As long as fracking is utilized in the drilling of oil and gas, water disposal will continue to be a consideration. According to the Groundwater Protection Council (GWPC), each fracking well uses about 45 million liters. As such, the industry generates enormous quantities of produced water–an estimated 3,400 billion liters!
The produced water that returns to the surface is very different from the water used to extract the desired products. Produced water usually contains large quantities of salts, naturally occurring radioactive materials, bacteria, and added chemicals among other solutes.
Due to the number of solvents in produced water, disposal and treatment can be costly. Currently, the most popular method of disposal of massive volumes of fracking wastes is underground injection. During underground injection, water is transported into deep underground wells. Despite the method’s efficacy, new regulations restrict the creation of additional wells and the current wells are quickly approaching capacity.
Some organizations, such as the U.S. Department of Energy (DOE) are exploring the feasibility of turning produced water from a waste into a resource. The DOE is sponsoring research and development projects, which aim to reduce the cost of produced water treatment and reuse.
If treatment becomes cost-effective, produced water can be reused for power generation, fire control, non-potable crop irrigation, and washing equipment and machinery. Chlorine dioxide treatment has shown extreme promise in oil and gas treatment over the last few years, boasting a number of benefits over traditional chemical solutions.
High concentrations of sulfide (a byproduct of bacteria) and iron sulfide (an added stabilizer) are also typically present in produced water. Many chlorine dioxide alternatives are amines, which may absorb (rather than “destroy”) sulfide. Because amines may re-release sulfide under the right conditions, they present a significant hazard for use in the treatment of produced water. Under the appropriate pH and concentration of chlorine dioxide, sulfides odixidize (or “transform”) into harmless molecules.
Chlorine dioxide is highly advantageous compared with alternative biocides that may be present in produced water. Chlorine dioxide is one of the most effective compounds in the prevention of microbial growth and can easily penetrates biomass and biofilms that may form within pipes, transport vehicles, gathering tanks/pits, and other methods of produced water storage and handling. And because it doesn’t react with the hydrocarbons within water, lower concentrations are required to eliminate microorganisms compared with other biocides.
During storage and transport, produced water is often under ideal conditions for the formation of emulsions that are costly to clean. Iron sulfide, an added stabilizer, results in costly disposal of byproducts and often further exacerbates formation of microbial growths.
Chlorine dioxide tackles both challenges with one chemical solution: it kills the bacteria and reacts with iron sulfide to form harmless byproducts that are easier and cheaper to dispose of. Additionally, routine treatment is effective at preventing future growth.
Easy to Monitor
Measuring efficacy of chlorine dioxide is also easier than other biocides. Because chlorine dioxide oxidizes (or “transforms”) cellular components and byproducts of bacteria, the “effective dose” is easily identified. Presence of residual chlorine dioxide following a reaction indicates successful bacterial disinfection.
Chlorine dioxide is uniquely positioned to resolve key challenges in oil and gas treatment. Because of its unique chemistry, chlorine dioxide can become an ideal chemical solution, particularly in the disposal of produced water.
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