrasonic treatment
In ultrasonic treatment, high-energy ultrasound is used to kill the cells of marine organisms from the ballast water. But this technique is often used in conjunction with other methods.
7. Plasma treatment or electric pulse method
Electric pulse or plasma treatment uses short bursts of energy to kill the organisms in the ballast water. In the electric pulse method, two metal electrodes produce energy in the ballast water with a very high power density and pressure. This energy kills the organisms. The plasma technology is almost the same as the electric pulse technology. It’s just in plasma technology; the system creates high-energy plasma arcs to kill the organisms.
Ballast water treatment filters are necessary to stop bio-invasion and meet IMO rules and regulations regarding ballast water treatment. There are numerous ways of treating ballast water. However, filters are the most efficient ones. You can read our guide to learn everything you should know about ballast water treatment filters.