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When it comes to mixing oil and water, oceans suffer from far more than an occasional devastating spill. Disasters make headlines, but hundreds of millions of gallons of oil quietly end up in the seas every year, mostly from non-accidental sources Large spills -- even though a relatively minor source of ocean oil pollution -- can be devastating. The same amount of oil can do more damage in some areas than others. Coral reefs and mangroves are more sensitive to oil than sandy beaches or sea-grass beds; intertidal zones are the most sensitive. Crude oil is most likely to cause problems. Because human error causes 46 % of oil spills and 34 % of equipment failure, the first strategy must be that of prevention.
However, assuming that in the particular case prevention has not been effective the remaining strategic options are: Containment and Recovery removes the pollutant from the environment by mechanical means. This strategy has the following characteristics: &# 61623; Need for Logistics Support &# 61623; Effectiveness Sharply Impacted by Weather &# 61623; Encounter Rate Very Important The usual method of containment and recovery involves deploying booms to prevent the oil from spreading and to concentrate it. Skimmers are then used to recover the concentrated oil. It is then transferred to temporary storage and eventually to a permanent storage / treatment facility.
When employing this strategy it is necessary to consider the following questions: &# 61623; Can the operation be mounted close to the source of the spill so that the spread of oil can be contained? &# 61623; Can sufficient vessels be mobilized to operate the appropriate numbers and types of booms and skimmers? &# 61623; Are vessels with adequate onboard oil storage capacity available? &# 61623; Will weather conditions permit the equipment to be used effectively, if at all? &# 61623; Is the type and condition of the oil amenable to mechanical recovery? &# 61623; Are the required number of trained equipment operators and maintenance personnel available? When a great deal of mixing energy is applied at the oil-water interface, i. e. such as a rough sea surface, the oil may disperse naturally. Using dispersant as a strategy involves the use of chemicals to speed up the process of natural dispersion. FEDERAL AUTHORIZATION MUST BE OBTAINED IN EACH CASE BEFORE THE USE OF DISPERSANTS.
Dispersant's act in the same way as household detergents; when they are added to a film of oil on the surface of the water the oil breaks up into very small droplets forming thin emulsions which disperse in the water column. In effect, they speed up the natural processes of dispersion. In dispersed form the oil is subject to degradation by micro-organisms which occur naturally in the sea. A characteristic plume can be seen spreading slowly down the water surface shortly after treatment if an oil has been satisfactorily dispersed. Dispersant's do not destroy the oil. However, this must be weighed against the fact that dispersing the oil in the water column makes its toxic components more readily available to marine organisms, particularly in shallow water.
Dispersant's do not work on all types of oil or in cold weather conditions under which oil tends to become very viscous. Evaporation and emulsification which render oil resistant to dispersant occur over time and in most cases, dispersant will likely be ineffective after a day or two. If the oil is very viscous (thick) dispersant's are ineffective, since they tend to run off the oil into the water before they can penetrate. As a general rule, dispersant's can be effective in dispersing most liquid oils and liquid water-in-oil emulsions with viscounties less than about 2000 centistokes. Oils that may be more susceptible to treatment on first entry to the water become progressively less so as mousse forms or weathering takes place. There are several Dispersant application methods: &# 61623; Hand application (sprayer) &# 61623; By aircraft spray system (for example ADDS Pack) &# 61623; By spray systems installed on ships and boats The method of application depends primarily on the type of dispersant, the size and location of the spill, and the availability of vessels or aircraft for spraying the dispersant.
For application to be effective, several factors in addition to the type of dispersant being used, need to be considered. This is important because they control the dispersant to oil application ratio, the vessel or aircraft speed, the swath width (path covered by the spray pattern), the size and number of the spray nozzles, and the thickness of the oil. In-situ Burning, igniting the oil on the surface of the water works well in removing large quantities of spilled oil from the water. To be successful, this is a strategy best initiated early prior to evaporation of the lighter ends which support combustion and prior to weathering of the oil. In-situ burning can only be done in open waters where no danger is posed to drilling rigs, ships, or shoreline. Fire boom is used to corral the oil and contain it during the burn.
Obviously some air pollution does occur when oil is burned. To Do Nothing is a strategy seldom used and is difficult to justify. However, this strategy may sometimes be appropriate. No action is taken except for monitoring the movement of the spilled oil. Natural and biological processes will disperse most spills given time.
