According to the specific situation of oil pollution, careful selection of treatment options is very important to effectively deal with oil pollution and protect the coastal environment. In order to minimize oil spill pollution, a treatment method is generally adopted that consists of the following two parts: preparation and prevention of oil pollution that may be caused by routine operations and leakage accidents; control and recovery of oil spills to reduce the consequences of pollution.
1. Conventional oil spill treatment measures
Traditional treatment methods are the first measures taken after an oil spill accident. They are also the most commonly used methods to deal with oil spill accidents. They are divided into different types according to the equipment used. Category three.
1. 1 Physical treatment method
The physical method is mainly to contain and recover the remaining oil on the sea surface. It is combined with other treatment methods such as combustion method, oil-absorbing materials, decomposition of oil dispersants, Biodegradation, etc. are closely coordinated, and the treatment efficiency is greatly affected by weather, ocean conditions and oil spill type. The following physical treatment methods are actually used in handling oil spill accidents:
(1) Fence method: After the oil leaks to the sea surface, it should first be surrounded by a fence to prevent it from spreading on the sea surface. , and then try to recycle it. The fence should have strong oil retention, good wave following, strong wind and wave resistance, easy to use, tough and durable, easy to maintain, and difficult for marine organisms to adhere to. The fence can not only prevent the spread of oil spills in the horizontal direction, but also prevent the crude oil from condensing into tar balls and spreading in the vertical direction of the sea surface, that is, drifting with the waves on the sea.
Fences can be divided into four categories:
Curtain fences: mainly used under conditions of good coastal conditions with calm seas;
Hedge fences: mainly used Used in sea areas with high water velocity;
Sealed fence: used in cyclic tidal sea areas;
Fire-proof fence: used in combination with incineration technology.
(2) Oil skimmer: Oil skimmer recovers oil without changing the physical and chemical properties of oil. The following types of oil skimmers are currently widely used:
< p>Suction oil skimmer: The main types are vacuum oil skimmer, Wei-type oil skimmer, and turbine oil skimmer.Adsorption oil skimmers: The main types include belt skimmers, drum skimmers, brush skimmers, disc skimmers, and mop skimmers.
Heavy oil skimmer: The operation method is the same as that of a general oil skimmer, but the heavy oil skimmer is used to remove highly viscous petroleum and emulsified oil-water mixtures.
(3) Oil-absorbing materials: lipophilic oil-absorbing materials can be used to make the spilled oil stick to its surface and be adsorbed and recovered. Oil-absorbing materials are mainly used in sea areas near coasts and ports to deal with small-scale oil spills.
There are three raw materials for making oil-absorbing materials:
Polymer materials: polyethylene, polypropylene, polyester, etc.;
Inorganic materials: diatoms Soil, perlite, pumice and bentonite, etc.;
Fiber: straw, wheat straw, sawdust, grass ash, reed, etc.
1. 2 Chemical treatment method
The main feature of chemical treatment method is to change the physical and chemical properties of oil. It can be directly applied to oil spill treatment or can be used as a follow-up to physical treatment method. deal with. Chemical treatment methods include the following:
(1) Dispersant: Oil spill dispersant is a uniform and transparent liquid composed of surfactants, penetrants, co-solvents, solvents, etc. Dispersants can reduce the surface tension between oil and water so that the spilled oil emulsifies on the water surface to form an emulsion, thereby dispersing the oil into fine oil droplets dispersed in the water, making the oil spill particles easy to react with chemicals in seawater and easily Microorganisms that can degrade petroleum hydrocarbons are degraded and eventually converted into CO2 and other water-soluble substances, which accelerates the purification process of petroleum in the ocean. The general dosage of oil dispersant is 1% to 20% of the oil spill. It is easy to use and its effect is not affected by weather and seawater conditions. It is the first choice method to deal with oil spills under harsh conditions. It is currently widely used in China to deal with conventional spills. Oil accidents, but dispersants may damage the ecological environment during use.
The main dispersants used internationally today are: traditional dispersants; concentrated anhydrous dispersants; concentrated water-added dispersants.
(2) Gel-gelling agent: It can gel petroleum into a viscous or hard jelly-like substance. Its advantage is that it has low toxicity, is not affected by wind and waves, and can effectively prevent oil from spreading. The development and application of oil coagulants has attracted the attention of various countries. In recent years, a large number of patent papers have been published.
(3) Other chemicals: demulsifiers used to destroy oil-water mixtures; bioremediation compounds used to accelerate petroleum biodegradation; in addition, there are combustion agents and viscous additives, etc.
1. 3 Natural degradation
People do not take any action, and the natural purification process of oil is carried out by the ocean.
2． Emerging oil spill treatment methods
Generally speaking, these methods are only used as follow-up treatment methods of other methods or are still in the experimental research stage.
2. 1 Bioremediation Technology
Some microorganisms naturally found in the ocean or soil have strong ability to oxidize and decompose oil. This characteristic of microorganisms can be used to remove it. Oil spill at sea. Biological treatment methods will not cause secondary pollution and can be used in combination with other additives that can accelerate natural biological degradation. Compared with chemical and physical methods, biological remediation has less impact on people and the environment, and the cost of remediation is only that of traditional physical and physical methods. 30% to 50% of chemical repair.
The natural biodegradation process of petroleum is slow, and a variety of measures can be taken to strengthen this process. Commonly used technologies include:
First, adding surfactants to promote microbial degradation Utilization of petroleum hydrocarbons;
Second, providing conditions required for microbial growth and reproduction (providing O2 or other electron acceptors, applying nutrients);
Third, addition can efficiently degrade Microorganisms in oil contaminants.
At present, it seems that the bioremediation of oil-polluted beaches mainly focuses on applying nutrients, and lacks crossover and integration with several other technologies. At the same time, because bioremediation faces multi-phase, heterogeneous and complex systems, involving knowledge from multiple disciplines such as microbiology, engineering, ecology, geology, chemistry, etc., its mechanism of action is still unclear.
2. 2 Combustion method
It is necessary to use various combustion accelerants so that a large amount of oil spill can be burned in a short time without complicated equipment and low processing costs. However, considering the impact of combustion products on the growth and reproduction of marine life, possible damage to nearby ships and coastal facilities, and the thick smoke generated during combustion will also pollute the atmosphere, the treatment targets are generally large-scale oil spills and Arctic Ocean waters. For oil pollution, this method is used only when the treatment location is usually on the high seas quite far away from the coast.
The best way to curb oil spill pollution is to control the occurrence of oil spill accidents, which is much better than dealing with the predictable and unpredictable consequences of oil spills. However, oil spill accidents will always happen. We use various physical, chemical and other methods to deal with oil spill pollution in order to protect the ecological environment, and the coastal ecological environment is the main target of oil spill pollution treatment.