Post-production water is the fluid that rises back up to the surface during the fracking process. It is expensive to clean and transport and is considered an environmental threat. Recently, the University of Texas at San Antonio and the Southwest Research Institute have claimed to revolutionize the cleaning process by lowering its price. The team used a plant matter called biochar to remove the toxic chemicals from the frack fluid. Biochar is made out of wood chips, paper, leaves and soybean or corn oil. It absorbs hydrocarbons, organics, biocides and some inorganic metal ions.
Flowback water is usually pumped down a water disposal well or cleaned in an expensive facility for the water to be reused. Post-production water is extremely toxic and usually radioactive.