Crude oils, particularly of the lighter kinds, that have been spilled a considerable distance offshore in the rough conditions characteristic of those waters are unlikely to pose an environmental threat unless in close proximity to vulnerable concentrations of sea birds. There is a likelihood that these oils will be dispersed by natural processes before reaching shore. Beach Clean-up. In some cases, despite all the efforts to deal with spilled oil offshore, some oil still reaches the shore. Or it may be an acceptable strategy depending upon the circumstances to allow the oil to come ashore for subsequent collection. In these instances the principal means of cleaning up the oil becomes physical.
Beach clean up is labor intensive. The tools used include buckets, shovels, skimmers, booms, earth moving equipment, pumps, vacuum equipment, absorbents, and temporary storage. If the beach has not been cleaned prior to oil impact, oiled debris must be disposed of along with oil and oiled sand. Chemicals used to treat oil spills include the following: &# 61623; Dispersant's. Dispersant's contain chemicals which reduce the surface tension between oil and water.
They therefore result in breakup and dispersal of an oil slick throughout the water column. &# 61623; Emulsion Breakers. Used to break down the water / oil mixture which develops as oil weathers. This mixture, called mousse, is around 80 % water and is very difficult to skim, pump, or separate. &# 61623; Gelling Agents. These are chemicals which increase the viscosity of the oil slick. They therefore reduce its rate of spread on the surface of the water. &# 61623; Herders. Also called collecting agents.
Herders work by affecting the surface tension of the oil and cause the oil to herd to a collection point. &# 61623; Viscoelastic Additives. Include Solidifying Agents and Gelling Agents. They convert liquid oil into a solid form, thereby facilitating recovery by manual means or nets. Gelling agents increase the viscosity of the oil slick and thereby reduce its rate of spread. These agents are rarely used because the quantity required to gel an oil are extremely high in relation to the volume of oil and it may take as long as 8 hours before the gel is strong enough to allow recovery. &# 61623; Bioremediation Chemicals.
These are biological agents. They are a combination of enzymes, natural organisms and nutrients which increase the rate of natural degradation of oil. This is a long term technique because it may take months and years to be effective. &# 61623; Burning Agents. Burning agents are substances that make it possible to ignite oil on the water or upon the shoreline. Getting oil on water to burn is often very difficult. Typical examples of burning agents are gasoline and light crude oils. &# 61623; Neutralizing Agents.
These are used to treat spilled oil and they work by reacting chemically with the oil to form less harmful substances. &# 61623; Sinking Agents. These are special materials applied to the oil which adsorb the oil to their surface. This combination of oil and the sinking agent is heavier than water and sinks. Oil boom is a floating barrier which is used in cleaning up oil on the surface of the water.
Boom is used: to contain oil (containment booming); to collect oil; as a barricade to exclude oil (exclusion booming) from a certain area; to absorb oil; and to deflect oil (diversion booming). Containment booming is the process of preventing the spread of an oil spill by confining the oil to the area in which it has been discharged. The purpose of containment is not only to localize the spill and thus minimize pollution but to assist in the removal of the oil by trying to concentrate it in thick layers on the surface of the water. Boom can also be used to divert pollutant to areas where cleanup can be conducted and to protect specific areas such as entrances to harbors and rivers or environmentally or economically sensitive areas. B. BOOM CHARACTERISTICS AND NOMENCLATURE Although boom can be classified several different ways, most types of boom share many of the characteristics shown in the drawing above.
The drawing shows an "end on" look at a section of boom. The boom consists of a fabric "fence" made of a flexible material. A tension member (such as a piece of cable) of greater strength than the fabric prevents the fabric from tearing under stress. Some sort of ballast such as chain or weights is attached to the bottom of the fabric to keep the boom vertical in the water. Flotation material keeps the boom afloat.
There are several different designs and methods of flotation. Floats may be rigid or flexible. Inflatable air chambers may be used to provide flotation. Freeboard is the vertical height of a boom above the water line. The freeboard prevents oil from washing over the top of the boom. If there is too much freeboard, however the boom may be pushed over in high winds.
The part of the fabric below the floats is called the skirt. The skirt prevents oil from being swept underneath the boom. End connectors are used to connect sections of boom together. Since there are many different types of boo...
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Research essay sample on Surface Of The Water Spilled Oil
