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Limited, need treatment facility 5 ton; NYC; Europe Unlimited; with time for treatment

Limited; need treatment facility

None known

None known

Asbestos is minimum if distributed in solution to avoid accidental dust inhalation Possible silicosis

Dry sprinkle only

Dry sprinkle & agitate Spray in solution of water

Dry sprinkle only no existing equipment suitable for recovery. The most frequently applied absorbents are hay and straw, because they are inexpensive, widely available, and easy to apply with mulching equipment. However, their application to floating oil requires slow trash bucket and rake recovery since all of the mechanical, weir, and suction-type recovery devices are clogged by the straw or their recovery rate is drastically reduced. Their best use is for cleaning up oil on beaches or in tidal pools. Straw will absorb about five times its weight in oil.

Polyurethane foams have the largest oil sorption capacity. They can hold 30-80 times their own weight in oil. Urea formaldehyde foam is equally effective. Polyethylene fibers and shredded polystyrene foam are only about half as effective. However, a patented grafted expanded polystyrene is reportedly as effective as polyurethane. Of the natural products, wood cellulose fiber and shredded redwood fiber are one-third to one-fifth as efficient as polyurethane. Ground corncobs are about as effective as straw. Foams take more time to absorb higher viscosity oils. On the open sea, wind prevents efficient distribution of the expensive low density absorbents. The more expensive materials also require that squeezing out the oil and reprocessing be economical.

Herding Agents

A novel method of oil recovery involves magnetism to separate the oil from the water and to lift it. A ferrofluid, consisting of a stable colloidal dispersion of super paramag netic particles, is mixed with the oil. However, there is no apparent advantage over mechanical methods where surface tension wetting and fluid shear attachment are sufficient for both separation of oil from the water and recovery. The latter approach avoids all expense for both treatment agent and its application.

Another method is the use of a nontoxic, biodegradable surface active agent to surround an oil spill and to change significantly the water-air surface tension. The U.S. Naval Research Laboratory reported on the use of sorbi-tan esters of fatty acids and polyoxyethylene alkyl ethers as monomolecular surface films having 40 dyne per centimeter spreading pressure. Also, Shell Oil Co. commercially introduced a similar acting proprietary chemical called "Oil Herder." The recommended application rate is 20 gal/mi of spill perimeter.

Burning Agents

Because of the rapid loss of volatile substances from an oil spill, ignition and the support of combustion requires assistance. Despite the cost implication and other problems, burning is attractive because it provides rapid disposal of a large quantity of oil with a minimum of material handling. Most burning agents are nontoxic or inert. The major problem is distributing the agent and the need for a better ignition technique. Among several agents evaluated by the EPA are straw, cellular glass beads and silane-treated fumed silica. All of the agents appeared capable of supporting combustion, even in extremely cold waters, by acting as a wicking agent. Based on very limited testing, the beads gave the best performance, followed by straw, and finally the fumed silica. Wind creates a severe problem in applying the agents, including the silica, which was mixed with water. Wind and waves also break up uncon-tained pools and cut off continued combustion. Both the beads and the fumed silica, when not used in combustion, appear recoverable by normal mechanical recovery systems. The straw presents a special problem.

phosphate. Industrial waste systems normally consume 20 lb of nitrogen and 40 lb phosphorus with this much oxygen, whereas the sea normally has less than half this amount available. Experiments by the Department of Oceanography, Florida State University, showed that selected microbial cultures can accelerate the removal of paraffinic crudes at a rate twice that of evaporation. The rate almost doubled with a 10°C rise in temperature; surfactants were produced, hastening emulsification.

Biodegradation

There are many toxic products in oil, most of which are associated with the lighter volatile compounds. Many microorganisms can utilize hydrocarbons as an energy source to convert them into cell mass. On a pilot plant basis, an oil company has produced protein from residual paraffin base oil by bacterial fermentation. One source estimates that consumption rates will be limited eventually by the 2-lb oxygen demand to convert 1 lb of oil into cell mass. They further estimate that under moderate conditions there are about 25,000 lb of oxygen absorbed per sq mi of sea per day. Hence, normal oxygenation may limit oil consumption to 12,500 lb/sq mi/day.

There may have to be an addition of nitrogen and phosphorus in the form of ammonium nitrate and potassium

References

Audubon. 1971. Oil pollution. Vol. 73:3 (May). p. 101. Bruch, B., and K.R. Maxwell. 1971. Lockheed oil spill recovery device. Joint Conference on Prevention and Control of Oil Spills. Washington, D.C. (June 15-17). Hoult, D.P., R.H. Cross, J.H. Milgram, E.G. Pollak, and H.J. Reynolds. 1970. Concept development of a prototype lightweight oil containment system. U.S. Coast Guard Rpt. No. 714102/A/003. (June). Jones, W.T. 1970. Air barriers as oil spill containment devices. SPE 3050, 45th Annual Fall Meeting of the Society of Petroleum Engineers. Houston, Tex. (Oct. 4-7). White, P.T., and J.S. Blair. 1971. Bare-handed battle to cleanse the bay. National Geographic 139. (June). p. 877.

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