Reducing The Water Intensity Of Hydraulic Fracturing: A Review Of Treatment Technologies

A novel thermal treatment technology is presented that can separate multitudes of dissolved solids, volatile contaminants, and azeotropes from wastewater, and may be able to fill a gap that currently exists in hydraulic fracturing wastewater treatment technologies. The vast majority of wastewater treatment methods are tuned to extract only certain contaminants; however, it can be difficult to predict the composition of hydraulic fracturing wastewater. This introduces a major technical challenge to design a treatment system that is largely composition agnostic. The novel technology presented in this paper uses humidification-dehumidification in nozzle-demister assembly to separate clean water from dissolved solids, suspended solids, and various volatile compounds. Several review papers already exist that discuss the difficulties and options around the treatment of hydraulic fracturing wastewater. These tend to focus on variations of existing desalination technologies which are adopted for hydraulic fracturing wastewater treatment. These reviews are also devoid of discussion of azeotrope removal from wastewater. This paper, in addition to discussing the difficulties and existing treatments for hydraulic fracturing wastewater, analyzes the treatment options for the separation of volatile contaminants and azeotropes, and illustrates the advantages of a thermal-based treatment. Treating hydraulic fracturing wastewater is different from treating seawater or other types of wastewater due to the higher concentration and variety of contaminants. The unique challenges as well as the necessity of treating hydraulic fracturing wastewater are explained. The relative merits of several existing treatment technologies are discussed. The existing literature on the topic lacks discussion of azeotropes in hydraulic fracturing wastewater as well as which technologies can be used to remove them. This paper addresses all of the above with particular focus on separation of contaminants and water-based azeotropes.