Magazine

The water's fine

In response to some of the concerns raised in last issue’s ‘Fracking up the country’ feature, Lee Petts, Managing Director of Remsol, says wastewater from the hydraulic fracturing process would be safely treated in this country

Lee PettsThe shale gas debate (should we, shouldn’t we, can we?) has been raging in recent months and, many would say, has become increasingly polarised – you’re apparently either for it, or against it. What I find striking is just how many ‘arm chair experts’ the debate has spawned: people with no obvious connection to the oil and gas industry, or any of the sectors that support it, such as waste management, who are prepared to express opinions on it based largely on what they’re able to glean from the internet. As Albert Einstein once famously said: “Information is not knowledge.”

This is particularly true when it comes to the management of the wastewaters generated in the hydraulic fracturing process, something my company has been working on with shale gas explorer Cuadrilla Resources since the start of 2012. I’ve seen it said that the waste, which is predominantly water containing dissolved metals, salts, and very low concentrations of Naturally Occurring Radioactive Material (or NORM) will be ‘dumped’ into canals, injected into disposal wells, or simply ‘diluted and dispersed’ somewhere. None of these are true in Cuadrilla’s case.

Our early research led us to a former United Kingdom Atomic Energy Authority (UKAEA) site that has been successfully treating effluent containing very low levels of artificially produced radionuclides for over 40 years, using a very simple method.

A variation of this physico-chemical treatment is performed commercially at several merchant waste treatment facilities around the UK, where it is already used to treat and dispose of a wide variety of industrial liquid wastes, including wastes from the extractive industries.

Laboratory and plant-scale trials, using material stored by Cuadrilla for exactly this purpose, showed that it is possible to remove the already low concentrations of NORM with an efficacy of around 90 per cent. It works by first blending the waste with a mixture of iron-rich substances that act as a flocculant – causing the microscopic solids within the waste to coalesce and become heavier. Iron hydroxide, which is present in the mixture, is also known to absorb radium 226 (the predominant radionuclide in Cuadrilla’s wastewater and a metallic element). This stage of the process also reduces the pH of the waste.

The resultant mixture is then further reacted with calcium-rich lime (or a lime substitute) to form a slurry. This causes a number of things to happen: firstly, the pH of the solution is raised again, and secondly, the metals present in the mixture precipitate out of solution and become bound to the solids in the lime slurry (this technique is well documented as a method of removing metals from solution). But there’s more to it than this: radium 226 is chemically attracted to the calcium found in the lime.

After ageing, the slurry is dewatered using a filterpress or centrifuge, which in essence creates two residues: a solid filtercake that can be safely disposed of to properly engineered landfill sites that are permitted to accept non-hazardous waste; and an aqueous filtrate that can be discharged to sewers for further biological treatment prior to release back into the natural environment.

We are confident that this method of treatment – proven to be safe over many decades and conducted for us at a carefully selected range of treatment sites that are appropriately permitted to receive and handle the wastewaters in question – will provide an operationally sustainable means of dealing with Cuadrilla’s exploration wastewaters that people can trust.

Read more about Remsol.