II. History of Bioremediation
1. ‘Courtship’ Period (Pre-1989)
2. ‘Honeymoon’ Period (1989-1991)
3. ‘Establishment’ Period (since 1992)
III. The Biological and Chemical Processes of Bioremediation
a. Biological Process
b. Degrading Species
c. Chemical Process
d. Need for Bioremediation
a. Seeding with Microbial Cultures
b. Environmental Modification
IV. Recent Applications of Bioremediation Techniques and their Effectiveness
1. Amoco Cadiz
2. Exxon Valdez
3. Mega Borg
4. Apex Barges
5. Arabian Gulf War
Bioremediation Methods for Oil Spills
Abstract. The increasing number of marine oil spills asks for effective solutions for the environment. Bioremediation techniques have become a major mechanism for removing oil residues on the affected shorelines. Among the different techniques to enhance natural biodegradation by indigenous microorganisms, seeding of new bacteria and fertilizing the indigenous populations have attracted the most interest. The application of nutrients as nitrogen and phosphorus in the form of fertilizers have shown to be most effective in accelerating the biodegradation process and at the same time to be environmentally safe.
Since the freighter Pallas caused the worst oil pollution of the tidel shallows in the North Sea last November, thousands of sea birds and probably numerous other species lost their lives in the polluted water. The responsible parties have not yet taken any measures to mitigate the damage, neither have they provided for the prevention of a similar catastrophe in the future. This is especially striking as the first devastating oil spill occurred no less than ten years ago, when the tanker Exxon Valdez ruptured in Prince William Sound. The number of oil tanker accidents is increasing with the amount of oil transported on the seas. In 1988, 1050 billion tons of crude oil has been ‘on the road’ (Frees, 1992). A way to mitigate the effects of oil spills is bioremediation.
Bioremediation is a process by which chemical substances are degraded by bacteria and other microorganisms. The use of these microorganisms has been successfully applied for the treatment of waste and wastewater in controlled systems. Several research studies have recently been performed to investigate the use of bioremediation for oil-spill cleanup in seawater, freshwater and terrestrial areas. The technique has been found to have a potential for broad applications in terrestrial and freshwater environments for treating soils and sediments contaminated with oil and other substances, as well as for coastal environments impacted by oil spills. Water is a more sensitive medium than soil and requires different remediation techniques. Spills to surface water are easier to clean up than spills to groundwater, for obvious reasons. It is not only much harder to see the extent of the contamination, but also to remove the source of the contamination as, for example, a leaking underground storage tank.
This paper will focus on the use of bioremediation for marine (surface water) oil spills. Part II will briefly describe the development of bioremediation techniques. Part III will explain the biological and chemical processes of bioremediation, while Part IV will have a look at a few recent applications of this technique after major oil spills and evaluate their effectiveness. Part V will draw a conclusion.
II. History of Bioremediation
Bioremediation is not a new concept. Microbiologists have studied the process since the 1940s. However, bioremediation became known to a broader public in the U.S. only in the late 1980s as a technology for cleanup of shorelines contaminated with spilled oil. The Exxon Valdez oil spill in 1989 in Prince William Sound, Alaska was the catalyst for...