Shale gas has become a new sweet spot of the global oil and gas exploration, and a large amount of flowback water produced during shale gas extraction is causing more and more attention. Internal recycling of flowback water for future hydraulic fracturing is currently the most effective method, and it is necessary to decrease the contents of divalent cations for eliminating scaling and maintaining effectiveness of friction reducer. Zeolite has been widely used as sorbents to remove cations from wastewater, this work was carried out to investigate effects of zeolite type, zeolite form, activation chemical, activation condition, and sorption condition on removals of Ca2+ and Mg2+ from shale gas flowback water. Results showed that low removals of Ca2+ and Mg2+ were found for raw zeolite 4A and zeolite 13X, and the efficiency of the mixture of both zeolites was slightly higher. Compared with the raw zeolites, the zeolites after activation using NaOH and NaCl greatly improved the sorption performance, and there was no significant difference between dynamic activation and static activation. Dynamic sorption outperformed static sorption, the difference exceeding 40% and 7%–70% for removals of Ca2+ and Mg2+, respectively. Moreover, powdered zeolites outperformed granulated zeolites in divalent cation removals.
- activated zeolite
- shale gas flowback water
- First received 21 November 2016.
- Accepted in revised form 10 April 2017.
- © IWA Publishing 2017