Allied Energy Transmix Processor
With BP having recalled 2.1 million gallons of bad regular gasoline in Chicagoland and NW Indiana and 20,000 gallons of premium gasoline limited to the Milwaukee, WI market, many have asked what happens to the tainted fuel?

It depends on what exactly contaminated the gasoline or fuel. BP has said it is due to a "higher than normal level of polymeric residue." No matter what contaminated the gasoline, there are multiple options and names for the processes to reclaim and re-use the gasoline. If water entered the gasoline, a separator is first used, separating the fuel from water. Sometimes the contaminated fuel is considered "transmix".

It's a really cool process that already exists. After crude oil is refined, it is turned into many usable products, such as diesel, kerosene, gasoline, heating oil, etc. These products are many times shipped in pipelines together. See the image for more information. Some products can mix with comparable products, which is normal. Some products, like heavier fuels and lighter fuels (think diesel and gasoline), can't mix. On occasion, pipelines use a device called a "pig" to separate the fuels that don't mix. Most of the time no pig is used, and part of the batch being shipped will mix. Any mix between incompatible fuel types is called "transmix". Transmix is not just discarded, but sent back to a reprocessing plant to be refined and re-certified for use so there is no waste.
Colonial Pipeline Diagram

Transmix is received by either pipeline or tanker truck and is offloaded through a filter and into a storage tank. Product is then pumped from the tank through another filter and into a heater. The heater powered with natural gas and the unit raises the product temperature nearly 500F, creating steam which is separated in a distillation column. The light fuel (gasoline) rises to the top and the heavy fuel (diesel) settles to the bottom of the column. A recycle stream is used to maintain temperature and quality in the column. The finished products are sampled and sent to an onsite lab for testing and certification. Once certified, the product is resold and is perfectly fine to use!

According to a timely response to our questions from Scott Dean, BP Spokesman, BP plans on having the gasoline re-processed. Many bigger terminals where gasoline is loaded have their own transmix processing areas, so in this case, BP may either sell the contaminated fuel to a re-processor, or it may have its own transmix processing facilities. That was a question we did not ask. However, once the contaminated fuel is processed as transmix, it will again meet specifications and will be safe to use in your engine, and like all gasoline sold at BP, it will have a quality guarantee. It sure is unfortunate what happened, but at least the contaminated gasoline won't be wasted, and I'm sure a lesson will be learned.