Page 5 - Opportunities in the Treatment of Water and Other Wast Streams

Barium and strontium exist naturally in subsurface geology. Dissolution and weathering of these minerals may result in their presence in groundwater. These compounds are of particular concern as they form sparingly soluble salts that precipitate in certain treatment processes and cause decreased efficiency or damage. These constituents occur at much higher concentrations in produced water than in groundwater resources.
Boron and Bromide
Both boron and bromide are present in seawater and may occur in flowback and produced water. Both these compounds are mentioned as they may be difficult to remove or detrimental to downstream users. Boron may not be readily removed in reverse osmosis, for instance, without raising the pH or adding ion-exchange treatment to polish the reverse osmosis permeate. Bromate is not always measured, and trace amounts may cause formation of disinfection byproducts when combined with ozone as a disinfectant.
Trace Metals
Mineral dissolution leads to the presence of various trace metals in flowback and produced water. Certain constituents, such as arsenic and chromium are detrimental to certain end uses. Care should be taken, as these constituents may be harmful—even at trace levels. Trace metals are not commonly measured in produced water, so subsequent analyses may be necessary to identify occurrence and concentration.
Radionuclides
Radionuclides occur naturally in subsurface formation and generally depend on subsurface geology. Therefore, certain areas nationally are predisposed to high concentrations of radioactive compounds. Care must be taken in areas with high concentrations as process equipment and solids bound for landfills may accumulate radioactive material, making them hazardous.
Well Additives and Fracturing Chemicals
Chemicals are added during well development and well production to maintain well operations or to improve fracturing conditions. A wide range of chemicals can reduce scaling, improve crosslinking, or act as biocides to removal microbial growth. Chemical disclosure is generally an industry practice, and databases with chemical registries may be used to identify compounds used by the industry.
Summary of Treatment Technologies
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