VERTIMAR-2005
Symposium on Marine Accidental Oil Spills

Biodegradation of the fuel oil from the Prestige oil tanker by the action of PUTIDOIL

José Ramón BERGUEIRO LÓPEZ1, Amalia SANTOS OLIVER2 and Sara GUIJARRO GONZÁLEZ3

1 Universitat de les Illes Balears -

2 Universitat de les Illes Balears -

3 Universitat de les Illes Balears -

ABSTRACT The objective of this work is the study of the degradation of fuel oil’s waste products from the PRESTIGE oil tanker by degrading microorganisms whose commercial name is PUTIDOIL, in the presence of the biodegradation catalyst called S200 and a zeolite under the following conditions: fuel and synthetic sea water inside a reactor with a thermostat, shook by an helix, and fuel inside reactors with magnetic shaking. The highest degradation percentages were obtained after two months by the reactor with a thermostat and shook in the presence of PUTIDOIL, the biodegradation catalyst S200 and the zeolite, obtaining a degradation percentage higher than 80%.

1. INTRODUCTION

When the viscosity of an oil spill, which reaches the coast, is quite high, like in the case of PRESTIGE oil tanker, the first measure to be taken should be the mechanical cleaning of the coast. However, waste hydrocarbons are always left in the coastal environment. Degradation of these waste products could take place by natural reactions; however their elimination time could be too long. For shorting this elimination time, specific bacteria are added to this environment acting on the degradation of this kind of hydrocarbon mixtures; biodegradation catalysts are also added.

Samples from different beaches (from A Coruña to Muxía) were taken to study the Prestige’s fuel oil biodegradation. First experiments were guided to the determination of the fuel’s composition obtaining next results: asphaltenes 25,89%, saturated hydrocarbons 26,36%, aromatics hydrocarbons 31,05% and resins 16,49%.

The study of biodegradation was done following two types of processes:

1.  Fuel oil’s biodegradation, partially emulsified in synthetic sea water, inside a tank shook reactor with a thermostat.

2.  Dispersed fuel oil’s biodegradation into small reactors with a shaker, in the presence of sea sand or a zeolite.

The studies were developed in two experimental series, presence and absence of the catalyst S200. Results were always related to a blank.

Degrading microorganisms’ mixture was activated by a freeze-dried sample by precipitation in sea water, which was perfectly shook and with air during six hours. For maintaining a high number of microorganisms, adding to the reactors activated PUTIDOIL every fortnight was necessary.

Once degradation period ended, the quantity of remanent hydrocarbons dispersed in water, those which were settled on the shaker helix, those which were settled on the reactor walls and the thermocouple which measured the temperature were determined. The different samples were treated with tetrachloroethylene until the total extraction of all the hydrocarbons. Then, samples were dried with sodium sulphate anhydrous, filtered and then the solvent was eliminated by evaporation at low temperature.

2. RESULTS AND DISCUSSION

The reactors with a magnetic shaker, the levels of degradation reached after two months were in the order of 60% when the degradation took part with sand beach. In the same type of reactors with zeolite, during the same period of time, fuel’s biodegradation reached the order of 80%. These experiments pretend the simulation when fuel is settled over sand beach in the breaker area.

As it was expected, the highest percentages of fuel biodegradation were obtained in the reactors with shaking by helix (Figure 1) arriving to a degradation of the 80% after two months. This high degradation is due to the breaking of the fuel mass by the helix of the shaker in small drops which stay dispersed in sea water. The consequence is the considerable increasing of the transfer area.

Figure 1. Reactor with a thermostat shook by a helix.

REFERENCES

Bergueiro López., J. R. y Moreno García-Luengo, S. (2002). Limpieza y Restauración de Costas Contaminadas por Hidrocarburos. Procedimiento Operacional. Área de Ingeniería Química. Facultad de Ciencias. Universitat de les Illes Balears. Palma de Mallorca (España). ISBN: 699-8769-0. Depósito legal: PM 1203-2002.

Bergueiro López, J. R. y Domínguez Laseca, F. (2001). La Gestión de los Derrames de Hidrocarburos en el Mar. Área de Ingeniería Química. Facultad de Ciencias. Universitat de les Illes Balears. Palma de Mallorca (España). ISBN: 84-699-60571. Depósito legal: PM 1894-2001.

Acknowledgement

Authors are grateful to Ministerio de Educación y Ciencia for the project’s concession VEM2003-20565/INTER, “Caracterización de la microbiota autóctona degradadora del fuel oil del Prestige y de su potencial de biorremediación”.