OPERATIONAL USE OF A MOBILE SAND-WASHING PLANT FOR CLEANING PEBBLES: THE AMAZZONE OIL SPILL

ABSTRACT On January 31, 1988, the Amazzone spilled about 1,500 tons of a highly paraffinic medium fuel oil (having a pour point of 36°C) along a distance of 300 km off the coast of Brittany. Due to very rough sea conditions, no offshore recovery operation could be carried out. Most of the pollution was beached as scattered patches on numerous sites, including pebble beaches in south Finistère, which had been especially difficult to clean during previous spills. In this area, the pebble banks that protect the dunes are relatively exposed to erosion. It was therefore decided to try cleaning these pebbles on site using the mobile plant that was designed for washing polluted sands and tested in 1985. The plant prototype was put in working order and conveyed to the site on the Baie d'Audierne. The equipment was very easily adapted to washing the pebbles polluted by a mixture of sand and fuel oil emulsion. A total of 1,400 m3 was cleaned during 10 days at the end of March. The plant worked smoothly with a load of 20 to 25 m3 of pebbles per hour and using a petroleum solvent as a washing agent. Because the ambient temperature was rather low (around 5°C), cleaning was performed with warmed water. Compared to other techniques that could be used to clean polluted pebble beaches, the washing plant proved very effective (providing good cleaning and high throughput) and competitive (costing less than quicklime treatment, for instance). Another advantage of this technique is that cleaned pebbles are returned to the beach, helping the pebble bank to keep its anti-erosion function.

Water-Contact-Angle Studies of Fabrics Radiation-Grafted with Methylhydrogensiloxane

The water-contact angles of the polymethylhydrogensiloxane (silicone)-grafted fabrics (wool, cotton, Vinylon, rayon, acetate, Tetoron, nylon, and silk) prepared by irradiation were measured and the results support the following conclusions: 1. For the same degree of grafting, the relation between the water-contact angles and the roughness factors (defined as the number of yarn crossover points per-unit-area) of various fabrics is linear. It is concluded that the surfaces of grafted fabrics are in the same state regardless of kinds of fabrics. 2. On fabrics of the same roughness the water-contact angles of grafted samples are greater by about 10° than those of the silicone-coated samples, which are padded with silicone, not irradiated, and heated. This fact can be explained by the hypothesis that the upheavals on the surface of a fabric are increased by radiation grafting. 3. By repeated washing with petroleum solvent, the water-contact angles of grafted fabrics decrease a few degrees after one washing and then do not change further even after repeated washing. This result suggests that the grafted silicone is “set” into a conformation which is not appreciably altered in spite of repeated solvent washing.

Transparency of Rubber and Its Solutions

When rubber is dissolved in benzene or a mixture of coal-tar hydrocarbons, a clear bright solution is usually obtained. On the other hand, when dissolved in a petroleum solvent, the solution is opalescent. In the latter case it is necessary to postulate the presence of small particles having a different refractive index from that of the solvent. As rubber gives a substantially clear solution in benzene, it follows that the foreign particles are invisible and must, therefore, possess the same refractive index as this solvent or one very close to it.

Calcium and Hydrogen ion Concentration and the Interfacial Tension of Pyrethrum Extracts (With Four Text-figures.)

1. The addition of a pyrethrum extract to a petroleum solvent, semirefined white spirit, considerably lowers its interfacial tension against water. The tension also depends upon the reaction of the aqueous phase, decreasing as the alkalinity increases.2. The addition of agral W.B. to a solution of pyrethrum extract further lowers the interfacial tension more especially against acid solutions, thereby decreasing the sensitivity of the tension value to the pH of the aqueous phase.3. The presence of calcium salts in the aqueous phase raises the interfacial tension of solutions of pyrethrum extract.4. Alkaline salts counteract the effect of calcium salts, and the resulting tension values can be correlated with the ratio of calcium to hydroxyl ion concentration.