New study reveals gaps in the methods used to assess chemicals in oilfield wastewater

A new study led by researchers with Colorado School of Mines exposes limitations with the current methods used to detect chemicals in oilfield wastewater and offers solutions to help regulators make better decisions for managing this waste stream.

Oilfield wastewater is extremely salty and can contain multiple combinations of many potentially harmful chemicals (approximately 1600 on a national basis). However, most standard or approved analytical methods available to regulators were designed to work with fresh water. Because oil and gas wastewater is so salty—sometimes 10 times saltier than seawater or more—chemists often have to dilute wastewater samples to manage the high salt content.

This means they may also be diluting chemicals of concern to concentrations too low to detect, even though they may be present at risky levels. For example, benzene is a chemical associated with petroleum hydrocarbons and a known carcinogen. It also has a drinking water standard of 5 parts per billion – that’s 5 cents in 10 million dollars. It really doesn’t take much dilution of a sample to lose that level of precision.

More concerning is that more than 75% of the chemicals associated with unconventional oil and gas production don’t have standard analytical methods. So, not only are the available analytical tools frequently inappropriate for saltwater samples, there are no tests at all for most of the chemicals that could be there.

Why it matters

In the United States oil and gas production generates nearly 900 billion gallons of wastewater per year. That’s the same amount as 30% of the water that went over the Hoover Dam last year.

Aerial view of wastewater pit at a drilling site

Historically, most of this wastewater has been pumped into underground wells for permanent disposal. But concerns about this practice leading to earthquakes, coupled with heightened demands for water and a desire to cut costs, has companies looking at new ways to manage this massive waste stream, from crop irrigation to discharge into surface waters.

(Learn more: Scientists Question Risks of Using Oilfield Wastewater on Crops)

Before this wastewater is reused in ways that could affect our water or food supplies, the right tools are needed to identify, measure, and treat the chemicals it may contain. This is a basic requirement for making sound decisions about protecting our health and our environment.

Advancing science to improve policy

Before new technologies and analytical methods developed in research laboratories are standardized and used in a regulatory context, they must undergo a rigorous and time-consuming validation process to assure they are robust, accurate, and precise.

Getting the job done right requires having the right tools. For this review, researchers combed through scores of research methods, evaluated which techniques are appropriate for oil and gas wastewater, discussed challenges associated with current methods, and offer potential solutions for detecting chemicals. In other words, the study offers us a starting point for making better decisions about cleaning or reusing wastewater.

Today, there’s a lot that isn’t – and can’t – be known about what’s in this wastewater, and, as a result, it’s nearly impossible to conclude that it won’t threaten human health and our environment if it is released into our ecosytem.

Fortunately, this review represents an important step toward identifying potential approaches to understanding the chemistry of this complex waste, and could lead to better treatment and disposal practices that will ultimately help keep our soil and water clean.

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