'Burning ice' could make fracking wastewater drinkable

Wastewater that is created through the process of hydraulic fracturing (fracking) could soon be reused as drinking water, according to scientists. Researchers have been working on a way to use a form of 'the ice that burns' in order to purify wastewater from gas and oil production. This water could then be used for irrigation purposes or be suitable for drinking.

Salty wastewater is a byproduct of fracking for natural gas and extracting oil. Both processes use large amounts of water to yield very small results - for every one barrel of oil, around ten barrels of wastewater are created. In order to be suitable to release into the environment, this water must undergo several types of chemical purification, which is expensive and time consuming. After this, the water is still not suitable for human consumption.

A study, published in the journal 'ACS Sustainable Chemistry and Engineering', reveals that the use of a 'burning ice' can remove up to 90 per cent of the salt from the wastewater, making it safe to drink. This discovery could help people that live in areas with restricted access to clean drinking water.

The new process was developed following on from a technique that has shown promise in this field, gas hydrate desalination. Gas hydrates are formed of a single gas, like methane, and water. Forming the hydrate means that all impurities, such as salt, are left behind as a byproduct.

As the hydrate is broken down, the gas is released and pure water is left behind. In order to create the hydrate in the first place, the water must be incredibly cold. The water needs to be chilled to around 28 degrees Fahrenheit, which is an incredibly costly process.

In order to create a cheaper process the researchers looked into using methane hydrates, which are ice chunks that are collected from miles below sea. This ice bursts into flames once it reaches the surface of the water.

Researching this 'ice that burns' led to the creation of hydrates formed from carbon dioxide and water, with the gases cyclohexane and cyclopentane. This new hydrate proved to be a much more effective and low energy technique. Instead of removing only 70 per cent of the salt from the wastewater, as the original gas hydrate process does, up to 90 per cent of the salt was removed. The process is also achievable at near-room temperature, reducing cost by not needing as much chilling.