The shipping of oil, petroleum and other chemicals forms a large portion of the marine shipping industry. With more and more amount of oil getting transported over oceans and seas day after day, the number of oil spill incidents have risen simultaneously. Oil spills can be very harmful to the marine environment. That’s why the latest oil cleanup methods are deployed to mitigate the oil spill disasters.
The catastrophic accidents create an adverse effect on the marine life forms as the layer of oil that gets spilled forms a layer above the surface of the water and cuts off the supply of oxygen to the marine life of that area resulting in their death. This is turn causes the industry as well as the people of the nearby area that are dependent on these industries to suffer.
The world has already seen major oil spills like Exxon Valdez ravage the environment. As oil spills are known to affect large areas of water bodies, they have become a major environmental issue. Hence, various oil spill clean-up processes have been devised to undermine the impact of accidents.
Over the years several methodologies have been adopted to carry out the tasks. Each of these oil cleanup methods has an advantage over the other depending on the situation.
Traditional Oil Cleanup Methods At Sea
Here is a list of 15 oil cleanup methods for clearing oil spills at sea:
1) Using Oil Booms for oil spills
Most commonly used and widely accepted method for cleaning up oil spills, comparatively environment-friendly is the immediate step taken. A containment boom or an oil boom is a floating barrier that is temporarily used to prevent the oil from spreading and polluting the shorelines. This barrier is flexible and designed in such a way that it surrounds an oil slick at the surface. It facilitates the recovery process.
Booms are setups that help to concentrate the oil on the thicker surface layers from where they can be collected easily with the help of vacuums, skimmers, etc. They are found in various different shapes and sizes and are used for various different conditions.
Made out of several different PVC coated fabrics and cables, blooms are efficient oil spill managers. They have 18 to 48 inches long material that extends beneath the surface of the water. But blooms are effective in calm water and are also easy to use. Once the water level rises due to waves then its effectiveness diminishes drastically as the contaminated water can just wash over the top of the boom.
- Easy to use and perform the disaster mitigation
- Only suitable for a few hours after the spill
- Not meant for huge oil spill incidents
- Unfit for high tides areas
2) Using Sorbent for Oil spills
This is a type of material used to absorb or adsorb (surface absorption) liquids or gases. They are like sponges that when put in the contaminated water absorbs the oil. These materials can include peat moss, clay and vermiculate. Some synthetic varieties can also include plastic fibers or foams in the forms of rolls, sheets or booms.
This method is usually used at a smaller scale because of its rudimentary nature. Other advanced oil cleanup methods have to be used for larger accidents. Another issue with such sorbents is their ability to yield back the oil.
Some sorbents make the oil totally unfit for use and extremely difficult to retrieve. Along with that, there is a risk of fire if hay or other fibrous sorbents are used.
- A cheaper method as hay and fiber is easily available
- Oil retrieval is tedious
- Risk of fire breakouts
3) Underwater or Superficial Dispersants
Dispersants can be defined as the chemicals agents which are used to break down oil slicks into small droplets. Just like soap takes away oil from our hands by trapping it, dispersants trap oil.
Every dispersant molecule has a structure with a water-soluble and insoluble region. The water-insoluble region attaches to the oil spill. And all the water-soluble regions form a micelle and cover the oil. Chemical arrangements without any additional human effort trap the oil.
These droplets dilute throughout the water and hence help in cleaning up the oil spill. Dispersants are sprayed into the affected area of water using planes or boats. A novel method suggests using underwater dispersant that would clear oil that has managed to sink in.
This method cannot be used to remove the spilled oil but as small oil droplets are biodegraded relatively easily. Dispersant acts like an emulsifier that breaks down the oil spill size. Such chemicals help in protecting sensitive habitats which would otherwise be threatened by the oil covering the water surface.
- Enhances the rate of biodegradation when oil removal is not possible
- Protects sensitive habitat from rapid damage
- Oil cannot be retrieved
We are all aware of the process of skimming in our daily lives. Milk, when kept in the open for quite some time, develops a thin layer on the top which we sometimes use a spoon to remove.
The same process can be used in the oil spillage clean-up process as well. However, since this is oil and not milk things are little trickier. Hence, we need some special equipment designed for the purpose.
Skimming process has some limitations as it can only be used for oil that is lighter than water. When the density of oil is more than water it starts seeping deeper into the sea. The underwater dispersant can work but skimming is not possible in that situation. Oil floating on the surface is a condition necessary for skimming.
- Helps cleaning lighter density oils
- Doesn’t require an additional process for retrieval of oil
- Not fit for heavy density oil types
- For large area spillage, the process becomes uneconomical
5) Gushing Hot water Under Pressure
In this method, hot water is forced into the contaminated regions at high speed to push the oil back to the surface. First, the water is raised to a temperature above the boiling point. To avoid the evaporation of water once boiling begins the pressure valves are tightened. As pressure rises the water still remains liquid but dangerously hot.
In situations where there is a heavy oil spill or mitigation has been delayed, hot water stirrups are prior steps. The entire region is given a rigorous swirl and oil comes up.
Whereby skimming tools and equipment can be used to carry on the rest of the clean-up process. Once the oil is present at the top layers all oil cleanup methods can be used. Time is a big factor here because the oil can return back. And repeated hot water cycling damages the ecosystem of the region and affects oil quality.
- Brings back lost oil to the sea bottom
- Damages marine life
- Contaminates and dilutes the oil
6) Using Cranes and Tractors for cleaning an Oil Spill
Sometimes, it is not possible to carry out the clean-up process in the affected area itself. For that technological aid as in cranes and tractors are used to carry the sand from the affected area of the beach to the lab where the oil and the sand are separated. This process is specifically carried out in the coastal regions and the beaches.
