As Bill Nye, the Science Guy debunks a number of recommendations on how to respond to the oil spill, sent in by ordinary citizens on CNN, there are a few viable solutions rising to the top, even as the oil continues to rise from the depths. The biggest buzz is about the actor Kevin Costner, pulling a massive piece of equipment that he has been developing with his scientist brother Dan since 1995, out of his closet (See video). He calls it Ocean Therapy. They claim that it is 97% effective in extracting clean water.
There is no question that a centrifuge device can effectively separate two fluids that are commingled. Indeed, such devices are used every day to do just that. They work on the principle that if two fluids have a different density, the heavier fluid will naturally move under rotation to the outer portion of the device where it can be selectively removed.
A centrifuge can also be used to remove particles or sediment from a fluid using the same principle.
There are, however, a couple of conditions under which a centrifuge will not be effective.
First of all, if the two fluids have the same or very similar density they cannot be separated centrifugally. Since sea water has a density of roughly 1022 kg/cu.m. and crude oil is around 850 kg/cu.m., that shouldn’t be a problem in this case.
The second condition which could be problematic, is if one fluid in dissolved in the other. This resulting fluid is now a solution as opposed to a mixture. If you put grains of sand in water, they could be easily separated out, but if instead, you put in sugar and stirred until it dissolved; it would no longer be separable using strictly mechanical means.
This should not be a problem for removing the oil either. However, the chemical dispersant that BP is using, and has now been asked to stop using, is water soluble. So unfortunately, while the centrifuge might be quite effective in removing the oil, it is not likely to be successful in removing the chemical contaminants, nearly 700,000 gallons of which have been introduced in an effort to manage the spill.
I mentioned the work of Recovery I in an earlier post. They have developed and tested an absorbent material based on corn cobs. Not only are corn cobs inherently great absorbers (they will absorb 400% of their weight in water), but they float extremely well and they rotate in moving water, exposing their entire surface to the contaminant and have been shown to be effective in absorbing chemicals as well as oil. This makes it superior to hay or cotton or hair, which have also been suggested. Recovery I has commitments of at least 30,000 tons of material ready to be deployed. While additional testing will be needed to verify how effective the product will be with Corexit and under the specific conditions in the Gulf, the product deserves a chance. In fact, an official who tested the product for Environment Canada back in 1994, said, “it would be logical to assume that it would absorb the dispersant.” Yet, according to CEO Adria Brown, despite the fact, that this product has received significant press coverage and the company has contacted BP, Homeland Security, the Coast Guard, the EPA, and Deep Water Horizon Response the Director of Administration, Region 6, which includes Louisiana, Department of Homeland Security, in Denton Texas, NOAA, and the Army Corps of Engineers, they have received no response whatsoever to date. Iowa Senator Grassley, has also received paperwork and has offered assistance moving through the legislative process, but so far, no one has asked for more information or requested even a small batch of product to be tested.
RP Siegel is a Professional Engineer and the co-author of Vapor Trails a story about an oil spill and the system that caused it.