Such oil cleanup methods using machinery for the transport of the oil spill is not for ocean spills. Only when the damage reaches the shores washing along with marine and coastal wildlife such methods are employed.
- Quick handling of on-shore damage
- Reduction in time spent due to working on the land
- Not meant for ocean and distant oil spillage
7) Using Manual Labour
The people living near the affected beaches can be of great help in the clean-up process. Simple tools like shovels and spades can be used to separate the affected portion from the safe portion.
Again they are pivotal for prevention of damage on the coasts. Poisoning of the birds and fishes near the human habitation multiply the effects.
- Ability to carry out specific and flexible clearance
- Possible to fine-tune the process using human communication compared to machinery
- Slow process and cannot cover the entire area
8) Burning In-situ
This is a fairly simple process which involves burning the oil on the site. This method needs to be executed at the earliest stage of the spillage before the oil spreads over a bigger region. Though the process is simple it is far from an ideal one because of the huge carbon emission and other toxic gases that cause a severe impact on not just oceanic air the but also affects the marine life form.
Fires are not easy to start in the ocean. Thus a huge setup is required and controlled burning is achieved. Even with the control and checks, the damage to the ecosystem takes months to recover and can be irreversible. The toxic particles released alongside do not improve the condition either.
- Fast process with limited steps
- Doesn’t require any oil retrieval steps
- Affects wildlife adversely
- Toxic fumes can spread and remain for a longer period
9) Using Natural oil cleanup methods
This is probably the easiest and definitely the slowest process as here natural components like the sun the wind, the air, etc. are used. More accurately this can be described as keeping your hands folded and see nature take its course. The particles of the oil spill evaporate slowly as time passes, the other elements contribute equally. It should come as no surprise that this happens to be the most cost-efficient method among all the ones mentioned here.
However, it’s not a method that can work in every zone. Only a few regions of the hydrosphere allow such natural methods as a choice. Rest of the regions require some basic mitigation if not at all. All factors such as cyclones, wind, sunlight, etc need to be assessed before leaving the oil spill on itself.
When no alternative works then natural recovery is opted, rather than going for other oil cleanup methods if natural recovery is not possible.
- No cost and no effort required
- Long term biodegradation affects generations of marine wildlife and can even lead to the extinction of rare species
10) Using bacteria that can utilize the oil (bioremediation)
Bacteria Pseudomonas putida has been used in the past for resolving the incident of oil spillage. https://www.sciencedirect.com/science/article/pii/S0964830599000487
These bacteria have a natural ability to utilize the oil and detox the environment. They may not be present at the site naturally or take time to culture. Artificially implanting them at the site of the oil spill in the sea can help to clear off the spill.
Sites of industrial waste discard from oil or petroleum factories have these bacteria as one of the oil cleanup methods. Research shows that they can utilize the oil as a nutritional source and thus detoxify the environment.
- Biodegradation is safe for the marine environment
- Slow and requires successful seeding of bacteria
5 Newer Oil Cleanup Methods For Clearing Oil Spill At Sea
Novel methods are being devised every day for handling oil spills in the sea. The damage is severe in the primary situation, to add on the consequence of oil cleanup methods to counter it. Every method has some disadvantage and climatic zone needs are different. So, there is room for newer technologies to be invented for such sites.
Here are 5 promising ways to clear oil spills in the future:
11) Employing gel-forming materials
The gel-forming material can convert the liquid oil into a solid layer. Vigorous action of the sea causes mixup of oil and gel-forming substance. Quantity of gelling agent is generally required double of the spilled oil. Thus, it is not feasible in cases of huge spills. In situations where the oil spill was of a light density oil that spreads fast gelling is an excellent approach.
12) Marsh Clearing
Removal of the restrictions such as marsh vegetation allows the oil to seep in the beach sand. Long been used for other purposes, marsh cleanups can be employed for coastal spillage. Gauging the damage to the coastal area versus damage from oil is the key step here. Clearing the damage from the marsh later gets tougher. Future impact of oil toxicity can be the same as the clearing of the coast. In that scenario, it will totally fit to remove the marsh earlier and allow clearing off.
Just like the use of bacteria like Pseudomonas Putida is a bioremediation example, some mushrooms can use oil. Myco refers to fungi and mycoremediation implies using fungi for curating environmental damage. Using such mushrooms and other fungi for clearing the spills can be easier than seeding bacteria. Managing fungi is easier than handling microorganisms.
14) Mechanized Devices
Newer machines are being designed that can fit in ships and make the entire process mechanized. These water-oil separating devices can themselves harvest and separate water and oil. However, the cost of construction and maintenance of such machines just for the sake of by chance incidents is not economic. Using machines for all steps until separation makes the task easier and finer.
15) Controlled Nuclear Blast
The last alternative to such oil cleanup methods is the use of nuclear energy. Considering the hazards of a single miss while using nuclear power such methods have limitations in trials too. Using nuclear reactions at pristine sites like oceans can affect the entire earth. Yet there have been successful findings of clearing oil spills with nuclear blasts.
Though there are ways and means of restoring the regions affected by oil spillage, it is worth noting that a hundred percent restoration is never possible. Whatever toxic matter remains, keeps affecting the surrounding ecosystem forever. So, it would be better if humans could be more careful and prevent spilling oil in the waterways.
Multi-panel conferences are held for nations to opt sustainable and renewable alternatives like wind energy, solar energy, and hydraulic energy. Several rules and regulations are being developed and following them are being made compulsory for ships carrying oil so that the oil spillage can be minimized. Damage already done is quite huge and these regulations are nothing but a temporary fix of a bigger problem. Solving the problem from the root can only be achieved by decreasing our dependence on oil.